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TOPIC: Distant Galaxies
Blobrana


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RE: Distant Galaxies
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Quasar light variability linked to black hole mass
Quasars are some of the most luminous and distant objects in the universe – and appear to have something in common with ordinary light bulbs, say researchers at the University of Illinois at Urbana-Champaign and at the National Centre for Supercomputing Applications.

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Blobrana


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Quasar Trio
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A tight-knit trio of ultrabright objects called quasars has been discovered for the first time. Their proximity is probably not a coincidence – violent interactions between their host galaxies may be turning on the quasars by feeding the galaxies' colossal black holes more matter than they can chew.
Quasars are very bright, compact objects in the distant universe. Each is thought to be powered by matter heating up as it falls into a supermassive black hole at the centre of a galaxy.
Of the 100,000 known quasars, only a few dozen are close enough together to be considered binaries. Even so, that is still greater than would be expected if the quasars were distributed randomly in the sky.
Now, astronomers have found the first case of a triple quasar system, an association that is even less likely to be due to chance. The trio hints that galaxy interactions have triggered the quasar activity.

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Blobrana


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Title: The Dynamical Distinction between Elliptical and Lenticular Galaxies in Distant Clusters: Further Evidence for the Recent Origin of S0 Galaxies
Authors: Sean M. Moran, Boon Liang Loh, Richard S. Ellis, Tommaso Treu, Kevin Bundy, Lauren A. MacArthur
(revised v2)

We examine resolved spectroscopic data obtained with the Keck II telescope for 44 spheroidal galaxies in the fields of two rich clusters, Cl0024+16 (z=0.40) and MS0451-03 (z=0.54), and contrast this with similar data for 23 galaxies within the redshift interval 0.3 < z < 0.65 in the GOODS northern field. For each galaxy we examine the case for systemic rotation, derive central stellar velocity dispersions \sigma and photometric ellipticities, \epsilon. Using morphological classifications obtained via Hubble Space Telescope imaging as the basis, we explore the utility of our kinematic quantities in distinguishing between pressure-supported ellipticals and rotationally-supported lenticulars (S0s). We demonstrate the reliability of using the v/(1-\epsilon) vs \sigma and v/\sigma vs \epsilon distributions as discriminators and further test these diagnostics using equivalent local data in the Coma cluster. According to our tests, both discriminators are reliable at at least the 70-85% level and limited by the accuracy of the morphological typing. Using our classifiers we then examine the morphology-density relation for elliptical and S0 galaxies separately at a mean redshift of z=0.5 confirming, from kinematic data alone, the recent growth of rotationally-supported spheroidals. We discuss the feasibility of extending the method to a more comprehensive study of cluster and field galaxies to z=1, in order to verify in detail the recent density-dependent growth of S0 galaxies.

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Blobrana


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Astronomers working with the infrared Spitzer Space Telescope believe they have found evidence of the first visible structure in the universe, clumps of patchy infrared light that can be observed when the light of closer stars and galaxies is masked.

"We have shut down the lights of the universe to see the outlines of its first fireworks" - Alexander Kashlinsky of NASA's Goddard Space Flight Centre, the lead author of two reports on the findings to be published in Astrophysical Journal Letters.

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Blobrana


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Cosmology: Ripples of early starlight
After all known sources are accounted for, puffy blobs of infrared light persist on deep-field telescope images. Evidence is mounting that these could be the signatures of stars in early 'protogalaxies'.

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Blobrana


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Title: COSMOS : Hubble Space Telescope Observations
Authors: N. Scoville, A. Benson, A. W. Blain, D. Calzetti, A. Comastri, P. Capak, C. Carilli, J. E. Carlstrom, C. M. Carollo, J. Colbert, E. Daddi, R. S. Ellis, M. Elvis, S. P. Ewald, M. Fall, A. Franceschini, M. Giavalisco, W. Green, R. E. Griffiths, L. Guzzo, G. Hasinger, C. Impey, J-P. Kneib, J. Koda, A. Koekemoer, O. Lefevre, S. Lilly, C. T. Liu, H. J. McCracken, R. Massey, Y. Mellier, S. Miyazaki, B. Mobasher, J. Mould, C. Norman, A. Refregier, A. Renzini, J. Rhodes, M. Rich, D. B. Sanders, D. Schiminovich, E. Schinnerer, M. Scodeggio, K. Sheth, P. L. Shopbell, Y. Taniguchi, N. Tyson, C. M. Urry, L. Van Waerbeke, P. Vettolani, S. D. M. White, L. Yan

The Cosmic Evolution Survey (COSMOS) was initiated with an extensive allocation (590 orbits in Cycles 12-13) using the Hubble Space Telescope (HST) for high resolution imaging.
Here we review the characteristics of the HST imaging with the Advanced Camera for Surveys (ACS) and parallel observations with NICMOS and WFPC2. A square field (1.8 deg˛) has been imaged with single-orbit ACS I-F814W exposures with 50% completeness for sources 0.5\arcsec in diameter at I_{AB} = 26.0 mag. The ACS imaging is a key part of the COSMOS survey, providing very high sensitivity and high resolution (0.09\arcsec FWHM, 0.05\arcsec pixels) imaging and detecting a million objects. These images yield resolved morphologies for several hundred thousand galaxies. The small HST PSF also provides greatly enhanced sensitivity for weak lensing investigations of the dark matter distribution.

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Blobrana


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Title:The discovery of the first luminous z~6 quasar in the UKIDSS Large Area Survey
Authors: B. P. Venemans (1), R. G. McMahon (1), S. J. Warren (2), E. A. Gonzalez-Solares (1), P. C. Hewett (1), D. J. Mortlock (2), S. Dye (3), R. G. Sharp (4) ((1) IoA, Cambridge, (2) Imperial, London, (3) Cardiff, (4) Anglo-Australian Observatory)

We present the initial results from our search for high redshift, z > 6, quasars using near infrared data from the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). Our analysis of the first 106 deg˛ of sky has resulted in the discovery of ULAS J020332.38+001229.2, a luminous (J_AB=20.0, J_Vega=19.1, M_1450=-26.2) quasar at z=5.86. Following candidate selection from the combined IR and optical catalogue data and stacking of multiple epoch Sloan Digital Sky Survey (SDSS) data, we have obtained optical spectroscopy for two candidates. The VLT FORS2 spectrum of ULAS J020332.38+001229.2 shows broad Ly alpha + NV1240 emission at ~8350 A and an abrupt continuum break due to absorption by the Ly alpha forest. The quasar is not present in the SDSS DR5 catalogue and the continuum spectral index of alpha=-1.4 (F_nu~nu^alpha) is redder than a composite of SDSS quasars at similar redshifts (alpha=-0.5). The discovery of one z~6 quasar in ~100 deg˛ down to Y_AB=20.4 (7 sigma) is consistent with existing SDSS results. ULAS J020332.38+001229.2 is the first quasar to be discovered from our programme to employ the planned 4000 deg˛ coverage of the UKIDSS LAS to detect quasars with z > 6.5. We describe our survey methodology, including the use of optical data from the SDSS and the highly effective procedures developed to isolate the very small surface density of high-probability quasar candidates.

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Blobrana


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Title: The Host Galaxy of the Quasar HE 0450-2958
Authors: Minjin Kim (1,2), Luis C. Ho (1), Chien Y. Peng (3), Myungshin Im (2) ((1) Carnegie Observatories, (2) Seoul National University, (3) Space Telescope Science Institute)

A recent study suggests that the quasar HE 0450-2958 is hosted by a galaxy substantially fainter than that inferred from the correlation between black hole mass and bulge luminosity. As this result has significant bearings on galaxy and black hole evolution, we revisit the issue by performing an independent analysis of the data, using a two-dimensional image fitting technique. We indeed find no evidence of a host galaxy either, but, due to the brightness of the quasar and uncertainties in the point-spread function, the limits are fairly weak. To derive an upper limit on the host galaxy luminosity, we perform simulations to deblend the quasar from the host under conditions similar to those actually observed. We find that the host galaxy has an absolute magnitude upper limit of -20 < M_V < -21, in good agreement with the previous determination. Since this limit is consistent with the value predicted from the current best estimate of the black hole mass, there is no compelling evidence that the quasar HE 0450-2958 has an abnormally underluminous host galaxy. We also show that, contrary to previous claims, the companion galaxy to HE 0450-2958 should not be be regarded as an ultraluminous infrared galaxy.

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Blobrana


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Title: When do early-type galaxies form?
Authors: Roberto G. Abraham (1), Patrick J. McCarthy (2), Erin Mentuch (1), Karl Glazebrook (3), Preethi Nair (1), Jean-Rene Gauthier (1), Sandra Savaglio (4), David Crampton (5), Stephanie Juneau (5,6), Richard Murowinski (5), Damien Le Borgne (1), R. G. Carlberg (1), Inger Jorgensen (7), Kathy Roth (7), Hsiao-Wen Chen (8), Ronald O. Marzke (9) ((1) Department of Astronomy & Astrophysics, University of Toronto, (2) Observatories of the Carnegie Institution of Washington, (3) Centre for Astrophysics and Supercomputing, Swinburne University of Technology, (4) Max-Planck-Institut fur extraterrestrische Physik, (5) Herzberg Institute of Astrophysics, (6) Steward Observatory, University of Arizona, (7) Gemini Observatory,(8) Dept. of Astronomy & Astrophysics, University of Chicago, (9) Dept. of Physics and Astronomy, San Francisco State University)

We have used the Hubble Space Telescope's Advanced Camera for Surveys to measure the mass density function of morphologically selected early-type galaxies in the Gemini Deep Deep Survey fields, over the redshift range 0.9 < z < 1.6. Our imaging data set covers four well-separated sight-lines, and is roughly intermediate (in terms of both depth and area) between the GOODS/GEMS imaging data, and the images obtained in the Hubble Deep Field campaigns. Our images contain 144 galaxies with ultra-deep spectroscopy, and they have been analysed using a new purpose-written morphological analysis code which improves the reliability of morphological classifications by adopting a 'quasi-petrosian' image thresholding technique. We find that at z = 1 approximately 70% of the stars in massive galaxies reside in early-type systems. This fraction is remarkably similar to that seen in the local Universe. However, we detect very rapid evolution in this fraction over the range 1.0 < z < 1.6, suggesting that in this epoch the strong colour-morphology relationship seen in the nearby Universe is beginning to fall into place.

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Blobrana


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MS 1512-cB58
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A team from the Sloan Digital Sky Survey (SDSS-II) and Fermi National Accelerator Laboratory today announced discovery of the brightest known image of a galaxy from the early universe.
While furious star formation makes the galaxy luminous, it enters the record books because the gravity of a foreground galaxy acts as a natural telescope, focusing its light on the earth.
The newly discovered galaxy, seen as an arc of four elongated images that encircle the foreground lens, offers a rare window into the state of the universe two billion years after the big bang.

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