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  • richardmitnick 1:33 pm on October 7, 2019 Permalink | Reply
    Tags: "Scientists Observe Year-long Plateaus in Decline of Type Ia Supernova Light Curves", , , , CfA-Harvard Smithsonian Center for Astrophysics,   

    From Harvard-Smithsonian Center for Astrophysics: “Scientists Observe Year-long Plateaus in Decline of Type Ia Supernova Light Curves” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    October 7, 2019
    Amy Oliver, Public Affairs
    Fred Lawrence Whipple Observatory
    Center for Astrophysics | Harvard & Smithsonian
    +1 520-879-4406
    amy.oliver@cfa.harvard.edu

    1
    Hubble Space Telescope color composite of SN2013dy within its host galaxy. Credit: HST, Adam Riess, Or Graur

    2
    Hubble Space Telescope color composite of SN2018gv within its host galaxy. Credit: HST, Adam Riess, Or Graur

    Scientists at the Center for Astrophysics | Harvard & Smithsonian have announced the discovery that, contrary to previously accepted knowledge, Type Ia supernovae experience light curve decline plateaus, and lengthy ones at that, lasting up to a year.

    CfA scientist Or Graur first noticed strange light curve behaviors while studying late-time Type Ia supernovae in 2015, and this year confirmed light curve plateaus in Type Ia supernovae. “Most supernova research is conducted in the weeks or months immediately following an explosion, but we wanted to see how light curves behave at late times, around 500 to 1000 days after explosion,” said Graur. “Optical observations of SN2012gc in 2015 revealed a slowdown in the light curve as expected, but as we studied additional supernovae over time, it became apparent that other mechanisms were at play, so we started looking for patterns to explain what was going on.”

    To better understand the strange behavior, Graur teamed up with Adam Riess of The Johns Hopkins University and the Space Telescope Science Institute, and 2011 winner of the Nobel Prize in Physics, to study nearby supernovae using Riess’s already-set HST programs. “Even though these were all nearby supernovae, at these late times they were very faint. We needed Hubble’s resolving power to be able to tell them apart from other stars in their respective galaxies,” said Graur. “But what made the difference to our observations was that Adam’s programs on Hubble also had near-infrared data in the H-band. What started as a fishing expedition revealed a portion of time where the light curve is flat, and that period lasts for up to a year. That was a surprise. I didn’t expect to see that.”

    The idea of supernova light curve plateaus is not new to cosmology. Type IIP supernovae, which are born of the collapse and explosion of hydrogen-rich red super giants, commonly experience light curve plateaus roughly 100 days in length. Until the discovery of the Type Ia supernova light curve plateau, 100 days was considered a long-period plateau. Type Ia supernova light curve plateaus begin at between 150 and 500 days after explosion, and last approximately 350 days, or nearly a year.

    “Up until this moment, the only plateaus seen in any type of supernova were in Type IIP, and they were relatively short compared to what we’re seeing in our observations. This is only the second time we’ve ever seen a plateau like this in a supernova,” said Graur. “What we’re seeing is in stark contrast to what we’ve always believed about Type Ia supernovae and it’s going to impact the way we apply Type Ia light curves to cosmological models in the future.”

    The results of the study are published in Nature Astronomy. In addition to Graur—who also serves as a Research Associate at the American Museum of Natural History—and Riess, the study involved CfA scientist Arturo Avelino along with scientists Kate Maguire, Trinity College Dublin; Russell Ryan, Space Telescope Science Institute; Matt Nicholl, University of Edinburgh; Luke Shingles, Queens University Belfast; Ivo R. Seitenzahl, University of New South Wales Canberra; and, Robert Fisher, University of Massachusetts Dartmouth.

    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 Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 12:04 pm on August 15, 2019 Permalink | Reply
    Tags: , , , CfA-Harvard Smithsonian Center for Astrophysics, , , The idea of pair-instability supernovas has been around for decades, The supernova SN2016iet   

    From Harvard-Smithsonian Center for Astrophysics: “Scientists Observe the Explosion of a Monster Star Requiring New Supernova Mechanism” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    August 15, 2019
    Amy Oliver
    Public Affairs Officer
    Fred Lawrence Whipple Observatory
    Center for Astrophysics | Harvard & Smithsonian
    amy.oliver@cfa.harvard.edu
    +1 520-879-4406
    mobile: +1-801-783-9067

    CfA Whipple Observatory, located near Amado, Arizona on the slopes of Mount Hopkins, Altitude 2,606 m (8,550 ft)

    1
    Artist’s conception of the explosion of SN2016iet’s host star within a dense stellar environment. Credit: Joy Pollard/Gemini

    Scientists at the Center for Astrophysics | Harvard & Smithsonian have announced the discovery of the most massive star ever known to be destroyed by a supernova explosion, challenging known models of how massive stars die and providing insight into the death of the first stars in the universe.

    First noticed in November 2016 by the European Space Agency’s (ESA) Gaia satellite, three years of intensive follow up observations of the supernova SN2016iet revealed characteristics—incredibly long duration and large energy, unusual chemical fingerprints, and an environment poor in metals—for which there are no analogues in the existing astronomical literature.

    ESA/GAIA satellite

    “When we first realized how thoroughly unusual SN2016iet is my reaction was ‘whoa – did something go horribly wrong with our data?'” said Mr. Sebastian Gomez, Harvard University graduate student and lead author of the paper. “After a while we determined that SN2016iet is an incredible mystery, located in a previously uncatalogued galaxy one billion light years from Earth.”

    The team used a variety of telescopes, including the CfA | Harvard & Smithsonian’s MMT Observatory located at the Fred Lawrence Whipple Observatory in Amado, AZ, and the Magellan Telescopes at the Las Campanas Observatory in Chile to show that SN2016iet is different than the thousands of supernovas observed by scientists for decades.

    CfA U Arizona Fred Lawrence Whipple Observatory Steward Observatory MMT Telescope at the summit of Mount Hopkins near Tucson, Arizona, USA, Altitude 2,616 m (8,583 ft)

    Carnegie 6.5 meter Magellan Baade and Clay Telescopes located at Carnegie’s Las Campanas Observatory, Chile. over 2,500 m (8,200 ft) high

    “Everything about this supernova looks different—its change in brightness with time, its spectrum, the galaxy it is located in, and even where it’s located within its galaxy, said Dr. Edo Berger, Professor of Astronomy at Harvard University and an author on the paper. “We sometimes see supernovas that are unusual in one respect, but otherwise are normal; this one is unique in every possible way.”

    The observations and analysis show that SN2016iet began as an incredibly massive star 200 times the mass of Earth’s Sun that mysteriously formed in isolation roughly 54,000 light years from the center of its host dwarf galaxy. The star lost about 85 percent of its mass during a short life of only a few million years, all the way up to its final explosion and demise. The collision of the explosion-debris with the material shed in the final decade before explosion led to SN2016iet’s unusual appearance, providing scientists with the first strong case of a pair-instability supernova.

    “The idea of pair-instability supernovas has been around for decades,” said Berger. “But finally having the first observational example that puts a dying star in the right regime of mass, with the right behavior, and in a metal-poor dwarf galaxy is an incredible step forward. SN2016iet represents the way in which the most massive stars in the universe, including the first stars, die.”

    The team will continue to observe and study SN2016iet for years, watching for additional clues as to how it formed, and how it will evolve. “Most supernovas fade away and become invisible against the glare of their host galaxies within a few months. But because SN2016iet is so bright and so isolated we can study its evolution for years to come,” said Gomez. “These observations are already in progress and we can’t wait to see what other surprises this supernova has in store for us.”

    The results of the study are published in The Astrophysical Journal. In addition to Gomez and Berger, the study involved scientists from CfA | Harvard & Smithsonian—Peter K. Blanchard, V. Ashley Villar, Locke Patton, Joel Leja, and Griffin Hosseinzadeh; along with scientists from the University of Edinburgh—Matt Nicholl; Ohio University—Ryan Chornock; and, The Observatories of the Carnegie Institution for Science—Philip S. Cowperthwaite.

    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 Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 11:25 am on March 27, 2019 Permalink | Reply
    Tags: , , , , Big Bounce, CfA-Harvard Smithsonian Center for Astrophysics, ,   

    From Harvard-Smithsonian Center for Astrophysics: “What Happened Before the Big Bang?” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    CfA the Big Bounce before the Big Bang

    March 25, 2019

    Peter Reuell
    Harvard Staff Writer
    preuell@fas.harvard.edu

    Tyler Jump
    Public Affairs
    Center for Astrophysics | Harvard & Smithsonian
    +1 617-495-7462
    tyler.jump@cfa.harvard.edu

    Peter Edmonds
    Public Affairs
    Center for Astrophysics | Harvard & Smithsonian
    +1 617-571-7279
    pedmonds@cfa.harvard.edu

    A team of scientists has proposed a powerful new test for inflation, the theory that the universe dramatically expanded in size in a fleeting fraction of a second right after the Big Bang.

    Inflation

    4
    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:
    5

    Their goal is to give insight into a long-standing question: what was the universe like before the Big Bang?

    Although cosmic inflation is well known for resolving some important mysteries about the structure and evolution of the universe, other very different theories can also explain these mysteries. In some of these theories, the state of the universe preceding the Big Bang – the so-called primordial universe – was contracting instead of expanding, and the Big Bang was thus a part of a Big Bounce.

    To help decide between inflation and these other ideas, the issue of falsifiability – that is, whether a theory can be tested to potentially show it is false – has inevitably arisen. Some researchers, including Avi Loeb of the Center for Astrophysics | Harvard & Smithsonian (CfA) in Cambridge, Mass., have raised concerns about inflation, suggesting that its seemingly endless adaptability makes it all but impossible to properly test.

    “Falsifiability should be a hallmark of any scientific theory. The current situation for inflation is that it’s such a flexible idea, it cannot be falsified experimentally,” Loeb said. “No matter what value people measure for some observable attribute, there are always some models of inflation that can explain it.”

    Now, a team of scientists led by the CfA’s Xingang Chen, along with Loeb, and Zhong-Zhi Xianyu of the Physics Department of Harvard University, have applied an idea they call a “primordial standard clock” [see paper below] to the non-inflationary theories, and laid out a method that may be used to falsify inflation experimentally. The study appears in Physical Review Letters as an Editors’ Suggestion.

    In an effort to find some characteristic that can separate inflation from other theories, the team began by identifying the defining property of the various theories – the evolution of the size of the primordial universe.

    “For example, during inflation, the size of the universe grows exponentially,” Xianyu said. “In some alternative theories, the size of the universe contracts. Some do it very slowly, while others do it very fast.

    “The attributes people have proposed so far to measure usually have trouble distinguishing between the different theories because they are not directly related to the evolution of the size of the primordial universe,” he continued. “So, we wanted to find what the observable attributes are that can be directly linked to that defining property.”

    The signals generated by the primordial standard clock can serve such a purpose. That clock is any type of heavy elementary particle in the primordial universe. Such particles should exist in any theory and their positions should oscillate at some regular frequency, much like the ticking of a clock’s pendulum.

    The primordial universe was not entirely uniform. There were tiny irregularities in density on minuscule scales that became the seeds of the large-scale structure observed in today’s universe. This is the primary source of information physicists rely on to learn about what happened before the Big Bang. The ticks of the standard clock generated signals that were imprinted into the structure of those irregularities. Standard clocks in different theories of the primordial universe predict different patterns of signals, because the evolutionary histories of the universe are different.

    “If we imagine all of the information we learned so far about what happened before the Big Bang is in a roll of film frames, then the standard clock tells us how these frames should be played,” Chen explained. “Without any clock information, we don’t know if the film should be played forward or backward, fast or slow, just like we are not sure if the primordial universe was inflating or contracting, and how fast it did so. This is where the problem lies. The standard clock put time stamps on each of these frames when the film was shot before the Big Bang, and tells us how to play the film.”

    The team calculated how these standard clock signals should look in non-inflationary theories, and suggested how they should be searched for in astrophysical observations. “If a pattern of signals representing a contracting universe were found, it would falsify the entire inflationary theory,” Xianyu said.

    The success of this idea lies with experimentation. “These signals will be very subtle to detect,” Chen said, “and so we may have to search in many different places. The cosmic microwave background radiation is one such place, and the distribution of galaxies is another. We have already started to search for these signals and there are some interesting candidates already, but we need more data.”

    CMB per ESA/Planck

    Cosmic Background Radiation per Planck

    ESA/Planck 2009 to 2013

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

    Many future galaxy surveys, such as US-lead LSST, European’s Euclid and the newly approved project by NASA, SphereX, are expected to provide high quality data that can be used toward the goal.

    LSST


    LSST Camera, built at SLAC



    LSST telescope, currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.


    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    ESA/Euclid spacecraft

    NASA’s SPHEREx Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer depiction

    This paper is available in Physical Review Letters. A related previous work can be found in Journal of Cosmology and Astroparticle Physics

    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 Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 2:46 pm on March 22, 2019 Permalink | Reply
    Tags: "What Ionized the Universe?", , , , CfA-Harvard Smithsonian Center for Astrophysics, , , Reionization era and first stars- Caltech   

    From Harvard-Smithsonian Center for Astrophysics: “What Ionized the Universe?” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    1
    A NASA/ESA Hubble Space Telescope image of the rapidly fading visible-light fireball from a gamma-ray burst (GRB) in a distant galaxy. A new study used the spectra of 140 GRB afterglows to estimate the amount of ionizing radiation from massive stars that escapes from galaxies to ionize the intergalactic medium, and finds the surprising result that it is very small. Andrew Fruchter (STScI) and NASA/ESA

    The sparsely distributed hot gas that exists in the space between galaxies, the intergalactic medium, is ionized. The question is, how? Astronomers know that once the early universe expanded and cooled enough, hydrogen (its main constituent) recombined into neutral atoms. Then, once newly formed massive stars began to shine in the so-called “era of reionization,” their extreme ultraviolet radiation presumably ionized the gas in processes that continue today.

    Reionization era and first stars, Caltech

    One of the key steps, however, is not well understood, namely the extent to which the stellar ionizing radiation escapes from the galaxies into the IGM. Only if the fraction escaping was high enough during the era of reionization could starlight have done the job, otherwise some other significant source of ionizing radiation is required. That might imply the existence of an important population of more exotic objects like faint quasars, X-ray binary stars, or perhaps even decaying/annihilating particles.

    Direct studies of extreme ultraviolet light are difficult because the neutral gas absorbs it very strongly. Because the universe is expanding, the spectrum absorbed covers more and more of the optical range with distance until optical observations of cosmologically remote galaxies are essentially impossible. CfA astronomer Edo Berger joined a large team of colleagues to estimate the amount of absorbing gas by looking at the spectra of gamma-ray burst (GRB) afterglows. GRBs are very bright bursts of radiation produced when the core of a massive star collapses. They are bright enough that when their radiation is absorbed in narrow spectral features by gas along the line-of sight, those features can be measured and used to calculate the amount of absorbing atomic hydrogen. That number can then be directly converted into an escape fraction for the ultraviolet light of the associated galaxy. Although a single observation of a GRB in one galaxy does not provide a robust measure, a sample of GRBs is thought to be able to provide a representative measure across all sightlines to massive stars.

    The astronomers carefully measured the spectra of 140 GRB afterglows in galaxies ranging as far away as epochs slightly less than one billion years after the big bang. They find a remarkably small escape fraction – less than about 1% of the ionizing photons make it out into the intergalactic medium. The dramatic result finds that stars provide only a small contribution to the ionizing radiation budget in the universe from that early period until today, not even in galaxies actively making new stars. The authors discuss possible reasons why GRBs might not provide an accurate measure of the absorption, although none is particularly convincing. The result needs confirmation and additional measurements, but suggests that a serious reconsideration of the ionizing budget of the intergalactic medium of the universe is needed.

    Science paper:
    “The Fraction of Ionizing Radiation from Massive Stars That Escapes to the Intergalactic Medium,” N. R. Tanvir et al.
    MNRAS

    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 Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 8:07 am on March 9, 2019 Permalink | Reply
    Tags: A "hot Jupiter"-like planet, CfA-Harvard Smithsonian Center for Astrophysics, First confirmed exoplanet Kepler-1658 b,   

    From Harvard-Smithsonian Center for Astrophysics: “Kepler Space Telescope’s First Exoplanet Candidate Confirmed, Ten Years After Launch” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    March 5, 2019

    Tyler Jump
    Public Affairs
    Center for Astrophysics | Harvard & Smithsonian
    +1 617-495-7462
    tyler.jump@cfa.harvard.edu

    Ashley Chontos
    +1 347-443-2505 (cell)
    achontos@hawaii.edu

    Daniel Huber
    +1 808-773-2898 (cell)
    huberd@hawaii.edu

    1

    An international team of astronomers, led by University of Hawai’i graduate student Ashley Chontos, announced the confirmation of the first exoplanet candidate identified by NASA’s Kepler Mission. The result was presented today at the fifth Kepler/K2 Science Conference held in Glendale, CA.

    NASA/Kepler Telescope, and K2 March 7, 2009 until November 15, 2018

    Launched almost exactly 10 years ago, the Kepler Space Telescope has discovered thousands of exoplanets using the transit method – small dips in a star’s brightness as planets cross in front of the star.

    Planet transit. NASA/Ames

    Because other phenomena can mimic transits, Kepler data reveal planet candidates, but further analysis is required to confirm them as genuine planets.

    Despite being the very first planet candidate discovered by NASA’s Kepler Space Telescope, the object now known as Kepler-1658 b had a rocky road to confirmation. The initial estimate of the size of the planet’s host star was incorrect, so the sizes of both the star and Kepler-1658 b were vastly underestimated. It was later set aside as a false positive when the numbers didn’t quite make sense for the effects seen on its star for a body of that size. Fortuitously, Chontos’ first year graduate research project, which focused on re-analyzing Kepler host stars, happened at just the right time.

    “Our new analysis, which uses stellar sound waves observed in the Kepler data to characterize the host star, demonstrated that the star is in fact three times larger than previously thought. This in turn means that the planet is three times larger, revealing that Kepler-1658 b is actually a hot Jupiter-like planet,” said Chontos. With this refined analysis, everything pointed to the object truly being a planet, but confirmation from new observations was still needed.

    “We alerted Dave Latham (a senior astronomer at the Smithsonian Astrophysical Observatory, and co-author on the paper) and his team collected the necessary spectroscopic data to unambiguously show that Kepler-1658 b is a planet,” said Dan Huber, co-author and astronomer at the University of Hawai’i. “As one of the pioneers of exoplanet science and a key figure behind the Kepler mission, it was particularly fitting to have Dave be part of this confirmation.”

    Kepler-1658 is 50% more massive and three times larger than the Sun. The newly confirmed planet orbits at a distance of only twice the starʻs diameter, making it one of the closest-in planets around a more evolved star – one that resembles a future version of our Sun. Standing on the planet, the star would appear 60 times larger in diameter than the Sun as seen from Earth.

    Planets orbiting evolved stars similar to Kepler-1658 are rare, and the reason for this absence is poorly understood. The extreme nature of the Kepler-1658 system allows astronomers to place new constraints on the complex physical interactions that can cause planets to spiral into their host stars. The insights gained from Kepler-1658b suggest that this process happens slower than previously thought, and therefore may not be the primary reason for the lack of planets around more evolved stars.

    “Kepler-1658 is a perfect example of why a better understanding of host stars of exoplanets is so important,” said Chontos. “It also tells us that there are many treasures left to be found in the Kepler data.”

    Paper preprint (Chontos et al., accepted for publication in AJ):
    http://www.ifa.hawaii.edu/~dhuber/docs/kepler1658-accepted.pdf

    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 Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 9:23 am on October 19, 2018 Permalink | Reply
    Tags: , , , , CfA-Harvard Smithsonian Center for Astrophysics, Cosmic microwave background radiation. Stephen Hawking Center for Theoretical Cosmology U Cambridge, , Measuring the Age of the Universe   

    From Harvard-Smithsonian Center for Astrophysics: “Measuring the Age of the Universe” 

    Harvard Smithsonian Center for Astrophysics


    From Harvard-Smithsonian Center for Astrophysics

    Inflationary Universe. NASA/WMAP


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

    1

    October 17, 2018

    Tyler Jump
    Public Affairs
    Harvard-Smithsonian Center for Astrophysics
    +1 617-495-7462
    tyler.jump@cfa.harvard.edu

    The single most important puzzle in today’s cosmology (the study of the universe as a whole) can be summarized in one question: How old is it? For nearly a century — since the discoveries by Einstein, Hubble, LeMaitre and others led to the big bang model of creation — we have known the answer. It is about 13.8 billion years old (using current data). But in just the past decade the two alternative measurement methods have narrowed the uncertainties in their results to a few percent to reach a stunning conclusion: The two do not agree with each other. Since both methods are based on exactly the same model and equations, our understanding of the universe is somehow wrong — perhaps fundamentally so.

    Enter the most exciting technical achievement in astronomy for decades, the detection of gravitational waves (GW) caused by the mergers of black holes or neutron stars with each other by LIGO-Virgo, soon to be joined by other similar GW detection facilities in other countries.


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger

    ESA/eLISA the future of gravitational wave research

    1
    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    The solution to the cosmological dilemma is likely to be settled soon by these instruments according to a new Nature paper by Hsin-Yu Chen of Harvard’s Black Hole Initiative, Maya Fishbach and Daniel E. Holz of the University of Chicago. The authors describe how upcoming detections of GW will have enough statistics to settle the question of age, forcing either one or the other (or perhaps even both) methods to re-think their basic understanding, or possibly even forcing a new variation of the When and How of the creation.

    The two currently conflicting methods rely on observations of vastly different parts of the cosmic order. The first method measures and models the cosmic microwave background radiation (the CMBR method) produced by the universe when, after about 380,000 years, it cooled down and allowed neutral hydrogen atoms to form and light to propagate without scattering.

    Cosmic microwave background radiation. Stephen Hawking Center for Theoretical Cosmology U Cambridge

    The second method, the one used by Hubble and interpreted by LeMaitre, measures galaxies. This method takes advantage of the expansion of the universe to correlate a galaxy’s distance with its recession velocity, the so-called Hubble-LeMaitre Law, and to derive the Hubble-LeMaitre parameter which describes how long these galaxies have been in motion, related to the age of the universe. All astronomers today rely on this expression to obtain the distances to galaxies too far away to measure directly but whose velocities are easily seen in the Doppler shifts (the redshift) of their spectral lines. While the most familiar use of the parameter is to obtain the age of the universe, its value influences all the other parameters in the cosmological model (about nine of them) which together also explain the shape and expansion character of the universe.

    Hubble calibrated his set of distances with nearby galaxies, but today we are capable of seeing galaxies so remote their light has been traveling to us for over ten billion years. Supernovae (SN), or at least those whose brightness is thought to be well understood, can be seen at great distances and so have been used to bootstrap the distance scale calibration outward from Hubble’s original neighborhood. There are subtle complexities in SN that are not well understood, however, resulting in an uncertainty that has been getting smaller as our understanding of them has improved. Today those uncertainties are small enough to exclude the comparable result from CMBR measurements.

    The GW method of distance measurement is completely independent of both galaxy and CMBR methods. General relativity alone provides the intrinsic strength of the GW signal from its peculiar ringing signal, and its observed strength provides a direct measure of its distance. (The velocity information is obtained from the redshift of atomic lines in the host galaxy). Dr. Chen and her colleagues simulated 90,000 merger events in binary black hole or binary neutron star systems, including the host galaxy properties, and included likely selection effects and other complexities. The GW strength, for example, depends on our viewing angle of inclination of the merger, while the number of events to expect is only roughly constrained by the detections so far. Including these and similar uncertainties, the astronomers conclude that within the next five years it is likely that the GW method will fix the Hubble-LeMaitre parameter (that is, the age of the universe) to a precision of 2%, and to 1% in a decade, good enough to exclude one or even both of the other methods. The new paper’s conclusions are bolstered by the fact that one paper using the GW method to estimate an age has already appeared. It had an uncertainty of between 11.9 billion years to 15.7 billion years, spanning both the current CMBR and galaxy values. But the new paper shows that in five years another roughly fifty GW events will be detected and these should be enough to settle the matter … and usher in a new era in precision cosmology.

    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 Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 3:24 pm on April 22, 2018 Permalink | Reply
    Tags: , , , , CfA-Harvard Smithsonian Center for Astrophysics, , Is Dark Matter Made of Primordial Black Holes?   

    From Center For Astrophysics: “Is Dark Matter Made of Primordial Black Holes?” 

    Harvard Smithsonian Center for Astrophysics


    Center For Astrophysics

    1
    The dwarf irregular galaxy IC1613. Astronomers wondering whether primordial black holes might compose the dark matter in the universe suggest that the shapes of faint dwarf galaxies with dark matter halos might reveal the answer. NASA/JPL-Caltech/SSC

    Astronomers studying the motions of galaxies and the character of the cosmic microwave background radiation came to realize in the last century that most of the matter in the universe was not visible.

    Cosmic Background Radiation per Planck

    ESA/Planck 2009 to 2013

    About 84% of the matter in the cosmos is dark matter, much of it located in halos around galaxies.

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

    Dark matter halo. Image credit: Virgo consortium / A. Amblard / ESA

    Milky Way Dark Matter Halo Credit ESO L. Calçada

    It was dubbed dark matter because it does not emit light, but it is also mysterious: it is not composed of atoms or their usual constituents like electrons and protons.

    Meanwhile, astronomers have observed the effects of black holes and recently even detected gravitational waves from a pair of merging black holes.

    Artist’s conception of two merging black holes similar to those detected by LIGO Credit LIGO-Caltech/MIT/Sonoma State /Aurore Simonnet

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Black holes usually are formed in the explosive death of massive stars, a process that can take many hundreds of millions of years as a star coalesces from ambient gas, evolves and finally dies. Some black holes are inferred to exist in the early universe, but there is probably is not enough time in the early universe for the normal formation process to occur. Some alternative methods have been proposed, like the direct collapse of primordial gas or processes associated with cosmic inflation, and many of these primordial black holes could have been made.

    CfA astronomer Qirong Zhu led a group of four scientists investigating the possibility that today’s dark matter is composed of primordial black holes, following up on previously published suggestions. If galaxy halos are made of black holes, they should have a different density distribution than halos made of exotic particles. There are some other differences as well – black hole halos are expected to form earlier in a galaxy’s evolution than do some other kinds of halos. The scientists suggest that looking at the stars in the halos of faint dwarf galaxies can probe these effects because dwarf galaxies are small and faint (they shine with a mere few thousand solar luminosities) where slight effects can be more easily spotted. The team ran a set of computer simulations to test whether dwarf galaxy halos might reveal the presence of primordial black holes, and they find that they could: interactions between stars and primordial halo black holes should slightly alter the sizes of the stellar distributions. The astronomers also conclude that such black holes would need to have masses between about two and fourteen solar masses, right in the expected range for these exotic objects (although smaller than the black holes recently spotted by gravitational wave detectors) and comparable to the conclusions of other studies. The team emphasizes, however, that all the models are still inconclusive and the nature of dark matter remains elusive.

    Science paper:
    Qirong Zhu, Eugene Vasiliev, Yuexing Li, and Yipeng Jing,
    Primordial Black Holes as Dark Matter: Constraints from Compact Ultra-faint Dwarfs
    MNRAS

    See the full article here .

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    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 3:55 pm on March 22, 2018 Permalink | Reply
    Tags: , , , CfA-Harvard Smithsonian Center for Astrophysics, , , Measuring White Dwarf Masses with Gravitational Lensing   

    From CfA: “Measuring White Dwarf Masses with Gravitational Lensing” 

    Harvard Smithsonian Center for Astrophysics


    Center For Astrophysics

    3.16.18

    Measuring the mass of a celestial body is one of the most challenging tasks in observational astronomy. The most successful method uses binary systems because the orbital parameters of the system depend on the two masses. In the case of black holes, neutron stars, and white dwarfs, the end states of stellar evolution, many are isolated objects, and most of them are also very faint. As a result, astronomers still do not know the distribution of their masses. They are of great interest, however, because they participate in dramatic events like the accretion of material and emission of energetic radiation, or in mergers that can result in gravitational waves, gamma-ray bursts, or Type Ia supernovae, all of which depend on an object’s mass.

    CfA astronomers Alexander Harding, Rosanne Di Stefano, and Claire Baker and three colleagues propose a new method for determining the masses of isolated compact objects: gravitational lensing.

    Gravitational Lensing NASA/ESA

    The path of a light beam will be bent by the presence of mass, an effect calculated by General Relativity. A massive body will act like a lens to distort the image of an object seen behind it when the two are close to being aligned along our line-of-sight, and the specifics of the image distortions will depend on the body’s mass. The astronomers describe the prospects for predicting lensing events generated by nearby compact objects as their motions take them across the field of background stars.

    The team estimates that the nearby population of compact objects contains about 250 neutron stars, 5 black holes, and about 35,000 white dwarf stars suitable for this study. Knowing the general motions of the white dwarfs across the sky, they obtain a statistical estimate of about 30-50 lensing events per decade that could be spotted by Hubble, ESA’s Gaia mission, or NASA’s new JWST telescope. The next step in this effort is to use ongoing stellar surveys like that of Gaia to refine the bodies’ positions and motions to be able to predict specifically which objects to monitor for lensing.

    NASA/ESA Hubble Telescope

    ESA/GAIA satellite

    NASA/ESA/CSA Webb Telescope annotated

    Science paper:
    Predicting gravitational lensing by stellar remnants , MNRAS

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 2:08 pm on January 12, 2018 Permalink | Reply
    Tags: Accelerating light beams in curved space, Acceleration, CfA-Harvard Smithsonian Center for Astrophysics, , , ,   

    From Technion, Harvard and CfA via phys.org: “Accelerating light beams in curved space” 

    Technion bloc

    Technion

    Harvard University

    Harvard University

    Harvard Smithsonian Center for Astrophysics

    Center For Astrophysics

    phys.org

    January 12, 2018
    Lisa Zyga

    1
    The accelerating light beam propagates on a nongeodesic trajectory, rather than the geodesic trajectory taken by a non-accelerating beam. Credit: Patsyk et al. ©2018 American Physical Society

    By shining a laser along the inside shell of an incandescent light bulb, physicists have performed the first experimental demonstration of an accelerating light beam in curved space. Rather than moving along a geodesic trajectory (the shortest path on a curved surface), the accelerating beam bends away from the geodesic trajectory as a result of its acceleration.

    Previously, accelerating light beams have been demonstrated on flat surfaces, on which their acceleration causes them to follow curved trajectories rather than straight lines. Extending accelerating beams to curved surfaces opens the doors to additional possibilities, such as emulating general relativity phenomena (for example, gravitational lensing) with optical devices in the lab.

    The physicists, Anatoly Patsyk, Miguel A. Bandres, and Mordechai Segev at the Technion – Israel Institute of Technology, along with Rivka Bekenstein at Harvard University and the Harvard-Smithsonian Center for Astrophysics, have published a paper on the accelerating light beams in curved space in a recent issue of Physical Review X.

    “This work opens the doors to a new avenue of study in the field of accelerating beams,” Patsyk told Phys.org. “Thus far, accelerating beams were studied only in a medium with a flat geometry, such as flat free space or slab waveguides. In the current work, optical beams follow curved trajectories in a curved medium.”

    In their experiments, the researchers first transformed an ordinary laser beam into an accelerating one by reflecting the laser beam off of a spatial light modulator. As the scientists explain, this imprints a specific wavefront upon the beam. The resulting beam is both accelerating and shape-preserving, meaning it doesn’t spread out as it propagates in a curved medium, like ordinary light beams would do. The accelerating light beam is then launched into the shell of an incandescent light bulb, which was painted to scatter light and make the propagation of the beam visible.

    When moving along the inside of the light bulb, the accelerating beam follows a trajectory that deviates from the geodesic line. For comparison, the researchers also launched a nonaccelerating beam inside the light bulb shell, and observed that that beam follows the geodesic line. By measuring the difference between these two trajectories, the researchers could determine the acceleration of the accelerating beam.

    3
    (a) Experimental setup, (b) propagation of the green beam inside of the red shell of an incandescent light bulb, and (c) photograph of the lobes of the accelerating beam. Credit: Patsyk et al. ©2018 American Physical Society

    Whereas the trajectory of an accelerating beam on a flat surface is determined entirely by the beam width, the new study shows that the trajectory of an accelerating beam on a spherical surface is determined by both the beam width and the curvature of the surface. As a result, an accelerating beam may change its trajectory, as well as periodically focus and defocus, due to the curvature.

    The ability to accelerate light beams along curved surfaces has a variety of potential applications, one of which is emulating general relativity phenomena.

    “Einstein’s equations of general relativity determine, among other issues, the evolution of electromagnetic waves in curved space,” Patsyk said. “It turns out that the evolution of electromagnetic waves in curved space according to Einstein’s equations is equivalent to the propagation of electromagnetic waves in a material medium described by the electric and magnetic susceptibilities that are allowed to vary in space. This is the foundation of emulating numerous phenomena known from general relativity by the electromagnetic waves propagating in a material medium, giving rise to the emulating effects such as gravitational lensing and Einstein’s rings, gravitational blue shift or red shift, which we have studied in the past, and much more.”

    The results could also offer a new technique for controlling nanoparticles in blood vessels, microchannels, and other curved settings. Accelerating plasmonic beams (which are made of plasma oscillations instead of light) could potentially be used to transfer power from one area to another on a curved surface. The researchers plan to further explore these possibilities and others in the future.

    “We are now investigating the propagation of light within the thinnest curved membranes possible—soap bubbles of molecular thickness,” Patsyk said. “We are also studying linear and nonlinear wave phenomena, where the laser beam affects the thickness of the membrane and in return the membrane affects the light beam propagating within it.”

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 3:15 pm on November 3, 2017 Permalink | Reply
    Tags: , CfA-Harvard Smithsonian Center for Astrophysics, ,   

    From CfA: “A New Kind of Quantum Computer” 

    Harvard Smithsonian Center for Astrophysics


    Center For Astrophysics

    November 3, 2017

    1
    A photograph of Google’s 1000+ qubit computer chip under development. CfA scientists and their colleagues have proposed a new way to use photons of light instead of silicon chips as qubits, opening the door to new technologies. WIRED

    Quantum mechanics incorporates some very non-intuitive properties of matter. Quantum superposition, for example, allows an atom to be simultaneously in two different states with its spin axis pointed both up and down, or combinations in between. A computer that uses quantum mechanical manipulation of atoms or particles therefore has many more possible options than a conventional one that works with “zeros” and “ones” and has only two choices, called bits. A quantum computer’s memory uses instead what are called quantum bits – qubits – and each qubit can be in a superposition of these two states. As a result, theoretical physicists estimate a quantum computer with only about one hundred of these qubits could in principle exceed the computing power of the powerful current classical computers. Building a quantum computer is therefore one of the main technological goals in modern physics and astrophysics.

    CfA physicist Hannes Pichler, of the CfA’s Institute for Theoretical Atomic, Molecular and Optical Physics (ITAMP), and three colleagues have proposed a new way to build a quantum computer using just a single atom. Light quanta (photons) can be used as information carriers and act as qubits, but to use them in a quantum computer they must interact with each other. Under normal conditions, however, light does not interact with itself and so the challenge is to create correlations between them. The key idea of their new paper is to allow light photons from an atom to interact with their own mirror image reflections Photons that the atom emits are reflected by the mirror and can interact again with the atom but with a very slight time delay. That delay, the scientists show, results in the combined waveform of the photons being so complex that in principle any quantum computation can be achieved by simply measuring the emitted photons.

    The theoretical discovery is not only a conceptual breakthrough in quantum optics and information, it opens the door to new technology. In particular, the proposed single atom setup is appealing since it minimizes the resources needed and relies only on elements that have already been demonstrated in state-of the-art experiments.

    Science paper:
    Universal Photonic Quantum Computation via Time-Delayed Feedback, PNAS

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
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