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News Article | April 18, 2017
Site: phys.org

Gravitational microlensing is an invaluable method of detecting new extrasolar planets circling their parent stars relatively closely. This technique is sensitive to low-mass planets orbiting beyond the so-called "snow line" around relatively faint host stars like M dwarfs or brown dwarfs. Such planets are of special interest for astronomers, as just beyond this line, the most active planet formation occurs. Hence, understanding the distribution of exoplanets in this region could offer important clues to how planets form. The microlensing event MOA-2016-BLG-227 was detected on May 5, 2016 by the Microlensing Observations in Astrophysics (MOA) group using the 1.8 m MOA-II telescope at the University of Canterbury Mt. John Observatory in New Zealand. Afterward, this event was the target of follow-up observations employing three telescopes located on Mauna Kea, Hawaii: the United Kingdom Infra-Red Telescope (UKIRT) 3.8m telescope, the Canada France Hawaii Telescope (CFHT) and the Keck II telescope. VLT Survey Telescope (VST) at ESO's Paranal Observatory in Chile and the Jay Baum Rich 0.71m Telescope (C28) at the Wise Observatory in Israel were also used for these observations. This subsequent observational campaign allowed the research team led by Naoki Koshimoto of the Osaka University in Japan to detect the new planet and to determine its basic parameters. "The event and planetary signal were discovered by the MOA collaboration, but much of the planetary signal is covered by the Wise, UKIRT, CFHT and VST telescopes, which were observing the event as part of the K2 C9 program (Campaign 9 of the Kepler telescope's prolonged mission)," the paper reads. The team found that MOA-2016-BLG-227Lb is a super-Jupiter planet with the mass of about 2.8 Jupiter masses. The parent star is most probably an M or K dwarf located in the galactic bulge. The mass of the star is estimated to be around 0.29 solar masses. MOA-2016-BLG-227Lb orbits its host at a distance of approximately 1.67 AU. Other main parameters like the radius of both objects and orbital period of the planet are yet to be determined. "Our analysis excludes the possibility that the host star is a G-dwarf, leading us to a robust conclusion that the planet MOA-2016-BLG-227Lb is a super-Jupiter mass planet orbiting an M or K-dwarf star likely located in the Galactic bulge," the researchers concluded. The authors call for further investigation of the MOA-2016-BLG-227 event, which could deliver essential more detailed information about the newly found planetary system. They noted that this event should be revisited with the Hubble Space Telescope (HST) and Keck adaptive optics (AO) system. Promising results could also come from future space and ground based telescopes like the James Webb Space Telescope (JWST), the Giant Magellan Telescope (GMT), the Thirty Meter Telescope and the Extremely Large Telescope (ELT). Explore further: Astronomers discover new substellar companion using microlensing More information: MOA-2016-BLG-227Lb: A Massive Planet Characterized by Combining Lightcurve Analysis and Keck AO Imaging, arXiv:1704.01724 [astro-ph.EP] arxiv.org/abs/1704.01724 Abstract We report the discovery of a microlensing planet —- MOA-2016-BLG-227Lb —- with a massive planet/host mass ratio of q≃9×10−3. This event was fortunately observed by several telescopes as the event location was very close to the area of the sky surveyed by Campaign 9 of the K2 Mission. Consequently, the planetary deviation is well covered and allows a full characterization of the lensing system. High angular resolution images by the Keck telescope show excess flux other than the source flux at the target position, and this excess flux could originate from the lens star. We combined the excess flux and the observed angular Einstein radius in a Bayesian analysis which considers various possible origins of the measured excess flux as priors, in addition to a standard Galactic model. Our analysis indicates that it is unlikely that a large fraction of the excess flux comes from the lens. We compare the results of the Bayesian analysis using different priors for the probability of hosting planets with respect to host mass and find the planet is likely a gas-giant around an M/K dwarf likely located in the Galactic bulge. This is the first application of a Bayesian analysis considering several different contamination scenarios for a newly discovered event. Our approach for considering different contamination scenarios is crucial for all microlensing events which have evidence for excess flux irrespective of the quality of observation conditions, such as seeing, for example.


Chou M.-Y.,Academia Sinica, Taiwan | Takami M.,Academia Sinica, Taiwan | Manset N.,Canada France Hawaii Telescope | Beck T.,US Space Telescope Science Institute | And 6 more authors.
Astronomical Journal | Year: 2013

We present optical spectrophotometric monitoring of four active T Tauri stars (DG Tau, RY Tau, XZ Tau, RW Aur A) at high spectral resolution (R ≳ 1 × 104), to investigate the correlation between time variable mass ejection seen in the jet/wind structure of the driving source and time variable mass accretion probed by optical emission lines. This may allow us to constrain the understanding of the jet/wind launching mechanism, the location of the launching region, and the physical link with magnetospheric mass accretion. In 2010, observations were made at six different epochs to investigate how daily and monthly variability might affect such a study. We perform comparisons between the line profiles we observed and those in the literature over a period of decades and confirm the presence of time variability separate from the daily and monthly variability during our observations. This is so far consistent with the idea that these line profiles have a long-term variability (3-20 yr) related to episodic mass ejection suggested by the structures in the extended flow components. We also investigate the correlations between equivalent widths and between luminosities for different lines. We find that these correlations are consistent with the present paradigm of steady magnetospheric mass accretion and emission line regions that are close to the star. © 2013. The American Astronomical Society. All rights reserved.


News Article | March 30, 2016
Site: www.techtimes.com

The astronomer responsible for "kicking out" Pluto as a member of the solar system announced earlier this year that he and his colleague at the California Institute of Technology (Caltech) found evidence of a huge, icy cosmic object lurking around the dark abyss of the outer solar system. They called this massive object "Planet Nine." Caltech planetary scientist Mike Brown estimated that Planet Nine appears to be revolving around the sun on a super-elongated orbit, which would take 10,000 to 20,000 years to complete. Although the idea of having a ninth planet – technically the eighth planet – is interesting, NASA clarified in February that the existence of Planet Nine is still theoretical and remains unproven. Still, Brown and his colleagues are not giving up. Now, thanks to a peculiar new object detected in the Kuiper Belt, Brown believes their case for the existence of Planet Nine has stronger pieces of supporting evidence. Planet Nine is estimated to be 10 times more massive than Earth, so scientists suppose that something as big would possess a gravitational force that could affect smaller objects floating around nearby. This was something Brown and his colleague Konstantin Batygin identified and reported in their January paper. Brown said they saw a strange signal in their data, indicating that something odd was happening in the outer solar system. In fact, all of the distant objects they detected were aligned in a strange way that shouldn't have typically happened. "We worked through the mundane explanations, but none of them worked out," said Brown. The duo had first detected six KBOs in a strange arrangement. Recently, they found a seventh KBO. How did they discover the seventh KBO? The researchers used the Canada France Hawaii Telescope to perform the Outer Solar System Origins Survey (OSSOS). The results were presented by Michele Bannister at the SETI Institute. This seventh object seemed to have been forced into a strange orbit about 149 billion kilometers (92.5 billion miles) away from the sun – 75 times more distant than Pluto. This is where Planet Nine is expected to be located. Brown has yet to write up his claims about the seventh KBO, so until then, the data should be treated as preliminary findings.


Huchra J.P.,Harvard - Smithsonian Center for Astrophysics | MacRi L.M.,Texas A&M University | Masters K.L.,University of Portsmouth | Masters K.L.,Network Physics | And 17 more authors.
Astrophysical Journal, Supplement Series | Year: 2012

We present the results of the 2MASS Redshift Survey (2MRS), a ten-year project to map the full three-dimensional distribution of galaxies in the nearby universe. The Two Micron All Sky Survey (2MASS) was completed in 2003 and its final data products, including an extended source catalog (XSC), are available online. The 2MASS XSC contains nearly a million galaxies with Ks ≤ 13.5 mag and is essentially complete and mostly unaffected by interstellar extinction and stellar confusion down to a galactic latitude of |b| = 5°for bright galaxies. Near-infrared wavelengths are sensitive to the old stellar populations that dominate galaxy masses, making 2MASS an excellent starting point to study the distribution of matter in the nearby universe. We selected a sample of 44,599 2MASS galaxies with Ks ≤ 11.75 mag and |b| ≥ 5°(≥8°toward the Galactic bulge) as the input catalog for our survey. We obtained spectroscopic observations for 11,000 galaxies and used previously obtained velocities for the remainder of the sample to generate a redshift catalog that is 97.6% complete to well-defined limits and covers 91% of the sky. This provides an unprecedented census of galaxy (baryonic mass) concentrations within 300Mpc. Earlier versions of our survey have been used in a number of publications that have studied the bulk motion of the Local Group, mapped the density and peculiar velocity fields out to 50 h -1Mpc, detected galaxy groups, and estimated the values of several cosmological parameters. Additionally, we present morphological types for a nearly complete sub-sample of 20,860 galaxies with Ks ≤ 11.25 mag and |b| ≥ 10°. © 2012. The American Astronomical Society. All rights reserved.


Howley K.M.,Lawrence Livermore National Laboratory | Guhathakurta P.,University of California at Santa Cruz | Van Der Marel R.,US Space Telescope Science Institute | Geha M.,Yale University | And 5 more authors.
Astrophysical Journal | Year: 2013

As part of the SPLASH survey of the Andromeda (M31) system, we have obtained Keck/DEIMOS spectra of the compact elliptical (cE) satellite M32. This is the first resolved-star kinematical study of any cE galaxy. In contrast to most previous kinematical studies that extended out to r ≲ 30″ ∼ 1 r eff I∼ 100 pc, we measure the rotation curve and velocity dispersion profile out to r ∼ 250″ and higher order Gauss-Hermite moments out to r ∼ 70″. We achieve this by combining integrated-light spectroscopy at small radii (where crowding/blending are severe) with resolved stellar spectroscopy at larger radii, using spatial and kinematical information to account statistically for M31 contamination. The rotation curve and velocity dispersion profile extend well beyond the radius (r ∼ 150″) where the isophotes are distorted. Unlike NGC 205, another close dwarf companion of M31, M32's kinematics appear regular and symmetric and do not show obvious sharp gradients across the region of isophotal elongation and twists. We interpret M31's kinematics using three-integral axisymmetric dynamical equilibrium models constructed using Schwarzschild's orbit superposition technique. Models with a constant mass-to-light ratio can fit the data remarkably well. However, since such a model requires an increasing tangential anisotropy with radius, invoking the presence of an extended dark halo may be more plausible. Such an extended dark halo is definitely required to bind a half-dozen fast-moving stars observed at the largest radii, but these stars may not be an equilibrium component of M32. © 2013. The American Astronomical Society. All rights reserved.


Benedict T.,Canada France Hawaii Telescope | Barrick G.A.,Canada France Hawaii Telescope
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

In 2009, the Canada-France-Hawaii Telescope converted the dewar for the ESPaDOnS spectrograph from using liquid nitrogen cooling to using a Polycold® closed-cycle cooler. It was found that the higher temperature of the closed-cycle cooler degraded the efficiency of the carbon getter for maintaining the vacuum to the point that vacuum could not be maintained long-term without the pumping of a cold-cathode gauge. This paper will detail this vacuum issue along with some experiments done to show the pumping rates of the carbon getter and cold-cathode vacuum gauges, and describe a light-baffle design for suppressing light from the gauge. © 2012 SPIE.


Michel-Dansac L.,University of Lyon | Duc P.-A.,University Paris Diderot | Bournaud F.,University Paris Diderot | Cuillandre J.-C.,Canada France Hawaii Telescope | And 6 more authors.
Astrophysical Journal Letters | Year: 2010

Extended H I structures around galaxies are of prime importance for probing galaxy formation scenarios. The giant H I ring in the Leo group is one of the largest and most intriguing H I structures in the nearby universe. Whether it consists of primordial gas, as suggested by the apparent absence of any optical counterpart and the absence of an obvious physical connection to nearby galaxies, or of gas expelled from a galaxy in a collision is actively debated. We present deep wide field-of-view optical images of the ring region obtained with MegaCam on the CFHT. They reveal optical counterparts to several H I and UV condensations along the ring, in the g′, r′, and i′ bands, which likely correspond to stellar associations formed within the gaseous ring. Analyzing the spectral energy distribution of one of these star-forming regions, we found it to be typical for a star-forming region in pre-enriched tidal debris. We then use simulations to test the hypothesis that the Leo ring results from a head-on collision between Leo group members NGC 3384 and M96. According to our model which is able to explain, at least qualitatively, the main observational properties of the system, the Leo ring is consistent with being a collisional ring. It is thus likely another example of extended intergalactic gas made-up of pre-enriched collisional debris. © 2010. The American Astronomical Society.


News Article | October 7, 2016
Site: phys.org

The study presents the first measurements of the changing strengths of oxygen emission lines from the present day and back to 12.5 billion years ago. The main conclusions are that the strength of doubly ionized oxygen increases going back in time, while the strength of singly ionized oxygen increases up to 11 billion years ago and then decreases for the remaining one to two billion years. The cause of the two different evolutions is due to the changing physical conditions inside star-forming galaxies. The amount of ionizing energy inputted into the gas by newly formed stars is much higher in the early universe. The results, recently published in the Monthly Notices of the Royal Astronomical Society, help set the framework for future surveys using next-generation telescopes, such as the upcoming James Webb Space Telescope, that will allow researchers to study the conditions inside star-forming galaxies to the era of the first galaxies. A galaxy can be thought of as a factory that produces stars from cold gas, with some galaxies being more productive than others. Therefore, what roughly defines the evolutionary parameters of a galaxy is the rate of star formation, stellar mass, and gas content. The rate at which stars form in galaxies has not always been the same. The typical star formation rate in galaxies rose for the first two to three billion years after the Big Bang and has steadily decreased for the past 10 to 11 billion years. In other words, the universe is in a production crisis as galaxies are becoming less active in creating new stars. Because cold gas is the fuel of star formation, it is imperative to understand how the physical conditions of the gas are changing throughout the universe's history. "One way to study the conditions of gas in star-forming regions of galaxies is to observe the spectral emission lines," said Ali Ahmad Khostovan, lead author of the paper and a graduate student in the Department of Physics and Astronomy at UC Riverside. "These lines are produced when light from bright, massive, short-lived stars interact with the surrounding medium resulting in regions where atoms are broken up or ionized." The emission lines are only visible while the most massive stars shine, therefore the timescales traced by these lines are dependent on the lifespan of these stars (about 10 to 50 million years). Therefore, emission lines can be used to trace the instantaneous activity and conditions in star-forming regions of galaxies. In the study, the researchers used a sample of emission line selected galaxies from the High-z Emission Line Survey (HiZELS) to trace the evolution in the strengths of emission lines associated with singly ionized and doubly ionized oxygen. The importance of these two lines is that they provide information regarding the energetic excitation (ionized) state of the gas since the main difference between the two lines is the energy needed to go from singly to doubly ionized oxygen. This is accomplished because of the unique design of HiZELS. The survey uses four narrowband filters, one installed on the Subaru Telescope in Hawaii and the other three on the United Kingdom InfraRed Telescope (UKIRT), also in Hawaii. These filters are narrow enough that the light from an emission line would dominate the detector of the telescope. As emission lines are narrow and redshifted, they act as testifiers of four different time slices (one for each filter) of the universe's history. The authors also used a wealth of ancillary data from various ground-based telescopes such as the Canada France Hawaii Telescope in Hawaii as well as space-based telescopes such as the Spitzer Space Telescope. Their samples also include spectroscopic follow up using the DEIMOS and MOSFIRE spectrographs on the W. M. Keck Observatory, and spectroscopy from other studies. The study is comprised of 7,000 galaxies. More information: A. A. Khostovan et al. The nature of Hβ+[O iii] and [O ii] emitters to∼ 5 with HiZELS: stellar mass functions and the evolution of EWs, Monthly Notices of the Royal Astronomical Society (2016). DOI: 10.1093/mnras/stw2174


News Article | October 10, 2016
Site: www.rdmag.com

A new study led by University of California, Riverside astronomers casts light on how young, hot stars ionize oxygen in the early universe and the effects on the evolution of galaxies through time. The study presents the first measurements of the changing strengths of oxygen emission lines from the present day and back to 12.5 billion years ago. The main conclusions are that the strength of doubly ionized oxygen increases going back in time, while the strength of singly ionized oxygen increases up to 11 billion years ago and then decreases for the remaining one to two billion years. The cause of the two different evolutions is due to the changing physical conditions inside star-forming galaxies. The amount of ionizing energy inputted into the gas by newly formed stars is much higher in the early universe. The results, recently published in the Monthly Notices of the Royal Astronomical Society, help set the framework for future surveys using next-generation telescopes, such as the upcoming James Webb Space Telescope, that will allow researchers to study the conditions inside star-forming galaxies to the era of the first galaxies. A galaxy can be thought of as a factory that produces stars from cold gas, with some galaxies being more productive than others. Therefore, what roughly defines the evolutionary parameters of a galaxy is the rate of star formation, stellar mass, and gas content. The rate at which stars form in galaxies has not always been the same. The typical star formation rate in galaxies rose for the first two to three billion years after the Big Bang and has steadily decreased for the past 10 to 11 billion years. In other words, the universe is in a production crisis as galaxies are becoming less active in creating new stars. Because cold gas is the fuel of star formation, it is imperative to understand how the physical conditions of the gas are changing throughout the universe's history. "One way to study the conditions of gas in star-forming regions of galaxies is to observe the spectral emission lines," said Ali Ahmad Khostovan, lead author of the paper and a graduate student in the Department of Physics and Astronomy at UC Riverside. "These lines are produced when light from bright, massive, short-lived stars interact with the surrounding medium resulting in regions where atoms are broken up or ionized." The emission lines are only visible while the most massive stars shine, therefore the timescales traced by these lines are dependent on the lifespan of these stars (about 10 to 50 million years). Therefore, emission lines can be used to trace the instantaneous activity and conditions in star-forming regions of galaxies. In the study, the researchers used a sample of emission line selected galaxies from the High-z Emission Line Survey (HiZELS) to trace the evolution in the strengths of emission lines associated with singly ionized and doubly ionized oxygen. The importance of these two lines is that they provide information regarding the energetic excitation (ionized) state of the gas since the main difference between the two lines is the energy needed to go from singly to doubly ionized oxygen. This is accomplished because of the unique design of HiZELS. The survey uses four narrowband filters, one installed on the Subaru Telescope in Hawaii and the other three on the United Kingdom InfraRed Telescope (UKIRT), also in Hawaii. These filters are narrow enough that the light from an emission line would dominate the detector of the telescope. As emission lines are narrow and redshifted, they act as testifiers of four different time slices (one for each filter) of the universe's history. The authors also used a wealth of ancillary data from various ground-based telescopes such as the Canada France Hawaii Telescope in Hawaii as well as space-based telescopes such as the Spitzer Space Telescope. Their samples also include spectroscopic follow up using the DEIMOS and MOSFIRE spectrographs on the W. M. Keck Observatory, and spectroscopy from other studies. The study is comprised of 7,000 galaxies.


News Article | December 4, 2015
Site: phys.org

At the core of most massive galaxies in the universe is a supermassive black hole – a concentration of matter so dense that it attracts anything nearby, including light. Such black holes have masses from millions to billions of times that of the Sun and are generally idle, only accreting the occasional star or gas cloud that ventures too close to the galaxy's centre. A small fraction of them are, however, extremely active, devouring matter at a very high rate, causing the surrounding material to shine brightly across the electromagnetic spectrum, from radio waves to X-rays and gamma rays. In some cases, emission from matter in the vicinity of the black hole is so intense that the core of the galaxy outshines the stars. These objects appear as point sources in the sky, like stars, and are known as quasars – short for quasi-stellar sources. Quasars allow scientists to study gravity in the very strong field of the supermassive black holes. In addition, comparing the properties of quasars with those of other galaxies that host either active or passive black holes can reveal interesting aspects about the evolution of galaxies over cosmic history. But one other aspect piqued the interest of two scientists from the Arcetri Astrophysical Observatory in Firenze, Italy: they realised that quasars can be used as probes of the expansion history of the universe. The results of their study are presented in a paper, published today in the Astrophysical Journal. "The history of cosmic expansion holds a wealth of information about the universe, including its age and the relative abundance of its components, and to pin it down we need to observe astronomical sources at a wide range of distances from us," explains Guido Risaliti, one of the scientists who led the study. "But determining distances in the universe is not at all trivial and can be best performed only with a few classes of sources. In this study, we show how it can be done with quasars," he adds. The main obstacle to measuring distances to astronomical objects lies in our ignorance of their true brightness, which makes it virtually impossible to assess whether a source is intrinsically bright or whether it just appears so because it is very close to us. For relatively nearby stars in our Galaxy, astronomers can get a very precise handle on distances using parallax – the tiny apparent shift of a star's position in the sky when viewed from different locations in the Earth's orbit. However, the greater the distance the smaller the parallax, which restricts the reach of this method to our local cosmic neighbourhood. Farther away, astronomers have to rely on 'standard candles' – astronomical objects whose intrinsic luminosity can be calculated from another of their observable properties. Amongst the most widely used standard candles are supernovae of type Ia – exploding white dwarf stars in a binary system. These explosions release roughly the same amount of energy every time, so their observed luminosity is a good indicator of the actual luminosity and, in turn, of their distance. In the 1990s, teams of scientists collected many observations of these supernovae to map distances to faraway galaxies and to study how these are affected by the overall cosmic expansion. This led to the surprising discovery that the universe's expansion is currently accelerating under the repulsive effect of a mysterious dark energy. In the standard cosmological model, dark energy dominates the present universe, making up about three quarters of its total energy budget, with the invisible dark matter accounting for about one fifth of the total, and ordinary matter amounting to a mere few percent. But it has not always been so, and delving deep into the history of our cosmos is crucial to figure out the nature and evolution of these 'dark' components. "Type Ia supernovae are a powerful tool for cosmology, but they cannot be observed at very large distances from us, so they are mostly used to probe the relatively recent universe," says co-author Elisabeta Lusso. Few supernovae of type Ia have been observed in earlier cosmic phases, when our almost 14 billion-year-old universe was younger than 5 billion years. "This is why we suggest to complement type Ia supernovae with quasars, which can be observed in large quantities out to much greater distances, probing cosmic history up to the epoch when the universe was only one billion years of age," she adds. To determine how far quasars are from us, Risaliti and Lusso used an interesting property of these sources: a link between the amount of light they emit at ultraviolet and X-ray wavelengths, which has been known since the late 1970s. Both types of emission derive from the black hole's activity, although they are caused by different processes. As the accreted material flows towards the black hole through a disc, it is heated by friction and shines brightly at visible and ultraviolet wavelengths. Then, part of the light emitted by the disc interacts with nearby electrons, receiving an extra energy boost and turning into X-rays. The key point underlying the application of this relation to cosmology is that the link between the luminosities at the two different wavelengths is not linear. This means that the ratio between a quasar's measured X-ray and ultraviolet emission is not fixed, but varies – in a known way – depending on the ultraviolet luminosity itself. So by measuring a quasar's X-ray and ultraviolet emission the scientists can estimate the absolute luminosity at ultraviolet wavelengths; in turn, this can be used to gauge the quasar's distance. While the physical mechanism underlying this relation is unclear, Risaliti and Lusso could still use it to treat quasars as standard candles and employ them as distance indicators for cosmological studies. To do so, they compiled a pilot sample of quasars with both ultraviolet and X-ray measurements, collecting 1138 sources from several data sets that were published in the scientific literature over the past decade. Most of the X-ray data came from surveys performed with ESA's XMM-Newton, including the COSMOS survey. "First, we verified that the relation between ultraviolet and X-ray luminosity holds for quasars observed at any cosmic epoch: this is an essential condition if we want to treat them as cosmological probes," explains Risaliti. Then, the scientists determined distances to the quasars in their sample and used these to study how the expansion of the universe changed in the span of cosmic history covered by these sources. From this, they evaluated the relative abundance of dark matter and dark energy in the universe, obtaining results that agree with current estimates obtained from supernovae and other observations, albeit with larger errors. "Quasars are a less precise tool to measure distances than supernovae of type Ia, but they yield complementary information about the distant universe that is inaccessible to supernova observations," says Lusso. The power of this new approach is best unleashed through the combination of quasars and supernovae of type Ia, spanning over 13 billion years of cosmic evolution to investigate how the universe changed across most of its history. In fact, combining data from current surveys of both types of sources yields constraints on the relative abundance of dark matter and dark energy that are tighter and more precise than those obtained from supernovae alone. The method developed by Risaliti and Lusso appears especially promising in light of future surveys, since a larger quasar sample means smaller errors on the cosmological parameters. On the X-ray front, the German-led eROSITA instrument on-board the Russian Spektr-RG satellite, planned for launch in 2017, is expected to observe millions of quasars, and ESA's Advanced Telescope for High-ENergy Astrophysics (ATHENA), planned for launch in 2028, could survey up to 10 million quasars. Meanwhile, ESA's Euclid mission, planned for launch in 2020, will observe a few million quasars at visible and near-infrared wavelengths – the portion of the spectrum where the ultraviolet light emitted by distant quasars is redshifted due to cosmic expansion. "It is very gratifying to see that the data collected by XMM-Newton over many years are being used as the basis for a creative and promising method to investigate the darkest secrets of our universe," comments Norbert Schartel, ESA XMM-Newton Project Scientist. The study is based on a sample of 1138 quasars that was obtained by compiling many different data sets published previously in scientific papers. The sample contains an estimate of the X-ray and ultraviolet luminosity for each quasar. The X-ray data come mainly from ESA's XMM-Newton X-ray observatory, as well as from NASA's Chandra X-ray Observatory and the German Aerospace Center-led ROSAT satellite. The ultraviolet luminosity was estimated using data from the Sloan Digital Sky Survey, NASA's Galaxy Evolution Explorer (GALEX) and Spitzer Space Telescope, NOAJ's Subaru Telescope, the Canada France Hawaii Telescope (CFHT), the Two Micron All Sky Survey (2MASS) and the UKIRT Infrared Deep Sky Survey (UKIDSS). The European Space Agency's X-ray Multi-Mirror Mission, XMM-Newton, was launched in December 1999. The largest scientific satellite to have been built in Europe, it is also one of the most sensitive X-ray observatories ever flown. More than 170 wafer-thin, cylindrical mirrors direct incoming radiation into three high-throughput X-ray telescopes. XMM-Newton's orbit takes it almost a third of the way to the Moon, allowing for long, uninterrupted views of celestial objects. Explore further: Astronomers discover new way to measure Universe

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