Tagged: Gravitational Lensing Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 5:17 pm on September 18, 2017 Permalink | Reply
    Tags: , , , , , Gravitational Lensing, , , Polarization of the waves, , sSupport for the idea that galaxy magnetic fields are generated by a rotating dynamo effect similar to the process that produces the Sun’s magnetic field, VLA Reveals Distant Galaxy’s Magnetic Field   

    From NRAO: “VLA Reveals Distant Galaxy’s Magnetic Field” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    August 28, 2017

    Artist’s conception of gravitational lens arrangement that allowed astronomers to measure galaxy’s magnetic field.
    Credit: Bill Saxton, NRAO/AUI/NSF; NASA, Hubble Heritage Team, (STScI/AURA), ESA, S. Beckwith (STScI). Additional Processing: Robert Gendler

    With the help of a gigantic cosmic lens, astronomers have measured the magnetic field of a galaxy nearly five billion light-years away. The achievement is giving them important new clues about a problem at the frontiers of cosmology — the nature and origin of the magnetic fields that play an important role in how galaxies develop over time.

    The scientists used the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) to study a star-forming galaxy that lies directly between a more-distant quasar and Earth. The galaxy’s gravity serves as a giant lens, splitting the quasar’s image into two separate images as seen from Earth. Importantly, the radio waves coming from this quasar, nearly 8 billion light-years away, are preferentially aligned, or polarized.

    “The polarization of the waves coming from the background quasar, combined with the fact that the waves producing the two lensed images traveled through different parts of the intervening galaxy, allowed us to learn some important facts about the galaxy’s magnetic field,” said Sui Ann Mao, Minerva Research Group Leader for the Max Planck Institute for Radio Astronomy in Bonn, Germany.

    Magnetic fields affect radio waves that travel through them. Analysis of the VLA images showed a significant difference between the two gravitationally-lensed images in how the waves’ polarization was changed. That means, the scientists said, that the different regions in the intervening galaxy affected the waves differently.

    “The difference tells us that this galaxy has a large-scale, coherent magnetic field, similar to those we see in nearby galaxies in the present-day universe,” Mao said. The similarity is both in the strength of the field and in its arrangement, with magnetic field lines twisted in spirals around the galaxy’s rotation axis.

    Since this galaxy is seen as it was almost five billion years ago, when the universe was about two-thirds of its current age, this discovery provides an important clue about how galactic magnetic fields are formed and evolve over time.

    “The results of our study support the idea that galaxy magnetic fields are generated by a rotating dynamo effect, similar to the process that produces the Sun’s magnetic field,” Mao said. “However, there are other processes that might be producing the magnetic fields. To determine which process is at work, we need to go still farther back in time — to more distant galaxies — and make similar measurements of their magnetic fields,” she added.

    “This measurement provided the most stringent tests to date of how dynamos operate in galaxies,” said Ellen Zweibel from the University of Wisconsin-Madison.

    Magnetic fields play a pivotal role in the physics of the tenuous gas that permeates the space between stars in a galaxy. Understanding how those fields originate and develop over time can provide astronomers with important clues about the evolution of the galaxies themselves.

    Mao and her colleagues are reporting their results in the journal Nature Astronomy.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (VLBA)*.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).



    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

    And the future Expanded Very Large Array (EVLA).

  • richardmitnick 12:44 pm on August 21, 2017 Permalink | Reply
    Tags: , , , , , Gravitational Lensing   

    From astrobites: “Sneaky pete baryons in gravitational lensing” 

    Astrobites bloc


    Aug 21, 2017
    Suk Sien Tie

    Title: Flux-ratio anomalies from discs and other baryonic structures in the Illustris simulation
    Authors: Jen-Wei Hsueh, Giulia Despali, Simona Vegetti et al.
    First Author’s Institution: University of California, Davis

    Status: Submitted to MNRAS, open access

    When a photon perilously escapes being engulfed by gases in its galaxy, it embarks on a long journey to reach our telescopes. Along the way, the combined gravitational field of nearby galaxies and galaxy clusters lures the photon away from sticking to a straight path. Occasionally, its path gets very bent when it passes very close to a galaxy, so much so that when the photon reaches our telescope, we see multiple images of the galaxy where the photon originates. This phenomenon of light bending due to the gravity of matter is known as gravitational lensing.

    Gravitational Lensing NASA/ESA

    As you gaze at the Sun later today during the solar eclipse, remember Albert Einstein, Sir Arthur Eddington, and gravitational lensing. Nearly a century ago on May 29, 1919 when the Sun was completely eclipsed by the Moon, on the west coast of Africa and Brazil, Sir Arthur Eddington and his team proved Einstein’s theory of general relativity. On the day of the eclipse, the Sun was destined to pass by the Hyades cluster, and the darkness that ensued cause the stars to be visible. Eddington and his team measured the stars to have shifted in positions due to the Sun’s gravitational field by the amounts predicted by Einstein. This was also the first observation of gravitational lensing.

    In the context of today’s paper, gravitational lensing is a tool to detect dark matter substructures in the halo of the lensing galaxy. Dark matter is that mysterious stuff that makes up nearly 85% of the Universe mass, does not emit light, and interacts only through gravity. The ratio of fluxes between any pair of lensed images is sensitive to the underlying mass distribution of the lens galaxy. In the absence of dark matter substructures, the flux ratios of the images are well predicted using a smooth lens model. But it does not work as well if dark matter substructures are present, resulting in anomalous flux ratios. Hence, flux ratio anomaly is a telltale sign of dark matter.

    Or is it?

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    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.

  • richardmitnick 4:20 pm on July 27, 2017 Permalink | Reply
    Tags: , , , , , , Gravitational Lensing   

    From CfA: “Mapping Dark Matter” 

    Harvard Smithsonian Center for Astrophysics

    Center For Astrophysics

    July 21, 2017 [Not making it into social media, but I need the work.]

    Abell 2744, a cluster of galaxies whose dark matter halo has imaged more distant galaxies as seen in this Hubble Space Telescope image. Astronomers have compared the image to simulations of dark matter lensing and found excellent agreement, indicating that that current models of dark matter behavior on the large scale are quite good. NASA/ESA/Hubble.

    About eighty-five percent of the matter in the universe is in the form of dark matter, whose nature remains a mystery. The rest of the matter in the universe is of the kind found in atoms. Astronomers studying the evolution of galaxies in the universe find that dark matter exhibits gravity and, because it is so abundant, it dominates the formation of large-scale structures in the universe like clusters of galaxies. Dark matter is hard to observe directly, needless to say, and it shows no evidence of interacting with itself or other matter other than via gravity, but fortunately it can be traced by modeling sensitive observations of the distributions of galaxies across a range of scales.

    Galaxies generally reside at the centers of vast clumps of dark matter called haloes because they surround the clusters of 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

    Gravitational lensing of more distant galaxies by dark matter haloes offers a particularly unique and powerful probe of the detailed distribution of dark matter.

    So-called strong gravitational lensing creates highly distorted, magnified and occasionally multiple images of a single source; so-called weak lensing results in modestly yet systematically deformed shapes of background galaxies that can also provide robust constraints on the distribution of dark matter within the clusters.

    Gravitational Lensing NASA/ESA

    Weak gravitational lensing HST

    CfA astronomers Annalisa Pillepich and Lars Hernquist and their colleagues compared gravitationally distorted Hubble images of the galaxy cluster Abell 2744 and two other clusters with the results of computer simulations of dark matter haloes. They found, in agreement with key predictions in the conventional dark matter picture, that the detailed galaxy substructures depend on the dark matter halo distribution, and that the total mass and the light trace each other. They also found a few discrepancies: the radial distribution of the dark matter is different from that predicted by the simulations, and the effects of tidal stripping and friction in galaxies are smaller than expected, but they suggest these issues might be resolved with more precise simulations. Overall, however, the standard model of dark matter does an excellent and reassuring job of describing galaxy clustering.

    Science paper:
    Mapping Substructure in the HST Frontier Fields Cluster Lenses and in Cosmological Simulations 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 2:52 pm on July 16, 2017 Permalink | Reply
    Tags: , , , Gravitational Lensing, How to Weigh a Star,   

    From Optics & Photonics: “How to Weigh a Star” 

    Optics & Photonics

    08 June 2017
    Stewart Wills

    Astronomers used the superior angular resolution of the Hubble Space Telescope’s Wide Field Camera 3 to assess the gravitational bending of light from a background star (small object in picture), about 5,000 light years away, by the much closer and brighter white-dwarf star Stein 2051B (larger object), 17 light years away. [Image: NASA, ESA, and K. Sahu (STScI)]

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble WFC3

    With excitement continuing to build over the next year’s planned launch of the James Webb Space Telescope, it’s easy to forget that its predecessor—the Hubble Space Telescope (HST), originally put into Earth orbit more than 27 years ago—still has some great science left to do.

    NASA/ESA/CSA Webb Telescope annotated

    The latest evidence: researchers have used the superior angular resolution of the HST’s Wide Field Camera 3 to directly determine, through the gravitational bending of light, the mass of a white-dwarf star 17 light years away (http://science.sciencemag.org/content/early/2017/06/06/science.aal2879).

    Radio galaxies gravitationally lensed by a very large foreground galaxy cluster Hubble

    Stellar lenses and “Einstein rings”

    What is now called “gravitational microlensing” was one of the most famous predictions of Einstein’s general theory of relativity. Under that theory of gravity, massive bodies such as stars actually deform the space around them; as a result, the theory predicts that the spatial warping could deflect light from distant stars around such a body. That prediction, made in 1915, was borne out four years later in a celebrated experiment by the British astronomer Arthur Eddington, who measured the deflection of a background star’s light by the sun’s gravity during a total solar eclipse.

    In a 1936 gloss [Science]on his original theory in the journal Science, Einstein noted “the results of a little calculation which I had made” on the lens-like effects of stars. If two stars were lined up precisely, he suggested, the observer would in principle perceive, because of the bending of the light from the far star by the nearer one, a “luminius [sic] circle” of a predictable angular radius around the closer star—a phenomenon that came to be called an “Einstein ring.”

    Einstein himself blithely noted that “of course, there is no hope of observing this phenomenon directly,” given that the chances of such alignment are remote in themselves, and because the angular deflection of light by a star outside of our solar system “will defy the resolving power of our instruments.” The most one could hope to observe, he wrote, would be an increase in the apparent brightness of the closer of the two stars.

    The gravity of a white dwarf star warps space and bends the light of a distant star behind it. [Image: NASA, ESA, and A. Feild (STScI)]

    Subtle signal

    Some eighty years later, scientists did have an instrument with potentially sufficient resolving power, the HST. But they still needed to find a pair of stars with the right alignment at the right time.

    To do so, researchers in the United States, Canada, and the United Kingdom—led by Kailash Sahu of the Space Telescope Science Institute (STScI) in Baltimore, Md., USA—computationally scoured a catalog of more than 5,000 nearby stars. They looked for candidates that had particularly rapid apparent motions in the sky, and that thus might have a better shot at lining up in the right way with a more distant star. They settled on the white-dwarf star called Stein 2051B, around 17 light years from earth. They then observed Stein 2051B (using the HST’s Wide Field Camera 3) seven times over the course of two years to assess its gravitational effect on light from a specific, much more distant background star around 5,000 light years away.

    Even with the HST’s superior resolving power, that effect was tough to see; Stein 2015B appears about 400 times brighter to an Earth observer than the background star, and the lensing effect was expected to be around three orders of magnitude smaller than the one observed by Eddington during the 1919 eclipse. Nonetheless, the team did indeed manage to tease out the gravitational lensing of the distant star’s light by the closer one—the first measurement of such a deflection by a star other than the sun.

    Weighing a star with light

    The STScI-led team went further, however, using the angular deflection they observed from the light of the background star to get at the mass of the closer Stein 2015B. Under Einstein’s equations, the radius of an Einstein ring relates directly to the square root of the mass of the closer (lensing) object. While, even with the HST’s sensitive instruments, the research team did not directly observe an Einstein ring, they were able to infer the ring’s radius over the series of measurements through the slightly asymmetric apparent offsets of the distant star and their impacts on the closer star’s brightness.

    As a result, the researchers were able to put the mass of Stein 2015B at 0.675±0.051 solar masses—right in line with the theoretical expectations for a white dwarf of its radius. That observation was interesting in itself, since Stein 2015B in particular has attracted some controversy, with suggestions that it might represent an exotic “iron-core” white dwarf with an anomalously large mass. The new observations suggest that the star actually lies right in the white-dwarf mainstream.

    More broadly, the “astrometric lensing” technique that the new research lays out offers a nice additional arrow in the quiver of astronomers seeking to suss out stellar masses across the sky. And the catalog of stars open for such analysis could expand significantly in coming years as new instruments come online, conducting even more massive sky surveys. (The Large Synoptic Survey Telescope, for example, slated to go online in 2023, will undertake a 10-year sky-survey campaign that’s expected to produce a 200-petabyte data set.)


    LSST Camera, built at SLAC

    LSST telescope, currently under construction 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.

    “This microlensing method is a very independent and direct way to determine the mass of a star,” team leader Sahu said in a press release. “It’s like placing the star on a scale.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Optics & Photonics News (OPN) is The Optical Society’s monthly news magazine. It provides in-depth coverage of recent developments in the field of optics and offers busy professionals the tools they need to succeed in the optics industry, as well as informative pieces on a variety of topics such as science and society, education, technology and business. OPN strives to make the various facets of this diverse field accessible to researchers, engineers, businesspeople and students. Contributors include scientists and journalists who specialize in the field of optics. We welcome your submissions.

  • richardmitnick 7:40 am on July 11, 2017 Permalink | Reply
    Tags: , , , , Gravitational Lensing, GTC-Gran Telescopio Canarias, ,   

    From IAC via Manu Garcia: “A lens galaxy” 

    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.


    Instituto de Astrofísica de Canarias – IAC

    Lensing galaxy. IAC.

    Thanks to the amplified image produced by a gravitational lens and the Gran Telescopio Canarias (GTC), a scientific team from the Polytechnic University of Cartagena and the Institute of Astrophysics of the Canary Islands (IAC) discovers one of the brightest galaxies to date when the Universe was 20% of its current age.

    Gravitational Lensing NASA/ESA

    According to the theory of General Relativity Einstein, when a ray of light passes near a massive object, the severity of that object attracts photons and deviates from its initial course. This phenomenon, called gravitational lens is the same producing lenses on light rays and acts as a magnifying glass, increasing the size of the object.

    Using this effect, a scientific team from the Institute of Astrophysics of the Canary Islands (IAC), led by researcher Anastasio Diaz-Sanchez, of the Polytechnic University of Cartagena (UPCT) has discovered a distant galaxy, about 10 billion years light and about 1,000 times brighter than the Milky Way. It is the brightest known submillimeter galaxies called strong emission present in the far infrared. In his characterization he has participated the Gran Telescopio Canarias (GTC) located at the Observatorio del Roque de los Muchachos (Garafía, La Palma).

    “Thanks to the gravitational lens -said Anastasio Diaz Sánchez, researcher UPCT and first author of the study consists of a cluster of galaxies, which acts like a telescope, the galaxy is 11 times bigger and brighter than which it is actually and produce different images of the same on an arc centered on the mass of the cluster, known as “Einstein ring”. The advantage of this type of amplification is not distorted the spectral properties of light can be studied very distant objects as if they were closer. ”

    To find this galaxy, whose discovery was recently published in an article in Astrophysical Journal Letters, a search was realized across the sky combining databases of WISE (NASA) and Planck (ESA) satellites to identify brightest submillimeter galaxies.

    NASA/WISE Telescope


    This light, amplified by a cluster of nearby galaxies that acts as a lens, gives an even greater apparent brightness of it actually has, and because of this effect might characterize their nature and properties spectroscopy using the GTC.

    Roque de los Muchachos Observatory, Garafía, La Palma, Canary I slands, Spain.

    Forming stars at high speed.

    This galaxy stands out as having a high rate of star formation, ie, is generating stars whose total mass is about 1,000 times the mass of the sun. By way of comparison, the Milky Way form each year stars with a total mass of twice the Sun. In this regard, Susana Iglesias-Groth, astrophysics IAC and co-author, adds: “These types of objects are home to the most powerful star-forming regions known in the universe and the next step will be to study their molecular wealth”.

    The fact that the galaxy is so bright, is amplified and has multiple images will delve into its gut, something impossible to carry out otherwise in such remote galaxies.

    “In the future, we can do more detailed studies of stellar formation using interferometers as the Northern Extended Millimeter Array (NOEMA / IRAM) in France and the Atacama Large Millimeter Array (ALMA) in Chile,” says Helmut Dannerbahuer, researcher IAC has also contributed to this discovery.

    IRAM NOEMA interferometer, Located in the French Alpes on the wide and isolated Plateau de Bure at an elevation of 2550 meters

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Science paper: Discovery of a very bright submillimeter galaxy at z = 2.0439 by Anastasio Diaz Sanchez, Susana Iglesias Groth, Rafael Rebolo and Helmut Dannerbauer, 2017, ApJ Letter.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    The Instituto de Astrofísica de Canarias(IAC) is an international research centre in Spain which comprises:

    The Instituto de Astrofísica, the headquarters, which is in La Laguna (Tenerife).
    The Centro de Astrofísica en La Palma (CALP)
    The Observatorio del Teide (OT), in Izaña (Tenerife).
    The Observatorio del Roque de los Muchachos (ORM), in Garafía (La Palma).

    These centres, with all the facilities they bring together, make up the European Northern Observatory(ENO).

    The IAC is constituted administratively as a Public Consortium, created by statute in 1982, with involvement from the Spanish Government, the Government of the Canary Islands, the University of La Laguna and Spain’s Science Research Council (CSIC).

    The International Scientific Committee (CCI) manages participation in the observatories by institutions from other countries. A Time Allocation Committee (CAT) allocates the observing time reserved for Spain at the telescopes in the IAC’s observatories.

    The exceptional quality of the sky over the Canaries for astronomical observations is protected by law. The IAC’s Sky Quality Protection Office (OTPC) regulates the application of the law and its Sky Quality Group continuously monitors the parameters that define observing quality at the IAC Observatories.

    The IAC’s research programme includes astrophysical research and technological development projects.

    The IAC is also involved in researcher training, university teaching and outreachactivities.

    The IAC has devoted much energy to developing technology for the design and construction of a large 10.4 metre diameter telescope, the ( Gran Telescopio CANARIAS, GTC), which is sited at the Observatorio del Roque de los Muchachos.

    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, SpainGran Telescopio CANARIAS, GTC

  • richardmitnick 4:55 pm on July 6, 2017 Permalink | Reply
    Tags: Gravitational lens helps reveal "fireworks" in the early universe, Gravitational Lensing, Hubble Pushed Beyond Limits to Spot Clumps of New Stars in Distant Galaxy,   

    From Hubble: “Hubble Pushed Beyond Limits to Spot Clumps of New Stars in Distant Galaxy” 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    Jul 6, 2017


    Christine Pulliam
    Space Telescope Science Institute, Baltimore, Maryland

    Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland

    Dr. Jane Rigby
    NASA’s Goddard Space Flight Center, Greenbelt, Maryland
    301-286-1507 (office) / 240-475-3917 (cell)

    Traci Johnson
    University of Michigan, Ann Arbor, Michigan

    Gravitational lens helps reveal “fireworks” in the early universe
    When the universe was young, stars formed at a much higher rate than they do today. By peering across billions of light-years of space, Hubble can study this early era. But at such distances, galaxies shrink to smudges that hide key details. Astronomers have teased out those details in one distant galaxy by combining Hubble’s sharp vision with the natural magnifying power of a gravitational lens. The result is an image 10 times better than what Hubble could achieve on its own, showing dense clusters of brilliant, young stars that resemble cosmic fireworks.


    When it comes to the distant universe, even the keen vision of NASA’s Hubble Space Telescope can only go so far. Teasing out finer details requires clever thinking and a little help from a cosmic alignment with a gravitational lens.

    By applying a new computational analysis to a galaxy magnified by a gravitational lens, astronomers have obtained images 10 times sharper than what Hubble could achieve on its own. The results show an edge-on disk galaxy studded with brilliant patches of newly formed stars.

    “When we saw the reconstructed image we said, ‘Wow, it looks like fireworks are going off everywhere,’” said astronomer Jane Rigby of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

    The galaxy in question is so far away that we see it as it appeared 11 billion years ago, only 2.7 billion years after the big bang. It is one of more than 70 strongly lensed galaxies studied by the Hubble Space Telescope, following up targets selected by the Sloan Giant Arcs Survey, which discovered hundreds of strongly lensed galaxies by searching Sloan Digital Sky Survey imaging data covering one-fourth of the sky.

    The gravity of a giant cluster of galaxies between the target galaxy and Earth distorts the more distant galaxy’s light, stretching it into an arc and also magnifying it almost 30 times. The team had to develop special computer code to remove the distortions caused by the gravitational lens, and reveal the disk galaxy as it would normally appear.

    The resulting reconstructed image revealed two dozen clumps of newborn stars, each spanning about 200 to 300 light-years. This contradicted theories suggesting that star-forming regions in the distant, early universe were much larger, 3,000 light-years or more in size.

    “There are star-forming knots as far down in size as we can see,” said doctoral student Traci Johnson of the University of Michigan, lead author of two of the three papers describing the research.

    Without the magnification boost of the gravitational lens, Johnson added, the disk galaxy would appear perfectly smooth and unremarkable to Hubble. This would give astronomers a very different picture of where stars are forming.

    While Hubble highlighted new stars within the lensed galaxy, NASA’s James Webb Space Telescope will uncover older, redder stars that formed even earlier in the galaxy’s history. It will also peer through any obscuring dust within the galaxy.

    “With the Webb Telescope, we’ll be able to tell you what happened in this galaxy in the past, and what we missed with Hubble because of dust,” said Rigby.

    These findings appear in a paper published in The Astrophysical Journal Letters[http://imgsrc.hubblesite.org/hvi/uploads/science_paper/file_attachment/241/Rigby_2017_ApJ_843_79_published_July_10.pdf], and two additional papers published in The Astrophysical Journal [http://imgsrc.hubblesite.org/hvi/uploads/science_paper/file_attachment/240/T_Johnson_published_ApJ_paper_July_10.pdf] and [http://imgsrc.hubblesite.org/hvi/uploads/science_paper/file_attachment/242/T_Johnson_published_ApJL_July_10.pdf].

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

    ESA50 Logo large

    AURA Icon

    NASA image

  • richardmitnick 2:28 pm on July 4, 2017 Permalink | Reply
    Tags: , , , , , Gravitational Lensing, Image of the initial SN Refsdal observations via the Hubble Space Telescope as well as the newly discovered magnified star LS1   

    From astrobites: “The Farthest Star Ever Seen” 

    Astrobites bloc


    Jul 4, 2017
    Gourav Khullar

    Title: An individual star at redshift 1.5 extremely magnified by a galaxy-cluster lens
    Authors: P. L. Kelly, J. M . Diego, S. Rodney et al.
    First Author’s Institution: University of California, Berkeley, USA

    Status: Submitted to Nature, closed access (with an open arXiv version in the link above)

    I write this astrobite in my living room, assisted heavily by the lenses in my spectacles. It’s quite a marvelous thing – a pair of glasses. For the last decade or so, a pair of glasses have been necessary for me to marvel at the wonders of the world (and universe, now that studying astrophysics allows me to do that at leisure). Then, imagine my surprise when I came across the cosmic equivalent of my glasses and what a marvel they are! Gravitational lenses are some of the most massive structures in the universe, teaching us about the most distant and the most massive objects in the cosmos.

    Radio galaxies gravitationally lensed by a very large foreground galaxy cluster Hubble

    Gravitational lensing, as you may know, is a phenomenon predicted by Albert Einstein’s theory of General Relativity, where a massive object creates a gravitational potential well in the space it occupies. Every particle that passes through this potential well will follow a distorted path, since this potential well is essentially modifying the path available to particles itself. This ‘distortion’ also applies to photons. Hence, even light coming from background objects – like a star or a galaxy – gets distorted (or bent) on its way to us, if it encounters a ‘gravitational lens’ in its way. The effect was first detected by Sir Arthur Eddington in 1919 via observations of the same patch of sky during the night as well as during the day behind the sun – the idea was to check if the sun bent the light coming from stars behind it, by observing the patch of sky around the sun during a solar eclipse. The slight distortions – just like a regular magnifying glass or a pair of myopia-correcting glasses would cause – were found, and gravitational lensing was first observed! Since then, we have discovered multiple gigantic structures that act like lenses. Since this effect is based on an object creating distortions in space around them proportional to the mass they contain, the more massive the object, the greater the distorting effect. Hence, most lenses that we have studied well so far are galaxies, or even galaxy clusters which are the most massive collapsed objects in the universe. For more details, check out this video (Credits: ESO).

    It is important to note that since a galaxy cluster can act as a gravitational lens, just like a magnifying glass it also has the capacity to ‘magnify’ background objects. Imagine a faint galaxy that we are not able to detect with regular telescopes. Now imagine the same galaxy when it happens to lie in the line of sight of a galaxy cluster. Based on its location and distance from the ‘lens’, a faint background galaxy can get magnified by several times, allowing its minimal flux to reach us at last. It is common for astrophysicists in this field to study large objects like faint blue galaxies at redshifts of 2-3 that get magnified by nearby galaxy clusters, which would not have been possible otherwise. This advancing field is only getting better with improved understanding of galaxy clusters as lenses – the calculations of their masses, and how this mass may be distributed throughout the cluster. Today’s study has gone one step further, into uncharted territory. Today’s study has observed a gravitationally lensed star!

    Fig 2. Image of the initial SN Refsdal observations via the Hubble Space Telescope, as well as the newly discovered magnified star LS1.

    From Hubble observations of a multiple-imaged supernova via gravitational lensing (see this astrobite for more details on Supernova Refsdal), Kelly et al. were successful in observing another extremely fascinating object too – a blue unresolved source of light, whose flux kept fluctuating. By taking spectra of that object, they concluded that it was a B-type star whose light was magnified approximately 2000 times on its way to us! In comparison, a typical galaxy is expected to be magnified by ~50 times. What makes this object undoubtedly a star are specific features seen in the spectra – namely the huge drop in flux around a rest-frame wavelength of ~3650 Angstroms called the Balmer break. Moreover, since the huge drop in flux is actually seen at a much higher wavelength, that allows for the calculation of the ‘redshift‘, or distance of the object. It turns out that this star, called LS1, is at a redshift of ~1.5, the farthest star ever discovered. For context, 99% of the stars you see in the night sky, are within the Milky Way. The farthest star we have discovered until now, is in a nearby galaxy few hundred thousand light years away. LS1, on the other hand, is 36 billion light years away!

    Fig 3. The complete Spectral Energy Distribution (or a Flux map) of the observed star LS1. You can see that different models of stars with different temperatures and properties have been fit to the observations, in order to ascertain the nature of the faint blue star. The ‘Balmer break’ can be seen at ~9000A instead of a rest-frame wavelength of ~3650A, corresponding to a redshift of ~1.5.

    Other properties of the star have also been observed – its temperature (~11000 K), its transverse velocity or motion in the sky (~1000 km/s) and the reason why this star magnified to the extent it did. In construction of mass models of galaxies (or clusters) that could cause gravitational lensing, there are certain surfaces around the lens that are called ‘caustics’. These surfaces correspond to a ‘mathematically infinite’ magnification in ideal lens models, and if an object is present on these unique surfaces, even a very faint object can pop out in lens observations! LS1 is no different – the models built in this paper suggest exactly that. This study also calculates the probability of a star to lie on a caustic, as well as the probability of such a massive hot star in the background existing at that distance. It is needless to say that observing such a distant star can tell us volumes about the nature of stellar population at high redshifts, as wells as test gravitational lens models to their extremes!

    Keep an eye out for more on this in the near future. After all, it’s the farthest star ever seen by a human, guys!

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    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.

  • richardmitnick 3:51 pm on June 6, 2017 Permalink | Reply
    Tags: , , , , Gravitational Lensing, Jackpot! Cosmic Magnifying-Glass Effect Captures Universe's Brightest Galaxies,   

    From Hubble: “Jackpot! Cosmic Magnifying-Glass Effect Captures Universe’s Brightest Galaxies” 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    Release type: American Astronomical Society Meeting

    Jun 6, 2017

    Donna Weaver
    Space Telescope Science Institute, Baltimore, Maryland

    Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland

    James Lowenthal
    Smith College, Northampton, Massachusetts

    Boosted by natural magnifying lenses in space, NASA’s Hubble Space Telescope has captured unique close-up views of the universe’s brightest infrared galaxies, which are as much as 10,000 times more luminous than our Milky Way.

    The galaxy images, magnified through a phenomenon called gravitational lensing, reveal a tangled web of misshapen objects punctuated by exotic patterns such as rings and arcs.

    Gravitational Lensing NASA/ESA

    Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835

    The odd shapes are due largely to the foreground lensing galaxies’ powerful gravity distorting the images of the background galaxies. The unusual forms also may have been produced by spectacular collisions between distant, massive galaxies in a sort of cosmic demolition derby.

    “We have hit the jackpot of gravitational lenses,” said lead researcher James Lowenthal of Smith College in Northampton, Massachusetts. “These ultra-luminous, massive, starburst galaxies are very rare. Gravitational lensing magnifies them so that you can see small details that otherwise are unimaginable. We can see features as small as about 100 light-years or less across. We want to understand what’s powering these monsters, and gravitational lensing allows us to study them in greater detail.”

    The galaxies are ablaze with runaway star formation, pumping out more than 10,000 new stars a year. This unusually rapid star birth is occurring at the peak of the universe’s star-making boom more than 8 billion years ago. The star-birth frenzy creates lots of dust, which enshrouds the galaxies, making them too faint to detect in visible light. But they glow fiercely in infrared light, shining with the brilliance of 10 trillion to 100 trillion suns.

    Gravitational lenses occur when the intense gravity of a massive galaxy or cluster of galaxies magnifies the light of fainter, more distant background sources. Previous observations of the galaxies, discovered in far-infrared light by ground- and space-based observatories, had hinted of gravitational lensing. But Hubble’s keen vision confirmed the researchers’ suspicion.

    Lowenthal is presenting his results at 3:15 p.m. (EDT), June 6, at the American Astronomical Society meeting in Austin, Texas.

    According to the research team, only a few dozen of these bright infrared galaxies exist in the universe, scattered across the sky. They reside in unusually dense regions of space that somehow triggered rapid star formation in the early universe.

    The galaxies may hold clues to how galaxies formed billions of years ago. “There are so many unknowns about star and galaxy formation,” Lowenthal explained. “We need to understand the extreme cases, such as these galaxies, as well as the average cases, like our Milky Way, in order to have a complete story about how galaxy and star formation happen.”

    In studying these strange galaxies, astronomers first must detangle the foreground lensing galaxies from the background ultra-bright galaxies. Seeing this effect is like looking at objects at the bottom of a swimming pool. The water distorts your view, just as the lensing galaxies’ gravity stretches the shapes of the distant galaxies. “We need to understand the nature and scale of those lensing effects to interpret properly what we’re seeing in the distant, early universe,” Lowenthal said. “This applies not only to these brightest infrared galaxies, but probably to most or maybe even all distant galaxies.”

    Lowenthal’s team is halfway through its Hubble survey of 22 galaxies. An international team of astronomers first discovered the galaxies in far-infrared light using survey data from the European Space Agency’s (ESA) Planck space observatory, and some clever sleuthing.


    The team then compared those sources to galaxies found in ESA’s Herschel Space Observatory’s catalog of far-infrared objects and to ground-based radio data taken by the Very Large Array in New Mexico.

    ESA/Herschel spacecraft

    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    The researchers next used the Large Millimeter Telescope (LMT) in Mexico to measure their exact distances from Earth.

    Large Millimeter Telescope or Gran Telescopio Milimétrico. It is located at the top of the Sierra Negra volcanoe in the Mexican state of Puebla

    The LMT’s far-infrared images also revealed multiple objects, hinting that the galaxies were being gravitationally lensed.

    These bright objects existed between 8 billion and 11.5 billion years ago, when the universe was making stars more vigorously than it is today. The galaxies’ star-birth production is 5,000 to 10,000 times higher than that of our Milky Way. However, the ultra-bright galaxies are pumping out stars using only the same amount of gas contained in the Milky Way.

    So, the nagging question is, what is powering the prodigious star birth? “We’ve known for two decades that some of the most luminous galaxies in the universe are very dusty and massive, and they’re undergoing bursts of star formation,” Lowenthal said. “But they’ve been very hard to study because the dust makes them practically impossible to observe in visible light. They’re also very rare: they don’t appear in any of Hubble’s deep-field surveys. They are in random parts of the sky that nobody’s looked at before in detail. That’s why finding that they are gravitationally lensed is so important.”

    These galaxies may be the brighter, more distant cousins of the ultra-luminous infrared galaxies (ULIRGS), hefty, dust-cocooned, starburst galaxies, seen in the nearby universe. The ULIRGS’ star-making output is stoked by the merger of two spiral galaxies, which is one possibility for the stellar baby boom in their more-distant relatives. However, Lowenthal said that computer simulations of the birth and growth of galaxies show that major mergers occur at a later epoch than the one in which these galaxies are seen.

    Another idea for the star-making surge is that lots of gas, the material that makes stars, is flooding into the faraway galaxies. “The early universe was denser, so maybe gas is raining down on the galaxies, or they are fed by some sort of channel or conduit, which we have not figured out yet,” Lowenthal said. “This is what theoreticians struggle with: How do you get all the gas into a galaxy fast enough to make it happen?”

    The research team plans to use Hubble and the Gemini Observatory in Hawaii to try to distinguish between the foreground and background galaxies so they can begin to analyze the details of the brilliant monster galaxies.

    Gemini/North telescope at Mauna Kea, Hawaii, USA

    Future telescopes, such as NASA’s James Webb Space Telescope, an infrared observatory scheduled to launch in 2018, will measure the speed of the galaxies’ stars so that astronomers can calculate the mass of these ultra-luminous objects.

    NASA/ESA/CSA Webb Telescope annotated

    “The sky is covered with all kinds of galaxies, including those that shine in far-infrared light,” Lowenthal said. “What we’re seeing here is the tip of the iceberg: the very brightest of all.”


    NASA, ESA, and J. Lowenthal (Smith College)

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

    ESA50 Logo large

    AURA Icon

    NASA image

  • richardmitnick 12:44 pm on May 9, 2017 Permalink | Reply
    Tags: , , , , , , Detecting infrared light, , Gravitational Lensing,   

    From JPL-Caltech: “NASA Delivers Detectors for ESA’s Euclid Spacecraft” 

    NASA JPL Banner


    May 9, 2017
    Elizabeth Landau
    Jet Propulsion Laboratory, Pasadena, Calif.

    Giuseppe Racca
    Euclid Project Manager
    Directorate of Science
    European Space Agency

    René Laureijs
    Euclid Project Scientist
    Directorate of Science
    European Space Agency

    ESA/Euclid spacecraft

    Three detector systems for the Euclid mission, led by ESA (European Space Agency), have been delivered to Europe for the spacecraft’s near-infrared instrument. The detector systems are key components of NASA’s contribution to this upcoming mission to study some of the biggest questions about the universe, including those related to the properties and effects of dark matter and dark energy — two critical, but invisible phenomena that scientists think make up the vast majority of our universe.

    “The delivery of these detector systems is a milestone for what we hope will be an extremely exciting mission, the first space mission dedicated to going after the mysterious dark energy,” said Michael Seiffert, the NASA Euclid project scientist based at NASA’s Jet Propulsion Laboratory, Pasadena, California, which manages the development and implementation of the detector systems.

    Euclid will carry two instruments: a visible-light imager (VIS) and a near-infrared spectrometer and photometer (NISP). A special light-splitting plate on the Euclid telescope enables incoming light to be shared by both instruments, so they can carry out observations simultaneously.

    The spacecraft, scheduled for launch in 2020, will observe billions of faint galaxies and investigate why the universe is expanding at an accelerating pace. Astrophysicists think dark energy is responsible for this effect, and Euclid will explore this hypothesis and help constrain dark energy models. This census of distant galaxies will also reveal how galaxies are distributed in our universe, which will help astrophysicists understand how the delicate interplay of the gravity of dark matter, luminous matter and dark energy forms large-scale structures in the universe.

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

    Additionally, the location of galaxies in relation to each other tells scientists how they are clustered. Dark matter, an invisible substance accounting for over 80 percent of matter in our universe, can cause subtle distortions in the apparent shapes of galaxies. That is because its gravity bends light that travels from a distant galaxy toward an observer, which changes the appearance of the galaxy when it is viewed from a telescope.

    Gravitational Lensing NASA/ESA

    Euclid’s combination of visible and infrared instruments will examine this distortion effect and allow astronomers to probe dark matter and the effects of dark energy.

    Detecting infrared light, which is invisible to the human eye, is especially important for studying the universe’s distant galaxies. Much like the Doppler effect for sound, where a siren’s pitch seems higher as it approaches and lower as it moves away, the frequency of light from an astronomical object gets shifted with motion. Light from objects that are traveling away from us appears redder, and light from those approaching us appears bluer. Because the universe is expanding, distant galaxies are moving away from us, so their light gets stretched out to longer wavelengths. Between 6 and 10 billion light-years away, galaxies are brightest in infrared light.

    JPL procured the NISP detector systems, which were manufactured by Teledyne Imaging Sensors of Camarillo, California. They were tested at JPL and at NASA’s Goddard Space Flight Center, Greenbelt, Maryland, before being shipped to France and the NISP team.

    Each detector system consists of a detector, a cable and a “readout electronics chip” that converts infrared light to data signals read by an onboard computer and transmitted to Earth for analysis. Sixteen detectors will fly on Euclid, each composed of 2040 by 2040 pixels. They will cover a field of view slightly larger than twice the area covered by a full moon. The detectors are made of a mercury-cadmium-telluride mixture and are designed to operate at extremely cold temperatures.

    “The U.S. Euclid team has overcome many technical hurdles along the way, and we are delivering superb detectors that will enable the collection of unprecedented data during the mission,” said Ulf Israelsson, the NASA Euclid project manager, based at JPL.

    Delivery to ESA of the next set of detectors for NISP is planned in early June. The Centre de Physique de Particules de Marseille, France, will provide further characterization of the detector systems. The final detector focal plane will then be assembled at the Laboratoire d’Astrophysique de Marseille, and integrated with the rest of NISP for instrument tests.

    For more information about Euclid, visit:


    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA JPL Campus

    Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. Although the facility has a Pasadena postal address, it is actually headquartered in the city of La Cañada Flintridge [1], on the northwest border of Pasadena. JPL is managed by the nearby California Institute of Technology (Caltech) for the National Aeronautics and Space Administration. The Laboratory’s primary function is the construction and operation of robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA’s Deep Space Network.

    Caltech Logo

    NASA image

  • richardmitnick 1:14 pm on May 7, 2017 Permalink | Reply
    Tags: , , , , Gravitational Lensing, Into the wild simulated yonder,   

    From Science Node: “Into the wild simulated yonder” 

    Science Node bloc
    Science Node

    28 Apr, 2017
    Tristan Fitzpatrick

    So much of our universe is known to us, but there is so much more we don’t know – yet.

    For example, normal matter that is easily observable (such as gas and rocks) makes up only four percent of the known mass-energy in the universe, according to the Canada-France Hawaii Lensing Survey (CFHTLenS).

    Image: NASA/ESA

    CFHT Telescope, Mauna Kea, Hawaii, USA

    The other 96 percent is dark matter and energy. These two components are critical to science’s understanding of how the galaxy was formed, but there’s one problem: A combination of dark matter and energy can only be observed by how it affects the four percent of the universe scientists can measure.

    Telescopes don’t help much in observing these galactic effects, and this creates a challenge for scholars.

    Building a mystery

    One research project seeks to bring science one step closer to solving this cosmic mystery.

    Carnegie Mellon University associate professor Rachel Mandelbaum uses generative adversarial networks (GANs) to simulate galaxies warped by gravitational lensing – and takes science one step closer to solving the origins of our cosmos.

    Gravitational Lensing NASA/ESA

    Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835

    Gravitational lensing is a process by which mass bends light, an effect predicted by Albert Einstein’s theory of general relativity. The larger an object, the greater its gravitational field will be, and the greater its ability to bend light rays.


    Because light bending is sensitive to the strength of the gravitational field it goes through, observing the lensing effect can be used to measure dark matter.

    There are several difficulties with observing rays of light, however. According to Mandelbaum’s research [ScienceDirect], detector imperfections, telescopic blurring and distortion, atmospheric effects, and noise can all affect the quality of the data, making research challenging for scientists.

    Unlike GANs, a traditional neural network, for example, will detect the difference between different images, but only if these images have been tagged by people and include descriptions. Eventually, the artificial intelligence will learn to distinguish images by itself, but only after it first sorts through images manually one-by-one.

    GANs save resources compared to other neural networks because fewer people are needed to operate them and because a GAN does not include a tagging and descriptor process. An image generator produces fake and real images on its own, without outside help, and the network will eventually learn to tell the difference between the two.

    Astronomical implications

    Mandelbaum’s research has wide implications in astronomy, as it can serve as a useful starting point for astronomical image analysis when telescopic problems and other issues create obstacles for scientists.

    A portion of Mandelbaum’s simulation of a focal plane on the Large Synoptic Survey Telescope [?Not built yet]. Courtesy Mandelbaum, et al.

    Astrophysicist Peter Nugent at the Computational Research Division of Lawrence Berkeley National Laboratory and his colleagues have researched a gravitationally lensed supernova using computer simulations, which will shed light on how matter is distributed throughout the galaxy.

    Discovering new ways to explore the unknown universe is just one of the many possibilities computational science offers.

    To learn more about gravitational lensing, visit the CFHTLenS website or check out Mandelbaum’s research paper.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    Science Node is an international weekly online publication that covers distributed computing and the research it enables.

    “We report on all aspects of distributed computing technology, such as grids and clouds. We also regularly feature articles on distributed computing-enabled research in a large variety of disciplines, including physics, biology, sociology, earth sciences, archaeology, medicine, disaster management, crime, and art. (Note that we do not cover stories that are purely about commercial technology.)

    In its current incarnation, Science Node is also an online destination where you can host a profile and blog, and find and disseminate announcements and information about events, deadlines, and jobs. In the near future it will also be a place where you can network with colleagues.

    You can read Science Node via our homepage, RSS, or email. For the complete iSGTW experience, sign up for an account or log in with OpenID and manage your email subscription from your account preferences. If you do not wish to access the website’s features, you can just subscribe to the weekly email.”

Compose new post
Next post/Next comment
Previous post/Previous comment
Show/Hide comments
Go to top
Go to login
Show/Hide help
shift + esc
%d bloggers like this: