Adam Burrows is a professor of astrophysics at the University and has served on the Board of Trustees of the Aspen Center for Physics. In the past, he was the chair of the Board on Physics and Astronomy of the National Research Council and has worked on a number of committees for NASA.

Recently, Burrows was awarded the 2020 Viktor Ambartsumian International Science Prize for his seminal and pioneering contributions to the theories of brown dwarfs and exoplanets and for his leadership role in educating a generation of scientists at the frontiers of brown dwarf and exoplanet research, according to the Prize Committees press release. He sat down with The Daily Princetonian for a virtual interview, touching on his work on brown dwarfs, his career path, and the importance of teaching to excel in research.

The Daily Princetonian: Id like to start by saying congratulations for winning this prestigious prize. I understand that you won for your research on brown dwarfs and exoplanets. Could you walk me through what that work entails?

Adam Burrows: A number of decades ago, it was interesting, theoretically, to look at objects that were significantly smaller than regular stars. As you go down in mass, from one solar mass to half a solar mass, to one-third, etc., the luminosities go down significantly and the temperatures get lower and lower at the surface. When you get down to about one-twelfth of a solar mass, you get to the point where you can't derive enough thermonuclear burning in the star to balance the losses from the surface. So below that mass, you have what are called brown dwarfs. The brown dwarfs will have a little bit of thermonuclear life, but they won't be able to compensate for the losses from the surface. They're like dying embers plucked from a fire.

What I did with collaborators over the years was to calculate what these things would look like... Over the last many years, people have developed the technology necessary to characterize brown dwarfs we have discovered a few thousand of them but what we did early on was try to provide the theoretical context for understanding these objects. And thats what is being recognized.

You can also ask the question, What if you have an object that is much less massive than this transition mass, which, as I said, is one-twelfth of the solar mass, or around 70 Jupiter masses? If you go down to 60 or 40 masses, you have brown dwarfs, but if you extend it down to five, four, three, or just the mass of Jupiter, youre starting to talk about exoplanets. So, at the same time, we started putting together a theory about these objects, which is an extension of the work on brown dwarfs that straddles the realm between brown dwarfs and the planets we know in our solar system...

At around the same time, the first unimpeachable brown dwarf was discovered. [Michel] Mayor and [Didier] Queloz discovered 51 Pegasi b, the first exoplanet around a solar-like star, and this discovery garnered the Nobel Prize in Physics for them last year. At that time, we were the only theorists working on this general subject, and we taught a generation of theorists and observers about these objects. Collectively, the giant planet and brown dwarf work we did is the origin of this prize and the kudos that I quite gratifyingly received.

DP: What direction do you wish to take this work in the future?

AB: Important in the near future is what we can learn using the James Webb Space Telescope because it will be exquisitely sensitive to brown dwarf and exoplanet observation. There will also be another space-based satellite Ariel that the Europeans are going to launch towards the end of this coming decade. What were going to be able to understand at the lower temperatures of brown dwarf and exoplanet surfaces is cool molecular atmospheres similar to those of the local planets with which we are familiar...

I used to be the director of the Planets and Life certificate program at Princeton, which is astrobiology, and part of the subject is the connection with the origin of life. Theres a lot of study to try to understand the origin of life on Earth there was just the launch of the Perseverance probe to Mars, part of the tradition of Mars probes to search for signs of past life but it would also be nice to have other targets outside of the solar system, where we may be able to discern signatures of life. Thats a goal, and its been a goal of a good fraction of astronomy and planetary science for a long time.

DP: I know your many other research interests include impressive topics such as nuclear astrophysics and supernova theory, so whats another particularly memorable research experience or project from your career, and could you tell me a bit about it?

AB: Im still working a lot on supernova theory, and what were trying to do is to understand the mechanism of explosion. Supernovae are important agencies of change in the universe. Theyre the source of many of the heavy elements in nature. The iron in your hemoglobin, the calcium in your bones, the oxygen you breathe, and the fluorine in your toothpaste come from the massive stars that explode in supernovae.

The galaxy is constantly enriched by these heavy elements, and the solar system and the Sun are actually the products of this progressive enrichment. But the mechanism of these explosions has been shrouded in mystery because they happen in the deep interior of a star, which we dont have access to directly. By dint of nuclear physics, particle physics, and large supercomputers, weve recently been able to simulate in some detail the internal dynamics of this object that gives us a supernova.

DP: How did you get your start in astrophysics? What drew you to the field?

AB: I was interested in how things work and in physics, and what I liked about physics was its broad applicability. But I didnt want to major in just one aspect of physics. I wanted to range broadly, and you can do that in astrophysics. You learn a little bit about everything and bring it together its at the interface of many of the disciplines in physics and in the process, you learn how nature works, because it doesn't silo these disciplines, but combines them effortlessly.

DP: How do you think we should approach the search for life in space, with issues like both forward and backward contamination to consider? Also, some scientists suggest first coming up with an accurate definition of life before continuing our search in space. What are your thoughts on that?

AB: Its a much discussed topic: Youre talking about planetary protection and contamination, both backwards and forwards. People worry about that, but Im not as worried I think people have been pretty careful. But over time, with commercial space initiatives and with the multitude of countries that are getting involved, the solar system is going to be contaminated. So we better hurry up if were trying to understand the origin of life in the solar system.

Having said that, you also want to have a protocol for understanding what the atmosphere of a life-bearing planet looks like the so-called biosignature. Theres a lot of caveats there do you really have a general theory about what lifes products will be? Do you really have a general theory of the evolution of life in many different contexts? And there could be very many contexts that could give rise to self-replicating organic lifeforms that satisfy Darwinian evolution. Its something that requires thought in all directions, and I certainly wouldnt want to stop things just to contemplate how best to proceed. The most important thing is to start getting data, both in the solar system and beyond.

DP: How was your experience in working with NASA, with roles such as co-chair of the organizations Universe Subcommittee?

AB: You learn how the sausage is made, which is probably the most important thing, but you also get an appreciation for how hard a lot of these things are, and how good and professional of an organization NASA is. No organization is perfect, but its been quite successful. Its well-configured to answer many of the questions that many of us have about the universe...

DP: How does teaching inform your research, and vice versa?

AB: You really need to be connected to students, or you dont get the energy that they provide. You need to collaborate with students, not only because that gives you a means to get work done, but it also sparks ideas. Its only in the academic environment that youre challenged by new results coming in all the time, and the ivory tower isnt the best place to do real science mathematics, perhaps. You need to be engaged, and youre best engaged in an academic context, which involves students. And your involvement with students and their involvement with you is central to real progress in science.

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Q&A with Astrophysics Professor, Viktor Ambartsumian International Science Prize winner Adam Burrows - The Daily Princetonian

Last winter Betelgeuse hit bottom. Although the star had been known for decades to vary in brightness, it reached a historic low in mid-February when it tumbled to magnitude 1.6, on par with its neighbor Bellatrix. Many of us watched the red supergiant star with great excitement, some even wondering if its behavior presaged a supernova explosion. Astronomers sought to explain its unprecedented dimming as possibly due to giant starspots darkening the stars surface or alternatively, light-absorbing dust clouds belched out by the monster star.

By March Betelgeuse had turned the corner and began to return to its former brilliance. Before it departed the evening sky in May it outshone nearby Aldebaran in Taurus. What happened?

When faintest in mid-February 2020, Betelgeuse equaled the star Bellatrix. It recovered in April and soon outshone Aldebaran. Magnitudes are shown in parentheses. (Bob King for the News Tribune)

Thanks to new Hubble Space Telescope observations a team of researchers now suggest that dust was the culprit. A large convective cell made of super-hot stellar gas called plasma welled up from Betelgeuses surface. A good way to picture this is to imagine rising air bubbles in a pot of boiling water. The plasma bubble ascended through the hot atmosphere and when it reached the colder, outer layers it cooled and formed dust. The resulting dust cloud blocked light from about a quarter of the stars surface, beginning in late 2019. By April the cloud had thinned or dissipated, and Betelgeuse returned to its normal brilliance.

With Hubble, we see the material as it left the stars visible surface and moved out through the atmosphere before the dust formed that caused the star appear to dim, said lead researcher Andrea Dupree, associate director of The Center for Astrophysics (Harvard & Smithsonian). We could see the effect of a dense, hot region in the southeast part of the star moving outward.

Like your unruly uncle or a husband whos a little too comfortable in a marriage Betelgeuse is a serial belcher. This infrared image from the Very Large Telescope (VLT) shows the immensity of the patchy dust clouds surrounding Betelgeuse in December 2019. The clouds form when the star sheds its material back into space. The black disk masks the star and its immediate surroundings so it can reveal the fainter dust plumes. The orange dot in the middle is an image of Betelgeuse itself. It looks tiny here, but if the star were swapped for our sun its outer surface would reach almost to Jupiter. In context, the dust clouds are enormous! (ESO / P. Kervella / M. Montargs et al. / Acknowledgement: Eric Pantin)

Astronomers kept track of the ejected material which was initially 2 to 4 times brighter than the stars normal brightness. Then a month later the southern hemisphere of Betelgeuse dimmed as the bright cloud cooled and darkened with dust. Specifically, astronomers looked at the element magnesium in the ejected gases and watched it travel from the surface to the outer atmosphere until it chilled to form dust.

Betelgeuse expands and contracts rhythmically, its surface rising and falling during each pulsation cycle. When the convective bubble erupted, observations show that the star was expanding at the same time. The team suspects that the pulsation may have given the hot gases an extra kick, hurrying them through the atmosphere and encouraging quick condensation.

Betelgeuse has a striking orange-red color and marks the shoulder of Orion the hunter. (Michael J. Boyle)

Every star is a time machine. Betelgeuse is about 650 light years away, so the dimming happened around the year 1370, not long after bubonic plague or Black Death (1346-1353) raged across Europe killing 50 million people. Vaccines were non-existent back then and medical care primitive. Lets hope science will soon get the current viral plague under control. One wonders what the world will be like 650 years from now. Will Betelgeuse still be around or will it have gone supernova and left a blank spot in Orions shoulder?

If youre getting up to see Orion at dawn, beam in on Betelgeuse and compare it to Bellatrix and Aldebaran. Guess what? The star is dimming again! This is very unusual since its normal bright-dim-bright cycle takes 420 days, and its only been a couple months since the last brightness peak in late May. Currently equal to Aldebaran, its anyones guess exactly what will happen next.

The mystery continues.

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Astro Bob: Hubble helps solve the mystery of why Betelgeuse faded - Duluth News Tribune

This guest post was written by Xing-Ye Zhu, a third-year undergraduate student at Nanjing University, for an assignment in the Astronomical Literature Reading and Writing class taught by Professor Zhi-Yu Zhang. Xing-Ye is currently working under the supervision of Professor Yi Xie on strong deflection gravitational lensing. When not doing science, he enjoys watching movies, plays, and Kunqu Opera. You can always find a Rubiks cube in his hands.

Title: Relativistic corrections to the rotation curves of disk galaxies

Authors: Alexandre Deur

First authors institution: Department of Physics, University of Virginia

Status: Open access on arXiv

For most astronomers, it is just common sense that dark matter accounts for approximately 85% of the matter in the universe. However, as long as the constituents of dark matter remain a mystery, some astronomers remain skeptical about our conventional understanding of dark matter. Recently, astronomer Alexandre Deur suggested that the theory of relativity itself may explain a phenomenon widely regarded as evidence for dark matter.

The theory of dark matter was proposed in the 1970s to explain the rotation curves of galaxies, which appeared inconsistent with the observed distribution of luminous matter (i.e. baryonic matter). The rotation curve of a disk galaxy, as shown in Figure 1, is the relation between the rotational velocity of stars in the galaxy and their radial distance from its centre. At larger radius, a typical spiral galaxy shows larger rotational velocity than the one predicted by the Newtonian gravitation of baryonic matter. The observed rotation curves typically show a plateau at large radius, therefore requiring more gravitation to keep the fast-moving stars from escaping the galaxy. This discrepancy is known as the missing mass problem. One possible explanation is the presence of additional mass which we cannot see. This missing mass is called dark matter. With the observed rotation curve, astronomers can easily calculate the missing mass required and therefore determine the distribution of dark matter.

Galaxy rotation curves are not the only evidence that exists for dark matter. For example, the Bullet Cluster is famous for being a smoking gun for dark matter. The Bullet Cluster consists of two merging galaxy clusters. The distribution of matter determined by X-ray imaging is very different to that inferred from gravitational lensing, suggesting the dark matter component has separated from the normal matter during the collision. See this website and this astrobite for further discussion. Dark matter also plays an important role in the widely accepted CDM model of cosmology.

For decades, astronomers have been searching for the essence of dark matter, both theoretically and experimentally. For example, astronomers have searched for WIMPs (Weakly Interacting Massive Particles) (read more in this astrobite and this one). It has also been hypothesised that dark matter may be made up of MACHOs (see this astrobite). However, the dark matter puzzle still remains unresolved, because it is challenging to completely verify or eliminate any of these theories (at least not yet). Some astronomers have suggested alternative theories. Is it possible that the missing mass is not actually mass, but an artefact arising from our mistaken understanding of the gravitation? After all, it is additional gravitation, rather than mass, that is required to explain the galaxy rotation curves.

It is not the first time physicists and astronomers have become skeptical about gravitation. One hundred years ago, the observation of Mercurys perihelion precession was initially interpreted as evidence of another planet inside the orbit of Mercury, but was later fully explained by a new theory of gravitation: general relativity. Today, astronomers are facing a similar problem is it something there, or is it just another correction to the theory of gravitation?

Modified Newtonian Dynamics, or MOND, for example, is the most discussed out of all the gravitation corrections to explain the missing mass problem (see this astrobite for further discussion of MOND vs. dark matter). It modifies the Newtonian gravitation law at low accelerations to enhance the effective gravitational attraction. Similarly, most of the other corrections require new descriptions of gravitation. But recently, as Deur proposes in this work, the effect of general relativity may account for the missing mass, without introducing any new corrections.

Generally, the predicted rotation of galaxies, as shown in Figure 1, is modelled by Newtonian dynamics. The rotation velocity is much smaller than the speed of light, especially at the outer part of the galaxy (typically , where is the velocity and is the speed of light). Therefore, it is believed that a non-relativistic treatment is reasonable. However, this assumption could be challenged due to the effect of field self-interaction in general relativity. This effect depends on the mass only, and is independent of the rotation velocity, thus making a difference regardless of how fast the stars move in the galaxy. Deur shows that field self-interaction, which reveals the non-linear nature of general relativity, is in fact not negligible in the missing mass problem.

To demonstrate this, Deur uses the gravitational lensing formalism. While light travels in straight lines in flat space, it can be deflected in the presence of a gravitational field. In exactly the same way, the gravitational field lines connecting two parts of the galaxy are distorted by the background field. That is to say, the gravitational field is deformed by the total galactic mass. With the field lines distorted, the strength of the gravitation consequently changes.

In addition to this, to reduce computation, Duer uses mean-field theory, an approximation technique widely employed in many fields (ha!) in physics. In this theory, the effect of all the other particles on any given individual particle is approximated by a single averaged effect, or the mean field, thus reducing a many-body problem to a one-body problem. Together with the gravitational lensing formalism, the self-interaction of the gravitational fields is computed. Figure 2 shows a demonstration of this effect it is clear that the self-interaction significantly distorts the gravitational field lines.

Duer demonstrates that field self-interaction increases gravitys strength compared to the Newtonian prediction. This effect will become noticeable in systems with sufficiently large mass. In Duers predicted rotation curve, shown in Figure 3, the observed plateau pattern is reproduced when field self-interaction is taken into consideration. Duer also computes the effective missing mass contribution derived from the comparison between the results of general relativity and Newtonian gravitation. This comparison leads to the prediction of a correlation between galactic dark mass and the vertical scale length of the disk galaxies and the prediction fits the observational data quite well.

In summary, Alexandre Deur proposes that the effect of field self-interaction needs to be included in the computation of rotation curve of the disk galaxy. Rather than merely taking the Newtonian gravitation into account, we need to consider the role general relativity plays in the physics of the galaxy. This consideration is able to partially explain the observed galaxy rotation curve, without modelling invisible dark matter or modifying the basic theory of gravitation.

In the debate about the existence of dark matter, Deur undoubtedly proposes another interesting possibility, yet more detailed investigation is needed to verify the significance of this effect. Maybe the relativistic effect is not enough to replace the missing mass completely, for there is other evidence for dark matter to explain. For disk galaxies at least, it is still important to know how much missing mass we have found. There is still a lot of work to be done before we can say that the puzzle of dark matter is resolved. However, we are getting closer all the time!

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The Alternative to Dark Matter May be General Relativity Itself - Astrobites

An artists impression of a black dwarf, a cooled-down stellar remnant that could form in trillions of years

By Adam MannAug. 11, 2020 , 5:35 PM

In the unimaginably far future, cold stellar remnants known as black dwarfs will begin to explode in a spectacular series of supernovae, providing the final fireworks of all time. Thats the conclusion of a new study, which posits that the universe will experience one last hurrah before everything goes dark forever.

Astronomers have long contemplated the ultimate end of the cosmos. The known laws of physics suggest that by about 10100 (the No. 1 followed by 100 zeros) years from now, star birth will cease, galaxies will go dark, and even black holes will evaporate through a process known as Hawking radiation, leaving little more than simple subatomic particles and energy. The expansion of space will cool that energy nearly to 0 kelvin, or absolute zero, signaling the heat death of the universe and total entropy.

But while teaching an astrophysics class this spring, theoretical physicist Matt Caplan of Illinois State University realized the fate of one last group of entities had never been accounted for. After exhausting their thermonuclear fuel, low mass stars like the Sun dont pop off in dramatic supernovae; rather, they slowly shed their outer layers and leave behind a scorching Earth-size core known as a white dwarf.

They are essentially pans that have been taken off the stove, Caplan says. Theyre going to cool and cool and cool, basically forever.

White dwarfs crushing gravitational weight is counterbalanced by a force called electron degeneracy pressure. Squeeze electrons together, and the laws of quantum mechanics prevent them from occupying the same state, allowing them to push back and hold up the remnants mass.

The particles in a white dwarf stay locked in a crystalline lattice that radiates heat for trillions of years, far longer than the current age of the universe. But eventually, these relics cool off and become a black dwarf.

Because black dwarfs lack energy to drive nuclear reactions, little happens inside them. Fusion requires charged atomic nuclei to overcome a powerful electrostatic repulsion and merge. Yet over long time periods, quantum mechanics allows particles to tunnel through energetic barriers, meaningfusion can still occur, albeit at extremely low rates.

When atoms such as silicon and nickel fuse toward iron, they produce positrons, the antiparticle of an electron. These positrons would ever-so-slowly destroy some of the electrons in a black dwarfs center and weaken its degeneracy pressure. For stars between roughly 1.2 and 1.4 times the Suns massabout 1% of all stars in the universe todaythis weakening would eventually result in a catastrophic gravitational collapse that drives a colossal explosion similar to the supernovae of higher mass stars, Caplan reports this month in the Monthly Notices of the Royal Astronomical Society.

Caplan says the dramatic detonations will begin to occurabout 101100 years from now, a number the human brain can scarcely comprehend. The already unfathomable number 10100 is known as a googol, so 101100 would be a googol googol googol googol googol googol googol googol googol googol googol years. The explosions would continue until 1032000 years from now, which would require most of a magazine page to represent in a similar fashion.

A time traveler hoping to witness this last cosmic display would be disappointed. By the start of this era, the mysterious substance acting in opposition to gravity called dark energy will have driven everything in the universe apart so much that each individual black dwarf would be surrounded by vast darkness: The supernovae would even be unobservable to each another.

In fact, Caplan showed that the radius of the observable universe will have by then grown by about e10^1100 (where e is approximately 2.72), a figure immensely larger than either of those given above. This is the biggest number Im ever going to have to seriously work with in my career, he says.

Gregory Laughlin, an astrophysicist at Yale University, praises the research as a fun thought experiment. The value of contemplating these mind-boggling timescales is that they allow scientists to consider physical processes that havent had enough time to unfold in the current era, he says.

Still, I think its important to stress that any investigations of the far future are necessarily tongue in cheek, Laughlin says. Our view of the extremely distant future is a reflection of our current understanding, and that view will change from one year to the next.

For example, some of the grand unified theories of physics suggest the proton eventually will decay. This would dissolve Caplans black dwarfs long before they would explode. And some cosmological models have hypothesized that the universe could collapse back in on itself in a big crunch, precluding the final light show.

Caplan himself enjoys peering into the distant future. I think our awareness of our own mortality definitely motivates some fascination with the end of the universe, he says. You can always reassure yourself, when things go wrong, that it wont matter once entropy is maximized.

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This is the way the universe ends: not with a whimper, but a bang - Science Magazine

A supernova is a powerful event. For a brief moment in time, a star shines as bright as a galaxy, ripping itself apart in a last, desperate attempt to fight against its gravity. While we see supernovae as rare and wondrous things, they are quite common. Based on observations of isotopes in our galaxy, we know that about twenty supernovae occur in the Milky Way every thousand years. These brilliant cosmic flashes fill the universe with heavy elements, and their remnant dust makes up almost everything we see around us. But supernovae wont keep happening forever. At some point in the far future, the universe will see the last supernova.

When the last supernova occurs is the subject of a new paper. Using what we know about astrophysics, it calculates when the last interesting astrophysical event will occur. Supernovae, as we see them today, are caused by massive stars. Since not all of a stars material is cast out by a supernova, the number of potential giant stars decreases with each generation. Within the next 100 billion years, large stars will stop forming, and the first supernova era will end.

But smaller stars such as red dwarfs will still be burning. They can continue to shine for trillions of years, but even they will exhaust their fuel by about 1014 years. By that time, there will only be the remnant cores of dead stars, collapsed into white dwarfs, neutron stars, or black holes, depending on their mass. Remnants larger than about two solar masses will collapse into black holes. Those with masses between 1.4 and 2.2 solar masses will become neutron stars, and the rest will become white dwarfs.

Black holes and neutron stars are effectively stable. Black holes are matter collapsed to their limit, and neutron stars are held against gravity by the strong force interaction between nucleons. But white dwarfs are a different story.

A white dwarf star is held against gravity by the degeneracy pressure of electrons. Subrahmanyan Chandrasekhar calculated their upper mass limit to be 1.4 solar masses in the 1930s, and figured that any remnant smaller than that would gradually cool to become a black dwarf. But we now know that things arent quite that simple. Heavier elements within the white dwarf will sink, creating a core of oxygen, neon, and magnesium. As the white dwarf cools into a black dwarf, the atoms in the core will move closer together.

Eventually, they will be close enough that an odd kind of fusion can occur. Normal fusion occurs at very high temperatures. Nuclei slam so close to each other that can quantum tunnel to fuse into heavier elements. Theres no minimum distance for quantum tunneling to occur; it is just extremely rare at larger distances. But within the heart of a black dwarf, it will happen. Given enough time, elements in the core will fuse into iron.

It is estimated that this transformation will take about 101100 years. As the core of a black dwarf becomes dense iron, it can reach a critical point. For black dwarfs between 1.2 and 1.4 solar masses, the iron core will become so dense that electron degeneracy cant prevent gravitational collapse. The core will implode and recoil, creating a supernova explosion. The largest black dwarfs will explode first, followed by increasingly lighter black dwarfs. Eventually, some black dwarf a bit more massive than our Sun will become the last supernova in history, sometime around 1032000 years in the future.

It will be the last burst of light in a cold, dark, and dead cosmos.

Reference: Caplan, M. E. Black Dwarf Supernova in the Far Future. Monthly Notices of the Royal Astronomical Society (2020).

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The Last Supernovae - Universe Today

ROCHESTER, N.Y. (WWTI) The University of Rochester will receive a National Science Foundation Award for $12.96 million.

U.S. Senator Charles E. Schumer and U.S. Senator Kirsten Gillibrand announced that the University will receive funding to launch a new Physics Frontier Center. The funding is part of a five-year agreement between the University of Rochester and NSF and will be used to establish a Center for Matter at Atomic Pressures.

The center will focus on understanding the physics and astrophysical implications of matter under pressures to disrupt the structure of individuals atoms. The research conducted will help to understand and address critical gaps in our understanding of the atomic and chemical constituents of the universe.

The senators explained, CMAP will bring together a diverse group of individuals from disciplines spanning from plasma physics, condensed matter, and atomic physics, to astrophysics and planetary science, to study matter under extreme conditions.

The NSF funding for the University of Rochesters Center for Matter at Atomic Pressures will ensure Rochester will help lead the country in the field of high energy density science,said Senator Schumer. Establishing this new Center in Rochester will support local jobs and enable UR researchers to make discoveries in cutting edge physics while bolstering our nations scientific workforce to keep the U.S. as a global leader in new scientific advances.

NSF funding will establish the University of Rochester as the latest member of a multi-university collaboration with MIT, Princeton, The Universities Of California at Berkeley And Davis, The University at Buffalo, And Lawrence Livermore National Laboratory.

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Nearly $13 million in federal funding awarded to University of Rochester for Physics Frontier Center - WWTI - InformNNY.com

Cable Break Damages Arecibo ObservatoryThe iconic Arecibo Observatory wasseverely damagedon Aug. 10 when one of the cables supporting the platform suspended above the radio telescopes aluminum reflector dish broke. The cable tore a30 metergash in the305 meterdiameter dish, which focuses radio waves on receiving equipment attached to the platform, and damaged a structure called the Gregorian dome that houses some of the equipment. Areciboreportsthat telescope operations have been suspended pending repairs and that the cause of the break is unclear, as the cable was designed to last at least another 15 years. It is not yet known how long the repairs might take, what the cost will be, or who will foot the bill. Currently, the National Science Foundation isdivestingits funding support for operations of the half-century-old facility and the University of Central Florida, which now manages it, is working to replenish that share of the budget through apatchworkof partnerships. Notably, the lead appropriator for NSF in the House, Rep. Jos Serrano (D-NY), has long been among the observatorys strongest champions in Congress, though he is retiring after this year. Arecibo is still conducting repairs to damage inflicted by Hurricane Maria in 2017 usingfundingprovided by Congress as part of an emergency relief package.

White House Updates R&D Priorities

Top DOE Official Taunts China Over Circular Collider Deferral

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NSF Establishes New Physics Frontiers Centers

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Six Former EPA Heads Urge Reset for the Agency

APS Names Physicist Jonathan Bagger as Next CEO

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The Week of August 17, 2020 - FYI: Science Policy News

Two numerical simulations predicting the distribution of dark matter around a galaxy similar to our Milky Way. The left panel assumes that dark matter particles were moving fast in the early universe (warm dark matter), while the right panel assumes that dark matter particles were moving slowly (cold dark matter). The warm dark matter model predicts many fewer small clumps of dark matter surrounding our Galaxy, and thus many fewer satellite galaxies that inhabit these small clumps of dark matter. By measuring the number of satellite galaxies, scientists can distinguish between these models of dark matter. (Images from Bullock & Boylan-Kolchin, Annual Review of Astronomy and Astrophysics 2017, based on simulations by V. Robles, T. Kelley, and B. Bozek)

Observations of dwarf galaxies around the Milky Way have yielded simultaneous constraints on three popular theories of dark matter.

A team of scientists led by cosmologists from the Department of Energys SLAC and Fermi national accelerator laboratories has placed some of the tightest constraints yet on the nature of dark matter, drawing on a collection of several dozen small, faint satellite galaxies orbiting the Milky Way to determine what kinds of dark matter could have led to the population of galaxies we see today.

The new study is significant not just for how tightly it can constrain dark matter, but also for what it can constrain, said Risa Wechsler, director of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at SLAC and Stanford University. One of the things that I think is really exciting is that we are actually able to start probing three of the most popular theories of dark matter, all at the same time, she said.

Dark matter makes up 85 percent of the matter in the universe and interacts very weakly with ordinary matter except through gravity. Its influence can be seen in the shapes of galaxies and in the large-scale structure of the universe, yet no one is sure exactly what dark matter is. In the new study, researchers focused on three broad possibilities for the nature of dark matter: relatively fast-moving or warm dark matter; another form of interacting dark matter that bumps off protons enough to have been heated up in the early universe, with consequences for galaxy formation; and a third, extremely light particle, known as fuzzy dark matter, that through quantum mechanics effectively stretches out across thousands of light years.

To test those models, the researchers first developed computer simulations of dark matter and its effects on the formation of relatively tiny galaxies inside denser patches of dark matter found circling larger galaxies.

The faintest galaxies are among the most valuable tools we have to learn about dark matter because they are sensitive to several of its fundamental properties all at once, said Ethan Nadler, the studys lead author and graduate student at Stanford University and SLAC. For instance, if dark matter moves a bit too fast or has gained a little too much energy through long-ago interactions with normal matter, those galaxies wont form in the first place. The same goes for fuzzy dark matter, which if stretched out enough will wipe out nascent galaxies with quantum fluctuations.

By comparing such models with a catalog of faint dwarf galaxies from the Dark Energy Survey and the Panoramic Survey Telescope and Rapid Response System, or Pan-STARRS, the researchers were able to put new limits on the likelihood of such events. In fact, those limits are strong enough that they start to constrain the same dark matter possibilities direct-detection experiments are now probing and with a new stream of data from the Rubin Observatory Legacy Survey of Space and Time expected in the next few years, the limits will only get tighter.

Its exciting to see the dark matter problem attacked from so many different experimental angles, said Fermilab and University of Chicago scientist Alex Drlica-Wagner, a Dark Energy Survey collaborator and one of the lead authors on the paper. This is a milestone measurement for DES, and Im very hopeful that future cosmological surveys will help us get to the bottom of what dark matter is.

Still, said Nadler, theres a lot of theoretical work to do. For one thing, there are a number of dark matter models, including a proposed form that can strongly interact with itself, where researchers arent sure of the consequences for galaxy formation. There are other astronomical systems as well, such as streams of stars that might reveal new details when they collide with dark matter.

Reference: Milky Way Satellite Census. III. Constraints on Dark Matter Properties from Observations of Milky Way Satellite Galaxies by E. O. Nadler, A. Drlica-Wagner, K. Bechtol, S. Mau, R. H. Wechsler, V. Gluscevic, K. Boddy, A. B. Pace, T. S. Li, M. McNanna, A. H. Riley, J. Garca-Bellido, Y.-Y. Mao, G. Green, D. L. Burke, A. Peter, B. Jain, T. M. C. Abbott, M. Aguena, S. Allam, J. Annis, S. Avila, D. Brooks, M. Carrasco Kind, J. Carretero, M. Costanzi, L. N. da Costa, J. De Vicente, S. Desai, H. T. Diehl, P. Doel, S. Everett, A. E. Evrard, B. Flaugher, J. Frieman, D. W. Gerdes, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, S. R. Hinton, K. Honscheid, D. Huterer, D. J. James, E. Krause, K. Kuehn, N. Kuropatkin, O. Lahav, M. A. G. Maia, J. L. Marshall, F. Menanteau, R. Miquel, A. Palmese, F. Paz-Chinchn, A. A. Plazas, A. K. Romer, E. Sanchez, V. Scarpine, S. Serrano, I. Sevilla-Noarbe, M. Smith, M. Soares-Santos, E. Suchyta, M. E. C. Swanson, G. Tarle, D. L. Tucker, A. R. Walker, W. Wester (DES Collaboration), 31 July 2020, Astrophysics > Cosmology and Nongalactic Astrophysics.arXiv:2008.00022

The research was a collaborative effort within the Dark Energy Survey. The research was supported by a National Science Foundation Graduate Fellowship, by the Department of Energys Office of Science through SLAC, and by Stanford University.

Read more from the original source:

Dark Matter Breakthrough Allows Probing Three of the Most Popular Theories, All at the Same Time - SciTechDaily

Astronomers at the Max Planck Institute for Astrophysics have found a look-alike of the Milky Way 12 billion light-years away with the help of the Atacama Large Millimetre/sub-millimetre Array (ALMA).

The galaxy is so far away its light has taken more than 12 billion years to reach us, the institute said in an official press release.

This makes it an even more fascinating discovery as according to the National Aeronautics and Space Administration (NASA) our universe is around 13 billion years, give or take a few billion.

This result represents a breakthrough in the field of galaxy formation, showing that the structures that we observe in nearby spiral galaxies and in our Milky Way were already in place 12 billion years ago, says Francesca Rizzo, PhD student from the Max Planck Institute for Astrophysics in Germany, who led the research published in the journal Nature.

The galaxy, called SPT0418-47, does not appear to have spiral arms lie our Milky Way but has at least two features that are similar to our galaxy: a rotating disc and a bulge.

This is the first time a bulge has been seen this early in the history of the Universe, making SPT0418-47 the most distant Milky Way look-alike, researchers said.

The big surprise was to find that this galaxy is actually quite similar to nearby galaxies, contrary to all expectations from the models and previous, less detailed, observations, said co-author Filippo Fraternali, from the Kapteyn Astronomical Institute, University of Groningen in the Netherlands.

It is difficult for researchers to observe these galaxies even with the most powerful telescopes due to the distance. The team utilized a nearby galaxy as a powerful magnifying glass an effect known as gravitational lensing to overcome this difficulty. This allowed ALMA to see into the distant past in unprecedented detail. In this effect, the gravitational pull from the nearby galaxy distorts and bends the light from the distant galaxy, causing it to appear misshapen and magnified.

What we found was quite puzzling; despite forming stars at a high rate, and therefore being the site of highly energetic processes, SPT0418-47 is the most well-ordered galaxy disc ever observed in the early Universe, said co-author Simona Vegetti, also from the Max Planck Institute for Astrophysics. This result is quite unexpected and has important implications for how we think galaxies evolve."

Though the galaxy is quite similar to ours, astronomers expect it to evolve into a galaxy very different from the Milky Way. It is likely to evolve into an elliptical galaxy, rather than a spiral.

Future studies will be conducted to further explore the evolution of these baby disc galaxies including those with ESOs Extremely Large Telescope.

Read the rest here:

Astronomers find Milky Way look-alike galaxy 12 billion light-years away - BusinessLine

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This is the way the world ends, said T. S. Eliot in his famous poem, Not with a bang buta whimper. These days, scientists considerthe heat-death of the universe to bethe whimper, buta new theoretical analysis predicts thatthe cosmos will breathe its final gasp in the form of exploding black dwarfs.

Trillions upon trillions of years from now,long after the last stars have fizzled out, the heaviest black dwarfs will start to go supernova, according to newresearchpublished in Monthly Notices of the Royal Astronomical Society. Black dwarfs are the frozen remnants of white dwarfs, which themselves are theremnants of low-mass stars. The sole author of the study, astrophysicist Matt Caplan from Illinois State University, says these explosions will be the last interesting thing to happen in the universe, as heexplainedin an ISUpress release.

The universe could end inany number of ways, but the current best guess is that itll continue to expand long after everything inside it has been torn to shreds, including galaxies, solar systems, stars, and even atoms. By the time black dwarfs are set to pop, the universe will be cold and lifeless,Caplan wrotein an email to me.

The expansion of the universe will have long since separated all remaining objects by distances so enormous that no light will ever be able to reach from one to another, he said. Every object will find itself in a universe completely devoid of anything else in every direction. It will be cold and near absolute zero.

When extant stars go supernova, its on account of excess iron in their coresthe result of internal nuclear reactions. The same cannot be said for smaller stars, which eventually burn out and shrink into white dwarfs. According to theory, white dwarfs will eventually lose their lustre and freeze in the far future, transitioning into black dwarfs.

Without a heat source,they simply cool off for all eternity, until they turn black and no longer shine, saidCaplan. Its a bit like taking a hot skillet off the oven all it can do is cool.

These hypothetical objects would be roughly the size of Earthbut with masses approaching that of our Sun. Importantly, nuclear reactions will still occur inside these dense, frozen worlds, but at appreciably slower rates than normal. And as the new study predicts, these reactions will result in a steady buildup of iron, though at cosmologically vast timescales. With this in mind, Caplan crunched the numbers to estimate how long it will take for these black dwarfs to produce enough iron to trigger a supernova explosion.

The answer, at 101,100years, is hilariously long, said Caplan. The age of the universe itself is closer to1010years, so if you were to try to write out 101,100it would have 1,100 zeros and take up most of a paragraph, he explained. Or as Caplan put it in the ISUrelease, its like saying the word trillion almost a hundred times.

Importantly, these explosions will only happen among the largest of the black dwarfs, namely those around 1.2 to 1.4 times the mass of the Sun. These supernovaethe last to ever happen in the universe will eventually stop around 1032,000years from now, after which time the cosmos will truly be a quiet and uneventful place.

Caplan said his analysis took the effects of an expanding universe into account. However, if dark energy is different than we currently suspect,then the expansion of the universe could destroy the black dwarfs long before they have a chance to explode, he said. Whats more, Caplans calculations were based on our current understanding of nuclear physics, astrophysics, and cosmology, but to be fair, scientists cant be certain if the laws of physics and the universal constants will remain the same in the far future. Itspossible, for example, that the universe wont even exist at this future juncture.

Some theories of particle physics predict that the proton is fundamentally unstable and will decay away, though this has yet to be observed or confirmed. If thats the case, then all matter will sort of evaporate long before any black dwarfs explode, said Caplan. Thats just one example. In a sense, our understanding of the far future is entirely dependent on our understanding of the laws of physics today, and small changes in physics as we know it can have enormous consequences for the final fate of the universe and its contents.

Though Caplan said these black dwarf supernovae will be the last interesting thing to happen in the universe,we asked him if something of consequence or interest might happen after this phase.

Depends on your definition of interesting, he said. If a cold iron ball floating in a universe where it is completely causally separated from all other objects is interesting, then I suppose you could find something of interest.

Okay, fair point. But if theres any consolation in all of this, its that the universe will continue to expand forever, at least according to some theories. Itll be dead, cold, and lifeless, but at least itll still be around.

Featured image:NASA / JPL-Caltech

Excerpt from:

Exploding Black Dwarfs Could Be the 'Last Interesting Thing to Happen in the Universe' - Gizmodo UK

Tribune News ServiceJalandhar, August 11

Lovely Professional Universitys Gopalchetty Brahma, a BTech Aerospace Engineering student, has won an international award named Silver Honour in the International Astronomy and Astrophysics Competition (IAAC-2020) held online.

The competition, which aims at sharpening the students minds to learn more in depth about astronomy and astrophysics, had contenders from US, UK, Russia, Canada, Germany, China, France, Italy, Spain, South Korea, New Zealand, Greece, Hong Kong, Singapore and many more. Gopalchetty proved his deftness and creativity in academic course related fields by bettering everyone.

The winning certificate issued under the signatures of IAAC public relations manager Stefan Amberg and team coordinator Fabian Schneider indicates that the final round of the competition was a supervised exam, where the LPU participant scored enough points to get placed among the top-seven per cent of all the participants from across the world to finish atop.

Excerpt from:

Lovely Professional Universitys Aerospace Engineering student wins international award - The Tribune India