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News Article | May 6, 2017
Site: news.yahoo.com

We've been asking ourselves one universal question since the dawn of modern science: Are we alone? In the early days of astronomy, scientists thought the Earth was the center of everything. But when that Earth-centric view eventually changed and we realized that we orbit but one star among countless millions, we couldn't help but wonder what else might be out there. It wasn't until 1992, when scientists discovered a planet around Pulsar PSR B1257+12, that astronomers were able to confirm what many had suspected-planets exist outside of our solar system. But how many? Fast forward 25 years, and we now know of over 5,000 extrasolar planets, or exoplanets, thanks mostly to the Kepler space telescope. Not only that, but there are around 3,000 with their own atmospheres. Now astronomers work tirelessly to answer the tantalizing question-are some of the planets out there similar to our own? A number of SETI researchers committed to answering this question recently gathered at Stanford University for the Breakthrough Discuss conference, an event hosted by the Breakthrough Initiatives founded by Russian billionaire Yuri Milner. Breakthrough is supported by the likes of Stephen Hawking, Mark Zuckerberg, Jill Tarter, and Frank Drake. The goal is simple and yet far reaching: They want to determine whether or not alien life exists not just in our solar system, but anywhere in the entire galaxy. The first step is to learn all we can from ground-based telescopes. While we can't see whether or not distant exoplanets actually harbor life, we can look for clues to help us determine whether they might be habitable. If there are other Earth-like planets out there with oceans, mountains, and active geology, then there's a reasonable chance that life has managed to take hold. There's a short list of about a dozen planets that scientists refer to as "Earth-like," though nothing we've found so far even comes close to the serendipitous combination of surface liquid, a protective atmosphere, and the correct distance from a star that created our world. For exoplanet hunters, distance is the biggest hurdle. The search for life beyond our solar system has turned to analyzing the compositions of alien atmospheres with telescopes at home, which is an incredibly difficult task. It's hard to resolve Pluto from Earth, let alone a small body billions of miles farther away. We know there are other planets out there that are roughly the same mass as Earth, have an atmosphere, and reside in the so-called "Goldilocks" zone of their solar systems, meaning there could be liquid water on those planets-the main conduit for life as we know it. A sort of misnomer in the exoplanet world, however, is the word "habitable." While it might conjure images of a lush landscape with meandering rivers, sandy beaches, and the convenience of breathable air, astronomers have a different idea of the word. In astronomy, "habitable" really only means two things: The planet is rocky, and it orbits in the Goldilocks zone. If we really want to think about a habitable world though, we need to understand what's happening in an exoplanet's atmosphere. "We have to look for the oxygen," said Mercedes Lopez-Morales in her Breakthrough Discuss presentation. Lopez-Morales is a staff scientist at the Smithsonian Astrophysical Observatory, and she gave a talk about the ways we can begin probing these atmospheres for signs of life. "Right now we know that we need water for life to exist. But we don't know if the planet is going to have water, but life has not kicked in yet. However, oxygen tells you about life. In the past, even though the Earth had water, there was no oxygen found until life appeared." She proposes looking for oxygen in these atmospheres using a technique called high-resolution spectroscopy, which is essentially collecting high-resolution data of the light passing through a planet's atmosphere. When an exoplanet passes in front of it's parent star, the starlight baths the planet, curving around and through the atmosphere. If a really large telescope is watching that happen, it can collect enough of those transient photons to create an entire spectrum of the light filtered through the atmosphere. Certain elements and molecules absorb specific frequencies of light, creating gaps in the spectrum-a sort of thumbprint of the planet's atmospheric composition. Depending on where those gaps fall, astrophysicists can deduce what elements are present in the atmospheres of alien worlds. (The same technique is used to identify the composition of stars). The problem is that there are no instruments available to perform this type of alien-hunting spectroscopy, especially not for the more distant Earth-sized bodies. "We know that one out of every four small stars should have a planet. Based on those numbers, there's around 250 [stars nearby], so by that count there will be around 60 Earth-like planets within 32 light-years from Earth, " says Lopez-Morales. And while these are close on the cosmic map, detecting oxygen in atmospheres that sit dozens of light-years away is still just too difficult. "There is no telescope that we have today that can do this in a reasonable amount of time," explains Lopez-Morales. "It could take 60 years." Fortunately, a few telescopes currently under construction could solve the problem. Astronomers are planning to use the Giant Magellan Telescope when it is completed in Chile, and the future 30-meter telescope in Hawaii, but multiple scopes would need to work in unison in order to collect enough data-an expensive feat. "We just need bigger photon buckets," says Lopez-Morales. "If we can collect enough of the photons from these stars then we can pick up the signatures of molecules like oxygen." At the moment, many are focused on better understanding our closest extrasolar neighbor, Proxima Centauri b, which is only 4.2 light-years away orbiting the closest star to us. It doesn't transit its host star Proxima Centauri, however, so scientists are unsure whether the planet has an atmosphere, much less what its chemical composition is. Dr. Victoria Meadows is a professor of astronomy and Director of the Astrobiology Program at the University of Washington working to find biomarkers at places like Proxima b. "Depending on Proxima's evolutionary history, it could have a temperature range of anywhere between 254 Kelvin, too cold for life, up to 640 Kelvin, which is more of a Venus," says Meadows. "This is a planet in a habitable zone. What happens to the planet matters in its evolution. Potentially habitable, and a 'great place for life,' might not be the best place for the 'origin of life.'" Or in other words, just because conditions are good for life to exist now doesn't necessarily mean that the conditions were ever right for life to spark in the first place. Another of Breakthrough's ambitious projects is called Breakthrough Starshot, and it aims to send a fleet of nano-sized spacecraft to Proxima b, considering it is the closest exoplanet to us. But in order to make that 25 trillion-mile journey worth the trip, the team needs to know if there's anything worthy to explore, so determining an atmosphere for the planet is a must. Much of this field is still a mystery given that only five years ago, little was yet known about exoplanets. Now researchers around the world are trying to find evidence of life. In five more years, there's no telling how much the science will have advanced. They no doubt have a long way to go and face a slew of technical challenges considering the cosmic distances. But with initiatives like Breakthrough working with the finest research institutions in the world, there's a chance we'll be able to pinpoint a beam of light coming from a far off world with a marker that reads "oxygen." But for now, the question that's as old as astronomy remains unanswered. We've been asking ourselves one universal question since the dawn of modern science: Are we alone? In the early days of astronomy, scientists thought the Earth was the center of everything. But when that Earth-centric view eventually changed and we realized that we orbit but one star among countless millions, we couldn't help but wonder what else might be out there. It wasn't until 1992, when scientists discovered a planet around Pulsar PSR B1257+12, that astronomers were able to confirm what many had suspected-planets exist outside of our solar system. But how many? Fast forward 25 years, and we now know of over 5,000 extrasolar planets, or exoplanets, thanks mostly to the Kepler space telescope. Not only that, but there are around 3,000 with their own atmospheres. Now astronomers work tirelessly to answer the tantalizing question-are some of the planets out there similar to our own? A number of SETI researchers committed to answering this question recently gathered at Stanford University for the Breakthrough Discuss conference, an event hosted by the Breakthrough Initiatives founded by Russian billionaire Yuri Milner. Breakthrough is supported by the likes of Stephen Hawking, Mark Zuckerberg, Jill Tarter, and Frank Drake. The goal is simple and yet far reaching: They want to determine whether or not alien life exists not just in our solar system, but anywhere in the entire galaxy. The first step is to learn all we can from ground-based telescopes. While we can't see whether or not distant exoplanets actually harbor life, we can look for clues to help us determine whether they might be habitable. If there are other Earth-like planets out there with oceans, mountains, and active geology, then there's a reasonable chance that life has managed to take hold. There's a short list of about a dozen planets that scientists refer to as "Earth-like," though nothing we've found so far even comes close to the serendipitous combination of surface liquid, a protective atmosphere, and the correct distance from a star that created our world. For exoplanet hunters, distance is the biggest hurdle. The search for life beyond our solar system has turned to analyzing the compositions of alien atmospheres with telescopes at home, which is an incredibly difficult task. It's hard to resolve Pluto from Earth, let alone a small body billions of miles farther away. We know there are other planets out there that are roughly the same mass as Earth, have an atmosphere, and reside in the so-called "Goldilocks" zone of their solar systems, meaning there could be liquid water on those planets-the main conduit for life as we know it. A sort of misnomer in the exoplanet world, however, is the word "habitable." While it might conjure images of a lush landscape with meandering rivers, sandy beaches, and the convenience of breathable air, astronomers have a different idea of the word. In astronomy, "habitable" really only means two things: The planet is rocky, and it orbits in the Goldilocks zone. If we really want to think about a habitable world though, we need to understand what's happening in an exoplanet's atmosphere. "We have to look for the oxygen," said Mercedes Lopez-Morales in her Breakthrough Discuss presentation. Lopez-Morales is a staff scientist at the Smithsonian Astrophysical Observatory, and she gave a talk about the ways we can begin probing these atmospheres for signs of life. "Right now we know that we need water for life to exist. But we don't know if the planet is going to have water, but life has not kicked in yet. However, oxygen tells you about life. In the past, even though the Earth had water, there was no oxygen found until life appeared." She proposes looking for oxygen in these atmospheres using a technique called high-resolution spectroscopy, which is essentially collecting high-resolution data of the light passing through a planet's atmosphere. When an exoplanet passes in front of it's parent star, the starlight baths the planet, curving around and through the atmosphere. If a really large telescope is watching that happen, it can collect enough of those transient photons to create an entire spectrum of the light filtered through the atmosphere. Certain elements and molecules absorb specific frequencies of light, creating gaps in the spectrum-a sort of thumbprint of the planet's atmospheric composition. Depending on where those gaps fall, astrophysicists can deduce what elements are present in the atmospheres of alien worlds. (The same technique is used to identify the composition of stars). The problem is that there are no instruments available to perform this type of alien-hunting spectroscopy, especially not for the more distant Earth-sized bodies. "We know that one out of every four small stars should have a planet. Based on those numbers, there's around 250 [stars nearby], so by that count there will be around 60 Earth-like planets within 32 light-years from Earth, " says Lopez-Morales. And while these are close on the cosmic map, detecting oxygen in atmospheres that sit dozens of light-years away is still just too difficult. "There is no telescope that we have today that can do this in a reasonable amount of time," explains Lopez-Morales. "It could take 60 years." Fortunately, a few telescopes currently under construction could solve the problem. Astronomers are planning to use the Giant Magellan Telescope when it is completed in Chile, and the future 30-meter telescope in Hawaii, but multiple scopes would need to work in unison in order to collect enough data-an expensive feat. "We just need bigger photon buckets," says Lopez-Morales. "If we can collect enough of the photons from these stars then we can pick up the signatures of molecules like oxygen." At the moment, many are focused on better understanding our closest extrasolar neighbor, Proxima Centauri b, which is only 4.2 light-years away orbiting the closest star to us. It doesn't transit its host star Proxima Centauri, however, so scientists are unsure whether the planet has an atmosphere, much less what its chemical composition is. Dr. Victoria Meadows is a professor of astronomy and Director of the Astrobiology Program at the University of Washington working to find biomarkers at places like Proxima b. "Depending on Proxima's evolutionary history, it could have a temperature range of anywhere between 254 Kelvin, too cold for life, up to 640 Kelvin, which is more of a Venus," says Meadows. "This is a planet in a habitable zone. What happens to the planet matters in its evolution. Potentially habitable, and a 'great place for life,' might not be the best place for the 'origin of life.'" Or in other words, just because conditions are good for life to exist now doesn't necessarily mean that the conditions were ever right for life to spark in the first place. Another of Breakthrough's ambitious projects is called Breakthrough Starshot, and it aims to send a fleet of nano-sized spacecraft to Proxima b, considering it is the closest exoplanet to us. But in order to make that 25 trillion-mile journey worth the trip, the team needs to know if there's anything worthy to explore, so determining an atmosphere for the planet is a must. Much of this field is still a mystery given that only five years ago, little was yet known about exoplanets. Now researchers around the world are trying to find evidence of life. In five more years, there's no telling how much the science will have advanced. They no doubt have a long way to go and face a slew of technical challenges considering the cosmic distances. But with initiatives like Breakthrough working with the finest research institutions in the world, there's a chance we'll be able to pinpoint a beam of light coming from a far off world with a marker that reads "oxygen." But for now, the question that's as old as astronomy remains unanswered. You Might Also Like


News Article | April 17, 2017
Site: www.newscientist.com

Just beyond the Local Group of galaxies that surround our Milky Way, where our map of the cosmos once plunged off an edge and into the unknown, lurks a galactic sea monster. Weirdo galaxy NGC 4258 has two extra tentacles reaching out from its middle – part of a system that could one day drive or quench a revolution in physics. It was 1961 when astronomers discovered the two anomalous arms in NGC 4258, which is 25 million light years away. They defied explanation. Unlike the arms in other spiral galaxies, which wind around in the same plane like the coils of a nautilus shell, these protruded out of the disc of the galaxy. That was weird enough. But it turns out that the extra arms were just one part of an intricate machine unspooling from the middle of the galaxy – a structure now teaching us about everything from black holes to the expansion of the universe. Zoom in close to where the arms begin, and you will see a short line of blobs at the centre of the galaxy. Each of these is a cloud full of steaming hot water molecules emitting microwave beams out into space. The blobs on the right are hurtling towards us at 1000 kilometres per second. At the left, they are receding from us just as fast. In the middle, they appear to stand still. To an astronomer, that’s a recognisable pattern: the line of blobs is really the edge of a gaseous wheel about half a light year in diameter, orbiting around an axis nearly perpendicular to our line of sight. “I don’t think anybody had ever seen anything like this in this much detail,” says Mark Reid at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts. The orbiting wheel obeys centuries-old laws. Isaac Newton or Johannes Kepler would have no problem understanding it. Because of that, this structure can double as a scientific apparatus to measure more exotic phenomena. An orbiting disc must be circling something. In the mid-1990s, this galaxy’s central wheel helped convince astronomers that nearly every galaxy has a supermassive black hole weighing down its center. For the blobs to be moving at 1000 kilometres per second on a racetrack less than a light year in diameter requires that they be yoked to the gravity of something about 40 million times heavier than the sun, crammed in a tiny area. Only a black hole fits the bill. Once you assume there is a black hole there, the galaxy starts to make sense. The spinning disc is caused by material orbiting the black hole like water swirling down the drain. And those wayward tentacles could form when the disc shoots out jets of energetic particles, which then eject heated material above and below the galaxy. These processes aren’t unique to NGC 4258. Other galaxies have central discs; some may even have faint tentacles of their own waving into space. But because NGC 4258 is relatively nearby and because we see it edge-on, they show up in exquisite detail. As such, this galaxy could also hold the key to understanding the expansion of the universe, a process driven by normal particles, mysterious dark matter and an equally mysterious ingredient called dark energy that pushes the expansion to accelerate. Studying this expansion requires precise measurements of cosmic distances, which are difficult to come by. Watching the blobs orbit around NGC 4258 can help. From observations, we can gauge the physical distance between the blobs and the black hole, then with trigonometry, comparing that distance with the angular separation between the objects in the sky lets you calculate how far away this galaxy is from us. That last part is crucial to cosmologists. Knowing the distances to faraway galaxies accurately is the key part of clocking the expansion rate of the universe. That makes this galaxy a crucial data point in an ongoing argument between astronomers and cosmologists about just how fast the expansion is happening – a conflict that, if unresolved, could force a revision of modern physics. Not a bad resume for a sea-monster galaxy that sports extra tentacles.


News Article | February 15, 2017
Site: spaceref.com

Fast radio bursts (FRBs) are brief spurts of radio emission, lasting just one-thousandth of a second, whose origins are mysterious. Fewer than two dozen have been identified in the past decade using giant radio telescopes such as the 1,000-foot dish in Arecibo, Puerto Rico. Of those, only one has been pinpointed to originate from a galaxy about 3 billion light-years away. The other known FRBs seem to also come from distant galaxies, but there is no obvious reason that, every once in a while, an FRB wouldn't occur in our own Milky Way galaxy too. If it did, astronomers suggest that it would be "loud" enough that a global network of cell phones or small radio receivers could "hear" it. "The search for nearby fast radio bursts offers an opportunity for citizen scientists to help astronomers find and study one of the newest species in the galactic zoo," says theorist Avi Loeb of the Harvard-Smithsonian Center for Astrophysics (CfA). Previous FRBs were detected at radio frequencies that match those used by cell phones, Wi-Fi, and similar devices. Consumers could potentially download a free smartphone app that would run in the background, monitoring appropriate frequencies and sending the data to a central processing facility. "An FRB in the Milky Way, essentially in our own back yard, would wash over the entire planet at once. If thousands of cell phones picked up a radio blip at nearly the same time, that would be a good sign that we've found a real event," explains lead author Dan Maoz of Tel Aviv University. Finding a Milky Way FRB might require some patience. Based on the few, more distant ones, that have been spotted so far, Maoz and Loeb estimate that a new one might pop off in the Milky Way once every 30 to 1,500 years. However, given that some FRBs are known to burst repeatedly, perhaps for decades or even centuries, there might be one alive in the Milky Way today. If so, success could become a yearly or even weekly event. A dedicated network of specialized detectors could be even more helpful in the search for a nearby FRB. For as little as $10 each, off-the-shelf devices that plug into the USB port of a laptop or desktop computer can be purchased. If thousands of such detectors were deployed around the world, especially in areas relatively free from Earthly radio interference, then finding a close FRB might just be a matter of time. This work has been accepted for publication in the Monthly Notices of the Royal Astronomical Society and is available online. Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe. Please follow SpaceRef on Twitter and Like us on Facebook.


Kenyon S.J.,Smithsonian Astrophysical Observatory | Bromley B.C.,University of Utah
Astrophysical Journal, Supplement Series | Year: 2010

We describe comprehensive calculations of the formation of icy planets and debris disks at 30-150 AU around 1-3M · stars. Disks composed of large, strong planetesimals produce more massive planets than disks composed of small, weak planetesimals. The maximum radius of icy planets ranges from ∼ 1500km to 11,500km. The formation rate of 1000km objects - "Plutos" - is a useful proxy for the efficiency of icy planet formation. Plutos form more efficiently in massive disks, in disks with small planetesimals, and in disks with a range of planetesimal sizes. Although Plutos form throughout massive disks, Pluto production is usually concentrated in the inner disk. Despite the large number of Plutos produced in many calculations, icy planet formation is inefficient. At the end of the main sequence lifetime of the central star, Plutos contain less than 10% of the initial mass in solid material. This conclusion is independent of the initial mass in the disk or the properties of the planetesimals. Debris disk formation coincides with the formation of planetary systems containing Plutos. As Plutos form, they stir leftover planetesimals to large velocities. A cascade of collisions then grinds the leftovers to dust, forming an observable debris disk. In disks with small (≲1-10km) planetesimals, collisional cascades produce luminous debris disks with maximum luminosity ∼ 10-2 times the stellar luminosity. Disks with larger planetesimals produce debris disks with maximum luminosity 5 × 10-4 (10km) to ∼ 5 × 10-5 (100km) times the stellar luminosity. Following peak luminosity, the evolution of the debris disk emission is roughly a power law, f α t -n with n ≈ 0.6-0.8. Observations of debris disks around A-type and G-type stars strongly favor models with small planetesimals. In these models, our predictions for the time evolution and detection frequency of debris disks agree with published observations. We suggest several critical observations that can test key features of our calculations. © 2010. The American Astronomical Society. All rights reserved.


Kenyon S.J.,Smithsonian Astrophysical Observatory | Bromley B.C.,University of Utah
Astronomical Journal | Year: 2014

Motivated by the New Horizons mission, we consider how Pluto's small satellites - currently Styx, Nix, Kerberos, and Hydra - grow in debris from the giant impact that forms the Pluto-Charon binary. After the impact, Pluto and Charon accrete some of the debris and eject the rest from the binary orbit. During the ejection, high-velocity collisions among debris particles produce a collisional cascade, leading to the ejection of some debris from the system and enabling the remaining debris particles to find stable orbits around the binary. Our numerical simulations of coagulation and migration show that collisional evolution within a ring or a disk of debris leads to a few small satellites orbiting Pluto-Charon. These simulations are the first to demonstrate migration-induced mergers within a particle disk. The final satellite masses correlate with the initial disk mass. More massive disks tend to produce fewer satellites. For the current properties of the satellites, our results strongly favor initial debris masses of 3-10 × 1019g and current satellite albedos A 0.4-1.We also predict an ensemble of smaller satellites,R ≲1-3 km, and very small particles, R 1-100 cm and optical depth τ ≲ 10-10. These objects should have semimajor axes outside the current orbit of Hydra. © 2014.The American Astronomical Society.All rights reserved.


Bromley B.C.,University of Utah | Kenyon S.J.,Smithsonian Astrophysical Observatory
Astrophysical Journal | Year: 2011

Planetary migration poses a serious challenge to theories of planet formation. In gaseous and planetesimal disks, migration can remove planets as quickly as they form. To explore migration in a planetesimal disk, we combine analytic and numerical approaches. After deriving general analytic migration rates for isolated planets, we use N-body simulations to confirm these results for fast and slow migration modes. Migration rates scale as m -1 (for massive planets) and (1 + (e H/3)3)-1, where m is the mass of a planet and e H is the eccentricity of the background planetesimals in Hill units. When multiple planets stir the disk, our simulations yield the new result that large-scale migration ceases. Thus, growing planets do not migrate through planetesimal disks. To extend these results to migration in gaseous disks, we compare physical interactions and rates. Although migration through a gaseous disk is an important issue for the formation of gas giants, we conclude that migration has little impact on the formation of terrestrial planets. © 2011. The American Astronomical Society. All rights reserved..


Schwartz D.A.,Smithsonian Astrophysical Observatory
Review of Scientific Instruments | Year: 2014

The Chandra X-ray Observatory is an orbiting x-ray telescope facility. It is one of the National Aeronautics and Space Administration's four "Great Observatories" that collectively have carried out astronomical observations covering the infrared through gamma-ray portion of the electromagnetic spectrum. Chandra is used by astronomers world-wide to acquire imaging and spectroscopic data over a nominal 0.1-10 keV (124-1.24 Å) range. We describe the three major parts of the observatory: the telescope, the spacecraft systems, and the science instruments. This article will emphasize features of the design and development driven by some of the experimental considerations unique to x-ray astronomy. We will update the on-orbit performance and present examples of the scientific highlights. © 2014 AIP Publishing LLC.


Drake J.J.,Smithsonian Astrophysical Observatory
Astrophysical Journal | Year: 2011

An analysis using modern atomic data of fluxes culled from the literature for O VIII and Ne IX lines observed in solar active regions by the P78 and Solar Maximum Mission satellites confirms that the coronal Ne/O abundance ratio varies by a factor of two or more, and finds an increase in Ne/O with increasing active region plasma temperature. The latter is reminiscent of evidence for increasing Ne/O with stellar activity in low-activity coronae that reaches a "neon saturation" in moderately active stars at approximately twice the historically accepted solar value of about 0.15 by number. We argue that neon saturation represents the underlying stellar photospheric compositions, and that low-activity coronae, including that of the Sun, are generally depleted in neon. The implication would be that the solar Ne/O abundance ratio should be revised upward by a factor of about two to n(Ne)/n(O) ∼ 0.3. Diverse observations of neon in the local cosmos provide some support for such a revision. Neon would still be of some relevance for reconciling helioseismology with solar models computed using recently advocated chemical mixtures with lower metal content. © 2011 The American Astronomical Society. All rights reserved.


Kim D.-W.,Smithsonian Astrophysical Observatory | Fabbiano G.,Smithsonian Astrophysical Observatory
Astrophysical Journal | Year: 2013

We have revisited the X-ray scaling relations of early-type galaxies (ETG) by investigating, for the first time, the L X,Gas-M Total relation in a sample of 14 ETGs. In contrast to the large scatter (a factor of 102-103) in the L X,Total-L B relation, we found a tight correlation between these physically motivated quantities with an rms deviation of a factor of three in L X,Gas = 1038-1043 erg s-1 or M Total = a few × 1010 to a few × 1012 M⊙. More striking, this relation becomes even tighter with an rms deviation of a factor of 1.3 among the gas-rich galaxies (with L X,Gas > 10 40 erg s-1). In a simple power-law form, the new relation is (L X,Gas/1040 erg s-1) = (M Total/3.2 × 1011 M⊙)3. This relation is also consistent with the steep relation between the gas luminosity and temperature, L X,Gas ∼ T Gas 4.5, identified by Boroson et al., if the gas is virialized. Our results indicate that the total mass of an ETG is the primary factor in regulating the amount of hot gas. Among the gas-poor galaxies (with L X,Gas < a few × 1039 erg s-1), the scatter in the L X,Gas-MTotal (and L X,Gas-T Gas) relation increases, suggesting⊙ that secondary factors (e.g., rotation, flattening, star formation history, cold gas, environment, etc.) may become important. © 2013. The American Astronomical Society. All rights reserved.


Bookbindera J.,Smithsonian Astrophysical Observatory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

The International X-ray Observatory (IXO) project is the result of a merger between the NASA Con-X and ESA/JAXA XEUS mission concepts. A facility-class mission, IXO will address the leading astrophysical questions in the "hot universe" through its breakthrough optics with 20 times more collecting area at 1 keV than any previous X-ray observatory, its 3 m2 collecting area with 5 arcsec angular resolution will be achieved using a 20m focal length deployable optical bench. To reduce risk, two independent optics technologies are currently under development in the U.S. and in Europe. Focal plane instruments will deliver a 100-fold increase in effective area for high-resolution spectroscopy, deep spectral imaging over a wide field of view, unprecedented polarimetric sensitivity, microsecond spectroscopic timing, and high count rate capability. IXO covers the 0.1-40 keV energy range, complementing the capabilities of the next generation observatories, such as ALMA, LSST, JWST, and 30-m ground-based telescopes. These capabilities will enable studies of a broad range of scientific questions such as what happens close to a black hole, how supermassive black holes grow, how large scale structure forms, and what are the connections between these processes? This paper presents an overview of the IXO mission science drivers, its optics and instrumental capabilities, the status of its technology development programs, and the mission implementation approach. © 2010 SPIE.

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