From The University of Nottingham (UK) And Tel Aviv University [אוניברסיטת תל אביב](IL) And New York University And The Institute for Fundamental Physics of the Universe (IT) Via “phys.org” : “Study explores the possibility that dark photons might be a heat source for intergalactic gas”

From The University of Nottingham (UK), and Tel Aviv University [אוניברסיטת תל אביב](IL), and New York University, and The Institute for Fundamental Physics of the Universe (IT)

Via

“phys.org”

12.7.22

(Top panel) Fit to the Doppler parameter distribution and column density distribution function of the “Lyman-alpha forest” at z=0.1 assuming a maximal contribution of dark photon heating to the line widths. Contours show the projection of the 68% and 95% intervals for the mass and mixing parameter of the dark photon. The colors correspond to different assumptions about the uncertainty of the intergalactic medium temperature at z = 2. (Bottom panel) The corresponding best-fit models compared to the COS observational data. The solid gray curve shows a result with no dark photon heating. Credit: Physical Review Letters (2022).

Gas clouds across the universe are known to absorb the light produced by distant massive celestial objects, known as quasars.

Now iconic image of a quasar. Credit: M.Kornmesser/The European Southern Observatory [La Observatorio Europeo Austral] [Observatoire européen austral][Europäische Südsternwarte](EU)(CL).

This light manifests as the so-called “Lyman alpha forest”, a dense structure composed of absorption lines that can be observed using spectroscopy tools.

Over the past decades, astrophysicists have been assessing the value of these absorption lines as a tool to better understand the universe and the relationships between cosmological objects. The “Lyman alpha forest” could also potentially aid the ongoing search for dark matter, offering an additional tool to test theoretical predictions and models.

Researchers at The University of Nottingham (UK), Tel Aviv University [אוניברסיטת תל אביב](IL), New York University, and The Institute for Fundamental Physics of the Universe (IT) have recently compared low-redshift Lyman alpha forest observations to hydrodynamical simulations of the intergalactic medium and dark matter made up of dark photons, a renowned dark matter candidate.

Their paper, published in Physical Review Letters [below], builds on an earlier work [MNRAS (below)] by some members of their team, which compared simulations of the intergalactic medium (IGM) with “Lyman-alpha forest” measurements collected by the Cosmic Origins Spectrograph (COS) aboard the Hubble Space Telescope.

National Aeronautics Space Agency Cosmic Origins Spectrograph.

The National Aeronautics and Space Agency European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganization](EU) Hubble Space Telescope Instrumentation annotated.

“In our analyses, we found that the simulation predicted line widths that were too narrow compared to the COS results, suggesting that there could be additional, noncanonical sources of heating occurring at low redshifts,” Hongwan Liu, Matteo Viel, Andrea Caputo and James Bolton, the researchers who carried out the study, told Phys.org via email.

“We explored several dark matter models that could act as this source of heating. Building on two of the authors’ experience with dark photons in a previous paper [Physical Review Letters (below)], we eventually realized that heating from dark photon dark matter could work.”

Based on their previous observations, Liu, Viel, Caputo and Bolton decided to alter a hydrodynamical simulation of the IGM (i.e., a sparse cloud of hydrogen that exists in the spaces between galaxies). In their new simulation, they included the effects of the heat that models predict would be produced by dark photon dark matter.

“In regions of space where the mass of the dark photon matches the effective plasma mass of the photon, conversions from dark photons to photons can occur,” Liu, Viel, Caputo and Bolton explained. “The converted photons are then rapidly absorbed by the “IGM” in those regions, heating the gas up. The amount of energy transferred from dark matter to the gas can be calculated theoretically.”

The researchers added this estimated energy transfer between dark photons and intergalactic clouds to their simulations. This ultimately allowed them to attain a series of simulated absorption line widths, which they could compare to actual “Lyman-alpha forest” observations collected by the COS.

“Broadly speaking, we have shown that the “Lyman-alpha forest” is extremely useful for understanding dark matter models where energy can be converted from dark matter into heating,” Liu, Viel, Caputo and Bolton said. “I think our study will encourage physicists interested in dark matter to pay more attention to the “Lyman-alpha forest”.”

Overall, the comparison between COS measurements and hydrodynamical simulations performed by this team of researchers suggests that dark photons could in fact be a source of heat in intergalactic gas clouds. Their findings could thus be the first hint of the existence of dark matter that is not observed through its gravitational effects.

While this is a fascinating possibility, Liu, Viel, Caputo and Bolton have not yet ruled out other possible theoretical explanations. They thus hope that their study will inspire other teams to similarly probe the properties of the “IGM” in the early universe.

“One particularly interesting consequence of dark photon heating is that underdense regions in the “IGM” are heated up at earlier times compared to overdense regions,” Liu, Viel, Caputo and Bolton said. “This can lead to underdense regions being hotter than overdense regions, which is contrary to standard expectations. There are some indications that the “IGM” does exhibit this behavior at high redshifts. If so, it could be another important piece of evidence in favor of dark photon dark matter heating.”

Science papers:
Physical Review Letters
MNRAS
Physical Review Letters

See the full article here .

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From Ethan Siegel: “These Are The Most Distant Astronomical Objects In The Known Universe”

From Ethan Siegel
Dec 30, 2019

Astronomy’s enduring quest is to go farther, fainter, and more detailed than ever before. Here’s the edge of the cosmic frontier.

The distant galaxy MACS1149-JD1 is gravitationally lensed by a foreground cluster, allowing it to be imaged at high resolution and in multiple instruments, even without next-generation technology.

Gravitational Lensing NASA/ESA

This galaxy’s light comes to us from 530 million years after the Big Bang, but the stars within it are at least 280 million years old. It is the second-most distant galaxy with a spectroscopically confirmed distance, placing it 30.7 billion light-years away from us. (ALMA (ESO/NAOJ/NRAO), NASA/ESA HUBBLE SPACE TELESCOPE, W. ZHENG (JHU), M. POSTMAN (STSCI), THE CLASH TEAM, HASHIMOTO ET AL.)

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

NASA/ESA Hubble Telescope

Astronomers have always sought to push back the viewable distance frontiers.

Although there are magnified, ultra-distant, very red and even infrared galaxies in the eXtreme Deep Field, there are galaxies that are even more distant out there than what we’ve discovered in our deepest-to-date views. These galaxies will always remain visible to us, but we will never see them as they are today: 13.8 billion years after the Big Bang. (NASA, ESA, R. BOUWENS AND G. ILLINGWORTH (UC, SANTA CRUZ))

More distant galaxies appear fainter, smaller, bluer, and less evolved overall.

Galaxies comparable to the present-day Milky Way are numerous, but younger galaxies that are Milky Way-like are inherently smaller, bluer, more chaotic, and richer in gas in general than the galaxies we see today. For the first galaxies of all, this ought to be taken to the extreme, and remains valid as far back as we’ve ever seen. The exceptions, when we encounter them, are both puzzling and rare. (NASA AND ESA)

Milky Way NASA/JPL-Caltech /ESO R. Hurt. The bar is visible in this image

Laniakea supercluster. From Nature The Laniakea supercluster of galaxies R. Brent Tully, Hélène Courtois, Yehuda Hoffman & Daniel Pomarède at http://www.nature.com/nature/journal/v513/n7516/full/nature13674.html. Milky Way is the red dot.

Individual planets and stars are only known relatively nearby, as our tools cannot take us farther.

Local Group. Andrew Z. Colvin 3 March 2011

A massive cluster (left) magnified a distant star known as Icarus more than 2,000 times, making it visible from Earth (lower right) even though it is 9 billion light years away, far too distant to be seen individually with current telescopes. It was not visible in 2011 (upper right). The brightening leads us to believe that this was a blue supergiant star, formally named MACS J1149 Lensed Star 1. (NASA, ESA, AND P. KELLY (UNIVERSITY OF MINNESOTA))

As the 2010s end, here are our presently known most distant astronomical objects.

The ultra-distant supernova SN UDS10Wil, shown here, is the farthest type Ia supernova ever discovered, whose light arrives today from a position 17 billion light-years away.

A white dwarf fed by a normal star reaches the critical mass and explodes as a type Ia supernova. Credit: NASA/CXC/M Weiss

Type Ia supernovae are used as distance indicators because of their standard intrinsic brightnesses, and are some of our strongest evidence for the accelerated expansion best explained by dark energy.

Standard Candles to measure age and distance of the universe from supernovae NASA

(NASA, ESA, A. RIESS (STSCI AND JHU), AND D. JONES AND S. RODNEY (JHU))

The farthest type Ia supernova, our most distant “standard candle” for probing the Universe, is SN UDS10Wil, located 17 billion light-years (Gly) away.

This illustration of superluminous supernova SN 1000+0216, the most distant supernova ever observed at a redshift of z=3.90, from when the Universe was just 1.6 billion years old, is the current record-holder for individual supernovae. Unlike SN UDS10Wil, this supernova is a Type II (core collapse) supernova, and may have formed via the pair instability mechanism, which would explain its extraordinarily large intrinsic brightness. (ADRIAN MALEC AND MARIE MARTIG (SWINBURNE UNIVERSITY))

The most distant supernova of all, 2012’s superluminous SN 1000+0216, occurred 23 Gly away.

The most distant X-ray jet in the Universe, from quasar GB 1428, sends us light from when the Universe was a mere 1.25 billion years old: less than 10% its current age. This jet comes from electrons heating CMB photons, and is over 230,000 light-years in extent: approximately double the size of the Milky Way. (X-RAY: NASA/CXC/NRC/C.CHEUNG ET AL; OPTICAL: NASA/STSCI; RADIO: NSF/NRAO/VLA)

NASA/Chandra X-ray Telescope

NRAO/Karl V Jansky Expanded Very Large Array, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

The most distant quasar jet, revealed by GB 1428+4217’s X-rays, is 25.4 Gly distant.

This image of ULAS J1120+0641, a very distant quasar powered by a black hole with a mass two billion times that of the Sun, was created from images taken from surveys made by both the Sloan Digital Sky Survey and the UKIRT Infrared Deep Sky Survey.

SDSS Telescope at Apache Point Observatory, near Sunspot NM, USA, Altitude2,788 meters (9,147 ft)

UKIRT, located on Mauna Kea, Hawai’i, USA as part of Mauna Kea Observatory,4,207 m (13,802 ft) above sea level

The quasar appears as a faint red dot close to the centre. This quasar was the most distant one known from 2011 until 2017, and is seen as it was just 745 million years after the Big Bang. It is the most distant quasar with a visual image available to be viewed by the public. (ESO/UKIDSS/SDSS)

The first discovered object whose light exceeds 13 billion years in age, quasar ULAS J1120+0641, is 28.8 Gly away.

This artist’s concept shows the most distant quasar and the most distant supermassive black hole powering it. At a redshift of 7.54, ULAS J1342+0928 corresponds to a distance of some 29.32 billion light-years; it is the most distant quasar/supermassive black hole ever discovered. Its light arrives at our eyes today, in the radio part of the spectrum, because it was emitted just 686 million years after the Big Bang. (ROBIN DIENEL/CARNEGIE INSTITUTION FOR SCIENCE)

However, quasar ULAS J1342+0928 is even farther at 29.32 Gly: our most distant black hole.

This illustration of the most distant gamma-ray burst ever detected, GRB 090423, is thought to be typical of most fast gamma-ray bursts. When one or two objects violently form a black hole, such as from a neutron star merger, a brief burst of gamma rays followed by an infrared afterglow (when we’re lucky) allows us to learn more about these events. The gamma rays from this event lasted just 10 seconds, but Nial Tanvir and his team found an infrared afterglow using the UKIRT telescope just 20 minutes after the burst, allowing them to determine a redshift (z=8.2) and distance (29.96 billion light-years) to great precision. (ESO/A. ROQUETTE)

Gamma-ray bursts exceed even that; GRB 090423’s verified light comes from 29.96 Gly away in the distant Universe, while GRB 090429B might’ve been even farther.

Here, candidate galaxy UDFj-39546284 appears very faint and red, and from the colors it displays, it has an inferred redshift of 10, giving it an age below 500 million years and a distance greater than 31 billion light-years. Without spectroscopic confirmation, however, this and similar galaxies cannot reliably be said to have a known distance; more data is needed, as photometric redshifts are notoriously unreliable. (NASA, ESA, G. ILLINGWORTH (UNIVERSITY OF CALIFORNIA, SANTA CRUZ), R. BOUWENS (UNIVERSITY OF CALIFORNIA, SANTA CRUZ, AND LEIDEN UNIVERSITY) AND THE HUDF09 TEAM)

Ultra-distant galaxy candidates abound, including SPT0615-JD, MACS0647-JD, and UDFj-39546284, all lacking spectroscopic confirmation.

The most distant galaxy ever discovered in the known Universe, GN-z11, has its light come to us from 13.4 billion years ago: when the Universe was only 3% its current age: 407 million years old. The distance from this galaxy to us, taking the expanding Universe into account, is an incredible 32.1 billion light-years. (NASA, ESA, AND G. BACON (STSCI))

The most distant galaxy of all is GN-z11, located 32.1 Gly away.

The James Webb Space Telescope vs. Hubble in size (main) and vs. an array of other telescopes (inset) in terms of wavelength and sensitivity. It should be able to see the truly first galaxies, even the ones that no other observatory can see. Its power is truly unprecedented. (NASA / JWST SCIENCE TEAM)

NASA/ESA/CSA Webb Telescope annotated

With the 2020s promising revolutionary new observatories, these records may all soon fall.

Our deepest galaxy surveys can reveal objects tens of billions of light years away, but there are more galaxies within the observable Universe we still have yet to reveal between the most distant galaxies and the cosmic microwave background [CMB], including the very first stars and galaxies of all.

CMB per ESA/Planck

It is possible that the coming generation of telescopes will break all of our current distance records. (SLOAN DIGITAL SKY SURVEY (SDSS))

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

From NASA Chandra: “X-rays Spot Spinning Black Holes Across Cosmic Sea”

NASA/Chandra Telescope

From NASA Chandra

2019-07-03

Quasars. Credit: NASA/CXC/Univ. of Oklahoma/X. Dai et al.

Like whirlpools in the ocean, spinning black holes in space create a swirling torrent around them. However, black holes do not create eddies of wind or water. Rather, they generate disks of gas and dust heated to hundreds of millions of degrees that glow in X-ray light.

Using data from NASA’s Chandra X-ray Observatory and chance alignments across billions of light years, astronomers have deployed a new technique to measure the spin of five supermassive black holes. The matter in one of these cosmic vortices is swirling around its black hole at greater than about 70% of the speed of light.

The astronomers took advantage of a natural phenomenon called a gravitational lens.

Gravitational Lensing NASA/ESA

With just the right alignment, the bending of space-time by a massive object, such as a large galaxy, can magnify and produce multiple images of a distant object, as predicted by Einstein.

In this latest research, astronomers used Chandra and gravitational lensing to study five quasars, each consisting of a supermassive black hole rapidly consuming matter from a surrounding accretion disk. Gravitational lensing of the light from each of these quasars by an intervening galaxy has created multiple images of each quasar, as shown by these Chandra images of four of the targets. The sharp imaging ability of Chandra is needed to separate the multiple, lensed images of each quasar.

The key advance made by researchers in this study was that they took advantage of “microlensing,” where individual stars in the intervening, lensing galaxy provided additional magnification of the light from the quasar.

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

A higher magnification means a smaller region is producing the X-ray emission.

The researchers then used the property that a spinning black hole is dragging space around with it and allows matter to orbit closer to the black hole than is possible for a non-spinning black hole. Therefore, a smaller emitting region corresponding to a tight orbit generally implies a more rapidly spinning black hole. The authors concluded from their microlensing analysis that the X-rays come from such a small region that the black holes must be spinning rapidly.

The results showed that one of the black holes, in the lensed quasar called the “Einstein Cross,” (labeled Q2237 in the image above) is spinning at, or almost at, the maximum rate possible. This corresponds to the event horizon, the black hole’s point of no return, spinning at the speed of light, which is about 670 million miles per hour. Four other black holes in the sample are spinning, on average, at about half this maximum rate.

For the Einstein Cross the X-ray emission is from a part of the disk that is less than about 2.5 times the size of the event horizon, and for the other 4 quasars the X-rays come from a region four to five times the size of the event horizon.

How can these black holes spin so quickly? The researchers think that these supermassive black holes likely grew by accumulating most of their material over billions of years from an accretion disk spinning with a similar orientation and direction of spin, rather than from random directions. Like a merry-go-round that keeps getting pushed in the same direction, the black holes kept picking up speed.

The X-rays detected by Chandra are produced when the accretion disk surrounding the black hole creates a multimillion-degree cloud, or corona above the disk near the black hole. X-rays from this corona reflect off the inner edge of the accretion disk, and the strong gravitational forces near the black hole distort the reflected X-ray spectrum, that is, the amount of X-rays seen at different energies. The large distortions seen in the X-ray spectra of the quasars studied here imply that the inner edge of the disk must be close to the black holes, giving further evidence that they must be spinning rapidly.

The quasars are located at distances ranging from 9.8 billion to 10.9 billion light years from Earth, and the black holes have masses between 160 and 500 million times that of the sun. These observations were the longest ever made with Chandra of gravitationally lensed quasars, with total exposure times ranging between 1.7 and 5.4 days.

A paper describing these results is published in the July 2nd issue of The Astrophysical Journal. The authors are Xinyu Dai, Shaun Steele and Eduardo Guerras from the University of Oklahoma in Norman, Oklahoma, Christopher Morgan from the United States Naval Academy in Annapolis, Maryland, and Bin Chen from Florida State University in Tallahassee, Florida.

See the full article here .

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NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

From COSMOS Magazine: “New class of quasars offers clue to fate of our galaxy”

From COSMOS Magazine

17 June 2019
Richard A Lovett

Astronomers looking for the blue ones make an important discovery.

The Milky Way, as seen from Lake Tekapo, New Zealand. There is a quasar in its future, astronomers now believe. ARUTTHAPHON POOLSAWASD / Getty Images

Astronomers peering back in time by studying galaxies so far away that their light has been travelling for more than half the age of the universe have discovered a new class of quasar – and a clue to the ultimate fate of our own galaxy.

Quasars are the most luminous objects in the universe, emitting as much energy as 10 trillion suns, says Allison Kirkpatrick, an astronomer at the University of Kansas, Lawrence, US, and are associated with gigantic black holes at the heart of the largest galaxies.

“I am a black-hole hunter, and quasars are the most massive of these,” she said at a meeting of the American Astronomical Society in St. Louis, Missouri.

Such giant black holes form when two galaxies, each with black holes at its own heart, collide.

At that point, several things happen.

First, the collision stirs up the gas and dust in these galaxies, pushing it toward their centres. Then, the gas and dust start to fall into the black holes, now in the process of merging.

“They begin to feed rapidly on the gas around them,” Kirkpatrick says. “This is the quasar stage. They are almost universally produced by major mergers.”

Feeding black holes produce large amounts of X-rays, but initially, these X-rays are blocked by the gas and dust clouds that have been drawn into the merging galaxies’ centre.

“It obscures the X-rays,” says Kirkpatrick says – but the heated gas and dust isn’t invisible. Instead of X-rays, it emits vast amounts of infrared light that can be detected by earthly astronomers.

“We have a dust-reddened quasar,” she says, “[with] very massive black-hole activity going on, but hidden from view.”

Then, things shift. The powerful radiation being emitted by the quasar overcomes the gravity drawing dust and gas inward toward it, and rapidly blows dust and gas entirely out of the galaxy. “Now we see a luminous blue quasar,” she says.

But nobody before had ever caught one in the act of making the transition, where the gas and dust have been blown out of the inner part of the galaxy, but not yet out of its outer reaches.

To find one, Kirkpatrick’s team examined the 1600 most active known quasars, looking for ones that were blue – indicating that their cores had been swept sufficiently free of gas and dust for us to see the quasar itself – but which also emitted a lot of infrared light, indicating that their outer reaches still contained rings of hot gas and dust.

And, while such objects were rare, Kirkpatrick’s team found 22 of them, all six to 12 billion light years away, including a galaxy that had both a blue quasar and 100 times more dust than our own Milky Way.

That said, it’s a transition phase. “This new population of quasars are rare and short-lived, she says.

They also mark the beginning of these galaxies’ deaths, because without their gas and dust, they can no longer form new stars. “We believe that it is the massive black hole that kills them,” Kirkpatrick says.

And while her study was peering six billion to 12 billion years back in time, it also predicts the future our own Milky Way. “There is a quasar in the Milky Way’s future,” she says.

That’s because our galaxy will eventually collide with the Andromeda galaxy, a galaxy about the size of our own, currently about 2.5 million light years away.

Both galaxies have giant black holes at their centres. Neither black hole is currently doing anything dangerous, but when they collide, Kirkpatrick says, both will light up dramatically.

“That will dominate our night sky,” she says. “They will be incredibly bright. The nice plane of the Milky Way will be dominated by this bright halo [marking the location of the merging black holes].”

Then, all the gas and dust will be blown out of the merged galaxies and star and planet formation will be shut off. Existing planets will probably survive, Kirkpatrick says, “but you won’t get anything new. They’ll just be going around red dwarfs until eventually [their stars] burn out”.

Not that this is anything of immediate concern to humans. The merger won’t occur for another three to four billion years, Kirkpatrick says. “That will be about the same time the sun has turned into a red giant, so we will have other problems to occupy us at the time.”

See the full article here .

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Netherlands Institute for Radio Astronomy (ASTRON): “Energy loss gives unexpected insights in evolution of quasar jets”

Netherlands Institute for Radio Astronomy (ASTRON)

The radio jet of the quasar 4C+19.44, powered by a supermassive black hole lying in the center of its host galaxy and shining at long radio wavelengths as seen by the LOFAR radio telescope (magenta). The background image shows neighboring galaxies in the visible light highlighted thanks to the Hubble Space Telescope (cyan and orange) having the radio jet passing into the dark voids of intergalactic space (Harris et al. 2019). Image Credit: NASA/HST/LOFAR; Courtesy of J. DePasquale

An international team of astrophysicists observed for the first time that the jet of a quasar is less powerful on long radio wavelengths than earlier predicted. This discovery gives new insights in the evolution of quasar jets. They made this observation using the international Low Frequency Array (LOFAR) telescope [below], that produced high resolution radio images of quasar 4C+19.44 located over 5 billion light-years from Earth.

Supermassive black holes, many millions of times more massive than our Sun reside in the central regions of galaxies. They grow even larger by attracting and consuming nearby gas and dust. If they consume material rapidly, the infalling matter shines brightly and the source is known as a quasar. Some of this infalling matter is not digested, but instead is ejected in the form of so-called jets that punch through the surrounding galaxy and into intergalactic space for millions of light years. These jets, shining brightly at radio wavelengths, are composed of particles accelerated up to nearly the speed of light, but exactly how these particles achieve energies not attainable on the Earth is yet to be completely solved.

The discovery on quasar 4C+19.44 gives new insights to the balance between the energy in the field surrounding the quasar and that residing in the quasar jet. This finding indicates to an intrinsic property of the source rather than due to absorption effects. It implies that the energy budget available to accelerate particles and the balance between energy stored in particles and in the magnetic field, is less than expected.

“This is an important discovery that will be used for the years to come to improve simulations of jets. We observed for the first time a new signature of particle acceleration in the power emitted of quasar jets at long radio wavelengths. An unexpected behaviour that changes our interpretation on their evolution.” Said Prof. Francesco Massaro from University of Turin. “We knew that this was already discovered in other cosmic sources but it was never before observed in quasars.”

The international team of astrophysicists had observed the jet of the quasar 4C+19.44 at short radio wavelengths, in visible light, and X-ray wavelengths. The addition of the LOFAR images allowed astrophysicists to make this discovery. LOFAR is the first radio facility operating at long radio wavelengths, which produces sharp images with a resolution similar to that of the Hubble Space Telescope.

“We have been able to perform this experiment thanks to the highest resolution ever achieved at these long radio wavelengths, made possible by LOFAR.” Said Dr Adam Deller, an astrophysicist of the Swinburne University of Technology who contributed to the LOFAR data analysis and imaging of 4C +19.44 while at ASTRON in the Netherlands, heart of the LOFAR collaboration.

Dr Raymond Oonk, an astronomer at ASTRON and Leiden University and Dr Javier Moldon, astronomer at the University of Manchester, explained that “We have developed new calibration techniques for LOFAR and this has allowed us to separate compact radio structures in the quasar jet known as radio knots, and measure their emitted light. This result was unexpected and demands to future deeper investigations. New insights and clues on particle acceleration will come soon thanks to the international stations of LOFAR.”

The observation performed on the radio jet of 4C+19.44 was designed by Dr D. E. Harris, supervisor of Prof. Francesco Massaro, while working at the Harvard-Smithsonian Center for Astrophysics, several years ago. He performed the observation in collaboration with Dr Raffaella Morganti and his friends and colleagues at ASTRON. He only got the opportunity to see preliminary results as he passed away on 2015 December 6th. This publication, published in the first March issue of The Astrophysical Journal, is in memory of a career spanned much of the history of radio astronomy.

See the full article here .

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LOFAR is a radio telescope composed of an international network of antenna stations and is designed to observe the universe at frequencies between 10 and 250 MHz. Operated by ASTRON, the network includes stations in the Netherlands, Germany, Sweden, the U.K., France, Poland and Ireland.

ASTRON LOFAR Radio Antenna Bank, Netherlands

Westerbork Synthesis Radio Telescope (WSRT)

ASTRON was founded in 1949, as the Foundation for Radio radiation from the Sun and Milky Way (SRZM). Its original charge was to develop and operate radio telescopes, the first being systems using surplus wartime radar dishes. The organisation has grown from twenty employees in the early 1960’s to about 180 staff members today.

From ALMA via NRAO: “Tale As Old As Time”

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

From ALMA

via

National Radio Astronomy Observatory

January 7, 2019

Hot spots in the cosmic microwave background tell us about the history and evolution of distant quasars.

Credit: NRAO/AUI/NSF

Image author of a quasar. Credit: NRAO / AUI / NSF.

Synopsis: Using data from ALMA, a team of astronomers studied the growth and evolution of bubbles of hot plasma produced by active quasar HE 0515-4414. The bubble was analyzed by observing its effect on light from the cosmic microwave background. It is the first time this method has been used to directly study outflows from quasars.

Cosmic microwave background radiation is the first light in the cosmos.

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

The light we see began its journey when the universe was just 380,000 years old, when the temperature of the universe had finally dropped to the point where the primordial plasma of electrons and protons cooled enough to form transparent hydrogen gas. At first, the cosmic background was a nearly perfect blackbody spectrum. A blackbody spectrum is the spectrum of light caused by the temperature of an object. Sunlight, for example, is also a blackbody spectrum. Shortly after it first appeared, the cosmic blackbody was an orange glow, but during its 13.7 billion year journey the expansion of the universe shifted it to infrared and then microwave radiation. We now see this background as a faint glow of microwave light coming from all directions.

CMB per ESA/Planck

ESA/Planck 2009 to 2013

The cosmic background is still a blackbody, but not a perfect one. There are small fluctuations in the background. Regions that are a bit warmer than average, and regions that are slightly cooler. Most of these fluctuations are due to variations in the early universe. Slightly warmer regions expanded to fill the vast voids between galaxies, while slightly cooler regions condensed into galaxies and clusters of galaxies.

But some of these fluctuations are due to the tremendously long journey the light took to reach us. While traveling for billions of years, the light of the cosmic background passed through all the gas, dust and plasma between us and its source. Some of the light was absorbed. Some lost energy by scattering and now appears cooler than it would otherwise. But some of it gained energy, making the cosmic background appear warmer than it should.

This warming process is known as the Sunyaev–Zel’dovich effect (or SZ effect). When low energy photons from the cosmic microwave background pass through a region of hot plasma, they can collide with fast-moving electrons. The photons are then scattered with a great deal of energy. So the cosmic light leaves the region warmer and brighter – leaving a “hole” in the background at low frequencies, corresponding to lower photon energies. By looking for temperature fluctuations in the cosmic background, astronomers can study regions of hot plasma.

In a recent paper published in the Monthly Notices of the Royal Astronomical Society, a team of researchers used the SZ effect to study bubbles of hot plasma near distant quasars. Quasars are bright radio beacons in the sky. They are powered by supermassive black holes in the hearts of galaxies. As the black holes consume matter near them, they radiate tremendous energy. They are often more than 100 times brighter than the galaxy in which they live. This can create a quasar wind of ionized gas that streams away from the galaxy, similar to the way our Sun creates a solar wind. When the quasar wind collides with the diffuse and cool gas of intergalactic space, it can create bubbles of hot plasma.

Quasars aren’t as distant as the cosmic microwave background, but they are still billions of light-years away. That means any light given off by the plasma bubbles is much too faint to be observed directly. But they can be studied through the SZ effect. In order to do that, however, you need to capture high-resolution images of the microwave background. This is where the Atacama Large Millimeter/submillimeter Array (ALMA) comes in. Located high in the Andes of northern Chile, ALMA can capture microwave images at a resolution similar to visible light images captured by the Hubble space telescope. Just as the Hubble can show us beautiful images of distant nebulae, ALMA can capture images of hot plasma bubbles.

Using data from ALMA, the astronomers detected a bubble near the quasar HE 0515-4414. This is a hyperluminous quasar, meaning that it is extremely bright and active. But surprisingly when they used their data to measure the quasar wind, they found it was smaller than anticipated. The quasar wind is only 0.01% of the total luminosity of the quasar. Theoretical models predicted that the quasar wind should be much stronger. It seems that while quasars can create hot bubbles of plasma around a galaxy, the process isn’t particularly efficient.

The scale of the bubble also told them it formed over a period of about 100 million years, and it will take about 600 million years to cool down. Those time scales are long enough that hot plasma bubbles could interact with cooler material in the galaxy to influence star production and the evolution of the galaxy.

Of course this is just the first hot plasma bubble to be observed, and it’s impossible to know if HE 0515-4414 is typical or a rare exception. So the search is on to find more bubble-blowing quasars.

See the full article here .

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The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

From Gemini Observatory: “Cosmic Telescope Zooms in on the Beginning of Time”

From Gemini Observatory

January 9, 2019

Media Contact:

Peter Michaud
Public Information and Outreach manager
Gemini Observatory
Email: pmichaud@gemini.edu
Desk: 808-974-2510
Cell: 808-936-6643

Science Contacts:

Xiaohui Fan
Regents’ Professor of Astronomy
Steward Observatory
University of Arizona
Email: fan@as.arizona.edu
Desk: 520-360-0956

John Blakeslee
Head Scientist
Gemini Observatory, La Serena, Chile
Email: jblakeslee@gemini.edu
Desk: 56-51-2205-628

The scientific result described in this release is based on a presentation at the 233rd meeting of the American Astronomical Society in Seattle, Washington and published in The Astrophysical Journal Letters. The research was sponsored by grants from the U.S. National Science Foundation (NSF) Division of Astronomical Sciences and NASA. The National Science Foundation also supports the Gemini Observatory.

Observations from Gemini Observatory identify a key fingerprint of an extremely distant quasar, allowing astronomers to sample light emitted from the dawn of time. Astronomers happened upon this deep glimpse into space and time thanks to an unremarkable foreground galaxy acting as a gravitational lens, which magnified the quasar’s ancient light.

Gravitational Lensing NASA/ESA

The Gemini observations provide critical pieces of the puzzle in confirming this object as the brightest appearing quasar so early in the history of the Universe, raising hopes that more sources like this will be found.

A number of large telescopes were used to observe quasar J0439+1634 in the optical and infrared light. The 6.5m MMT Telescope was used to discovery this distant quasar.

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)

It and the 10m Keck-I Telescope obtained a sensitive spectrum of the quasar in optical light.

Keck 1 Telescope, Keck Observatory, Maunakea, Hawaii, USA.4,207 m (13,802 ft), above sea level,

The 8.1m Gemini Telescope obtained an infrared spectrum that accurately determined the quasar distance and the mass of its powerful black hole.

The 2×8.4m Large Binocular Telescope captured an adaptive optics corrected image that suggests the quasar is lensed, later confirmed by the sharper Hubble image. Credit: Feige Wang (UCSB), Xiaohui Fan (University of Arizona)

U Arizona Large Binocular Telescope, Large Binocular Telescope Interferometer, or LBTI, is a ground-based instrument connecting two 8-meter class telescopes on Mount Graham, Arizona, USA, Altitude 3,221 m (10,568 ft.) to form the largest single-mount telescope in the world. The interferometer is designed to detect and study stars and planets outside our solar system. Image credit: NASA/JPL-Caltech.

Before the cosmos reached its billionth birthday, some of the very first cosmic light began a long journey through the expanding Universe. One particular beam of light, from an energetic source called a quasar, serendipitously passed near an intervening galaxy, whose gravity bent and magnified the quasar’s light and refocused it in our direction, allowing telescopes like Gemini North to probe the quasar in great detail.

“If it weren’t for this makeshift cosmic telescope, the quasar’s light would appear about 50 times dimmer,” said Xiaohui Fan of the University of Arizona who led the study. “This discovery demonstrates that strongly gravitationally lensed quasars do exist despite the fact that we’ve been looking for over 20 years and not found any others this far back in time.”

The Gemini observations provided key pieces of the puzzle by filling a critical hole in the data. The Gemini North telescope on Maunakea, Hawai‘i, utilized the Gemini Near-InfraRed Spectrograph (GNIRS) to dissect a significant swath of the infrared part of the light’s spectrum.

Gemini/North telescope at Maunakea, Hawaii, USA,4,207 m (13,802 ft) above sea level

Gemini Near-Infrared Spectrograph on Gemini North, Mauna Kea, Hawaii USA

The Gemini data contained the tell-tale signature of magnesium which is critical for determining how far back in time we are looking. The Gemini observations also led to a determination of the mass of the black hole powering the quasar. “When we combined the Gemini data with observations from multiple observatories on Maunakea, the Hubble Space Telescope, and other observatories around the world, we were able to paint a complete picture of the quasar and the intervening galaxy,” said Feige Wang of the University of California, Santa Barbara, who is a member of the discovery team.

That picture reveals that the quasar is located extremely far back in time and space – shortly after what is known as the Epoch of Reionization — when the very first light emerged from the Big Bang.

Reionization era and first stars, Caltech

“This is one of the first sources to shine as the Universe emerged from the cosmic dark ages,” said Jinyi Yang of the University of Arizona, another member of the discovery team. “Prior to this, no stars, quasars, or galaxies had been formed, until objects like this appeared like candles in the dark.”

The foreground galaxy that enhances our view of the quasar is especially dim, which is extremely fortuitous. “If this galaxy were much brighter, we wouldn’t have been able to differentiate it from the quasar,” explained Fan, adding that this finding will change the way astronomers look for lensed quasars in the future and could significantly increase the number of lensed quasar discoveries. However, as Fan suggested, “We don’t expect to find many quasars brighter than this one in the whole observable Universe.”

The intense brilliance of the quasar, known as J0439+1634 (J0439+1634 for short), also suggests that it is fueled by a supermassive black hole at the heart of a young forming galaxy. The broad appearance of the magnesium fingerprint captured by Gemini also allowed astronomers to measure the mass of the quasar’s supermassive black hole at 700 million times that of the Sun. The supermassive black hole is most likely surrounded by a sizable flattened disk of dust and gas. This torus of matter — known as an accretion disk — most likely continually spirals inward to feed the black hole powerhouse. Observations at submillimeter wavelengths with the James Clerk Maxwell Telescope on Maunakea suggest that the black hole is not only accreting gas but may be triggering star birth at a prodigious rate — which appears to be up to 10,000 stars per year; by comparison, our Milky Way Galaxy makes one star per year. However, because of the boosting effect of gravitational lensing, the actual rate of star formation could be much lower.

Quasars are extremely energetic sources powered by huge black holes thought to have resided in the very first galaxies to form in the Universe. Because of their brightness and distance, quasars provide a unique glimpse into the conditions in the early Universe. This quasar has a redshift of 6.51, which translates to a distance of 12.8 billion light years, and appears to shine with a combined light of about 600 trillion Suns, boosted by the gravitational lensing magnification. The foreground galaxy which bent the quasar’s light is about half that distance away, at a mere 6 billion light years from us.

Fan’s team selected J0439+1634 as a very distant quasar candidate based on optical data from several sources: the Panoramic Survey Telescope and Rapid Response System1 (Pan-STARRS1; operated by the University of Hawai‘i’s Institute for Astronomy), the United Kingdom Infra-Red Telescope Hemisphere Survey (conducted on Maunakea, Hawai‘i), and NASA’s Wide-field Infrared Survey Explorer (WISE) space telescope archive.

Pann-STARSR1 Telescope, U Hawaii, Mauna Kea, Hawaii, USA, Altitude 3,052 m (10,013 ft)

UKIRT, located on Mauna Kea, Hawai’i, USA as part of Mauna Kea Observatory,4,207 m (13,802 ft) above sea level

NASA Wise Telescope

The first follow-up spectroscopic observations, conducted at the Multi-Mirror Telescope in Arizona, confirmed the object as a high-redshift quasar. Subsequent observations with the Gemini North and Keck I telescopes in Hawai‘i confirmed the MMT’s finding, and led to Gemini’s detection of the crucial magnesium fingerprint — the key to nailing down the quasar’s fantastic distance. However, the foreground lensing galaxy and the quasar appear so close that it is impossible to separate them with images taken from the ground due to blurring of the Earth’s atmosphere. It took the exquisitely sharp images by the Hubble Space Telescope to reveal that the quasar image is split into three components by a faint lensing galaxy.r.

The quasar is ripe for future scrutiny. Astronomers also plan to use the Atacama Large Millimeter/submillimeter Array, and eventually NASA’s James Webb Space Telescope, to look within 150 light-years of the black hole and directly detect the influence of the gravity from black hole on gas motion and star formation in its vicinity.

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

NASA/ESA/CSA Webb Telescope annotated

Any future discoveries of very distant quasars like J0439+1634 will continue to teach astronomers about the chemical environment and the growth of massive black holes in our early Universe.

See the full article here .

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Gemini/North telescope at Maunakea, Hawaii, USA,4,207 m (13,802 ft) above sea level

Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile, at an altitude of 7200 feet

Gemini’s mission is to advance our knowledge of the Universe by providing the international Gemini Community with forefront access to the entire sky.

The Gemini Observatory is an international collaboration with two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located on Mauna Kea, Hawai’i (Gemini North) and the other telescope on Cerro Pachón in central Chile (Gemini South); together the twin telescopes provide full coverage over both hemispheres of the sky. The telescopes incorporate technologies that allow large, relatively thin mirrors, under active control, to collect and focus both visible and infrared radiation from space.

The Gemini Observatory provides the astronomical communities in six partner countries with state-of-the-art astronomical facilities that allocate observing time in proportion to each country’s contribution. In addition to financial support, each country also contributes significant scientific and technical resources. The national research agencies that form the Gemini partnership include: the US National Science Foundation (NSF), the Canadian National Research Council (NRC), the Chilean Comisión Nacional de Investigación Cientifica y Tecnológica (CONICYT), the Australian Research Council (ARC), the Argentinean Ministerio de Ciencia, Tecnología e Innovación Productiva, and the Brazilian Ministério da Ciência, Tecnologia e Inovação. The observatory is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF. The NSF also serves as the executive agency for the international partnership.

From National Radio Astronomy Observatory via Science Alert: “BREAKING: We Just Found The Brightest Object in The Early Universe – 13 Billion Light-Years Away”

From National Radio Astronomy Observatory

via

Science Alert

9 JUL 2018
MICHELLE STARR

(NASA Goddard)

Astronomers have found the brightest object ever discovered in the early Universe, 13 billion light-years away – a quasar from a time when our Universe was just seven percent of its current age.

A quasar is a galaxy that orbits a supermassive black hole actively feeding on material. The light and radio emissions we see are caused by material around the black hole, called an accretion disk.

This disk contains dust and gas swirling at tremendous speeds like water going down a drain, generating immense friction as it’s pulled by the massive gravitational force of the black hole in the centre.

As they consume matter, these quasar black holes expel powerful jets of plasma at near light-speed from the coronae – regions of hot, swirling gas above and below the accretion disk.

These jets are extremely bright in the radio frequency spectrum. It was this signal emanating from the newly discovered quasar, named PSO J352.4034-15.3373 (P352-15 for short), that was picked up by the Very Long Baseline Array radio telescope.

NRAO/VLBA

“There is a dearth of known strong radio emitters from the Universe’s youth and this is the brightest radio quasar at that epoch by a factor of 10,” said astrophysicist Eduardo Bañados of the Carnegie Institution for Science in Pasadena, California.

(Momjian, et al.; B. Saxton (NRAO/AUI/NSF))

The VLBA’s observations showed the quasar split into three distinct components, for which there are two possible interpretations.

The first is that the black hole is at one end, and the two other components are parts of a single jet. The second is that the black hole is in the middle, with a jet on either side.

According to optical telescopes, which show the quasar in visible light, the position of the black hole aligns with one of the end components – making the first interpretation the most likely.

This means that, by studying and analysing the two parts of the jet, astrophysicists may be able to measure how fast it is expanding.

“This quasar may be the most distant object in which we could measure the speed of such a jet,” said NRAO astronomer Emmanuel Momjian.

On the other hand, if the black hole turns out to be in the centre, it means the jets are much smaller – which would mean a much younger object, or one that is embedded in dense material that’s slowing down the jets.

Further research will need to be done to determine which of the two scenarios is true. In the meantime, P352-15 is still a highly valuable object for study.

It’s not as old as J1342+0928, a quasar also discovered by a team led by Bañados, from when the Universe was only five percent of its current age.

J1342+0928

But the light of quasars can be used to study the intergalactic medium. This is because the hydrogen it travels through on its long journey to Earth changes the light’s spectrum – recently, a quasar was used in just this way to find the Universe’s missing baryonic matter in the space between galaxies.

P352-15 has great potential as a tool of this nature.

“We are seeing P352-15 as it was when the Universe was less than a billion years old,” said astrophysicist Chris Carilli of NRAO.

“This is near the end of a period when the first stars and galaxies were re-ionising the neutral hydrogen atoms that pervaded intergalactic space. Further observations may allow us to use this quasar as a background ‘lamp’ to measure the amount of neutral hydrogen remaining at that time.

“This quasar’s brightness and its great distance make it a unique tool to study the conditions and processes that prevailed in the first galaxies in the Universe.”

The research has been published in The Astrophysical Journal Resolving the Powerful Radio-loud Quasar at z ~ 6, and A Powerful Radio-loud Quasar at the End of Cosmic Reionization.

See the full article here .

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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).

NRAO VLBA

NRAO VLBA

*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).

From NAOJ: “Double or Nothing: Astronomers Rethink Quasar Environment”

NAOJ

March 12, 2018
No writer credit

Using Hyper Suprime-Cam (HSC) mounted on the Subaru Telescope, astronomers have identified nearly 200 “protoclusters,” the progenitors of galaxy clusters, in the early Universe, about 12 billion years ago, about ten times more than previously known.

NAOJ Subaru Hyper Suprime-Cam

NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

They also found that quasars don’t tend to reside in protoclusters; but if there is one quasar in a protocluster, there is likely a second nearby. This result raises doubts about the relation between protoclusters and quasars.

In the Universe, galaxies are not distributed uniformly. There are some places, known as clusters, where dozens or hundreds of galaxies are found close together. Other galaxies are isolated. To determine how and why clusters formed, it is critical to investigate not only mature galaxy clusters as seen in the present Universe but also observe protoclusters, galaxy clusters in the process of forming.

Because the speed of light is finite, observing distant objects allows us to look back in time. For example, the light from an object 1 billion light-years away was actually emitted 1 billion years ago and has spent the time since then traveling through space to reach us. By observing this light, astronomers can see an image of how the Universe looked when that light was emitted.

Even when observing the distant (early) Universe, protoclusters are rare and difficult to discover. Only about 20 were previously known. Because distant protoclusters are difficult to observe directly, quasars are sometimes used as a proxy. When a large volume of gas falls towards the super massive black hole in the center of a galaxy, it collides with other gas and is heated to extreme temperatures. This hot gas shines brightly and is known as a quasar. The thought was that when many galaxies are close together, a merger, two galaxies colliding and melding together, would create instabilities and cause gas to fall into the super massive black hole in one of the galaxies, creating a quasar. However, this relationship was not confirmed observationally due to the rarity of both quasars and protoclusters.

In order to understand protoclusters in the distant Universe a larger observational sample was needed. A team including astronomers from the National Astronomical Observatory of Japan, the University of Tokyo, the Graduate University for Advanced Studies, and other institutes is now conducting an unprecedented wide-field systematic survey of protoclusters using the Subaru Telescope’s very wide-field camera, Hyper Suprime-Cam (HSC). By analyzing the data from this survey, the team has already identified nearly 200 regions where galaxies are gathering together to form protoclusters in the early Universe 12 billion years ago.

Figure 1: Galaxy distribution and close-ups of some protoclusters revealed by HSC. Higher- and lower-density regions are represented by redder and bluer colors, respectively. In the close-ups, white circles indicate the positions of distant galaxies. The red regions are expected to evolve into galaxy clusters. From the close-ups, we can see various morphologies of the overdense regions: some have another neighboring overdense region, or are elongated like a filament, while there are also isolated overdense regions. (Credit: NAOJ)

The team also addressed the relationship between protoclusters and quasars. The team sampled 151 luminous quasars at the same epoch as the HSC protoclusters and to their surprise found that most of those quasars are not close to the overdense regions of galaxies. In fact, their most luminous quasars even avoid the densest regions of galaxies. These results suggest that quasars are not a good proxy for protoclusters and more importantly, mechanisms other than galactic mergers may be needed to explain quasar activity. Furthermore, since they did not find many galaxies near the brightest quasars, that could mean that hard radiation from a quasar suppresses galaxy formation in its vicinity.

On the other hand, the team found two “pairs” of quasars residing in protoclusters. Quasars are rare and pairs of them are even rarer. The fact that both pairs were associated with protoclusters suggests that quasar activity is perhaps synchronous in protocluster environments. “We have succeeded in discovering a number of protoclusters in the distant Universe for the first time and have witnessed the diversity of the quasar environments thanks to our wide-and-deep observations with HSC,” says the team’s leader Nobunari Kashikawa (NAOJ).

Figure 2: The two quasar pairs and surrounding galaxies. Stars indicate quasars and bright (faint) galaxies at the same epoch are shown as circles (dots). The galaxy overdensity with respect to the average density is shown by the contour. The pair members are associated with high density regions of galaxies. (Credit: NAOJ)

“HSC observations have enabled us to systematically study protoclusters for the first time.” says Jun Toshikawa, lead author of the a paper reporting the discovery of the HSC protoclusters, “The HSC protoclusters will steadily increase as the survey proceeds. Thousands of protoclusters located 12 billion light-years away will be found by the time the observations finish. With those new observations we will clarify the growth history of protoclusters.”

These results were published on January 1, 2018 in the HSC special issue of the Publications of the Astronomical Society of Japan (Toshikawa et al. 2018, GOLDRUSH. III. A Systematic Search of Protoclusters at z~4 Based on the >100 deg2 Area, PASJ, 70, S12; Uchiyama et al. 2018, Luminous Quasars Do Not Live in the Most Overdense Regions of Galaxies at z~4, PASJ, 70, S32; Onoue et al. 2018, Enhancement of Galaxy Overdensity around Quasar Pairs at z<3.6 based on the Hyper Suprime-Cam Subaru Strategic Program Survey, PASJ, 70, S31). These projects are supported by Grants-In-Aid JP15H03645, JP15K17617, and JP15J02115.

See the full article here .

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The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

In the 2004 reform of national research organizations, NAOJ became a division of the National Institutes of Natural Sciences.

NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

ESO/NRAO/NAOJ ALMA Array

Solar Flare Telescope

Nobeyama Radio Observatory

Nobeyama Radio Observatory: Solar

Mizusawa VERA Observatory

Okayama Astrophysical Observatory

The National Astronomical Observatory of Japan (NAOJ) is an astronomical research organisation comprising several facilities in Japan, as well as an observatory in Hawaii. It was established in 1988 as an amalgamation of three existing research organizations – the Tokyo Astronomical Observatory of the University of Tokyo, International Latitude Observatory of Mizusawa, and a part of Research Institute of Atmospherics of Nagoya University.

From U Arizona: “Students Help Little Telescope Do Big Things”

University of Arizona

Jan. 11, 2018
Daniel Stolte

A four-year effort involving UA students helped a team of astronomers measure the masses of a large sample of supermassive black holes in the farthest reaches of the universe. As part of a robotic telescope network in southern Arizona, instruments such as the Bok Telescope could play a crucial role in future “grand challenge” science endeavors.

2.3-metre Bok Telescope at the Steward Observatory at Kitt Peak in Arizona, USA, altitude 2,096 m (6,877 ft)

U Arizona Steward Observatory at Kitt Peak, AZ, USA, altitude 2,096 m (6,877 ft)

The Bok Telescope on Kitt Peak is the largest telescope operated solely by the UA’s Steward Observatory. Named in honor of Bart Bok, who was Steward’s director from 1966-1969, the telescope operates every night of the year except Christmas Eve and a maintenance period scheduled during the summer rainy season.

By today’s standards, the University of Arizona’s Bok Telescope, perched on Kitt Peak southwest of Tucson, is a small telescope: Its primary mirror stands a mere five inches taller than Dušan Ristić, the 7-foot center of the UA men’s basketball team.

Yet, despite its modest size and advanced age of almost 50 years, the instrument keeps churning out big science, helping us unravel some of the biggest questions about the cosmos. Using observations made with the Bok Telescope, a team of astronomers managed to directly measure the masses of an unprecedented number of the universe’s most distant supermassive black holes, also called quasars. Lurking in the centers of nearly every large galaxy, these Leviathans range from 5 million to 1.7 billion times the mass of the sun.

“This is the first time that we have directly measured masses for so many supermassive black holes so far away,” said Catherine Grier, a postdoctoral fellow at the Penn State University, who led the research. “These new measurements, and future measurements like them, will provide vital information for people studying how galaxies grow and evolve throughout cosmic time.”

The results, presented at the American Astronomical Society meeting in National Harbor, Maryland, are published in The Astrophysical Journal and represent a major step forward in our ability to measure supermassive black hole masses in large numbers of distant quasars and galaxies. In addition to the Bok Telescope, the project used the Sloan Digital Sky Survey, or SDSS, and the Canada-France-Hawaii Telescope, or CFHT, atop Hawaii’s Mauna Kea volcano.

SDSS Telescope at Apache Point Observatory, near Sunspot NM, USA, Altitude 2,788 meters (9,147 ft)

Apache Point Observatory, near Sunspot, New Mexico Altitude 2,788 meters (9,147 ft)

CFHT Telescope, Maunakea, Hawaii, USA, at Maunakea, Hawaii, USA,4,207 m (13,802 ft) above sea level

An artist’s rendering of the inner regions of a quasar, with a supermassive black hole at the center surrounded by a disk of hot material falling in. The two light curves at the bottom illustrates how astronomers use reverberation to map black holes. (Image: Nahks Tr’Ehnl and Catherine Grier/Penn State, SDSS)

“The Bok Telescope provided key data that allow measurement of how the quasars vary over time, which tells us about the size of the light-emitting region around the black hole,” said Xiaohui Fan, a Regents’ Professor of Astronomy at the UA’s Steward Observatory and a member of the Sloan Digital Sky Survey. “The data is then used to determine the mass of the black hole.”

Producing ‘World-Class Results’

The Bok Telescope’s large field of view, combined with the sensitive detectors, means that astronomers can monitor many quasars at the same time, a feat that is crucial to establish the large sample used in the study.

“This result shows that the Bok can still produce world-class results,” said Ian McGreer, an assistant astronomer at Steward and one of the study’s authors, who managed the observations with the Bok Telescope. “We got involved because the SDSS did a survey of facilities that could support this program, and the Bok came out as one of the few with the required capabilities.”

The Bok investment was quite substantial, McGreer explained, with more than 100 nights spread over four years so far.

“The data in this paper are based on the first year, 2014, when the monitoring was the most intense,” he said. “Sixty nights that year were covered by a rotating cast of observers, many of whom were UA undergrads, grads and visiting students.

“The Bok does not have a nighttime operator, which means the students received valuable training not only in collecting the data and operating the instrument, but in learning how to operate a telescope at night. This is a fairly rare opportunity these days.”

As they suck in nearby dust and gas, supermassive black holes heat the material to such high temperatures that it glows brightly enough to be seen all the way across the universe. These bright disks of hot gas are known as quasars, and they are clear indicators of the presence of supermassive black holes. By studying these quasars, we learn not only about supermassive black holes, or SMBHs, but also about the distant galaxies they live in. But to do all of this requires measurements of the properties of the SMBHs, most importantly their masses.

Measuring the masses of extragalactic SMBHs — in this study, up to 8 billion light-years away — is a daunting task and requires a technique called reverberation mapping. Reverberation mapping works by comparing the brightness of light coming from gas very close in to the black hole (referred to as the “continuum” light) to the brightness of light coming from fast-moving gas farther out. Changes occurring in the continuum region impact the outer region, but light takes time to travel outward, or “reverberate.” By measuring this time delay, astronomers can determine how far out the gas is from the black hole. Knowing that distance allows them to measure the mass of the supermassive black hole — even though they can’t see the details of the black hole itself.

In this new work, the team used an industrial-scale application of the reverberation mapping technique, with the goal of measuring black hole masses in tens to hundreds of quasars. These new SDSS measurements increase the total number of active galaxies with SMBH mass measurements by about two-thirds, and push the measurements farther back in time to when the universe was only half of its current age.

Faint Quasars Pose a Challenge

The key to the success of the SDSS reverberation mapping project lies in the SDSS’ ability to study many quasars at once — the program is currently observing 850 quasars simultaneously. But even with the SDSS’ powerful telescope, this is a challenging task because these distant quasars are incredibly faint.

“You have to calibrate these measurements very carefully to make sure you really understand what the quasar system is doing,” said Jon Trump, an assistant professor at the University of Connecticut and a member of the research team.

Observing the quasars over the same season with the Bok Telescope and the CFHT improved these calibrations, allowing the team to find reverberation time delays for 44 quasars and use the time delay measurements to calculate black hole masses that range from about 5 million to 1.7 billion times the mass of our sun.

In the words of McGreer, the future is bright for this kind of work, with plans to develop a robotic telescope network in southern Arizona using telescopes such as the Bok, which could help guide efforts to combine such a network with “grand challenge” science projects like the Large Synoptic Survey Telescope, or LSST.

Slated to begin operations in 2023, the LSST will conduct an unprecedented 10-year survey, repeatedly imaging every part of the visible sky every few nights. The heart of the instrument, a 8.4-meter primary mirror, was cast and polished at the UA’s Richard F. Caris Mirror Lab.

“The lessons learned from this reverberation mapping project serve as a pathfinder, or proof of concept, for something that could be done on a much larger scale when LSST arrives,” McGreer said.

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.

See the full article here .

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