141
141
Jul 20, 2013
07/13
by
B. Luo; W. N. Brandt; Y. Q. Xue; D. M. Alexander; M. Brusa; F. E. Bauer; A. Comastri; A. C. Fabian; R. Gilli; B. D. Lehmer; D. A. Rafferty; D. P. Schneider; C. Vignali
texts
eye 141
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(abridged) We identify a numerically significant population of heavily obscured AGNs at z~0.5-1 in the Chandra Deep Field-South (CDF-S) and Extended Chandra Deep Field-South by selecting 242 X-ray undetected objects with infrared-based star formation rates (SFRs) substantially higher (a factor of 3.2 or more) than their SFRs determined from the UV after correcting for dust extinction. An X-ray stacking analysis of 23 candidates in the central CDF-S region using the 4 Ms Chandra data reveals a...
Source: http://arxiv.org/abs/1107.3148v1
83
83
Sep 18, 2013
09/13
by
Anton M. Koekemoer; D. M. Alexander; F. E. Bauer; J. Bergeron; W. N. Brandt; E. Chatzichristou; S. Cristiani; S. M. Fall; N. A. Grogin; M. Livio; V. Mainieri; L. Moustakas; P. Padovani; P. Rosati; E. J. Schreier; C. M. Urry
texts
eye 83
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We describe a possible new class of X-ray sources that have robust detections in ultra-deep Chandra data, yet have no detections at all in our deep multi-band GOODS Hubble Space Telescope (HST) ACS images, which represent the highest quality optical imaging obtained to date on these fields. These extreme X-ray / Optical ratio sources ("EXO"s) have values of Fx/Fopt at least an order of magnitude above those generally found for other AGN, even those that are harbored by reddened hosts....
Source: http://arxiv.org/abs/astro-ph/0306407v1
53
53
Sep 24, 2013
09/13
by
M. A. Worsley; A. C. Fabian; F. E. Bauer; D. M. Alexander; G. Hasinger; S. Mateos; H. Brunner; W. N. Brandt; D. P. Schneider
texts
eye 53
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We extend our earlier work on X-ray source stacking in the deep XMM-Newton observation of the Lockman Hole, to the 2 Ms Chandra Deep Field North and the 1 Ms Chandra Deep Field South. The XMM-Newton work showed the resolved fraction of the X-ray background to be ~80-100 per cent at
Source: http://arxiv.org/abs/astro-ph/0412266v1
60
60
Sep 22, 2013
09/13
by
W. N. Brandt; D. M. Alexander; F. E. Bauer; C. Vignali
texts
eye 60
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This "pedagogical" review describes the key Chandra and XMM-Newton extragalactic surveys to date and details some of their implications for AGN physics and evolution. We additionally highlight two topics of current widespread interest: (1) X-ray constraints on the AGN content of luminous submillimeter galaxies, and (2) the demography and physics of high-redshift (z > 4) AGN as revealed by X-ray observations. Finally, we discuss prospects for future X-ray surveys with Chandra,...
Source: http://arxiv.org/abs/astro-ph/0403646v1
58
58
Sep 23, 2013
09/13
by
J. E. Geach; D. M. Alexander; B. D. Lehmer; Ian Smail; Y. Matsuda; S. C. Chapman; C. A. Scharf; R. J. Ivison; M. Volonteri; T. Yamada; A. W. Blain; R. G. Bower; F. E. Bauer; A. Basu-Zych
texts
eye 58
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We present the results of a 400ks Chandra survey of 29 extended Ly-alpha emitting nebulae (Ly-alpha Blobs, LABs) in the z=3.09 proto-cluster in the SSA22 field. We detect luminous X-ray counterparts in five LABs, implying a large fraction of active galactic nuclei (AGN) in LABs, f_AGN = 17% down to L_2-32keV ~ 10^44 erg/s. All of the AGN appear to be heavily obscured, with spectral indices implying obscuring column densities of N_H > 10^23 cm^-2. The AGN fraction should be considered a lower...
Source: http://arxiv.org/abs/0904.0452v3
51
51
Sep 21, 2013
09/13
by
D. A. Rafferty; W. N. Brandt; D. M. Alexander; Y. Q. Xue; F. E. Bauer; B. D. Lehmer; B. Luo; C. Papovich
texts
eye 51
favorite 0
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We present an analysis of deep multiwavelength data for z ~ 0.3-3 starburst galaxies selected by their 70 um emission in the Extended-Chandra Deep Field-South and Extended Groth Strip. We identify active galactic nuclei (AGNs) in these infrared sources through their X-ray emission and quantify the fraction that host an AGN. We find that the fraction depends strongly on both the mid-infrared color and rest-frame mid-infrared luminosity of the source, rising to ~ 50-70% at the warmest colors and...
Source: http://arxiv.org/abs/1108.3229v1
59
59
Sep 20, 2013
09/13
by
A. D. Goulding; D. M. Alexander; F. E. Bauer; W. R. Forman; R. C. Hickox; C. Jones; J. R. Mullaney; M. Trichas
texts
eye 59
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We explore the origin of mid-infrared (mid-IR) dust extinction in all 20 nearby (z < 0.05) bona-fide Compton-thick (N_H > 1.5 x 10^24 cm^-2) AGN with hard energy (E > 10 keV) X-ray spectral measurements. We accurately measure the silicate absorption features at lambda~9.7um in archival low-resolution (R~57-127) Spitzer Infrared Spectrograph (IRS) spectroscopy, and show that only a minority (~45%) of nearby Compton-thick AGN have strong Si-absorption features (S_9.7 =...
Source: http://arxiv.org/abs/1205.1800v1
55
55
Sep 21, 2013
09/13
by
J. D. Silverman; V. Mainieri; B. D. Lehmer; D. M. Alexander; F. E. Bauer; J. Bergeron; W. N. Brandt; R. Gilli; G. Hasinger; D. P. Schneider; P. Tozzi; C. Vignali; A. M. Koekemoer; T. Miyaji; P. Popesso; P. Rosati; G. Szokoly
texts
eye 55
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We present an analysis of 109 moderate-luminosity (41.9 < Log L{0.5-8.0 keV} < 43.7) AGN in the Extended Chandra Deep Field-South survey, which is drawn from 5,549 galaxies from the COMBO-17 and GEMS surveys having 0.4 < z < 1.1. These obscured or optically-weak AGN facilitate the study of their host galaxies since the AGN provide an insubstantial amount of contamination to the galaxy light. We find that the color distribution of AGN host galaxies is highly dependent upon (1) the...
Source: http://arxiv.org/abs/0709.3455v2
50
50
Sep 18, 2013
09/13
by
D. M. Alexander; R. R. Chary; A. Pope; F. E. Bauer; W. N. Brandt; E. Daddi; M. Dickinson; D. Elbaz; N. A. Reddy
texts
eye 50
favorite 0
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Many models that seek to explain the origin of the unresolved X-ray background predict that Compton-thick Active Galactic Nuclei (AGNs) are ubiquitious at high redshift. However, few distant Compton-thick AGNs have been reliably identified to date. Here we present Spitzer-IRS spectroscopy and 3.6-70um photometry of a z=2.2 optically identified AGN (HDF-oMD49) that is formally undetected in the 2Ms Chandra Deep Field-North (CDF-N) survey. The Spitzer-IRS spectrum and spectral energy distribution...
Source: http://arxiv.org/abs/0803.0636v4
39
39
Sep 18, 2013
09/13
by
W. N. Brandt; C. Vignali; D. P. Schneider; D. M. Alexander; S. F. Anderson; F. E. Bauer; X. Fan; G. P. Garmire; S. Kaspi; G. T. Richards
texts
eye 39
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X-ray studies of high-redshift (z > 4) active galaxies have advanced substantially over the past few years, largely due to results from the new generation of X-ray observatories. As of this writing X-ray emission has been detected from nearly 60 high-redshift active galaxies. This paper reviews the observational results and their implications for models of the first massive black holes, and it discusses future prospects for the field.
Source: http://arxiv.org/abs/astro-ph/0212082v2
55
55
Sep 21, 2013
09/13
by
B. D. Lehmer; W. N. Brandt; A. E. Hornschemeier; D. M. Alexander; F. E. Bauer; A. M. Koekemoer; D. P. Schneider; A. T. Steffen
texts
eye 55
favorite 0
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We analyze a population of intermediate-redshift (z ~ 0.05-0.3), off-nuclear X-ray sources located within optically-bright galaxies in the Great Observatories Origins Deep Survey (GOODS) and Galaxy Evolution from Morphology and SEDs (GEMS) fields. A total of 24 off-nuclear source candidates are classified using deep Chandra exposures from the Chandra Deep Field-North, Chandra Deep Field-South, and Extended Chandra Deep Field-South; 15 of these are newly identified. These sources have average...
Source: http://arxiv.org/abs/astro-ph/0602001v1
10
10.0
Jun 28, 2018
06/18
by
J. Aird; D. M. Alexander; D. R. Ballantyne; F. Civano; A. Del-Moro; R. C. Hickox; G. B. Lansbury; J. R. Mullaney; F. E. Bauer; W. N. Brandt; A. Comastri; A. C. Fabian; P. Gandhi; F. A. Harrison; B. Luo; D. Stern; E. Treister; L. Zappacosta; M. Ajello; R. Assef; S. E. Boggs; M. Brightman; F. E. Christensen; W. W. Craig; M. Elvis; K. Forster; M. Balokovic; B. W. Grefenstette; C. J. Hailey; M. Koss; S. M. LaMassa; K. K. Madsen; S. Puccetti; C. Saez; C. M. Urry; D. R. Wik; W. Zhang
texts
eye 10
favorite 0
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We present the first direct measurements of the rest-frame 10-40 keV X-ray luminosity function (XLF) of Active Galactic Nuclei (AGNs) based on a sample of 94 sources at 0.1 < z
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1511.04184
4
4.0
Jun 29, 2018
06/18
by
Y. Q. Xue; B. Luo; W. N. Brandt; D. M. Alexander; F. E. Bauer; B. D. Lehmer; G. Yang
texts
eye 4
favorite 0
comment 0
We present improved point-source catalogs for the 2 Ms Chandra Deep Field-North (CDF-N) and the 250 ks Extended Chandra Deep Field-South (E-CDF-S), implementing a number of recent improvements in Chandra source-cataloging methodology. For the CDF-N/E-CDF-S, we provide a main catalog that contains 683/1003 X-ray sources detected with wavdetect at a false-positive probability threshold of $10^{-5}$ that also satisfy a binomial-probability source-selection criterion of $P
Topics: Astrophysics, High Energy Astrophysical Phenomena, Cosmology and Nongalactic Astrophysics,...
Source: http://arxiv.org/abs/1602.06299
52
52
Sep 19, 2013
09/13
by
E. Daddi; M. Dickinson; R. Chary; A. Pope; G. Morrison; D. M. Alexander; F. E. Bauer; W. N. Brandt; M. Giavalisco; H. Ferguson; K. -S. Lee; C. Papovich; A. Renzini
texts
eye 52
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We investigate the multi-wavelength emission of BzK selected star forming galaxies at z~2 in the Great Observatories Origins Deep Survey (GOODS) North region. Most (82%) of the sources are individually detected at 24um in the Spitzer MIPS imaging, and one fourth (26%) in the VLA radio data. Significant detections of the individually undetected objects are obtained through stacking in the radio, submm and X-ray domains. The typical star forming galaxy with stellar mass ~10^{11}Mo at z=2 is an...
Source: http://arxiv.org/abs/astro-ph/0507504v1
28
28
Sep 20, 2013
09/13
by
E. D. Feigelson; A. E. Hornschemeier; G. Micela; F. E. Bauer; D. M. Alexander; W. N. Brandt; F. Favata; S. Sciortino; G. P. Garmire; Penn State; Johns Hopkins; Palermo; Cambridge; ESTEC
texts
eye 28
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comment 0
The extremely sensitive Chandra Deep Field-North (CDF-N) pencil-beam X-ray survey is used to identify and characterize the X-ray emission from old high-latitude main sequence Galactic stars. Our principal goal is to investigate the expected long-term decay of magnetic activity of late-type stars due to the gradual spindown of stellar rotation from a magnetized stellar wind. Eleven X-ray sources constitute a well-defined sample of 2 G, 2 K0-K4, and 7 M2-M5 stars with median distance around 300...
Source: http://arxiv.org/abs/astro-ph/0405026v1
14
14
Jun 28, 2018
06/18
by
J. R. Mullaney; A. Del-Moro; J. Aird; D. M. Alexander; F. M. Civano; R. C. Hickox; G. B. Lansbury; M. Ajello; R. Assef; D. R. Ballantyne; M. Balokovic; F. E. Bauer; W. N. Brandt; S. E. Boggs; M. Brightman; F. E. Christensen; A. Comastri; W. W. Craig; M. Elvis; K. Forster; P. Gandhi; B. W. Grefenstette; C. J. Hailey; F. A. Harrison; M. Koss; S. M. LaMassa; B. Luo; K. K. Madsen; S. Puccetti; C. Saez; D. Stern; E. Treister; C. M. Urry; D. R. Wik; L. Zappacosta; W. Zhang
texts
eye 14
favorite 1
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We present initial results and the source catalog from the NuSTAR survey of the Extended Chandra Deep Field South (hereafter, ECDFS) - currently the deepest contiguous component of the NuSTAR extragalactic survey program. The survey covers the full ~30 arcmin x 30 arcmin area of this field to a maximum depth of ~360 ks (~220 ks when corrected for vignetting at 3-24 keV), reaching sensitivity limits of ~1.3 x 10^-14 erg/cm2/s (3-8 keV), ~3.4 x 10^-14 erg/cm2/s (8-24 keV) and ~3.0 x 10^-14...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1511.04186
9
9.0
Jun 28, 2018
06/18
by
F. A. Harrison; J. Aird; F. Civano; G. Lansbury; J. R. Mullaney; D. R. Ballantyne; D. M. Alexander; D. Stern; M. Ajello; D. Barret; F. E. Bauer; M. Balokovic; W. N. Brandt; M. Brightman; S. E. Boggs; F. E. Christensen; A. Comastri; W. W. Craig; A. Del Moro; K. Forster; P. Gandhi; P. Giommi; B. W. Grefenstette; C. J. Hailey; R. C. Hickox; A. Hornstrup; T. Kitaguchi; J. Koglin; B. Luo; K. K. Madsen; P. H. Mao; H. Miyasaka; K. Mori; M. Perri; M. Pivovaroff; S. Puccetti; V. Rana; E. Treister; D....
texts
eye 9
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We present the 3-8 keV and 8-24 keV number counts of active galactic nuclei (AGN) identified in the NuSTAR extragalactic surveys. NuSTAR has now resolved 33-39% of the X-ray background in the 8-24 keV band, directly identifying AGN with obscuring columns up to approximately 1e25 /cm2. In the softer 3-8 keV band the number counts are in general agreement with those measured by XMM-Newton and Chandra over the flux range 5e-15 < S(3 - 8 keV)/(erg/cm2/s) < 1e-12 probed by NuSTAR. In the hard...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1511.04183
47
47
Sep 18, 2013
09/13
by
M. Young; W. N. Brandt; Y. Q. Xue; M. Paolillo; D. M. Alexander; F. E. Bauer; B. D. Lehmer; B. Luo; O. Shemmer; D. P. Schneider; C. Vignali
texts
eye 47
favorite 1
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The 4 Ms Chandra Deep Field-South (CDF-S) and other deep X-ray surveys have been highly effective at selecting active galactic nuclei (AGN). However, cosmologically distant low-luminosity AGN (LLAGN) have remained a challenge to identify due to significant contribution from the host galaxy. We identify long-term X-ray variability (~month-years, observed frame) in 20 of 92 CDF-S galaxies spanning redshifts z~0.08-1.02 that do not meet other AGN selection criteria. We show that the observed...
Source: http://arxiv.org/abs/1201.4391v1
9
9.0
Jun 29, 2018
06/18
by
C. Ricci; R. J. Assef; D. Stern; R. Nikutta; D. M. Alexander; D. Asmus; D. R. Ballantyne; F. E. Bauer; A. W. Blain; S. Boggs; P. G. Boorman; W. N. Brandt; M. Brightman; C. S. Chang; C. -T. J. Chen; F. E. Christensen; A. Comastri; W. W. Craig; T. Díaz-Santos; P. R. Eisenhardt; D. Farrah; P. Gandhi; C. J. Hailey; F. A. Harrison; H. D. Jun; M. J. Koss; S. LaMassa; G. B. Lansbury; C. B. Markwardt; M. Stalevski; F. Stanley; E. Treister; C. -W. Tsai; D. J. Walton; J. W. Wu; L. Zappacosta; W. W. Zhang
texts
eye 9
favorite 0
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Hot, Dust-Obscured Galaxies (Hot DOGs), selected from the WISE all sky infrared survey, host some of the most powerful Active Galactic Nuclei (AGN) known, and might represent an important stage in the evolution of galaxies. Most known Hot DOGs are at $z> 1.5$, due in part to a strong bias against identifying them at lower redshift related to the selection criteria. We present a new selection method that identifies 153 Hot DOG candidates at $z\sim 1$, where they are significantly brighter and...
Topics: Astrophysics, High Energy Astrophysical Phenomena, Cosmology and Nongalactic Astrophysics,...
Source: http://arxiv.org/abs/1609.04808
8
8.0
Jun 30, 2018
06/18
by
B. Luo; W. N. Brandt; D. M. Alexander; D. Stern; S. H. Teng; P. Arévalo; F. E. Bauer; S. E. Boggs; F. E. Christensen; A. Comastri; W. W. Craig; D. Farrah; P. Gandhi; C. J. Hailey; F. A. Harrison; M. Koss; P. Ogle; S. Puccetti; C. Saez; A. E. Scott; D. J. Walton; W. W. Zhang
texts
eye 8
favorite 0
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We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z=0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z 330 times weaker than expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence...
Topics: Astrophysics of Galaxies, High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1408.3633
8
8.0
Jun 30, 2018
06/18
by
D. J. Rosario; D. H. McIntosh; A. van der Wel; J. Kartaltepe; P. Lang; P. Santini; S. Wuyts; D. Lutz; M. Rafelski; C. Villforth; D. M. Alexander; F. E. Bauer; E. F. Bell; S. Berta; W. N. Brandt; C. J. Conselice; A. Dekel; S. M. Faber; H. C. Ferguson; R. Genzel; N. A. Grogin; D. D. Kocevski; A. M. Koekemoer; D. C. Koo; J. M. Lotz; B. Magnelli; R. Maiolino; M. Mozena; J. R. Mullaney; C. J. Papovich; P. Popesso; L. J. Tacconi; J. R. Trump; S. Avadhuta; R. Bassett; A. Bell; M. Bernyk; F. Bournaud;...
texts
eye 8
favorite 0
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We study the relationship between the structure and star-formation rate (SFR) of X-ray selected low and moderate luminosity active galactic nuclei (AGNs) in the two Chandra Deep Fields, using Hubble Space Telescope imaging from the Cosmic Assembly Near Infrared Extragalactic Legacy Survey (CANDELS) and deep far-infrared maps from the PEP+GOODS-Herschel survey. We derive detailed distributions of structural parameters and FIR luminosities from carefully constructed control samples of galaxies,...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1409.5122
66
66
Sep 23, 2013
09/13
by
F. E. Bauer; D. M. Alexander; W. N. Brandt; D. P. Schneider; E. Treister; A. E. Hornschemeier; G. P. Garmire
texts
eye 66
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We investigate the X-ray number counts in the 1-2 Ms Chandra Deep Fields (CDFs) to determine the contributions of faint X-ray source populations to the extragalactic X-ray background (XRB). X-ray sources were separated into Active Galactic Nuclei (AGN), star-forming galaxies, and Galactic stars based on several criteria. We find that AGN continue to dominate the number counts in the 0.5-2.0 keV and 2-8 keV bands. At flux limits of ~2.5e-17 erg cm-2 s-1 (0.5-2.0 keV) and ~1.4e-16 erg cm-2 s-1...
Source: http://arxiv.org/abs/astro-ph/0408001v2
51
51
Sep 20, 2013
09/13
by
B. D. Lehmer; W. N. Brandt; D. M. Alexander; E. F. Bell; D. H. McIntosh; F. E. Bauer; G. Hasinger; V. Mainieri; T. Miyaji; D. P. Schneider; A. T. Steffen
texts
eye 51
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We investigate the evolution over the last 6.3 Gyr of cosmic time (i.e., since z ~ 0.7) of the average X-ray properties of early-type galaxies within the Extended Chandra Deep Field-South (E-CDF-S). Our early-type galaxy sample includes 539 objects with red-sequence colors and Sersic indices larger than n = 2.5, which were selected jointly from the COMBO-17 (Classifying Objects by Medium-Band Observations in 17 Filters) and GEMS (Galaxy Evolution from Morphologies and SEDs) surveys. We utilize...
Source: http://arxiv.org/abs/astro-ph/0612003v1
42
42
Sep 18, 2013
09/13
by
A. J. Barger; L. L. Cowie; P. Capak; D. M. Alexander; F. E. Bauer; E. Fernandez; W. N. Brandt; G. P. Garmire; A. E. Hornschemeier
texts
eye 42
favorite 0
comment 0
We present an optical and NIR catalog for the X-ray sources in the 2 Ms Chandra observation of the Hubble Deep Field-North region. We have high-quality multicolor images of all 503 X-ray point sources and reliable spectroscopic redshifts for 284. We spectroscopically identify six z>1 type II quasars. Our spectroscopic completeness for the R
Source: http://arxiv.org/abs/astro-ph/0306212v1
64
64
Jul 20, 2013
07/13
by
W. N. Brandt; A. E. Hornschemeier; D. P. Schneider; D. M. Alexander; F. E. Bauer; G. P. Garmire; C. Vignali
texts
eye 64
favorite 0
comment 0
We present results from stacking analyses, using the 1 Ms Chandra Deep Field North data, that constrain the X-ray emission of Lyman break galaxies at z = 2-4. Stacking the counts from 24 individually undetected Lyman break galaxies located within the Hubble Deep Field North, we have obtained average detections of these objects in the resulting 0.5-8.0 keV and 0.5-2.0 keV images; these images have effective exposure times of 22.4 Ms (260 days). Monte Carlo testing empirically shows the...
Source: http://arxiv.org/abs/astro-ph/0107392v1
50
50
Sep 18, 2013
09/13
by
E. Daddi; M. Dickinson; G. Morrison; R. Chary; A. Cimatti; D. Elbaz; D. Frayer; A. Renzini; A. Pope; D. M. Alexander; F. E. Bauer; M. Giavalisco; M. Huynh; J. Kurk; M. Mignoli
texts
eye 50
favorite 0
comment 0
Examining a sample of massive galaxies at 1.410^{11}L_sun, show a mid-IR excess which is likely due to the presence of obscured active nuclei, as shown in a companion paper. There is a tight and roughly linear correlation between stellar mass and SFR for 24um-detected galaxies. For a given mass, the SFR at z=2 was larger by a factor of ~4 and ~30 relative to that in star forming galaxies at z=1 and z=0, respectively. Typical ultraluminous infrared galaxies (ULIRGs) at z=2 are relatively...
Source: http://arxiv.org/abs/0705.2831v2
48
48
Sep 20, 2013
09/13
by
B. Luo; W. N. Brandt; Y. Q. Xue; M. Brusa; D. M. Alexander; F. E. Bauer; A. Comastri; A. Koekemoer; B. D. Lehmer; V. Mainieri; D. A. Rafferty; D. P. Schneider; J. D. Silverman; C. Vignali
texts
eye 48
favorite 0
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[Abridged] We present reliable multiwavelength identifications and high-quality photometric redshifts for the 462 X-ray sources in the ~2 Ms Chandra Deep Field-South. Source identifications are carried out using deep optical-to-radio multiwavelength catalogs, and are then combined to create lists of primary and secondary counterparts for the X-ray sources. We identified reliable counterparts for 446 (96.5%) of the X-ray sources, with an expected false-match probability of ~6.2%. A...
Source: http://arxiv.org/abs/1002.3154v2
73
73
Jul 20, 2013
07/13
by
Y. Q. Xue; W. N. Brandt; B. Luo; D. A. Rafferty; D. M. Alexander; F. E. Bauer; B. D. Lehmer; D. P. Schneider; J. D. Silverman
texts
eye 73
favorite 0
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[Abridged] We extend color-magnitude relations for moderate-luminosity X-ray AGN hosts and non-AGN galaxies through the galaxy formation epoch in the Chandra Deep Fields. We utilized analyses of color-magnitude diagrams (CMDs) to assess the role of moderate-luminosity AGNs in galaxy evolution. First, we confirm some previous results and extend them to higher redshifts, e.g., there is no apparent color bimodality for AGN hosts from z~0-2, but non-AGN galaxy color bimodality exists up to z~3;...
Source: http://arxiv.org/abs/1007.1453v1
45
45
Sep 19, 2013
09/13
by
J. D. Silverman; V. Mainieri; M. Salvato; G. Hasinger; J. Bergeron; P. Capak; G. Szokoly; A. Finoguenov; R. Gilli; P. Rosati; P. Tozzi; C. Vignali; D. M. Alexander; W. N. Brandt; B. D. Lehmer; B. Luo; D. Rafferty; Y. Q. Xue; I. Balestra; F. E. Bauer; M. Brusa; A. Comastri; J. Kartaltepe; A. M. Koekemoer; T. Miyaji; D. P. Schneider; E. Treister; L. Wisotski; M. Schramm
texts
eye 45
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We present the results of a program to acquire high-quality optical spectra of X-ray sources detected in the E-CDF-S and its central area. New spectroscopic redshifts are measured for 283 counterparts to Chandra sources with deep exposures (t~2-9 hr per pointing) using multi-slit facilities on both the VLT and Keck thus bringing the total number of spectroscopically-identified X-ray sources to over 500 in this survey field. We provide a comprehensive catalog of X-ray sources detected in the...
Source: http://arxiv.org/abs/1009.1923v1
8
8.0
Jun 30, 2018
06/18
by
P. Gandhi; G. B. Lansbury; D. M. Alexander; D. Stern; P. Arévalo; D. R. Ballantyne; M. Baloković; F. E. Bauer; S. E. Boggs; W. N. Brandt; M. Brightman; F. E. Christensen; A. Comastri; W. W. Craig; A. Del Moro; M. Elvis; A. C. Fabian; C. J. Hailey; F. A. Harrison; R. C. Hickox; M. Koss; S. M. LaMassa; B. Luo; G. M. Madejski; A. F. Ptak; S. Puccetti; S. H. Teng; C. M. Urry; D. J. Walton; W. W. Zhang
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We present Nustar 3-40 keV observations of the optically selected Type 2 quasar (QSO2) SDSS J1034+6001 or Mrk 34. The high-quality hard X-ray spectrum and archival XMM-Newton data can be fitted self-consistently with a reflection-dominated continuum and strong Fe Kalpha fluorescence line with equivalent-width >1 keV. Prior X-ray spectral fitting below 10 keV showed the source to be consistent with being obscured by Compton-thin column densities of gas along the line-of-sight, despite...
Topics: Astrophysics of Galaxies, High Energy Astrophysical Phenomena, Astrophysics, Cosmology and...
Source: http://arxiv.org/abs/1407.1844
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50
Sep 17, 2013
09/13
by
F. E. Bauer; Lin Yan; A. Sajina; D. M. Alexander
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eye 50
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We report X-ray constraints for 20 of 52 high-z ULIRGs identified in the Spitzer xFLS to constrain their obscuration. Notably, decomposition of Spitzer-IRS spectra for the 52 objects already indicates that most are weak-PAH ULIRGs dominated by hot-dust continua, characteristic of AGN. Given their redshifts, they have AGN bolometric luminosities of ~1e45-1e47 erg/s comparable to powerful QSOs. This, coupled with their high IR-to-optical ratios and often significant silicate absorption, strongly...
Source: http://arxiv.org/abs/0912.4267v1
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8.0
Jun 30, 2018
06/18
by
B. D Lehmer; M. Berkeley; A. Zezas; D. M. Alexander; A. Basu-Zych; F. E. Bauer; W. N. Brandt; T. Fragos; A. E. Hornschemeier; V. Kalogera; A. Ptak; G. R. Sivakoff; P. Tzanavaris; M. Yukita
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eye 8
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We present direct constraints on how the formation of low-mass X-ray binary (LMXB) populations in galactic fields depends on stellar age. In this pilot study, we utilize Chandra and Hubble Space Telescope (HST) data to detect and characterize the X-ray point source populations of three nearby early-type galaxies: NGC 3115, 3379, and 3384. The luminosity-weighted stellar ages of our sample span 3-10 Gyr. X-ray binary population synthesis models predict that the field LMXBs associated with...
Topics: Astrophysics of Galaxies, High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1405.2069
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57
Sep 23, 2013
09/13
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Y. Q. Xue; B. Luo; W. N. Brandt; F. E. Bauer; B. D. Lehmer; P. S. Broos; D. P. Schneider; D. M. Alexander; M. Brusa; A. Comastri; A. C. Fabian; R. Gilli; G. Hasinger; A. E. Hornschemeier; A. Koekemoer; T. Liu; V. Mainieri; M. Paolillo; D. A. Rafferty; P. Rosati; O. Shemmer; J. D. Silverman; I. Smail; P. Tozzi; C. Vignali
texts
eye 57
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[abridged] We present point-source catalogs for the 4Ms Chandra Deep Field-South (CDF-S), which is the deepest Chandra survey to date and covers an area of 464.5 arcmin^2. We provide a main source catalog, which contains 740 X-ray point sources that are detected with wavdetect at a false-positive probability threshold of 1E-5 and also satisfy a binomial-probability source-selection criterion of P
Source: http://arxiv.org/abs/1105.5643v1
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7.0
Jun 28, 2018
06/18
by
F. Civano; R. C. Hickox; S. Puccetti; A. Comastri; J. R. Mullaney; L. Zappacosta; S. M. LaMassa; J. Aird; D. M. Alexander; D. R. Ballantyne; F. E. Bauer; W. N. Brandt; S. E. Boggs; F. E. Christensen; W. W. Craig; A. Del-Moro; M. Elvis; K. Forster; P. Gandhi; B. W. Grefenstette; C. J. Hailey; F. A. Harrison; G. B. Lansbury; B. Luo; K. Madsen; C. Saez; D. Stern; E. Treister; M. C. Urry; D. R. Wik; W. Zhang
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eye 7
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To provide the census of the sources contributing to the X-ray background peak above 10 keV, NuSTAR is performing extragalactic surveys using a three-tier "wedding cake" approach. We present the NuSTAR survey of the COSMOS field, the medium sensitivity and medium area tier, covering 1.7 deg2 and overlapping with both Chandra and XMM-Newton data. This survey consists of 121 observations for a total exposure of ~3 Ms. To fully exploit these data, we developed a new detection strategy,...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1511.04185
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43
Sep 18, 2013
09/13
by
F. E. Bauer; C. Vignali; D. M. Alexander; W. N. Brandt; G. P. Garmire; A. E. Hornschemeier; P. Broos; L. Townsley; D. P. Schneider
texts
eye 43
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We briefly report here on our ongoing X-ray spectroscopy and variability analyses of 136 faint X-ray sources discovered in the 2 Ms Chandra Deep Field North observations spanning 1.4x10-15 to 2x10-13 ergs s-1 cm-2. Most sources are adequatley fitted with a simple intrinsic absorption plus power-law model, although the resulting photon index is much lower than the canonical average unabsorbed spectral slope found locally (suggesting additional spectral complexity). Among the 136 sources, 7% show...
Source: http://arxiv.org/abs/astro-ph/0210310v1
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37
Sep 18, 2013
09/13
by
Y. Q. Xue; S. X. Wang; W. N. Brandt; B. Luo; D. M. Alexander; F. E. Bauer; A. Comastri; A. C. Fabian; R. Gilli; B. D. Lehmer; D. P. Schneider; C. Vignali; M. Young
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eye 37
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Using the 4 Ms Chandra Deep Field-South (CDF-S) survey, we have identified a sample of 6845 X-ray undetected galaxies that dominates the unresolved ~ 20-25% of the 6-8 keV cosmic X-ray background (XRB). This sample was constructed by applying mass and color cuts to sources from a parent catalog based on GOODS-South HST z-band imaging of the central 6'-radius area of the 4 Ms CDF-S. The stacked 6-8 keV detection is significant at the 3.9 sigma level, but the stacked emission was not detected in...
Source: http://arxiv.org/abs/1209.0467v1
82
82
Jul 20, 2013
07/13
by
D. M. Alexander; W. N. Brandt; A. E. Hornschemeier; G. P. Garmire; D. P. Schneider; F. E. Bauer; R. E. Griffiths
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eye 82
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We provide constraints on the nature of the optically faint (I>=24) X-ray source population from a 1 Ms Chandra exposure of a 8.4x8.4 arcmin region containing the Hubble Deep Field North. We detect 47 (2,400 deg^-2) optically faint X-ray sources. The fraction of optically faint X-ray sources is approximately constant (at approx 35%) for 0.5-8.0 keV fluxes from 3x10^-14 cgs down to the X-ray flux limit. A considerable fraction (approx 30%) of the sources are Very Red Objects (I-K>=4)....
Source: http://arxiv.org/abs/astro-ph/0107450v2
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33
Sep 18, 2013
09/13
by
D. M. Alexander; F. E. Bauer; W. N. Brandt; G. P. Garmire; A. E. Hornschemeier; D. P. Schneider; C. Vignali
texts
eye 33
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With ~2 Ms of Chandra exposure, the Chandra Deep Field-North (CDF-N) survey provides the deepest view of the Universe in the 0.5-8.0 keV band. Five hundred and three (503) X-ray sources are detected down to on-axis 0.5-2.0 keV and 2-8 keV flux limits of ~1.5x10^{-17} erg cm^{-2} s^{-1} and ~1.0x10^{-16} erg cm^{-2} s^{-1}, respectively. These flux limits correspond to L_{0.5-8.0 keV}~3x10^{41} erg s^{-1} at z=1 and L_{0.5-8.0 keV}~2x10^{43} erg s^{-1} at z=6; thus this survey is sensitive...
Source: http://arxiv.org/abs/astro-ph/0210308v2
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46
Sep 18, 2013
09/13
by
C. Vignali; F. E. Bauer; D. M. Alexander; W. N. Brandt; A. E. Hornschemeier; D. P. Schneider; G. P. Garmire
texts
eye 46
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We present X-ray spectral analyses of the three z>4 Active Galactic Nuclei (AGNs) thus far spectroscopically identified in the Chandra Deep Field-North Survey, at redshifts of 5.186, 4.424, and 4.137. These analyses are made possible by the extremely deep exposure (2 Ms) and the low Chandra background. The rest-frame 2.5-40 keV spectra are the first for optically faint (two of the three sources have I>24) z>4 AGNs. The z=5.186 quasar is well fitted by a power-law model with photon...
Source: http://arxiv.org/abs/astro-ph/0210552v1
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42
Sep 18, 2013
09/13
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P. Santini; D. J. Rosario; L. Shao; D. Lutz; R. Maiolino; D. M. Alexander; B. Altieri; P. Andreani; H. Aussel; F. E. Bauer; S. Berta; A. Bongiovanni; W. N. Brandt; M. Brusa; J. Cepa; A. Cimatti; E. Daddi; D. Elbaz; A. Fontana; N. M. Forster Schreiber; R. Genzel; A. Grazian; E. Le Floc'h; B. Magnelli; V. Mainieri; R. Nordon; A. M. Perez Garcia; A. Poglitsch; P. Popesso; F. Pozzi; L. Riguccini; G. Rodighiero; M. Salvato; M. Sanchez-Portal; E. Sturm; L. J. Tacconi; I. Valtchanov; S. Wuyts
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eye 42
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We compare the average star formation (SF) activity in X-ray selected AGN hosts with mass-matched control inactive galaxies,including star forming and quiescent sources, at 0.510sigma) for bright AGNs. However, when comparing to star forming galaxies only, AGN hosts are broadly consistent with the locus of their `main sequence'. We investigate the relative far-IR luminosity distributions of active and inactive galaxies, and find a higher fraction of PACS detected, hence normal and highly star...
Source: http://arxiv.org/abs/1201.4394v3
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47
Sep 18, 2013
09/13
by
E. Daddi; D. M. Alexander; M. Dickinson; R. Gilli; A. Renzini; D. Elbaz; A. Cimatti; R. Chary; D. Frayer; F. E. Bauer; W. N. Brandt; M. Giavalisco; N. A. Grogin; M. Huynh; J. Kurk; M. Mignoli; G. Morrison; A. Pope; S. Ravindranath
texts
eye 47
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Approximately 20-30% of 1.46.2 keV. The stacked X-ray spectrum rises steeply at >10 keV, suggesting that these sources host Compton-thick Active Galactic Nuclei (AGNs) with column densities N_H~10^{24} cm^-2 and an average, unobscured X-ray luminosity L_{2-8 keV}~(1-4)x10^43 erg/s. Their sky density(~3200 deg^-2) and space density (~2.6x10^-4 Mpc^-3) are twice those of X-ray detected AGNs at z~2, and much larger than those of previously-known Compton thick sources at similar redshifts. The...
Source: http://arxiv.org/abs/0705.2832v2
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54
Sep 18, 2013
09/13
by
L. P. Jenkins; A. E. Hornschemeier; B. Mobasher; D. M. Alexander; F. E. Bauer
texts
eye 54
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We present the first results of a Spitzer IRAC (Infrared Array Camera) wide-field survey of the Coma cluster. The observations cover two fields of different galaxy densities; the first is a 0.733 deg^2 region in the core of the cluster (Coma 1), the second a 0.555 deg^2 off-center region located ~57 arcmin (1.7 Mpc) south-west from the core (Coma 3). The observations, although short 70-90 s exposures, are very sensitive; we detect ~29,200 sources at 3.6 micron over the total ~1.3 deg^2 survey...
Source: http://arxiv.org/abs/0705.3681v2
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65
Sep 22, 2013
09/13
by
B. D. Lehmer; W. N. Brandt; D. M. Alexander; F. E. Bauer; C. J. Conselice; M. E. Dickinson; M. Giavalisco; N. A. Grogin; A. M. Koekemoer; K. S. Lee; L. A. Moustakas; D. P. Schneider
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eye 65
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We constrain the X-ray emission properties of Lyman break galaxies (LBGs) at z ~ 3-6 using the 2 Ms Chandra Deep Field-North and 1 Ms Chandra Deep Field-South. Large samples of LBGs were discovered using HST as part of the Great Observatories Origins Deep Survey (GOODS). Deep optical and X-ray imaging over the GOODS fields have allowed us to place the most significant constraints on the X-ray properties of LBGs to date. Mean X-ray properties of 449, 1734, 629, and 247 LBGs with z ~ 3, 4, 5, and...
Source: http://arxiv.org/abs/astro-ph/0409600v1
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49
Sep 22, 2013
09/13
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O. Almaini; J. S. Dunlop; C. J. Willott; D. M. Alexander; F. E. Bauer; C. T. Liu
texts
eye 49
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We present evidence for a positive angular correlation between bright submillimetre sources and low-redshift galaxies. The study was conducted using 39 sources selected from 3 contiguous, flux-limited SCUBA surveys, cross-correlated with optical field galaxies with magnitudes R 10mJy. We conduct Monte-Carlo simulations of clustered submm populations, and find that the probability of obtaining these correlations by chance is less than 0.4 per cent. The results may suggest that a larger than...
Source: http://arxiv.org/abs/astro-ph/0501169v1
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48
Sep 18, 2013
09/13
by
W. N. Brandt; D. M. Alexander; F. E. Bauer; A. E. Hornschemeier
texts
eye 48
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Chandra has performed a 1.4 Ms survey centred on the Hubble Deep Field-North (HDF-N), probing the X-ray Universe 55-550 times deeper than was possible with pre-Chandra missions. We describe the detected point and extended X-ray sources and discuss their overall multiwavelength (optical, infrared, submillimeter, and radio) properties. Special attention is paid to the HDF-N X-ray sources, luminous infrared starburst galaxies, optically faint X-ray sources, and high-to-extreme redshift AGN. We...
Source: http://arxiv.org/abs/astro-ph/0202311v1
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45
Sep 20, 2013
09/13
by
A. J. Barger; L. L. Cowie; P. Capak; D. M. Alexander; F. E. Bauer; W. N. Brandt; G. P. Garmire; A. E. Hornschemeier
texts
eye 45
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Deep Chandra X-ray exposures provide an efficient route for locating optically faint active galactic nuclei (AGN) at high redshifts. We use deep multicolor optical data to search for z>5 AGN in the 2 Ms X-ray exposure of the Chandra Deep Field-North. Of the 423 X-ray sources bright enough (z' 6. The z>5 object is spectroscopically confirmed at z=5.19. Only 31 of the 77 sources with z'>25.2 are undetected in the B or V bands at the 2-sigma level and could lie at z>5. There are too...
Source: http://arxiv.org/abs/astro-ph/0301232v1
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16
Jun 28, 2018
06/18
by
G. B. Lansbury; P. Gandhi; D. M. Alexander; R. J. Assef; J. Aird; A. Annuar; D. R. Ballantyne; M. Balokovic; F. E. Bauer; S. E. Boggs; W. N. Brandt; M. Brightman; F. E. Christensen; F. Civano; A. Comastri; W. W. Craig; A. Del Moro; B. W. Grefenstette; C. J. Hailey; F. A. Harrison; R. C. Hickox; M. Koss; S. M. LaMassa; B. Luo; S. Puccetti; D. Stern; E. Treister; C. Vignali; L. Zappacosta; W. W. Zhang
texts
eye 16
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The intrinsic column density (NH) distribution of quasars is poorly known. At the high obscuration end of the quasar population and for redshifts z 1.5e24 cm^-2) type 2 quasars (CTQSO2s); five new NuSTAR observations are reported herein, and four have been previously published. The candidate CTQSO2s lie at z ~ 90 net source counts at 8-24 keV). For these NuSTAR-detected sources direct (i.e., X-ray spectral) constraints on the intrinsic AGN properties are feasible, and we measure column...
Topics: High Energy Astrophysical Phenomena, Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1506.05120
3
3.0
Jun 28, 2018
06/18
by
C. M. Harrison; D. M. Alexander; J. R. Mullaney; J. P. Stott; A. M. Swinbank; V. Arumugam; F. E. Bauer; R. G. Bower; A. J. Bunker; R. M. Sharples
texts
eye 3
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We present the first results from the KMOS AGN Survey at High redshift (KASHz), a VLT/KMOS integral-field spectroscopic survey of z>0.6 AGN. We present galaxy-integrated spectra of 89 X-ray AGN (Lx=10^42-10^45 erg/s), for which we observed [O III] (z=1.1-1.7) or Halpha emission (z=0.6-1.1). The targets have X-ray luminosities representative of the parent AGN population and we explore the emission-line luminosities as a function of X-ray luminosity. For the [O III] targets, ~50 per cent have...
Topics: Astrophysics, Astrophysics of Galaxies, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1511.00008
5
5.0
Jun 30, 2018
06/18
by
F. E. Bauer; E. Treister; K. Schawinski; S. Schulze; B. Luo; D. M. Alexander; W. N. Brandt; A. Comastri; F. Forster; R. Gilli; D. A. Kann; K. Maeda; K. Nomoto; M. Paolillo; P. Ranalli; D. P. Schneider; O. Shemmer; M. Tanaka; A. Tolstov; N. Tominaga; P. Tozzi; C. Vignali; J. Wang; Y. Xue; G. Yang
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eye 5
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We report on the detection of a remarkable new fast high-energy transient found in the Chandra Deep Field-South, robustly associated with a faint ($m_{\rm R}=27.5$ mag, $z_{\rm ph}$$\sim$2.2) host in the CANDELS survey. The X-ray event is comprised of 115$^{+12}_{-11}$ net 0.3-7.0 keV counts, with a light curve characterised by a $\approx$100 s rise time, a peak 0.3-10 keV flux of $\approx$5$\times$10$^{-12}$ erg s$^{-1}$ cm$^{-2}$, and a power-law decay time slope of $-1.53\pm0.27$. The...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1702.04422
5
5.0
Jun 30, 2018
06/18
by
A. Annuar; D. M. Alexander; P. Gandhi; G. B. Lansbury; D. Asmus; D. R. Ballantyne; F. E. Bauer; S. E. Boggs; P. G. Boorman; W. N. Brandt; M. Brightman; F. E. Christensen; W. W. Craig; D. Farrah; A. D. Goulding; C. J. Hailey; F. A. Harrison; M. J. Koss; S. M. LaMassa; S. S. Murray; C. Ricci; D. J. Rosario; F. Stanley; D. Stern; W. Zhang
texts
eye 5
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NGC 1448 is one of the nearest luminous galaxies ($L_{8-1000\mu m} >$ 10$^{9} L_{\odot}$) to ours ($z$ $=$ 0.00390), and yet the active galactic nucleus (AGN) it hosts was only recently discovered, in 2009. In this paper, we present an analysis of the nuclear source across three wavebands: mid-infrared (MIR) continuum, optical, and X-rays. We observed the source with the Nuclear Spectroscopic Telescope Array (NuSTAR), and combined this data with archival Chandra data to perform broadband...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1701.00497
