42
42
Sep 23, 2013
09/13
by
A. Alonso-Herrero; P. G. Perez-Gonzalez; D. M. Alexander; G. H. Rieke; D. Rigopoulou; E. Le Floc'h; P. Barmby; C. Papovich; J. R. Rigby; F. E. Bauer; W. N. Brandt; E. Egami; S. P. Willner; H. Dole; J. -S. Huang
texts
eye 42
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We investigate the nature of a sample of 92 Spitzer/MIPS 24 micron selected galaxies in the CDFS, showing power law-like emission in the Spitzer/IRAC 3.6-8 micron bands. The main goal is to determine whether the galaxies not detected in X-rays (47% of the sample) are part of the hypothetical population of obscured AGN not detected even in deep X-ray surveys. The majority of the IR power-law galaxies are ULIRGs at z>1, and those with LIRG-like IR luminosities are usually detected in X-rays....
Source: http://arxiv.org/abs/astro-ph/0511507v1
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20
Jun 28, 2018
06/18
by
A. Annuar; P. Gandhi; D. M. Alexander; G. B. Lansbury; P. Arévalo; D. R. Ballantyne; M. Baloković; F. E. Bauer; S. E. Boggs; W. N. Brandt; M. Brightman; F. E. Christensen; W. W. Craig; A. Del Moro; C. J. Hailey; F. A. Harrison; R. C. Hickox; G. Matt; S. Puccetti; C. Ricci; J. R. Rigby; D. Stern; D. J. Walton; L. Zappacosta; W. Zhang
texts
eye 20
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We present two NuSTAR observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton and Swift-BAT, we perform a high-quality broadband spectral analysis of the AGN over two decades in energy ($\sim$0.5-100 keV). Previous X-ray observations suggested that the AGN is obscured by a Compton-thick (CT) column of obscuring gas along our line-of-sight. However, the lack of...
Topics: High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1509.03322
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36
Sep 23, 2013
09/13
by
A. Comastri; P. Ranalli; K. Iwasawa; C. Vignali; R. Gilli; I. Georgantopoulos; X. Barcons; W. N. Brandt; H. Brunner; M. Brusa; N. Cappelluti; F. J. Carrera; F. Civano; F. Fiore; G. Hasinger; V. Mainieri; A. Merloni; F. Nicastro; M. Paolillo; S. Puccetti; P. Rosati; J. D. Silverman; P. Tozzi; G. Zamorani; I. Balestra; F. E. Bauer; B. Luo; Y. Q. Xue
texts
eye 36
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We present the first results of the spectroscopy of distant, obscured AGN as obtained with the ultra-deep (~3.3 Ms) XMM-Newton survey in the Chandra Deep Field South (CDFS). One of the primary goals of the project is to characterize the X-ray spectral properties of obscured and heavily obscured Compton-thick AGN over the range of redhifts and luminosities that are relevant in terms of their contribution to the X-ray background. The ultra-deep exposure, coupled with the XMM detector's spectral...
Source: http://arxiv.org/abs/1012.4011v2
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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
12
12
Jun 27, 2018
06/18
by
A. Del Moro; D. M. Alexander; F. E. Bauer; E. Daddi; D. D. Kocevski; D. H. McIntosh; F. Stanley; W. N. Brandt; D. Elbaz; C. M. Harrison; B. Luo; J. R. Mullaney; Y. Q. Xue
texts
eye 12
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We present the infrared (IR) and X-ray properties of a sample of 33 mid-IR luminous quasars ($\nu$L(6 micron)>6x10$^{44}$ erg/s) at redshift z~1-3, identified through detailed spectral energy distribution analyses of distant star-forming galaxies, using the deepest IR data from Spitzer and Herschel in the GOODS-Herschel fields. The aim is to constrain the fraction of obscured, and Compton-thick (CT, N$_H$>1.5x10$^{24}$ cm$^{-2}$) quasars at the peak era of nuclear and star-formation...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1504.03329
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48
Sep 22, 2013
09/13
by
A. Del Moro; D. M. Alexander; J. R. Mullaney; E. Daddi; M. Pannella; F. E. Bauer; A. Pope; M. Dickinson; D. Elbaz; P. D. Barthel; M. A. Garrett; W. N. Brandt; V. Charmandaris; R. R. Chary; K. Dasyra; R. Gilli; R. C. Hickox; H. S. Hwang; R. J. Ivison; S. Juneau; E. Le Floc'h; B. Luo; G. E. Morrison; E. Rovilos; M. T. Sargent; Y. Q. Xue
texts
eye 48
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We present here a new spectral energy distribution (SED) fitting approach that we adopt to select radio-excess sources amongst distant star-forming galaxies in the GOODS-Herschel (North) field and to reveal the presence of hidden, highly obscured AGN. Through extensive SED analysis of 458 galaxies with radio 1.4 GHz and mid-IR 24 um detections using some of the deepest Chandra X-ray, Spitzer and Herschel infrared, and VLA radio data available to date, we have robustly identified a sample of 51...
Source: http://arxiv.org/abs/1210.2521v1
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42
Sep 22, 2013
09/13
by
A. E. Hornschemeier; D. M. Alexander; F. E. Bauer; W. N. Brandt; R. Chary; C. Conselice; N. A. Grogin; A. M. Koekemoer; B. Mobasher; M. Paolillo; S. Ravindranath; E. J. Schreier
texts
eye 42
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We have identified a sample of 10 highly reliable off-nuclear (> 2 kpc) X-ray sources at z=0.03-0.25 in late-type host galaxies within the two GOODS fields (i.e., the two Chandra Deep Fields). The combination of the superb spatial resolution and great depth of the HST ACS and Chandra ACIS coverage in the GOODS fields is critical to the identification of these sources. We extend the study of this enigmatic population up to higher redshifts and larger look-back times than has been possible...
Source: http://arxiv.org/abs/astro-ph/0308408v1
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51
Sep 17, 2013
09/13
by
A. E. Hornschemeier; F. E. Bauer; D. M. Alexander; W. N. Brandt; W. L. W. Sargent; M. W. Bautz; C. Conselice; G. P. Garmire; D. P. Schneider; G. Wilson
texts
eye 51
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We have analyzed optically bright, X-ray faint [OBXF; i.e., log(fX/fR) < -2] sources identified in an 178.9 square arcminute area within the Chandra Deep Field-North (CDF-N) 2 Ms survey. We find 43 OBXF sources in this area, comprising ~15% of the X-ray sources above a 0.5--2 keV flux of 2.3e-17 erg cm^-2 s^-1. We present spectroscopic identifications for 42 of the OBXF sources and optical spectra for 25, including 5 previously unpublished redshifts. Deep optical imaging data (either HST or...
Source: http://arxiv.org/abs/astro-ph/0305086v1
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60
Sep 18, 2013
09/13
by
A. E. Hornschemeier; W. N. Brandt; D. M. Alexander; F. E. Bauer; G. P. Garmire; D. P. Schneider; M. W. Bautz; G. Chartas
texts
eye 60
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We present a statistical X-ray study of spiral galaxies in the Hubble Deep Field-North and its Flanking Fields using the Chandra Deep Field North 1 Ms dataset. We find that approximately L_star galaxies with 0.4 < z < 1.5 have ratios of X-ray to B-band luminosity similar to those in the local Universe, although the data indicate a likely increase in this ratio by a factor of approximately 2-3. We have also determined that typical spiral galaxies at 0.4 < z < 1.5 should be detected...
Source: http://arxiv.org/abs/astro-ph/0110094v2
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11
Jun 26, 2018
06/18
by
A. Finoguenov; M. Tanaka; M. Cooper; V. Allevato; N. Cappelluti; A. Choi; C. Heymans; F. E. Bauer; F. Ziparo; P. Ranalli; J. Silverman; W. N. Brandt; Y. Q. Xue; J. Mulchaey; L. Howes; C. Schmid; D. Wilman; A. Comastri; G. Hasinger; V. Mainieri; B. Luo; P. Tozzi; P. Rosati; P. Capak; P. Popesso
texts
eye 11
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Ultra-deep observations of ECDF-S with Chandra and XMM-Newton enable a search for extended X-ray emission down to an unprecedented flux of $2\times10^{-16}$ ergs s$^{-1}$ cm$^{-2}$. We present the search for the extended emission on spatial scales of 32$^{\prime\prime}$ in both Chandra and XMM data, covering 0.3 square degrees and model the extended emission on scales of arcminutes. We present a catalog of 46 spectroscopically identified groups, reaching a redshift of 1.6. We show that the...
Topics: Cosmology and Nongalactic Astrophysics, Astrophysics, Astrophysics of Galaxies, High Energy...
Source: http://arxiv.org/abs/1501.03506
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41
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 41
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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
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44
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 44
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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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77
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 77
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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
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41
Sep 19, 2013
09/13
by
B. D. Lehmer; D. M. Alexander; F. E. Bauer; W. N. Brandt; A. D. Goulding; L. P. Jenkins; A. Ptak; T. P. Roberts
texts
eye 41
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We present new Chandra observations that complete a sample of seventeen (17) luminous infrared galaxies (LIRGs) with D < 60 Mpc and low Galactic column densities of N_H < 5 X 10^20 cm^-2. The LIRGs in our sample have total infrared (8-1000um) luminosities in the range of L_IR ~ (1-8) X 10^11 L_sol. The high-resolution imaging and X-ray spectral information from our Chandra observations allow us to measure separately X-ray contributions from active galactic nuclei (AGNs) and normal galaxy...
Source: http://arxiv.org/abs/1009.3943v1
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48
Sep 18, 2013
09/13
by
B. D. Lehmer; D. M. Alexander; J. E. Geach; Ian Smail; A. Basu-Zych; F. E. Bauer; S. C. Chapman; Y. Matsuda; C. A. Scharf; M. Volonteri; T. Yamada
texts
eye 48
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We present results from a new ultra-deep 400 ks Chandra observation of the SSA22 protocluster at z = 3.09. We have studied the X-ray properties of 234 z ~ 3 Lyman break galaxies (LBGs; protocluster and field) and 158 z = 3.09 Ly-alpha emitters (LAEs) in SSA22 to measure the influence of the high-density protocluster environment on the accretion activity of supermassive black holes (SMBHs) in these UV-selected star forming populations. We detect individually X-ray emission from active galactic...
Source: http://arxiv.org/abs/0809.5058v1
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52
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 52
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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
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49
Sep 18, 2013
09/13
by
B. D. Lehmer; W. N. Brandt; D. M. Alexander; E. F. Bell; A. E. Hornschemeier; D. H. McIntosh; F. E. Bauer; R. Gilli; V. Mainieri; D. P. Schneider; J. D. Silverman; A. T. Steffen; P. Tozzi; C. Wolf
texts
eye 49
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We report on the X-ray evolution over the last ~9 Gyr of cosmic history (i.e., since z = 1.4) of late-type galaxy populations in the Chandra Deep Field-North and Extended Chandra Deep Field-South (CDF-N and E-CDF-S, respectively; jointly CDFs) survey fields. Our late-type galaxy sample consists of 2568 galaxies, which were identified using rest-frame optical colors and HST morphologies. We utilized X-ray stacking analyses to investigate the X-ray emission from these galaxies, emphasizing the...
Source: http://arxiv.org/abs/0803.3620v2
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49
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 49
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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
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61
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
texts
eye 61
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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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48
Sep 20, 2013
09/13
by
B. D. Lehmer; W. N. Brandt; D. M. Alexander; F. E. Bauer; D. P. Schneider; P. Tozzi; J. Bergeron; G. P. Garmire; R. Giacconi; R. Gilli; G. Hasinger; A. E. Hornschemeier; A. M. Koekemoer; V. Mainieri; T. Miyaji; M. Nonino; P. Rosati; J. D. Silverman; G. Szokoly; C. Vignali
texts
eye 48
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We present Chandra point-source catalogs for the Extended Chandra Deep Field-South (E-CDF-S) survey. The E-CDF-S consists of four contiguous 250 ks Chandra observations covering an approximately square region of total solid angle ~0.3 deg^2, which flank the existing ~1 Ms Chandra Deep Field-South (CDF-S). The survey reaches sensitivity limits of 1.1 X 10^-16 erg/cm^2/s and 6.7 X 10^-16 erg/cm^2/s for the 0.5-2.0 keV and 2-8 keV bands, respectively. We detect 762 distinct X-ray point sources...
Source: http://arxiv.org/abs/astro-ph/0506607v2
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50
Sep 21, 2013
09/13
by
B. D. Lehmer; Y. Q. Xue; W. N. Brandt; D. M. Alexander; F. E. Bauer; M. Brusa; A. Comastri; R. Gilli; A. E. Hornschemeier; B. Luo; M. Paolillo; A. Ptak; O. Shemmer; D. P. Schneider; P. Tozzi; C. Vignali
texts
eye 50
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We present 0.5-2 keV, 2-8 keV, 4-8 keV, and 0.5-8 keV cumulative and differential number counts (logN-logS) measurements for the recently completed ~4 Ms Chandra Deep Field-South (CDF-S) survey, the deepest X-ray survey to date. We implement a new Bayesian approach, which allows reliable calculation of number counts down to flux limits that are factors of ~1.9-4.3 times fainter than the previously deepest number-counts investigations. In the soft band, the most sensitive bandpass in our...
Source: http://arxiv.org/abs/1204.1977v1
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75
Sep 17, 2013
09/13
by
B. Luo; W. N. Brandt; A. T. Steffen; F. E. Bauer
texts
eye 75
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Luminous X-ray outbursts with variability amplitudes as high as ~1000 have been detected from a small number of galactic nuclei. These events are likely associated with transient fueling of nuclear supermassive black holes. In this paper, we constrain X-ray outbursts with harder spectra, higher redshifts, and lower luminosities than have been studied previously. We performed a systematic survey of 24668 optical galaxies in the Chandra Deep Fields to search for such X-ray outbursts; the median...
Source: http://arxiv.org/abs/0711.2517v1
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47
Sep 21, 2013
09/13
by
B. Luo; W. N. Brandt; J. D. Silverman; I. V. Strateva; F. E. Bauer; P. Capak; J. Kartaltepe; B. D. Lehmer; V. Mainieri; M. Salvato; G. Szokoly; D. P. Schneider; C. Vignali
texts
eye 47
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We report the discovery of the most-distant double-peaked emitter, CXOECDFS J033115.0-275518, at z=1.369. A Keck/DEIMOS spectrum shows a clearly double-peaked broad Mg II $\lambda2799$ emission line, with FWHM 11000 km/s for the line complex. The line profile can be well fit by an elliptical relativistic Keplerian disk model. This is one of a handful of double-peaked emitters known to be a luminous quasar, with excellent multiwavelength coverage and a high-quality X-ray spectrum. CXOECDFS...
Source: http://arxiv.org/abs/0901.2929v1
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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
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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
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58
Sep 20, 2013
09/13
by
C. M. Harrison; D. M. Alexander; A. M. Swinbank; Ian Smail; S. Alaghband-Zadeh; F. E. Bauer; S. C. Chapman; A. Del Moro; R. C. Hickox; R. J. Ivison; Karin Menendez-Delmestre; J. R. Mullaney; N. P. H. Nesvadba
texts
eye 58
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We present integral field spectroscopy observations, covering the [O III]4959,5007 emission-line doublet of eight high-redshift (z=1.4-3.4) ultra-luminous infrared galaxies (ULIRGs) that host Active Galactic Nuclei (AGN) activity, including known sub-millimetre luminous galaxies (SMGs). The targets have moderate radio luminosities that are typical of high-redshift ULIRGs (L(1.4GHz)=10^(24)-10^(25)W/Hz) and therefore are not radio-loud AGN. We de-couple kinematic components due to the galaxy...
Source: http://arxiv.org/abs/1205.1801v3
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48
Sep 22, 2013
09/13
by
C. Meunier; F. E. Bauer; V. V. Dwarkadas; B. Koribalski; B. Emonts; R. W. Hunstead; D. Campbell-Wilson; C. Stockdale; S. J. Tingay
texts
eye 48
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We present archival radio observations of SN1996cr from ATCA and MOST, and model its radio lightcurves using X-ray constrained hydrodynamical simulations of the interaction between the SN ejecta and the CSM. The early radio data show signs of free-free absorption (FFA), which decreases gradually and is minimal above 1.4 GHz after day ~3000. FFA optical depth constraints provide estimates of the CSM free electron density, which allows insight into the ionisation of SN1996cr's CSM and offers a...
Source: http://arxiv.org/abs/1302.5432v1
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11
Jun 27, 2018
06/18
by
C. Saez; B. D. Lehmer; F. E. Bauer; D. Stern; A. Gonzales; I. Rreza; D. M. Alexander; Y. Matsuda; J. E. Geach; F. A. Harrison; T. Havashino
texts
eye 11
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We present VLT VIMOS, Keck DEIMOS and Keck LRIS multi-object spectra of 367 sources in the field of the z ~ 3.09 protocluster SSA22. Sources are spectroscopically classified via template matching, allowing new identifications for 206 extragalactic sources, including 36 z > 2 Lyman-break galaxies (LBGs) and Lyman-\alpha\ emitters (LAEs), 8 protocluster members, and 94 X-ray sources from the ~ 400 ks Chandra deep survey of SSA22. Additionally, in the area covered by our study, we have...
Topics: Astrophysics of Galaxies, Astrophysics
Source: http://arxiv.org/abs/1504.00737
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63
Sep 23, 2013
09/13
by
C. Saez; G. Chartas; W. N. Brandt; B. D. Lehmer; F. E. Bauer; X. Dai; G. P. Garmire
texts
eye 63
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We present results from a statistical analysis of 173 bright radio-quiet AGNs selected from the Chandra Deep Field-North and Chandra Deep Field-South surveys (hereafter, CDFs) in the redshift range of 0.1 < z < 4. We find that the X-ray power-law photon index (Gamma) of radio-quiet AGNs is correlated with their 2-10 keV rest-frame X-ray luminosity (L_X) at the > 99.5 percent confidence level in two redshift bins, 0.3 < z < 0.96, and 1.5 < z < 3.3 and is slightly less...
Source: http://arxiv.org/abs/0801.3599v1
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69
Sep 19, 2013
09/13
by
C. Vignali; D. M. Alexander; F. E. Bauer; W. N. Brandt; A. E. Hornschemeier; G. P. Garmire; D. P. Schneider
texts
eye 69
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Understanding the nature of Extremely Red Objects [EROs; (I-K)>=4] is one of the most challenging issues in observational cosmology. Here we report on the X-ray constraints provided by the 2 Ms Chandra Deep Field-North Survey (CDF-N). X-ray emission has been detected from 11 out of 36 EROs (approx 30%). Five of these have hard X-ray emission and appear to be obscured AGNs, while non-AGN emission (star formation or normal elliptical galaxy emission) is likely to be the dominant source of...
Source: http://arxiv.org/abs/astro-ph/0209415v1
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45
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 45
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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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13
Jun 28, 2018
06/18
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C. Vignali; K. Iwasawa; A. Comastri; R. Gilli; G. Lanzuisi; P. Ranalli; N. Cappelluti; V. Mainieri; I. Georgantopoulos; F. J. Carrera; J. Fritz; M. Brusa; W. N. Brandt; F. E. Bauer; F. Fiore; F. Tombesi
texts
eye 13
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In active galactic nuclei (AGN)-galaxy co-evolution models, AGN winds and outflows are often invoked to explain why super-massive black holes and galaxies stop growing efficiently at a certain phase of their lives. They are commonly referred to as the leading actors of feedback processes. Evidence of ultra-fast (v>0.05c) outflows in the innermost regions of AGN has been collected in the past decade by sensitive X-ray observations for sizable samples of AGN, mostly at low redshift. Here we...
Topics: High Energy Astrophysical Phenomena, Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1509.05413
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44
Sep 18, 2013
09/13
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C. Vignali; W. N. Brandt; D. P. Schneider; G. P. Garmire; S. Kaspi; F. E. Bauer; D. M. Alexander
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The study of the X-ray properties of z>4 quasars has grown substantially over the last few years, mostly thanks to Chandra. Here we focus on (1) the average X-ray properties of an optically selected, luminous sample of nine z>4 Palomar Digital Sky Survey quasars recently observed by Chandra, and (2) the X-ray spectral properties of three z>4 AGNs in the Chandra Deep Field-North (CDF-N) using the 2 Ms exposure.
Source: http://arxiv.org/abs/astro-ph/0210309v1
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51
Sep 21, 2013
09/13
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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
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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
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112
Jul 20, 2013
07/13
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D. J. Rosario; P. Santini; D. Lutz; L. Shao; 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; T. J. Cox; E. Daddi; D. Elbaz; A. Fontana; N. M. Förster Schreiber; R. Genzel; A. Grazian; E. Le Floch; B. Magnelli; V. Mainieri; H. Netzer; R. Nordon; I. Pérez Garcia; A. Poglitsch; P. Popesso; F. Pozzi; L. Riguccini; G. Rodighiero; M. Salvato; M. Sanchez-Portal; E. Sturm; L. J. Tacconi; I....
texts
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(Abridged) We study relationships between the SFR and the nuclear properties of X-ray selected AGNs out to z=2.5, using far-IR data in three extragalactic deep fields as part of the PACS Evolutionary Probe (PEP) program. Guided by studies of intrinsic infra-red AGN SEDs, we show that the majority of the FIR emission in AGNs is produced by cold dust heated by star-formation. We uncover characteristic redshift-dependent trends between the mean FIR luminosity (L_fir) and accretion luminosity...
Source: http://arxiv.org/abs/1203.6069v2
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43
Sep 22, 2013
09/13
by
D. M. Alexander; C. Vignali; F. E. Bauer; W. N. Brandt; A. E. Hornschemeier; G. P. Garmire; D. P. Schneider
texts
eye 43
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The multi-wavelength properties of Very Red Objects (VROs; I-K>=4) are largely unknown as many of these sources are optically faint (I>=24) and undetected at most wavelengths. Here we provide constraints on the X-ray properties of VROs using the 1 Ms Chandra exposure of an 8.4'x8.4' region within the Hawaii Flanking-Field area containing the HDF-N. We find that VROs detected in the hard band (2-8 keV) have flat X-ray spectral slopes (Gamma ~ 0.9) and X-ray properties consistent with those...
Source: http://arxiv.org/abs/astro-ph/0111397v1
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45
Sep 22, 2013
09/13
by
D. M. Alexander; F. E. Bauer; W. N. Brandt; A. E. Hornschemeier
texts
eye 45
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The 2 Ms Chandra Deep Field-North survey provides the deepest view of the Universe in the 0.5--8.0 keV X-ray band. In this brief review we investigate the diversity of X-ray selected sources and focus on the constraints placed on AGNs (including binary AGNs) in high-redshift submm galaxies.
Source: http://arxiv.org/abs/astro-ph/0308079v1
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37
Sep 18, 2013
09/13
by
D. M. Alexander; F. E. Bauer; W. N. Brandt; A. E. Hornschemeier; C. Vignali; G. P. Garmire; D. P. Schneider
texts
eye 37
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We provide constraints on optically faint (I>=24) X-ray sources, z>6 AGN, Very Red Objects (VROs; I-K>=4), and optically faint radio sources using the 1 Ms Chandra Deep Field North survey. We argue that the majority of the optically faint X-ray sources are obscured AGN at z=1-3. These sources comprise up to 50% of the X-ray detected AGN. Approximately 30% of the optically faint X-ray sources have properties consistent with those expected for z>6 AGN; however we argue that the...
Source: http://arxiv.org/abs/astro-ph/0202044v1
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70
Sep 19, 2013
09/13
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D. M. Alexander; F. E. Bauer; W. N. Brandt; D. P. Schneider; A. E. Hornschemeier; C. Vignali; A. J. Barger; P. S. Broos; L. L. Cowie; G. P. Garmire; L. K. Townsley; M. W. Bautz; G. Chartas; W. L. W. Sargent
texts
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We present catalogs for the ~2 Ms Chandra Deep Field-North, currently the deepest X-ray observation of the Universe in the 0.5-8.0 keV band. Five hundred and three (503) X-ray sources are detected over an ~448 sq.arcmin area in up to seven bands; 20 of these X-ray sources lie in the Hubble Deep Field-North. Source positions are determined using matched-filter and centroiding techniques; the median positional uncertainty is ~0.3 arcsecs. The X-ray colors of the detected sources indicate a broad...
Source: http://arxiv.org/abs/astro-ph/0304392v1
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51
Sep 21, 2013
09/13
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D. M. Alexander; F. E. Bauer; W. N. Brandt; E. Daddi; R. C. Hickox; B. D. Lehmer; B. Luo; Y. Q. Xue; M. Young; A. Comastri; A. Del Moro; A. C. Fabian; R. Gilli; A. D. Goulding; V. Mainieri; J. R. Mullaney; M. Paolillo; D. A. Rafferty; D. P. Schneider; O. Shemmer; C. Vignali
texts
eye 51
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We use the 4Ms CDF-S survey to place direct X-ray constraints on the ubiquity of z~2 heavily obscured AGNs in K 1E43 erg/s) heavily obscured and Compton-thick AGNs at z~2. Our space-density constraints are conservative lower limits but they are already consistent with the range of predictions from X-ray background models.
Source: http://arxiv.org/abs/1106.1443v1
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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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59
Sep 23, 2013
09/13
by
D. M. Alexander; G. Chartas; F. E. Bauer; W. N. Brandt; C. Simpson; C. Vignali
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We present a ~20 ks Chandra ACIS-S observation of the strongly lensed z=2.285 ultra-luminous infrared galaxy FSC10214+4724. Although this observation achieves the equivalent sensitivity of an up-to ~4 Ms Chandra exposure (when corrected for gravitational lensing), the rest-frame 1.6-26.3 keV emission from FSC10214+4724 is weak (L_X~2E42 erg/s for a lensing boost of ~100); a significant fraction of this X-ray emission appears to be due to vigorous star-formation activity. If FSC10214+4724 hosts...
Source: http://arxiv.org/abs/astro-ph/0411289v1
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47
Sep 18, 2013
09/13
by
D. M. Alexander; H. Aussel; F. E. Bauer; W. N. Brandt; A. E. Hornschemeier; C. Vignali; G. P. Garmire; D. P. Schneider
texts
eye 47
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Using the 1 Ms Chandra Deep Field North and 15 micron ISOCAM HDF-N surveys we find a tight correlation between the population of strongly evolving starbursts discovered in faint 15 micron ISOCAM surveys and the apparently normal galaxy population detected in deep X-ray surveys. Up to 100% of the X-ray detected emission-line galaxies (ELGs) have 15 micron counterparts, in contrast to 10-20% of the X-ray detected absorption-line galaxies and AGN-dominated sources. None of the X-ray detected ELGs...
Source: http://arxiv.org/abs/astro-ph/0202493v1
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48
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
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eye 48
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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
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81
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
texts
eye 81
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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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36
Sep 18, 2013
09/13
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D. M. Alexander; W. N. Brandt; I. Smail; A. M. Swinbank; F. E. Bauer; A. W. Blain; S. C. Chapman; K. E. K. Coppin; R. J. Ivison; K. Menendez-Delmestre
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We place direct observational constraints on the black-hole masses of the cosmologically important z~2 submillimeter-emitting galaxy (SMG; f850>4mJy) population, and use measured host-galaxy masses to explore their evolutionary status. We employ the well-established virial black-hole mass estimator to 'weigh' the black holes of a sample of z~2 SMGs with broad Halpha or Hbeta emission. The average black-hole mass and Eddington ratio (eta) of the lower-luminosity broad-line SMGs (L_X~10^44...
Source: http://arxiv.org/abs/0803.0634v1
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116
Jul 20, 2013
07/13
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E. A. Richards; F. E. Bauer; A. J. Barger; L. Cowie
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Using a combination of radio and optical imaging at 0.1\arcs to 0.2\arcs resolution with the VLA/MERLIN and HST has led to a breakthrough in our understanding of radio emission from distant (0.1 4-6) and submillimeter sources with S > 2 mJy at 850 microns as measured with SCUBA on the JCMT. The far-infrared luminosities of these galaxies exceeds even the most intense starbursts found in the local universe (e.g., Arp 220), suggesting they are in the process of converting the bulk of their...
Source: http://arxiv.org/abs/astro-ph/9910497v2
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28
Sep 20, 2013
09/13
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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
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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
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Sep 18, 2013
09/13
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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
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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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Sep 18, 2013
09/13
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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
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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
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Sep 19, 2013
09/13
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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
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eye 50
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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
