From Astrobites : “The Origin of the Origin of the Universe”

From Astrobites

2.4.23
Katherine Lee

Title: Measurement of the Cosmic Microwave Background Spectrum by the COBE FIRAS Instrument

Authors: J. C. Mather, E. S. Cheng, D. A. Cottingham, R. E. Eplee Jr., D. J. Fixsen, T. Hewagama, R. B. Isaacman, K. A. Jensen, S. S. Meyer, P. D. Noerdlinger, S. M. Read, L. P. Rosen, R. A. Shafer, E. L. Wright, C. L. Bennett, N. W. Boggess, M. G. Hauser, T. Kelsall, S. H. Moseley Jr., R. F. Silverberg, G. F. Smoot, R. Weiss, and D. T. Wilkinson

First Author’s Institution: NASA Goddard Space Flight Center, Greenbelt, Maryland, USA

Status: published in ApJ [open access]

Back in the mid-20th century, there were two competing theories about the origin of the Universe. Scientists, including Edwin Hubble and Georges Lemaître, had already established that space was expanding.

______________________________________________________________________________
Edwin Hubble

Edwin Hubble looking through the 100-inch Hooker telescope at Mount Wilson in Southern California(US), 1929 discovers the Universe is Expanding. Credit: Margaret Bourke-White/Time & Life Pictures/Getty Images.

Mount Wilson Hooker 100in Telescope interior.

Mt Wilson 100 inch Hooker Telescope, perched atop the San Gabriel Mountains outside Los Angeles, CA, Altitude 1,742 m (5,715 ft).

Edwin Hubble Cepheid variable with Messier 31 at the 100 inch Hooker telescope on Mt Wilson, California.

Edwin Hubble at Caltech Palomar Samuel Oschin 48 inch Telescope Credit: Emilio Segre Visual Archives/AIP/SPL.

.

Caltech Palomar Samuel Oschin 48 inch Telescope, located in San Diego County, California, altitude 1712 m (5617 ft). Credit: Caltech.

______________________________________________________________________________

Some argued that if you run this expansion back in time, it implies a beginning when everything must have been compressed into a hot, dense singularity, exploding outward from that point in a “Big Bang”. Other astronomers, however, were uncomfortable with the idea that the Universe even had an origin at all. These scientists, most notably Fred Hoyle, argued instead for a cosmology in which the Universe had always existed and had always been expanding, with new galaxies springing up periodically to fill in the gaps. This picture of our Universe is referred to as the “Steady State Theory”.

These two theories predict fundamentally different things about the background temperature of the Universe. If matter in the Universe does not originate from a single point, as in the Steady State picture, then we would expect the background radiation to be chaotic in nature; there would be no reason for different unconnected regions of spacetime to look the same as each other.

However, if everything in the Universe comes from the same initial conditions, then everything should be roughly the same temperature. This can also be expressed as the idea that the Universe should be in thermodynamic equilibrium on large scales, and that if you measure the intensity of background radiation at all frequencies, you should see a blackbody spectrum—the characteristic spectrum of an object in equilibrium, dependent only on the object’s temperature. Thus, a key prediction of the Big Bang theory is that the temperature should be nearly constant over the entire sky, with the differences (called anisotropies) from this constant average temperature being extremely small—around one part in 100,000!

COBE comes to the rescue

Big Bang cosmologists in the 1960s believed that the peak of the Universe’s blackbody spectrum should be in the microwave frequency range, defined as between 300 MHz and 300 GHz. This would be expected from a massive explosion of energy at the Big Bang, the light from which would have been redshifted into the microwave range as it traveled through the expanding universe. So, if the Big Bang theory is true, we should expect to see a constant source of background radiation coming from all directions in the microwave sky: a so-called Cosmic Microwave Background, or CMB.

The detection of this CMB radiation in 1965 by Arno Penzias and Robert Woodrow Wilson, as well as the cosmological interpretation of that detection by Robert Dicke, Jim Peebles, Peter Roll, and David Wilkinson, laid the groundwork for modern cosmology, and was the beginning of the end for the idea that the Universe had no origin.

Arno Penzias and Robert Wilson, AT&T, Holmdel, NJ USA, with the Holmdel horn antenna, first caught the faint echo of the Big Bang.

However, Penzias and Wilson’s discovery was not an accurate measurement of the CMB’s temperature or spectrum. No anisotropies had been detected, and there was still debate over whether or not the CMB spectrum was truly a blackbody. The goal of the Cosmic Background Explorer (COBE) satellite, launched by NASA in 1989, was to answer these lingering questions.

COBE was split into three instruments: the Differential Microwave Radiometer (DMR), the Far-InfraRed Absolute Spectrophotometer (FIRAS), and the Diffuse Infrared Background Experiment (DIRBE). DMR measured the CMB anisotropies, while DIRBE mapped infrared radiation from foreground dust.

igure 1: A diagram of the FIRAS instrument, taken from Figure 1a of Mather et. al. (1999).

FIRAS, meanwhile, was designed to measure the CMB spectrum. It scanned the entire sky multiple times in order to minimize errors, and measured the temperature over a wide range of frequencies between 30 and FIRAS, meanwhile, was designed to measure the CMB spectrum. It scanned the entire sky multiple times in order to minimize errors and measured the temperature over a wide range of frequencies between 30 and nearly 3000 GHz. After eliminating known sources of interference such as cosmic rays, as well as subtracting the effects of light from the Milky Way galaxy and of the Doppler shift caused by the movement of the Earth through space, these scans were then averaged together to create direct measurements of the CMB intensity at various frequencies.

Figure 2: The cosmic microwave background spectrum, as measured by FIRAS. It shows a near-perfect blackbody, with any deviations from total thermodynamic equilibrium being much too small to see. This plot is taken from Figure 4 of Fixsen et al. (1996), which notes that “uncertainties are a small fraction of the line thickness.”line thickness.”

The authors found that the background radiation in our universe is in fact extremely close to being a perfect bThe authors of today’s paper found that the background radiation in our Universe is in fact extremely close to being a perfect blackbody! The final temperature found by FIRAS was reported by Mather et al. (1999) to be 2.725 K, with an uncertainty of just 0.002 K! This is an incredibly high-precision measurement and represents the final nail in the coffin for cosmologies other than the Big Bang. John C. Mather received the Nobel Prize in 2006 for his work as FIRAS’s project lead.

Figure 3: A comparison of the abilities of the COBE [above], WMAP, and Planck satellites to resolve tiny fluctuations in the CMB temperature, called anisotropies. Image: NASA/JPL-Caltech/ESA (Wikimedia Commons)

National Aeronautics Space AgencyCosmic Background Explorer COBE 1989 to 1993.

COBE image of the CMB, the earliest image of the CMB

NASA/Wilkinson Microwave Anisotropy Probe (WMAP) 2001 to 2010 annotated.

Cosmic Microwave Background NASA/WMAP

The European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganization](EU) Planck microwave telescope 2009 to 2013.

CMB per European Space Agency(EU) Planck.

Today, cosmologists use the CMB and its anisotropies to characterize the early history of the universe, find galaxy clusters in the later universe, and even look for new physics! The COBE measurements represented the dawn of a new era in cosmology, and laid the groundwork for modern CMB measurements. The science we do toToday, cosmologists use the CMB and its anisotropies to characterize the early history of the Universe, find galaxy clusters in the later Universe, and even look for new physics! Later full-sky measurements taken by the Wilkinson Microwave Anisotropy Probe (WMAP) and the Planck satellite added never-before-seen levels of precision to our ability to study the structure and content of the Universe, and future missions like LiteBIRD will continue to improve our ability to study the CMB even more closely, building on COBE’s groundbreaking data. These experiments still rely upon the CMB temperature established by FIRAS, which remains the definitive result even 23 years after its publication.

___________________________________________________________________
Inflation

In physical cosmology, cosmic inflation, cosmological inflation is a theory of exponential expansion of space in the early universe. The inflationary epoch lasted from 10^−36 seconds after the conjectured Big Bang singularity to some time between 10^−33 and 10^−32 seconds after the singularity. Following the inflationary period, the universe continued to expand, but at a slower rate. The acceleration of this expansion due to dark energy began after the universe was already over 7.7 billion years old (5.4 billion years ago).

Inflation theory was developed in the late 1970s and early 80s, with notable contributions by several theoretical physicists, including Alexei Starobinsky at Landau Institute for Theoretical Physics, Alan Guth at Cornell University, and Andrei Linde at Lebedev Physical Institute. Alexei Starobinsky, Alan Guth, and Andrei Linde won the 2014 Kavli Prize “for pioneering the theory of cosmic inflation.” It was developed further in the early 1980s. It explains the origin of the large-scale structure of the cosmos. Quantum fluctuations in the microscopic inflationary region, magnified to cosmic size, become the seeds for the growth of structure in the Universe. Many physicists also believe that inflation explains why the universe appears to be the same in all directions (isotropic), why the cosmic microwave background radiation is distributed evenly, why the universe is flat, and why no magnetic monopoles have been observed.

The detailed particle physics mechanism responsible for inflation is unknown. The basic inflationary paradigm is accepted by most physicists, as a number of inflation model predictions have been confirmed by observation; however, a substantial minority of scientists dissent from this position. The hypothetical field thought to be responsible for inflation is called the inflaton.

In 2002 three of the original architects of the theory were recognized for their major contributions; physicists Alan Guth of M.I.T., Andrei Linde of Stanford, and Paul Steinhardt of Princeton shared the prestigious Dirac Prize “for development of the concept of inflation in cosmology”. In 2012 Guth and Linde were awarded the Breakthrough Prize in Fundamental Physics for their invention and development of inflationary cosmology.

Alan Guth, from M.I.T., who first proposed Cosmic Inflation.

Lambda Cold Dark Matter Expansion ΛCDM of the Universe. Credit Alex Mittelmann Coldcreation.

Alan Guth’s notes:
Alan Guth’s original notes on inflation.
___________________________________________________________________

Nobel Prize in Physics for 2011 Expansion of the Universe

Saul Perlmutter (center) [The Supernova Cosmology Project] shared the 2006 Shaw Prize in Astronomy, the 2011 Nobel Prize in Physics, and the 2015 Breakthrough Prize in Fundamental Physics with Brian P. Schmidt (right) and Adam Riess (left) [The High-z Supernova Search Team] for providing evidence that the expansion of the universe is accelerating.

4 October 2011

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2011

with one half to

Saul Perlmutter
The Supernova Cosmology Project
The DOE’s Lawrence Berkeley National Laboratory and The University of California-Berkeley,

and the other half jointly to

Brian P. SchmidtThe High-z Supernova Search Team, The Australian National University, Weston Creek, Australia.

and

Adam G. Riess

The High-z Supernova Search Team,The Johns Hopkins University and The Space Telescope Science Institute, Baltimore, MD.

Written in the stars

“Some say the world will end in fire, some say in ice…” *

What will be the final destiny of the Universe? Probably it will end in ice, if we are to believe this year’s Nobel Laureates in Physics. They have studied several dozen exploding stars, called supernovae, and discovered that the Universe is expanding at an ever-accelerating rate. The discovery came as a complete surprise even to the Laureates themselves.

In 1998, cosmology was shaken at its foundations as two research teams presented their findings. Headed by Saul Perlmutter, one of the teams had set to work in 1988. Brian Schmidt headed another team, launched at the end of 1994, where Adam Riess was to play a crucial role.

The research teams raced to map the Universe by locating the most distant supernovae. More sophisticated telescopes on the ground and in space, as well as more powerful computers and new digital imaging sensors (CCD, Nobel Prize in Physics in 2009), opened the possibility in the 1990s to add more pieces to the cosmological puzzle.

The teams used a particular kind of supernova, called Type 1a supernova. It is an explosion of an old compact star that is as heavy as the Sun but as small as the Earth. A single such supernova can emit as much light as a whole galaxy. All in all, the two research teams found over 50 distant supernovae whose light was weaker than expected – this was a sign that the expansion of the Universe was accelerating. The potential pitfalls had been numerous, and the scientists found reassurance in the fact that both groups had reached the same astonishing conclusion.

For almost a century, the Universe has been known to be expanding as a consequence of the Big Bang about 14 billion years ago. However, the discovery that this expansion is accelerating is astounding. If the expansion will continue to speed up the Universe will end in ice.

The acceleration is thought to be driven by dark energy, but what that dark energy is remains an enigma – perhaps the greatest in physics today. What is known is that dark energy constitutes about three quarters of the Universe. Therefore the findings of the 2011 Nobel Laureates in Physics have helped to unveil a Universe that to a large extent is unknown to science. And everything is possible again.

*Robert Frost, Fire and Ice, 1920
______________________________________________________________________________

See the full article here .

Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

What do we do?

Astrobites is a daily astrophysical literature journal written by graduate students in astronomy. Our goal is to present one interesting paper per day in a brief format that is accessible to undergraduate students in the physical sciences who are interested in active research.
Why read Astrobites?

Reading a technical paper from an unfamiliar subfield is intimidating. It may not be obvious how the techniques used by the researchers really work or what role the new research plays in answering the bigger questions motivating that field, not to mention the obscure jargon! For most people, it takes years for scientific papers to become meaningful.

Our goal is to solve this problem, one paper at a time. In 5 minutes a day reading Astrobites, you should not only learn about one interesting piece of current work, but also get a peek at the broader picture of research in a new area of astronomy.

From Ethan Siegel: “This Is What The Milky Way’s Magnetic Field Looks Like”

From Ethan Siegel
Sep 30 . 2019

The dust in the Milky Way, shown in darker and redder colors, are regions where new star formation is taking place. These dusty regions are correlated with the magnetic fields present in our galaxy, and the background light gets polarized in a measurable way as a result. (ESA/PLANCK COLLABORATION. ACKNOWLEDGMENT: M.-A. MIVILLE-DESCHÊNES, CNRS — INSTITUT D’ASTROPHYSIQUE SPATIALE, UNIVERSITÉ PARIS-XI, ORSAY, FRANCE)

ESA/Planck 2009 to 2013

If you thought the Planck satellite just made temperature maps of the cosmic microwave background, this will astound you.

The Milky Way, to human eyes, appears as simply a mix of stars and light-blocking dust.

A map of star density in the Milky Way and surrounding sky, clearly showing the Milky Way, the Large and Small Magellanic Clouds (our two largest satellite galaxies), and if you look more closely, NGC 104 to the left of the SMC, NGC 6205 slightly above and to the left of the galactic core, and NGC 7078 slightly below. In visible light, only starlight and the presence of light-blocking dust is revealed, but other wavelengths have the capacity to reveal fascinating and informative structures far beyond what the optical part of the spectrum can. (ESA/GAIA)

ESA/GAIA satellite

However, a glimpse in additional wavelengths reveals enormously rich, detailed structures.

This ultra-detailed view of the Milky Way spans many different wavelengths of light, and as such it can reveal gas, charged particles, many types of dust, and many other signals that appear in the microwave and millimeter wavelength ranges. The Planck satellite provides us with our best all-sky view of the cosmos in this wavelength range. (ESA/NASA/JPL-CALTECH)

NASA/ESA Hubble Telescope

Observations show galactic foreground signals combined with cosmic signals originating way back from the Big Bang.

The Planck satellite constructed all-sky maps of the sky in nine different wavelengths of light, at frequencies spanning from 30 GHz all the way up to 857 GHz: frequencies that can only be observed from space. Although the foreground features in the Milky Way are quite prominent, the main science goal of Planck was to analyze the background light: the cosmic microwave background. (ESA AND THE PLANCK COLLABORATION)

Leveraging observations across many different wavelengths, Planck scientists identified the cause and source of many galactic foregrounds.

The signal of the Milky Way galaxy as revealed by the Planck satellite during its first year of data-taking observations. Planck is now 10 years old, and understanding which components of the Planck signal are galactic versus extragalactic is of paramount importance to extracting correct information about our Universe. (ESA/ LFI & HFI CONSORTIA)

The Milky Way’s gas, dust, stars and more create fascinating, measurable structures.

The fluctuations in the Cosmic Microwave Background, as seen by Planck. There is no evidence for any repeating structures, and although there is some uncertainty in how accurate and comprehensive our foreground subtraction is, the success of the Planck data in matching and superseding other CMB observations like COBE, Boomerang, WMAP, AFI and others tells us that if we’re not on the perfectly correct track, we’re extremely close. (ESA AND THE PLANCK COLLABORATION)

Cosmic Microwave Background NASA/WMAP

NASA/WMAP 2001 to 2010

COBE/CMB

NASA/ Cosmic Background Explorer COBE 1989 to 1993.

Subtracting out all the foregrounds yields the cosmic background signal, which possesses tiny temperature imperfections.

This map is of the galactic magnetic foreground of the Milky Way. The contour lines show the direction of the magnetic field projected on the plane of the sky, while light/dark regions correspond to fully-unpolarized/fully-polarized regions of emission from the galaxy. (ESA AND THE PLANCK COLLABORATION)

But the galactic foreground isn’t useless; it’s a map unto itself.

The all-sky map of the galactic foreground emissions overlaid with polarization and magnetic field data. This is the first accurate, high-resolution, all-sky map of our galaxy’s magnetic field and foreground structures. (ESA AND THE PLANCK COLLABORATION)

All background light gets polarized by these foregrounds, enabling the reconstruction of our galaxy’s magnetic field.

The alignment of neutral hydrogen (white lines) with the polarization data from the CMB (gradients) is an inexplicable surprise, unless there’s an additional galactic foreground. In theory, only ionized hydrogen should align with the polarization data. This surprise is one of the very few observations that the Planck science team exhibits tension with other measurements, such as radio pencil-beam data taken from Arecibo. (CLARK ET AL., PHYSICAL REVIEW LETTERS, VOLUME 115, ISSUE 24, ID.241302 (2015))

NAIC Arecibo Observatory operated by University of Central Florida, Yang Enterprises and UMET, Altitude 497 m (1,631 ft).

Quite surprisingly, neutral hydrogen appears to be aligned with the CMB’s polarization.

As seen in yellow, a bridge of hot gas (detected by Planck) connects the galaxy clusters Abell 399 and Abell 401. The Planck data, when combined with X-ray data (in red) and LOFAR radio data (in blue) reveals a bridge of relativistic electrons connecting these two clusters across a distance of 10 million light-years. This is the largest-scale magnetic field ever detected in our Universe, and shows how successful Planck can be for reconstructing magnetic fields. (ESA/PLANCK COLLABORATION / STSCI/DSS (L); M. MURGIA / INAF, BASED ON F. GOVONI ET AL., 2019, SCIENCE (R))

ASTRON LOFAR European Map

ASTRON LOFAR Radio Antenna Bank, Netherlands

However, Planck data of distant galaxies matches well with reconstructed magnetic fields.

The current models of galactic (and other) foregrounds along with the cosmic microwave background. There is some evidence that indicates the possibility that free-free scattering (from free electrons) has been modeled insufficiently, but other observations indicate that we may be spot on. This is a minor issue, but one that has not been conclusively resolved. (ESA AND THE PLANCK COLLABORATION)

A close-up view of one of many regions of our galaxy, with the dustiest regions shown in red. The dark red regions are locations where new stars are forming, and the contour lines that show the reconstructed magnetic fields from our galaxy illustrate the interplay of star-forming regions with these fields. (ESA/PLANCK COLLABORATION. ACKNOWLEDGMENT: M.-A. MIVILLE-DESCHÊNES, CNRS — INSTITUT D’ASTROPHYSIQUE SPATIALE, UNIVERSITÉ PARIS-XI, ORSAY, FRANCE)

What’s certain is that dust grains correlate with these giant magnetic structures.

A quick look at any zoomed-in region of the galaxy shows that magnetic fields are not coherent and unidirectional on scales of the Milky Way, but rather only on the scales of individual star clusters. Beyond distance scales of a few dozen light-years, magnetic fields flip and switch directions, dominated by local, rather than galaxy-scale, dynamics. (ESA/PLANCK COLLABORATION. ACKNOWLEDGMENT: M.-A. MIVILLE-DESCHÊNES, CNRS — INSTITUT D’ASTROPHYSIQUE SPATIALE, UNIVERSITÉ PARIS-XI, ORSAY, FRANCE)

The link is through star-formation, which occurs inside these obscured regions.

Although an image like this might remind you of Van Gogh’s famous ‘Starry Night’ painting, this doesn’t illustrate atmospheric turbulence at all, since 100% of the data used in creating this image was taken from space. These lines represent magnetic fields and polarization instead, which illuminate the Universe in an entirely different way. (ESA/PLANCK COLLABORATION. ACKNOWLEDGMENT: M.-A. MIVILLE-DESCHÊNES, CNRS — INSTITUT D’ASTROPHYSIQUE SPATIALE, UNIVERSITÉ PARIS-XI, ORSAY, FRANCE)

Extragalactic light is unavoidably affected by our galactic magnetic fields, enabling the construction of these beautiful maps.

Even in the direction that points directly away from the galactic center, the plane of our Milky Way still contains dusty, star-forming regions, still generates its own magnetic field, and still polarizes any background light that passes through this region of space. In order to understand the Universe, we have to model and account for every single component successfully. (ESA/PLANCK COLLABORATION. ACKNOWLEDGMENT: M.-A. MIVILLE-DESCHÊNES, CNRS — INSTITUT D’ASTROPHYSIQUE SPATIALE, UNIVERSITÉ PARIS-XI, ORSAY, FRANCE)

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

“Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

From European Space Agency: “From an almost perfect Universe to the best of both worlds”

From European Space Agency

Jan Tauber
ESA Planck Project Scientist
European Space Agency
Email: jan.tauber@esa.int

Markus Bauer
ESA Science Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
Email: markus.bauer@esa.int

17 July 2018

The Planck consortium has made their final data release, including new processing of the cosmic microwave background temperature and polarisation data. This legacy dataset confirms the model of an ‘almost perfect Universe’, with some remaining oddities giving researchers some intriguing details to puzzle over.

The Cosmic Microwave Background – as seen by Planck. Credit: ESA and the Planck Collaboration

ESA/Planck 2009 to 2013

It was 21 March 2013. The world’s scientific press had either gathered in ESA’s Paris headquarters or logged in online, along with a multitude of scientists around the globe, to witness the moment when ESA’s Planck mission revealed its ‘image’ of the cosmos. This image was taken not with visible light but with microwaves.

Whereas light that our eyes can see is composed of small wavelengths – less than a thousandth of a millimetre in length – the radiation that Planck was detecting spanned longer wavelengths, from a few tenths of a millimetre to a few millimetres. Most importantly, it had been generated at very beginning of the Universe.

Collectively, this radiation is known as the cosmic microwave background, or CMB. By measuring its tiny differences across the sky, Planck’s image had the ability to tell us about the age, expansion, history, and contents of the Universe. It was nothing less than the cosmic blueprint.

Astronomers knew what they were hoping to see. Two NASA missions, COBE in the early 1990s and WMAP in the following decade, had already performed an analogous set of sky surveys that resulted in similar images. But those images did not have the precision and sharpness of Planck.

The new view would show the imprint of the early Universe in painstaking detail for the first time. And everything was riding on it.

If our model of the Universe were correct, then Planck would confirm it to unprecedented levels of accuracy. If our model were wrong, Planck would send scientists back to the drawing board.

When the image was revealed, the data had confirmed the model. The fit to our expectations was too good to draw any other conclusion: Planck had showed us an ‘almost perfect Universe’. Why almost perfect? Because a few anomalies remained, and these would be the focus of future research.

Now, five years later, the Planck consortium has made their final data release, known as the legacy data release. The message remains the same, and is even stronger.

Planck’s view of the sky in nine channels at microwave and sub-millimetre wavelenghts.
Credit: ESA and the Planck Collaboration, animated

“This is the most important legacy of Planck,” says Jan Tauber, ESA’s Planck Project Scientist. “So far the standard model of cosmology has survived all the tests, and Planck has made the measurements that show it.”

Standard Model of Cosmology Timeline

Standard Model of Cosmology Cornell

All cosmological models are based upon Albert Einstein’s General Theory of Relativity. To reconcile the general relativistic equations with a wide range of observations, including the cosmic microwave background, the standard model of cosmology includes the action of two unknown components.

Firstly, an attractive matter component, known as cold dark matter, which unlike ordinary matter does not interact with light. Secondly, a repulsive form of energy, known as dark energy, which is driving the currently accelerated expansion of the Universe. They have been found to be essential components to explain our cosmos in addition to the ordinary matter we know about. But as yet we do not know what these exotic components actually are.

Planck was launched in 2009 and collected data until 2013. Its first release – which gave rise to the almost perfect Universe – was made in the spring of that year. It was based solely on the temperature of the cosmic microwave background radiation, and used only the first two sky surveys from the mission.

The data also provided further evidence for a very early phase of accelerated expansion, called inflation, in the first tiny fraction of a second in the Universe’s history, during which the seeds of all cosmic structures were sown. Inflation

Alan Guth, from Highland Park High School and M.I.T., who first proposed cosmic inflation

HPHS Owls

Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

Alan Guth’s notes:

Yielding a quantitative measure of the relative distribution of these primordial fluctuations, Planck provided the best confirmation ever obtained of the inflationary scenario.

Besides mapping the temperature of the cosmic microwave background across the sky with unprecedented accuracy, Planck also measured its polarisation, which indicates if light is vibrating in a preferred direction. The polarisation of the cosmic microwave background carries an imprint of the last interaction between the radiation and matter particles in the early Universe, and as such contains additional, all-important information about the history of the cosmos. But it could also contain information about the very first instants of our Universe, and give us clues to understand its birth.

In 2015, a second data release folded together all data collected by the mission, which amounted to eight sky surveys. It gave temperature and polarisation but came with a caution.

“We felt the quality of some of the polarisation data was not good enough to be used for cosmology,” says Jan. He adds that – of course – it didn’t prevent them from doing cosmology with it but that some conclusions drawn at that time needed further confirmation and should therefore be treated with caution.

And that’s the big change for this 2018 Legacy data release. The Planck consortium has completed a new processing of the data. Most of the early signs that called for caution have disappeared. The scientists are now certain that both temperature and polarisation are accurately determined.

“Now we really are confident that we can retrieve a cosmological model based on solely on temperature, solely on polarisation, and based on both temperature and polarisation. And they all match,” says Reno Mandolesi, principal investigator of the LFI instrument on Planck at the University of Ferrara, Italy.

“Since 2015, more astrophysical data has been gathered by other experiments, and new cosmological analyses have also been performed, combining observations of the CMB at small scales with those of galaxies, clusters of galaxies, and supernovae, which most of the time improved the consistency with Planck data and the cosmological model supported by Planck,” says Jean-Loup Puget, principal investigator of the HFI instrument on Planck at the Institut d’Astrophysique Spatiale in Orsay, France.

This is an impressive feat and means that cosmologists can be assured that their description of the Universe as a place containing ordinary matter, cold dark matter and dark energy, populated by structures that had been seeded during an early phase of inflationary expansion, is largely correct.

But there are some oddities that need explaining – or tensions as cosmologists call them. One in particular is related to the expansion of the Universe. The rate of this expansion is given by the so-called Hubble Constant.

To measure the Hubble constant astronomers have traditionally relied on gauging distances across the cosmos. They can only do this for the relatively local Universe by measuring the apparent brightness of certain types of nearby variable stars and exploding stars, whose actual brightness can be estimated independently. It is a well-honed technique that has been developed over the course of the last century, pioneered by Henrietta Leavitt and later applied, in the late 1920s, by Edwin Hubble and collaborators, who used variable stars in distant galaxies and other observations to reveal that the Universe was expanding.

The figure astronomers derive for the Hubble Constant using a wide variety of cutting-edge observations, including some from Hubble’s namesake observatory, the NASA/ESA Hubble Space Telescope, and most recently from ESA’s Gaia mission, is 73.5 km/s/Mpc, with an uncertainty of only two percent. The slightly esoteric units give the velocity of the expansion in km/s for every million parsecs (Mpc) of separation in space, where a parsec is equivalent to 3.26 light-years.

A second way to estimate the Hubble Constant is to use the cosmological model that fits the cosmic microwave background image, which represents the very young Universe, and calculate a prediction for what the Hubble Constant should be today. When applied to Planck data, this method gives a lower value of 67.4 km/s/Mpc, with a tiny uncertainty of less than a percent.

Measurements of the Hubble constant over the past two decades.
Credit: ESA and the Planck Collaboration

On the one hand, it is extraordinary that two such radically different ways of deriving the Hubble constant – one using the local, mature Universe, and one based on the distant, infant Universe – are so close to each other. On the other hand, in principle these two figures should agree to within their respective uncertainties. This is the tension, and the question is how can they be reconciled?

Both sides are convinced that any remaining errors in their measurement methodologies are now too small to cause the discrepancy. So could it be that there is something slightly peculiar about our local cosmic environment that makes the nearby measurement somewhat anomalous? We know for example that our Galaxy sits in a slightly under-dense region of the Universe, which could affect the local value of the Hubble constant. Unfortunately, most astronomers think that such deviations are not large enough to resolve this problem.

“There is no single, satisfactory astrophysical solution that can explain the discrepancy. So, perhaps there is some new physics to be found,” says Marco Bersanelli, deputy principal investigator of the LFI instrument at the University of Milan, Italy.

‘New physics’ means that exotic particles or forces could be influencing the results. Yet, as exciting as this prospect feels, the Planck results place severe constraints on this train of thought because it fits so well with the majority of observations.

“It is very hard to add new physics alleviating the tension and still keep the standard model’s precise description of everything else that already fits,” says François Bouchet, deputy principal investigator of the HFI instrument at the Institut d’Astrophysique de Paris, France.

As a result, no one has been able to come up with a satisfactory explanation for the differences between the two measurements, and the question remains to be resolved.

“For the moment, we shouldn’t get too excited about finding new physics: it could well be that the relatively small discrepancy can be explained by a combination of small errors and local effects. But we need to keep improving our measurements and thinking about better ways to explain it,” says Jan.

This is the legacy of Planck: with its almost perfect Universe, the mission has given researchers confirmation of their models but with a few details to puzzle over. In other words: the best of both worlds.

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

From LBNL: “Tiny Distortions in Universe’s Oldest Light Reveal Clearer Picture of Strands in Cosmic Web”

Berkeley Lab

April 10, 2018

Glenn Roberts Jr.
geroberts@lbl.gov
(510) 486-5582

In this illustration, the trajectory of cosmic microwave background (CMB) light is bent by structures known as filaments that are invisible to our eyes, creating an effect known as weak lensing captured by the Planck satellite (left), a space observatory. Researchers used computers to study this weak lensing of the CMB and produce a map of filaments, which typically span hundreds of light years in length. (Credit: Siyu He, Shadab Alam, Wei Chen, and Planck/ESA)

Cosmic Background Radiation per ESA/Planck

ESA/Planck

Weak gravitational lensing NASA/ESA Hubble

Scientists have decoded faint distortions in the patterns of the universe’s earliest light to map huge tubelike structures invisible to our eyes – known as filaments – that serve as superhighways for delivering matter to dense hubs such as galaxy clusters.

The international science team, which included researchers from the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley, analyzed data from past sky surveys using sophisticated image-recognition technology to home in on the gravity-based effects that identify the shapes of these filaments. They also used models and theories about the filaments to help guide and interpret their analysis.

Published April 9 in the journal Nature Astronomy, the detailed exploration of filaments will help researchers to better understand the formation and evolution of the cosmic web – the large-scale structure of matter in the universe – including the mysterious, unseen stuff known as dark matter that makes up about 85 percent of the total mass of the universe.

Cosmic web Millenium Simulation Max Planck Institute for Astrophysics

Dark matter cosmic web and the large-scale structure it forms The Millenium Simulation, V. Springel et al

Caterpillar Project A Milky-Way-size dark-matter halo and its subhalos circled, an enormous suite of simulations . Griffen et al. 2016

Dark matter constitutes the filaments – which researchers learned typically stretch and bend across hundreds of millions of light years – and the so-called halos that host clusters of galaxies are fed by the universal network of filaments. More studies of these filaments could provide new insights about dark energy, another mystery of the universe that drives its accelerating expansion.

Filament properties could also put gravity theories to the test, including Einstein’s theory of general relativity, and lend important clues to help solve an apparent mismatch in the amount of visible matter predicted to exist in the universe – the “missing baryon problem.”

“Usually researchers don’t study these filaments directly – they look at galaxies in observations,” said Shirley Ho, a senior scientist at Berkeley Lab and Cooper-Siegel associate professor of physics at Carnegie Mellon University who led the study. “We used the same methods to find the filaments that Yahoo and Google use for image recognition, like recognizing the names of street signs or finding cats in photographs.”

Filament structures in the cosmic web are shown at different time periods, ranging from when the universe was 12.3 billion years old (left) to when the universe was 7.4 billion years old (right). The area in the animation spans 7,500 square degrees of space. Evidence is strongest for the filament structures represented in blue. Other likely filament structures are shaded purple, magenta, and red. (Credit: Yen-Chi Chen and Shirley Ho)

The study used data from the Baryon Oscillation Spectroscopic Survey, or BOSS, an Earth-based sky survey that captured light from about 1.5 million galaxies to study the universe’s expansion and the patterned distribution of matter in the universe set in motion by the propagation of sound waves, or “baryonic acoustic oscillations,” rippling in the early universe.

BOSS Supercluster Baryon Oscillation Spectroscopic Survey (BOSS)

The BOSS survey team, which featured Berkeley Lab scientists in key roles, produced a catalog of likely filament structures that connected clusters of matter that researchers drew from in the latest study.

Researchers also relied on precise, space-based measurements of the cosmic microwave background, or CMB, which is the nearly uniform remnant signal from the first light of the universe. While this light signature is very similar across the universe, there are regular fluctuations that have been mapped in previous surveys.

In the latest study, researchers focused on patterned fluctuations in the CMB. They used sophisticated computer algorithms to seek out the imprint of filaments from gravity-based distortions in the CMB, known as weak lensing effects, that are caused by the CMB light passing through matter.

Since galaxies live in the densest regions of the universe, the weak lensing signal from the deflection of CMB light is strongest from those parts. Dark matter resides in the halos around those galaxies, and was also known to spread from those denser areas in filaments.

“We knew that these filaments should also cause a deflection of CMB and would also produce a measurable weak gravitational lensing signal,” said Siyu He, the study’s lead author who is a Ph.D. researcher from Carnegie Mellon University – she is now at Berkeley Lab and is also affiliated with UC Berkeley. The research team used statistical techniques to identify and compare the “ridges,” or points of higher density that theories informed them would point to the presence of filaments.

“We were not just trying to ‘connect the dots’ – we were trying to find these ridges in the density, the local maximum points in density,” she said. They checked their findings with other filament and galaxy cluster data, and with “mocks,” or simulated filaments based on observations and theories. The team used large cosmological simulations generated at Berkeley Lab’s National Energy Research Scientific Computing Center (NERSC), for example, to check for errors in their measurements.

NERSC Cray XC40 Cori II supercomputer

LBL NERSC Cray XC30 Edison supercomputer

The Genepool system is a cluster dedicated to the DOE Joint Genome Institute’s computing needs. Denovo is a smaller test system for Genepool that is primarily used by NERSC staff to test new system configurations and software.

NERSC PDSF

PDSF is a networked distributed computing cluster designed primarily to meet the detector simulation and data analysis requirements of physics, astrophysics and nuclear science collaborations.

The filaments and their connections can change shape and connections over time scales of hundreds of millions of years. The competing forces of the pull of gravity and the expansion of the universe can shorten or lengthen the filaments.

“Filaments are this integral part of the cosmic web, though it’s unclear what is the relationship between the underlying dark matter and the filaments,” and that was a primary motivation for the study, said Simone Ferraro, one of the study’s authors who is a Miller postdoctoral fellow at UC Berkeley’s Center for Cosmological Physics.

Scientists have decoded faint distortions in the patterns of the universe’s earliest light to map huge tubelike structures invisible to our eyes – known as filaments – that serve as superhighways for delivering matter to dense hubs such as galaxy clusters.

The international science team, which included researchers from the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley, analyzed data from past sky surveys using sophisticated image-recognition technology to home in on the gravity-based effects that identify the shapes of these filaments. They also used models and theories about the filaments to help guide and interpret their analysis.

Published April 9 in the journal Nature Astronomy, the detailed exploration of filaments will help researchers to better understand the formation and evolution of the cosmic web – the large-scale structure of matter in the universe – including the mysterious, unseen stuff known as dark matter that makes up about 85 percent of the total mass of the universe.

Dark matter constitutes the filaments – which researchers learned typically stretch and bend across hundreds of millions of light years – and the so-called halos that host clusters of galaxies are fed by the universal network of filaments. More studies of these filaments could provide new insights about dark energy, another mystery of the universe that drives its accelerating expansion.

Filament properties could also put gravity theories to the test, including Einstein’s theory of general relativity, and lend important clues to help solve an apparent mismatch in the amount of visible matter predicted to exist in the universe – the “missing baryon problem.”

“Usually researchers don’t study these filaments directly – they look at galaxies in observations,” said Shirley Ho, a senior scientist at Berkeley Lab and Cooper-Siegel associate professor of physics at Carnegie Mellon University who led the study. “We used the same methods to find the filaments that Yahoo and Google use for image recognition, like recognizing the names of street signs or finding cats in photographs.”
Image – Filament structures in the cosmic web are shown at different time periods: ranging from when the was 12.3 billion years old (left) to when the universe was 7.4 billion years old. The area in the animation spans 7,500 square degrees of space. Evidence is strongest for the filament structures represented in blue – other likely filament structures are shaded pink and red. (Credit: Yen-Chi Chen and Shirley Ho)

Filament structures in the cosmic web are shown at different time periods, ranging from when the universe was 12.3 billion years old (left) to when the universe was 7.4 billion years old (right). The area in the animation spans 7,500 square degrees of space. Evidence is strongest for the filament structures represented in blue. Other likely filament structures are shaded purple, magenta, and red. (Credit: Yen-Chi Chen and Shirley Ho)

The study used data from the Baryon Oscillation Spectroscopic Survey, or BOSS, an Earth-based sky survey that captured light from about 1.5 million galaxies to study the universe’s expansion and the patterned distribution of matter in the universe set in motion by the propagation of sound waves, or “baryonic acoustic oscillations,” rippling in the early universe.

The BOSS survey team, which featured Berkeley Lab scientists in key roles, produced a catalog of likely filament structures that connected clusters of matter that researchers drew from in the latest study.

Researchers also relied on precise, space-based measurements of the cosmic microwave background, or CMB, which is the nearly uniform remnant signal from the first light of the universe. While this light signature is very similar across the universe, there are regular fluctuations that have been mapped in previous surveys.

In the latest study, researchers focused on patterned fluctuations in the CMB. They used sophisticated computer algorithms to seek out the imprint of filaments from gravity-based distortions in the CMB, known as weak lensing effects, that are caused by the CMB light passing through matter.

Since galaxies live in the densest regions of the universe, the weak lensing signal from the deflection of CMB light is strongest from those parts. Dark matter resides in the halos around those galaxies, and was also known to spread from those denser areas in filaments.

“We knew that these filaments should also cause a deflection of CMB and would also produce a measurable weak gravitational lensing signal,” said Siyu He, the study’s lead author who is a Ph.D. researcher from Carnegie Mellon University – she is now at Berkeley Lab and is also affiliated with UC Berkeley. The research team used statistical techniques to identify and compare the “ridges,” or points of higher density that theories informed them would point to the presence of filaments.

“We were not just trying to ‘connect the dots’ – we were trying to find these ridges in the density, the local maximum points in density,” she said. They checked their findings with other filament and galaxy cluster data, and with “mocks,” or simulated filaments based on observations and theories. The team used large cosmological simulations generated at Berkeley Lab’s National Energy Research Scientific Computing Center (NERSC), for example, to check for errors in their measurements.

The filaments and their connections can change shape and connections over time scales of hundreds of millions of years. The competing forces of the pull of gravity and the expansion of the universe can shorten or lengthen the filaments.

“Filaments are this integral part of the cosmic web, though it’s unclear what is the relationship between the underlying dark matter and the filaments,” and that was a primary motivation for the study, said Simone Ferraro, one of the study’s authors who is a Miller postdoctoral fellow at UC Berkeley’s Center for Cosmological Physics.

Visualizing the cosmic web: This computerized simulation by the Virgo Consortium, called the Millennium Simulation, shows a web-like structure in the universe composed of galaxies and the dark matter around them. (Credit: Millennium Simulation Project)

New data from existing experiments, and next-generation sky surveys such as the Berkeley Lab-led Dark Energy Spectroscopic Instrument (DESI) now under construction at Kitt Peak National Observatory in Arizona should provide even more detailed data about these filaments, he added.

Researchers noted that this important step in sleuthing the shapes and locations of filaments should also be useful for focused studies that seek to identify what types of gases inhabit the filaments, the temperatures of these gases, and the mechanisms for how particles enter and move around in the filaments. The study also allowed them to determine the length of filaments.

Siyu He said that resolving the filament structure can also provide clues to the properties and contents of the voids in space around the filaments, and “help with other theories that are modifications of general relativity,” she said.

Ho added, “We can also maybe use these filaments to constrain dark energy – their length and width may tell us something about dark energy’s parameters.”

Shadab Alam, a researcher at the University of Edinburgh and Royal Observatory in Edinburgh, U.K.; and Yen-Chi Chen, an assistant professor at the University of Washington, also participated in the study. The work was supported by the U.S. Department of Energy Office of Science, NASA, the National Science Foundation, the European Research Council, and the Miller Institute for Basic Research in Science at UC Berkeley.

NERSC is a DOE Office of Science User Facility

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

A U.S. Department of Energy National Laboratory Operated by the University of California

From ESA via Manu: “History of the formation of cosmic structures”

Manu Garcia, a friend from IAC.

The universe around us.
Astronomy, everything you wanted to know about our local universe and never dared to ask.

European Space Agency

Undated
No writer credit

ESA/Planck

CMB per ESA/Planck

Cosmic Background Radiation per Planck

ESA Planck All Sky Map 1

How did seed fluctuations grow into today’s cosmic structures such as galaxies and galaxy clusters?
How did the formation of structure effect the CMB?
How is the history of cosmic structure formation encoded in the CMB and power spectrum?

No image credit

How did seed fluctuations grow into today’s cosmic structures such as galaxies and galaxy clusters?

The growth of seed fluctuations into cosmic structure can be summarised into three main phases:

Between inflation and the release of the cosmic microwave background
Between the release of the cosmic microwave background and the formation of the first stars and galaxies
After the formation of the first stars and galaxies

Between inflation and the release of the cosmic microwave background (t <1 sec to t =380,000 years)

How did seed fluctuations grow into today’s cosmic structures such as galaxies and galaxy clusters?
How did the formation of structure effect the CMB?
How is the history of cosmic structure formation encoded in the CMB and power spectrum?
History of structure formation in the Universe

How did seed fluctuations grow into today’s cosmic structures such as galaxies and galaxy clusters?

The growth of seed fluctuations into cosmic structure can be summarised into three main phases:

Between inflation and the release of the cosmic microwave background
Between the release of the cosmic microwave background and the formation of the first stars and galaxies
After the formation of the first stars and galaxies

Between inflation and the release of the cosmic microwave background (t <1 sec to t =380,000 years)

After the end of inflation, the Universe consisted of a more or less uniform bath of fundamental particles, like quarks, electrons and their anti-particles. There were also neutrinos, photons (the particles of light) and dark matter particles, an unknown type of massive particle that does not interact with photons and is therefore dark (as it does not emit light). At this time there was slightly more matter than anti-matter, but as the particles collided with their anti-particles they annihilated, leaving the Universe dominated by particles, and anti-matter disappeared. Quarks then teamed up in trios, forming protons or neutrons – the constituents of atomic nuclei as we know them today. This all happened within the first second after the Big Bang. About three minutes after the Big Bang, protons and neutrons had combined to form the nuclei of hydrogen and helium.

The density and temperature of particles in the early Universe were extremely high, and collisions between the particles were very frequent. Cosmologists refer to this by saying that ordinary matter (such as electrons, protons, neutrons and the few atomic nuclei that had formed by then) was tightly coupled to the photons. Because of these frequent interactions, photons could not travel freely: the Universe was opaque. Besides, ordinary matter is subject to gravity, and ideally any denser region – such as the seed fluctuations that were present at the end of inflation – would draw more matter from their surroundings, growing denser and more massive. However, ordinary matter at this epoch was coupled to the photons, and the radiation pressure of photons pushes away any concentration of matter that may be created under the effect of gravity. This phenomenon prevents any fluctuations in the distribution of ordinary matter to grow denser as long as matter is coupled to the photons.

At the same time, dark matter particles were not bound to the photons, since the two species do not interact with one another. This type of dark matter particle is also referred to as cold dark matter because the velocity of these particles is much lower than the speed of light. Hence, fluctuations in the distribution of cold dark matter can grow denser and more massive even before the release of the cosmic microwave background.

Astronomers also refer to hot dark matter, or neutrinos – particles with a very small mass and no electric charge that travel nearly at the speed of light. In the first second of the Universe, neutrinos were coupled to the photons, but these two types of particles decoupled immediately after. Since they do not interact with light during most of the Universe's history, neutrinos can be considered as a type of dark matter, and since their velocity is close to the speed of light, they are regarded as hot dark matter. Fluctuations in the distribution of hot dark matter can grow denser and more massive, but due to their high velocity, these particles tend to dissipate and their fluctuations are damped on small scales so, effectively, only fluctuations on intermediate and large scales can grow.

The growth of primordial fluctuations in hot and cold dark matter give rise to two completely different distributions of cosmic structure. In hot dark matter models, the first structures to form are the most massive, that subsequently fragment into smaller and smaller structures. This has been discarded on the basis of observations of galaxies in the early Universe: since the first objects that are seen to emerge in cosmic history have low mass, and they gradually evolve into more massive structures, cosmologists have established that the bulk of dark matter in the Universe is cold. However, a small fraction of hot dark matter is present in the Universe as neutrinos. Depending on the mass of neutrinos (which has not been determined yet) the effect of hot dark matter can be more or less evident in the distribution of cosmic structure on different scales, since neutrinos tend to smooth out the formation of small-scale structures.

Between the release of the cosmic microwave background and the formation of the first stars and galaxies (t = 380,000 years to t = a few hundred million years)

About 380,000 years after the Big Bang, the Universe had expanded enough so that its density was much lower than at earlier epochs. Likewise, the temperature of the Universe had cooled down from the billions of Kelvin of the first few minutes and had reached about 3000 Kelvin. Protons and electrons could finally combine to form atoms of neutral hydrogen. Electrons disappeared from the view of photons and these two species decoupled from one another. This marked the beginning of the period known as the Dark Ages – a name arising from the fact that there were no individual sources of light, like stars, only clouds of neutral hydrogen.

The decoupling had two effects: photons were free to propagate across the Universe, which was now largely transparent, and which we observe as the cosmic microwave background (CMB); on the other hand, ordinary matter particles were free to assemble under the effect of gravity. From this moment on, ordinary and dark matter could both react to gravity: denser concentrations of matter (both ordinary and dark) grew denser and more massive. Since dark matter particles had already created a network of dense and empty structure, ordinary matter particles could feel the gravitational attraction from the densest concentrations of dark matter and fall toward them. But ordinary matter could also get rid of energy quite effectively by heating up and emitting radiation, which caused it to sink even further into the already existing regions of high matter density. These processes gave rise to a highly sub-structured network of sheets and filaments of ordinary and dark matter known as the cosmic web, which constitutes the skeleton supporting the later emergence of stars and galaxies. Eventually the densest concentrations gave rise to the first stars, leading to the end of the Dark Ages.

After the formation of the first stars and galaxies (t = a few hundred million years to t = now)

A few hundred million years after the Big Bang, the distribution of matter in the Universe had produced very dense knots at the intersections of the sheets and filaments that make up the cosmic web. In these knots, the density of ordinary matter was so high that the formation of stars and galaxies became possible. Eventually the first stars and galaxies sparked into existence and light could escape from them, revealing the distant Universe to telescopes today.

The first stars were formed almost exclusively out of hydrogen and helium and are believed to have been extremely massive (about 100 times the mass of the Sun or more) and to have lived very short lives, exploding soon after their formation as supernovae and releasing their material in the surroundings, triggering the birth of new stellar generations. Later generations included other elements formed in the nuclear furnace of previous stars, and their masses were typically smaller. The first generation of stars formed in relatively low-mass galaxies. Massive galaxies, and even more massive structures such as galaxy clusters, formed later.

How did the formation of structure effect the cosmic microwave background?

The birth of the first stars and galaxies had an interesting effect on the cosmic microwave background (CMB) photons. Ultraviolet radiation released by these objects ionised hydrogen atoms, turning them back into protons and electrons. This created a series of expanding bubbles of ionised gas – a bit like the holes in Swiss cheese – and within a few hundred million years these bubbles had merged and the entire Universe was ionised again, a period of time termed reionisation.

The CMB photons were affected by the reionisation; they were scattered off the free electrons in the reionised Universe, washing out some of the primordial fluctuations in the CMB as we observe it today. Since this happened when the Universe was already mature and had reached a substantial size, the effect of reionisation can be detected in the fluctuations of the CMB on large scales. This effect is expressed in terms of the ‘opacity’, which describes the average density of free electrons that are present along the line of sight between an observer (in this case, the telescope on board Planck) and the CMB. This parameter also provides a tool to estimate when the first stars formed.

How is the history of cosmic structure encoded in the cosmic microwave background and power spectrum?

The variations in the density of matter at the time when the cosmic microwave background (CMB) formed derive from the seed fluctuations that were produced at the end of inflation and can be deciphered by looking at the power spectrum for cosmic structure in the Universe at a range of scales.

At scales smaller than about one degree – or twice the size of the full Moon on the sky – the graph shows the imprint and oscillation pattern of sound waves that were present in the fluid of ordinary matter and radiation in the very early Universe, before the CMB was released. At this epoch, ordinary matter was tightly coupled to the photons, and the radiation pressure of photons pushed away any concentration of matter that might have been created under the effect of gravity.

The interplay between gravity, which pulled together the fluid of matter and radiation, and the radiation pressure, which pushed it away, caused a series of rhythmical compressions and rarefactions everywhere in the fluid. This results in the pattern of sound waves that is visible in the central part of the power spectrum graph. Since gravity is caused by both dark and ordinary matter particles, but the radiation pressure of photons is only experienced by ordinary matter (because dark matter particles are not coupled to photons), the shape of these oscillations contains information about the amount of ordinary matter relative to the amount of dark matter. As dark matter was not bound to the photons, any concentration of dark matter could grow denser and denser even before the release of the CMB. The relative contribution of ordinary matter particles (also referred to as baryons) to the overall cosmic budget is expressed in terms of the ‘Omega_b’ parameter, where b stands for baryons, and the relative contribution of cold dark matter particles is expressed in terms of the ‘Omega_c’ parameter, where c stands for cold. The ‘cold’ in cold dark matter refers to the low speed of these particles (‘warm’ dark matter particles move at higher speed and ‘hot’ dark matter particles move at the speed of light).
While gravity pulls matter together to form structures, the expansion of the Universe may counteract this effect and hamper the formation of cosmic structure. For this reason, the amount of fluctuations in the Universe depends also on the speed of cosmic expansion, and this quantity can be extracted from the shape of the oscillations in the power spectrum of the CMB. The speed of the Universe is expressed in terms of the Hubble constant, H_0, which quantifies the expansion of the Universe at present time.

What does the cosmic microwave background tell us about the overall ‘shape’ of the Universe?

The CMB holds clues to the nature and distribution of structure in the Universe, and the average density of this matter plays a key role in determining the geometry of the Universe. The geometry of the Universe can take on one of three shapes: it can be curved like the surface of a ball and finite in extent (positively curved); curved like a saddle and infinite in extent (negatively curved), or it can be flat and infinite. The geometry and density of the Universe are related in such a way that, if the average density of matter in the Universe is found to be less than the so-called critical density (roughly equal to 6 hydrogen atoms per cubic metre) the Universe is open and infinite. If the density is greater than the critical density the Universe is closed and finite. If the density just equals the critical density, the Universe is flat.

Cosmologists study the relative sizes of the oscillations of the fluid of matter and radiation at the time the CMB was released to learn more about the shape of the Universe. The oscillations translate into regions of higher and lower temperature on the CMB map, and contain information about the amount of particles present. More specifically, the shape of the Universe can be determined by looking at where the first of these oscillations appears in the power spectrum.

The location of the first oscillation corresponds to a specific size in the early Universe called the sound horizon – the maximum distance that a sound wave could have crossed from the Big Bang until the time of the CMB release. To cosmologists, the sound horizon works like a standard measure of known length. By measuring its length in the temperature fluctuations of the CMB, it is possible to determine if the Universe is flat or curved. This is expressed in terms of the parameter ‘Omega_K’ and is equal to zero for exactly flat space.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

From ESA via Manu: “The Planck mission and cosmic radiation” 2010

Manu Garcia, a friend from IAC.

The universe around us.
Astronomy, everything you wanted to know about our local universe and never dared to ask.

European Space Agency

The Planck Mission.

Deflection of light from the Big Bang.
This artist shows how photons in the cosmic microwave background (CMB detected by the space telescope Planck ESA) are deflected by the gravitational lensing of cosmic structures massive as they travel through the universe.

Gravitational Lensing NASA/ESA

CMB per ESA/Planck

Gravitational lenses create additional distortions small speckled pattern of temperature fluctuations WBC. A small fraction of CMB is polarized; a component of this polarized light modes B, has been given an additional signature by lensing. This footprint was found for the first time by combining data from ground – based telescope South Pole and the space observatory Herschel ESA. Copyright ESA Planck and collaboration.

Objective.
To map background radiation produced by the Big Bang with unprecedented resolution and sensitivity and test theories about the birth and evolution of the universe.

Mission.
Planck is the time machine ESA. Looks back at early times, near the Big Bang, what happened about 13,700 million years ago. Planck will analyze with accuracy not achieved so far, the remnants of the radiation that filled the Universe immediately after the Big Bang – radiation observed today as the Cosmic Microwave Background (CMB Cosmic Microwave Background).

The results will help astronomers decide which theories of the birth and evolution of the universe are correct, for example, how the universe began life with a period of rapid expansion?

But first, Planck to detect and understand the issue of the cosmic background that lies between us and the first light of the universe. The first scientific data from Planck and first results were released in January 2011, and the first cosmological results are expected in early 2013.

What makes it special?
Planck is the first European mission to study the relic left over from the Big Bang, radiation after those first moments.

The temperature of the CMB radiation has been measured at about 2.7 degrees Kelvin, but Planck will provide even more accurate measurements with an accuracy set by fundamental astrophysical limits. In other words, it is impossible to obtain better images of this radiation that you get Planck.

Scientists already know from previous observations, that in heaven appear slightly warmer or colder, anisotropy, with differences in some areas by 100,000. These temperature differences are the traces in the WBC by the primitive seeds of immense concentrations current art, for example, galaxies and clusters of galaxies. The high sensitivity of Planck will result in the best map of those present in the CMB anisotropy, allowing scientists to learn more about the evolution of the structure of the universe.

To complete these measures high precision, Planck observed in nine bands of the electromagnetic spectrum, from one centimeter to one third of a millimeter, corresponding to the range of the wavelength ranging from microwaves to infrared far away. Planck’s detectors are cooled to temperatures near absolute zero because otherwise, its own heat emission alter measures.

The ship.

ESA/Planck

Planck ship is about 4.2 m high and 4.2 m wide. The primary mirror is 1.5 m and has two scientific instruments: LFI (Low Frequency Instrument, Instrument low frequency) which operates between 30 and 70 GHz, and HFI (High Frequency Instrument, Instrument high frequency), operating between 100 and 857 GHz. HFI completed its poll in January 2012. LFI continues in operation.

Trip.

Planck was launched on May 14, 2009 on an Ariane 5 from the spaceport of Kourou ESA, in French Guiana. He shared journey with the ship Herschel, ESA. The two ships operate independently. Planck ended its operations on 23 October 2.013.

Planck operates from a Lissajous orbit around the second Lagrange point of the Sun-Earth system (L2), a virtual point located 1.5 million km from Earth in the opposite direction to the sun.

History.

Planck was initially called COBRAS / SAMBA (acronym deCosmic Background Radiation Anisotropy Satellite ySatellite for Measurement of Background anisotropies), as the mission grew from two proposals with similar objectives.

Following approval of the mission in 1996, it was renamed in honor of the German scientist Max Planck (1858-1947) who won the Nobel Prize for Physics in 1918.

The ESA Planck observatory is a continuation of the mission COBE (Cosmic Background Explorer ) and WMAP (Wilkinson Microwave Anisotropy Probe), both NASA.

Cosmic Infrared Background, Credit: Michael Hauser (Space Telescope Science Institute), the COBE/DIRBE Science Team, and NASA

NASA/COBE

NASA/WMAP

NASA WMAP satellite

Participation.

The Planck satellite prime contractor Alcatel Alenia Space was (Cannes, France), who led the consortium of industrial partners with the industrial department of Alcatel Alenia Space in Torino (Italy) responsible for the service module. ESA and the Danish National Space Center (Copenhagen, Denmark, founded by the Research Council of Natural Sciences Denmark) were responsible for providing the Planck telescope mirrors, manufactured by EADS Astrium (Friedrichshafen, Germany).

The LFI instrument (led by IASF, Istituto di Astrofisica Spaziale e Fisica Cosmica in Bologna, Italy) was designed and built by a consortium of scientists and institutions from Italy, Finland, UK, Spain, USA, Germany, Netherlands , Switzerland, Norway, Sweden and Denmark.

The HFI instrument (led by the Institut d’Astrophysique Spatiale (CNRS) in Orsay, France) was designed and built by a consortium of scientists and institutions from France, USA, UK, Canada, Italy, Spain, Ireland, Germany, Netherlands, Denmark and Switzerland.

Numerous agencies contributed to the financing of hardware LFI and HFI instruments; The most prominent are: CNES (France), ASI (Italy), NASA (United States), PPARC (United Kingdom), Tekes (Finland), Ministry of Education and Science (Spain) and ESA.

Sky image of the cosmic background radiation. Credit: ESA / LFI & HFI.

This image microwave sky was synthesized using data covering the frequency range of light detected by Planck. These low frequencies, which can not be seen with the human eye, covering the range 30-857 GHz.

Granulosa structure of the cosmic microwave background, with its tiny temperature fluctuations that reflect density variations from which the cosmic web of our universe originated, is clearly visible in the high latitude regions of the map.

A large portion of the sky, which extends well above and below the galactic plane, is dominated by the diffuse emission of gas and dust in our galaxy, the Milky Way. While the first galactic plane signal hidden cosmic microwave background from our view, also it highlights the extent of large-scale structure of our galaxy.

Although the two main components of the microwave sky appear to be separable only in certain areas, one in the foreground removal across the sky is made possible by sophisticated image analysis techniques which have been developed by scientists Planck teams. These techniques are based on single frequency coverage of the observatory and unprecedented precision of their measurements.

This image is derived from data collected by Planck during its first survey of the entire sky, and covers about 12 months of observations.

Planck is a mission of the European Space Agency, with significant participation from NASA. The Planck Project Office at NASA is headquartered at JPL. JPL contributed enabling technology for both mission Planck scientific instruments. Scientists from Europe, Canada and the United States Planck will work together to analyze the Planck data.

More information is online at:
http://www.nasa.gov/planck
http://www.esa.int/Our_Activities/Space_Science/Planck

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

From Goddard: “NASA’s James Webb Space Telescope and the Big Bang: A Short Q&A with Nobel Laureate Dr. John Mather”

NASA Goddard Space Flight Center

Oct. 11, 2017
Maggie Masetti
NASA’s Goddard Space Flight Center

Dr. John Mather, a Nobel laureate and the senior project scientist for NASA’s James Webb Space Telescope. Credits: NASA/Chris Gunn

Q: What is the Big Bang?

A: The Big Bang is a really misleading name for the expanding universe that we see. We see an infinite universe with distant galaxies all rushing away from each other.

Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

The name Big Bang conveys the idea of a firecracker exploding at a time and a place — with a center. The universe doesn’t have a center, at least not one we can find. The Big Bang happened everywhere at once and was a process happening in time, not a point in time. We know this because 1) we see galaxies rushing away from each other, not from a central point; 2) we see the heat that was left over from early times, and that heat uniformly fills the universe; and 3) we can calculate and imagine what the universe was like when the parts were much closer together, and the calculations match everything we can see.

Q: Can we see the Big Bang?

A: No, the Big Bang itself is not something we can see.

Q: What can we see?

A: We can see the heat radiation that was there when the universe was young. We see this heat as it was about 380,000 years after the expansion of the universe began 13.8 billion years ago (which is what we refer to as the Big Bang). This heat covers the entire sky and fills the universe. (In fact it still does.) We were able to map it with satellites we (NASA and ESA) built called the Cosmic Background Explorer (COBE), the Wilkinson Microwave Anisotropy Probe (WMAP), and Planck. The universe at this point was extremely smooth, with only tiny ripples in temperature.

Cosmic Infrared Background, Credit: Michael Hauser (Space Telescope Science Institute), the COBE/DIRBE Science Team, and NASA

NASA/COBE

All-sky image of the infant universe, created from nine years of data from the Wilkinson Microwave Anisotropy Probe (WMAP).
Credits: NASA/WMAP Science Team

NASA/WMAP

CMB per ESA/Planck

ESA/Planck

Q: I heard the James Webb Space Telescope will see back further than ever before. What will Webb see?

NASA/ESA/CSA Webb Telescope annotated

A: COBE, WMAP, and Planck all saw further back than Webb, though it’s true that Webb will see farther back than Hubble.

NASA/ESA Hubble Telescope

Webb was designed not to see the beginnings of the universe, but to see a period of the universe’s history that we have not seen yet.

Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

Specifically, we want to see the first objects that formed as the universe cooled down after the Big Bang. That time period is perhaps hundreds of millions of years later than the one COBE, WMAP, and Planck were built to see. We think that the tiny ripples of temperature they observed were the seeds that eventually grew into galaxies. We don’t know exactly when the universe made the first stars and galaxies — or how for that matter. That is what we are building Webb to help answer.

Q: Why can’t Hubble see the first stars and galaxies forming?

A: The only way we can see back to the time when these objects were forming is to look very far away. Hubble isn’t big enough or cold enough to see the faint heat signals of these objects that are so far away.

Q: Why do we want to see the first stars and galaxies forming?

A: The chemical elements of life were first produced in the first generation of stars after the Big Bang. We are here today because of them — and we want to better understand how that came to be! We have ideas, we have predictions, but we don’t know. One way or another the first stars must have influenced our own history, beginning with stirring up everything and producing the other chemical elements besides hydrogen and helium. So if we really want to know where our atoms came from, and how the little planet Earth came to be capable of supporting life, we need to measure what happened at the beginning.

Dr. John Mather is the senior project scientist for the James Webb Space Telescope. Dr. Mather shares the 2006 Nobel Prize for Physics with George F. Smoot of the University of California for their work using the COBE satellite to measure the heat radiation from the Big Bang.

The James Webb Space Telescope, the scientific complement to NASA’s Hubble Space Telescope, will be the premier space observatory of the next decade. Webb is an international project led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

For more information about the Webb telescope, visit: http://www.webb.nasa.gov or http://www.nasa.gov/webb

See the full article here.

Please help promote STEM in your local schools.

Stem Education Coalition

NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

NASA/Goddard Campus

From ESA: “Magnetic mirror design for finding evidence of primordial gravitational waves”

European Space Agency

20 February 2017
No writer credit

Title Polarisation of the Cosmic Microwave Background: finer detail
Released 05/02/2015 3:00 pm
Copyright ESA and the Planck Collaboration
Description

A visualisation of the polarisation of the Cosmic Microwave Background, or CMB, as detected by ESA’s Planck satellite on a small patch of the sky measuring 20º across.

The CMB is a snapshot of the oldest light in our Universe, imprinted on the sky when the Universe was just 380 000 years old. It shows tiny temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all future structure: the stars and galaxies of today.

A small fraction of the CMB is polarised – it vibrates in a preferred direction. This is a result of the last encounter of this light with electrons, just before starting its cosmic journey. For this reason, the polarisation of the CMB retains information about the distribution of matter in the early Universe, and its pattern on the sky follows that of the tiny fluctuations observed in the temperature of the CMB.

In this image, the colour scale represents temperature differences in the CMB, while the texture indicates the direction of the polarised light. The curly textures are characteristic of ‘E-mode’ polarisation, which is the dominant type for the CMB.

In this image, both data sets have been filtered to show mostly the signal detected on scales around 20 arcminutes on the sky. This shows the fine structure of the measurement obtained by Planck, revealing fluctuations in both the CMB temperature and polarisation on very small angular scales.

ESA has backed the development of a ‘metamaterial’ device to sift through the faint afterglow of the Big Bang, to search for evidence of primordial gravitational waves triggered by the rapidly expanding newborn Universe.

“This technological breakthrough widens the potential for a future follow-on to ESA’s 2009-launched Planck mission, which would significantly increase our detailed understanding of the Universe as it began,” explains Peter de Maagt, heading ESA’s Antennas and Sub-Millimetre Wave section.

ESA/Planck

Planck mapped the ‘cosmic microwave background’ (CMB) – leftover light from the creation of the cosmos, subsequently redshifted to microwave wavelengths – across the deep sky in more detail than ever before.

CMB per ESA/Planck

The CMB retains properties of ordinary light, including its tendency to polarise in differing directions – employed in everyday life by polarised sunglasses to cut out glare, or 3D glasses used to see alternating differently polarised cinema images through separate eyes.

Title Metamaterial-reflective half-wave plate
Released 10/02/2017 4:16 pm
Copyright Cardiff University
Description

Cardiff University’s magnetic mirror half-wave plate design for b-mode polarisation modulation across wide bandwidths. Less than 1 mm thick, this metamaterial-based design employs a combination of a grid-based ‘artificial magnetic conductor’ and metal ‘perfect electrical conductor’ surfaces. The overall effect is to create a differential phase-shift between orthogonal polarisations equal to 180 degrees. The rotation of the plate causes modulation of the polarisation signal.

Researchers are now searching for one particular corkscrew polarisation of the CMB, known as ‘B-mode polarisation’, predicted to have been caused by gravitational waves rippling through the early Universe as it underwent exponential expansion – surging from a subatomic singularity to its current vastness.

Identifying these theorised ‘stretchmarks’ within the CMB would offer solid proof that expansion did indeed occur, bringing cosmologists a big step closer to unifying the physics of the very large and the very small.

“This would be the holy grail of cosmology,” comments Giampaolo Pisano of Cardiff University, heading the team that built the new prototype B-mode polarisation device for ESA.

The history of the Universe

Into what is the universe expanding NASA Goddard, Dana Berry

“Our contribution is only a small bit of the hugely complex instrument that will be necessary to accomplish such a detection. It won’t be easy, not least because it involves only a tiny fraction of the overall CMB radiation.”

One of the main obstacles in detecting primordial B-modes is additional sources of polarisation located between Earth and the CMB, such as dust within our own galaxy.

Such polarised foreground contributions have different spectral signatures to that of the CMB, however, enabling their removal if measurements are taken over a large frequency range.

The challenge is therefore to devise a polarisation modulator that operates across a wide frequency bandwidth with high efficiency.

“Our new ‘magnetic mirror’-based modulator can do just that, thanks to the quite new approach we adopted,” said Giampaolo Pisano.

Polarisation modulation is often achieved with rotating ‘half-wave plates’. These induce the rotation of the polarised signals which can ‘stick out’ from the unpolarised background. However, the physical thickness of these devices defines their operational bandwidths, which cannot be too large.

“Our new solution is based on a combination of metal grids embedded in a plastic substrate – what we call a ‘metamaterial’ – possessing customised electromagnetic properties not found in nature.

“This flat surface transforms and reflects the signal back like a half-wave plate, facing none of the geometrical constraints of previous designs.”

The team’s prototype multiband magnetic mirror polarisation modulator measures 20 cm across. Any post-Planck space mission would need one larger than a metre in diameter, its design qualified to survive the harsh space environment. The team are now working on enlarging it.

“To come so far, the University of Cardiff team has had to develop all the equipment and engineering processes making it possible,” adds Peter. “Their work has been supported through ESA’s long-running Basic Technology Research Programme, serving to investigate promising new ideas to help enable future missions.”

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

From ESA: “A mysterious ring of microwaves”

European Space Agency

06/06/2016
ESA and the Planck Collaboration

Fifty years ago, astronomers discovered a mystery. They called it Loop I. Today, we still have not fully resolved the mystery of how this giant celestial structure formed but we do now have the best image of it, thanks to ESA’s Planck satellite.

ESA/Planck

Loop I is a nearly circular formation that covers one third of the sky. In reality, it is probably a spherical ‘bubble’ that stretches to more than 100º across, making it wider than 200 full Moons. Its absolute size, however, is extremely uncertain because astronomers do not know how close it is to us: estimates to the centre of the bubble vary from 400 light-years to 25 000 light-years.

What they do know is that the structure shows up in many different wavelengths, from radio waves to gamma rays. Planck sees Loop I in microwaves. This image’s colours reflect the polarisation – the direction in which the microwaves are oscillating.

Our eyes are not sensitive to this information in the visible light, where we perceive only the intensity and colour. Planck, however, can detect all three of these characteristics in the microwaves it targets.

The microwaves detected by Planck are emitted by electrons that are being accelerated by the Galaxy’s magnetic field.

Loop I is most visible in the sky’s northern hemisphere. Astronomers refer to this portion as the north polar spur. It can be seen in this image as the yellow arc. This fades to purple and can be traced into the southern hemisphere, completing the circle. The blue band spanning the image horizontally is the Galactic Plane.

The most popular interpretation places Loop I close to us. If this is correct, it could be related to the ‘Scorpius–Centaurus OB Association’, a region of high-mass star formation that has been active for over 10 million years. Loop I could well be a supernova remnant, a giant bubble hollowed out by the explosion of stars in the OB association.

It is likely that the stars responsible for Loop I have long since dispersed, so what we see is the ‘smoke’ rather than the ‘fire’ of the explosions.

High-mass stars burn their nuclear fuel so quickly that they live only a few million years before exploding. As these titanic supernovas bloom, their blast waves carve bubbles in the surrounding gas. This compresses the Galaxy’s magnetic field into the bubble ‘walls’, making it stronger and more efficient at accelerating the electrons to produce the observed radiation.

Loop I could well be the combined super-bubble from a number of such cataclysms. As the electrons lose energy and diffuse into the wider Galaxy, so Loop I will eventually fade and disappear. This is likely to take a few million years.

If the loop is more distant, then it could conceivably be the result of an outburst from around the black hole at the centre of the Galaxy.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

From ESA: “Polarisation of the Cosmic Microwave Background: zoom”

European Space Agency

Credits: ESA and the Planck Collaboration

A visualisation of the polarisation of the Cosmic Microwave Background, or CMB, as detected by ESA’s Planck satellite on a small patch of the sky measuring 20º across.

CMB

Planck

The CMB is a snapshot of the oldest light in our Universe, imprinted on the sky when the Universe was just 380 000 years old. It shows tiny temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all future structure: the stars and galaxies of today.

A small fraction of the CMB is polarised – it vibrates in a preferred direction. This is a result of the last encounter of this light with electrons, just before starting its cosmic journey. For this reason, the polarisation of the CMB retains information about the distribution of matter in the early Universe, and its pattern on the sky follows that of the tiny fluctuations observed in the temperature of the CMB.

In this image, the colour scale represents temperature differences in the CMB, while the texture indicates the direction of the polarised light. The patterns seen in the texture are characteristic of ‘E-mode’ polarisation, which is the dominant type for the CMB.

For the sake of illustration, both data sets have been filtered to show mostly the signal detected on scales around 5º on the sky. However, fluctuations in both the CMB temperature and polarisation are present and were observed by Planck also on larger as well as smaller angular scales.

See the full article here .

Please help promote STEM in your local schools.

Stem Education Coalition

The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.