41
41
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 41
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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
4
4.0
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 4
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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
17
17
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 17
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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
33
33
Sep 21, 2013
09/13
by
A. C. Fabian; A. Celotti; G. Pooley; K. Iwasawa; W. N. Brandt; R. G. McMahon; M. D. Hoenig
texts
eye 33
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We report X-ray and radio variability of GB 1428+4217 which confirm its blazar nature. IR observations reveal a powerful optical-UV component, not obscured by dust, which is suggestive of the presence of a billion solar mass black hole, already formed by z ~ 5. A detailed comparison of the broad band spectral properties of GB 1428+4217 with those of nearby blazars shows it to be extreme, but nevertheless consistent with the trend found for nearby sources.
Source: http://arxiv.org/abs/astro-ph/9907033v1
58
58
Sep 22, 2013
09/13
by
A. C. Fabian; A. Celotti; K. Iwasawa; R. G. McMahon; C. L. Carilli; W. N. Brandt; G. Ghisellini; I. M. Hook
texts
eye 58
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We report optical, radio and X-ray observations of a new distant blazar, PMN J0525-3343, at a redshift of 4.4. The X-ray spectrum measured from ASCA and BeppoSAX flattens below a few keV, in a manner similar to the spectra of two other z>4 blazars, GB 1428+4217 (z=4.72) reported by Boller et al and RXJ 1028.6-0844 (z=4.28) by Yuan et al. The spectrum is well fitted by a power-law continuum which is either absorbed or breaks at a few keV. An intrinsic column density corresponding to 2 x 10^23...
Source: http://arxiv.org/abs/astro-ph/0011566v1
55
55
Sep 21, 2013
09/13
by
A. C. Fabian; A. Zoghbi; R. R. Ross; P. Uttley; L. C. Gallo; W. N. Brandt; A. Blustin; T. Boller; M. D. Caballero-Garcia; J. Larsson; J. M. Miller; G. Miniutti; G. Ponti; R. C. Reis; C. S. Reynolds; Y. Tanaka; A. J. Young
texts
eye 55
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Since the discovery of the first broad iron-K line in 1995 from the Seyfert Galaxy MCG--6-30-15, broad iron-K lines have been found in several other Seyfert galaxies, from accreting stellar mass black holes and even from accreting neutron stars. The iron-K line is prominent in the reflection spectrum created by the hard X-ray continuum irradiating dense accreting matter. Relativistic distortion of the line makes it sensitive to the strong gravity and spin of the black hole. The accompanying...
Source: http://arxiv.org/abs/0905.4383v1
44
44
Sep 18, 2013
09/13
by
A. C. Fabian; J. C. Lee; W. N. Brandt; K. Iwasawa; K. Jahoda; C. S. Reynolds
texts
eye 44
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We report on two observations of the Seyfert galaxy IRAS18325-5926 made in 1997 December and 1998 February with the Rossi X-ray Timing Explorer (RXTE). We find evidence for periodicities in the resulting X-ray lightcurves which are shorter than the 58~ks period found from data of the source taken in 1997 March with the imaging satellite ASCA. It is therefore likely that IRAS18325-5926 has a quasi-periodic oscillation (QPO) similar to, but at a much longer period than, the QPO seen in some...
Source: http://arxiv.org/abs/astro-ph/9803075v3
45
45
Sep 19, 2013
09/13
by
A. C. Fabian; K. Iwasawa; A. Celotti; W. N. Brandt; R. G. McMahon; I. M. Hook
texts
eye 45
favorite 0
comment 0
The X-ray luminous quasar GB 1428+4217 at redshift 4.72 has been observed with ASCA. The observed 0.5-10 keV flux is 3.2E-12 erg/s/cm2. We report here on the intrinsic 4-57 keV X-ray spectrum, which is very flat (photon index of 1.29). We find no evidence for flux variability within the ASCA dataset or between it and ROSAT data. We show that the overall spectral energy distribution of GB 1428+4217 is similar to that of lower redshift MeV blazars and present models which fit the available data....
Source: http://arxiv.org/abs/astro-ph/9801288v1
56
56
Jul 20, 2013
07/13
by
A. Comastri; F. Fiore; M. Guainazzi; G. Matt; G. M. Stirpe; G. Zamorani; W. N. Brandt; K. M. Leighly; L. Piro; S. Molendi; A. N. Parmar; A. Siemiginowska; E. M. Puchnarewicz
texts
eye 56
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We report on the first spectrum up to 10 keV of the bright narrow-line Seyfert 1 galaxy Ton S 180, obtained with the imaging instruments onboard BeppoSAX. This is the first observed source in a sample of a dozen narrow-line Seyfert 1 galaxies in the BeppoSAX Core Program. We also present and discuss a high quality optical spectrum taken at the 1.5 m telescope at La Silla two months before the BeppoSAX observation. The X-ray spectrum shows a clear hardening above about 2 keV, where a power law...
Source: http://arxiv.org/abs/astro-ph/9712182v1
41
41
Sep 24, 2013
09/13
by
A. Comastri; G. M. Stirpe; C. Vignali; W. N. Brandt; K. M. Leighly; F. Fiore; M. Guainazzi; G. Matt; F. Nicastro; E. M. Puchnarewicz; A. Siemiginowska
texts
eye 41
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The BeppoSAX observations of the bright Narrow-Line Seyfert 1 galaxy Ark 564 are presented along with a high quality optical spectrum taken at the 1.5m telescope at La Silla. The 0.1-10 keV X-ray spectrum is characterized by a strong soft component which is best described by blackbody-like emission with a temperature of about 160 eV. At higher energies a steep (Gamma = 2.4) power-law tail is present. There is evidence of an ionized reflector in the form of an iron line and edge. We do not find...
Source: http://arxiv.org/abs/astro-ph/0010476v1
34
34
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 34
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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
74
74
Jul 20, 2013
07/13
by
A. Comastri; W. N. Brandt; K. M. Leighly; F. Fiore; M. Guainazzi; G. Matt; G. M. Stirpe
texts
eye 74
favorite 0
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Results are presented for the first year of observations of a selected sample of Narrow-Line Seyfert 1 galaxies (Ton S 180, RE J1034+396, Ark 564) obtained with the imaging instruments onboard BeppoSAX. These are the first simultaneous broad band (0.1--10 keV) spectra so far obtained for this class of objects.
Source: http://arxiv.org/abs/astro-ph/9712278v1
11
11
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 11
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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
46
46
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 46
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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
5
5.0
Jun 30, 2018
06/18
by
A. Del Moro; J. R. Mullaney; D. M. Alexander; A. Comastri; F. E. Bauer; E. Treister; D. Stern; F. Civano; P. Ranalli; C. Vignali; J. A. Aird; D. R. Ballantyne; M. Baloković; S. E. Boggs; W. N. Brandt; F. E. Christensen; W. W. Craig; P. Gandhi; R. Gilli; C. J. Hailey; F. A. Harrison; R. C. Hickox; S. M. LaMassa; G. B. Lansbury; B. Luo; S. Puccetti; M. Urry; W. W. Zhang
texts
eye 5
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We report NuSTAR observations of NuSTAR J033202-2746.8, a heavily obscured, radio-loud quasar detected in the Extended Chandra Deep Field-South, the deepest layer of the NuSTAR extragalactic survey (~400 ks, at its deepest). NuSTAR J033202-2746.8 is reliably detected by NuSTAR only at E>8 keV and has a very flat spectral slope in the NuSTAR energy band (Gamma=0.55^{+0.62}_{-0.64}; 3-30 keV). Combining the NuSTAR data with extremely deep observations by Chandra and XMM-Newton (4 Ms and 3 Ms,...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1403.2491
38
38
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 38
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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
50
50
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 50
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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
59
59
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 59
favorite 0
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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
43
43
Sep 18, 2013
09/13
by
A. E. Hornschemeier; W. N. Brandt; G. P. Garmire; D. P. Schneider; A. J. Barger; P. S. Broos; L. L. Cowie; L. K. Townsley; M. W. Bautz; D. N. Burrows; G. Chartas; E. D. Feigelson; R. Griffiths; D. Lumb; J. A. Nousek; L. W. Ramsey; W. L. W. Sargent
texts
eye 43
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We present results from a 221.9 ks Chandra exposure of the HDF-N and its vicinity, concentrating on the 8.6' X 8.7' area covered by the Caltech Faint Field Galaxy Redshift Survey (the `Caltech area'). The minimum detectable fluxes in the 0.5-2 keV and 2-8 keV bands are 1.3e-16 cgs and 6.5e-16 cgs, respectively and a total of 82 sources are detected. More than 80% of the extragalactic X-ray background in the 2-8 keV band is resolved. Redshifts are available for 96% of the sources with R 5.0)...
Source: http://arxiv.org/abs/astro-ph/0101494v1
45
45
Sep 22, 2013
09/13
by
A. E. Hornschemeier; W. N. Brandt; G. P. Garmire; D. P. Schneider; P. S. Broos; L. K. Townsley; M. W. Bautz; D. N. Burrows; G. Chartas; E. D. Feigelson; R. Griffiths; D. Lumb; J. A. Nousek; W. L. W. Sargent
texts
eye 45
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We present first results from an X-ray study of the Hubble Deep Field North (HDF-N) and its environs obtained using 166 ks of data collected by the Advanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-ray Observatory. This is the deepest X-ray observation ever reported, and in the HDF-N itself we detect six X-ray sources down to a 0.5--8 keV flux limit of 4E-16 erg cm^-2 s^-1. Comparing these sources with objects seen in multiwavelength HDF-N studies shows positional coincidences...
Source: http://arxiv.org/abs/astro-ph/0004260v1
12
12
Jun 27, 2018
06/18
by
A. E. Scott; W. N. Brandt; B. P. Miller; B. Luo; S. C. Gallagher
texts
eye 12
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We present the results of recent Chandra, XMM-Newton, and Hubble Space Telescope observations of the radio-loud (RL), broad absorption line (BAL) quasar PG 1004+130. We compare our new observations to archival X-ray and UV data, creating the most comprehensive, high signal-to-noise, multi-epoch, spectral monitoring campaign of a RL BAL quasar to date. We probe for variability of the X-ray absorption, the UV BAL, and the X-ray jet, on month-year timescales. The X-ray absorber has a low column...
Topics: High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1505.01161
3
3.0
Jun 30, 2018
06/18
by
A. E. Scott; W. N. Brandt; E. Behar; D. M. Crenshaw; J. R. Gabel; R. R. Gibson; S. Kaspi; S. B. Kraemer; T. J. Turner
texts
eye 3
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We present the results of recent Chandra High-Energy Transmission Grating Spectrometer and Hubble Space Telescope Cosmic Origins Spectrograph observations of the nearby Seyfert 1 galaxy NGC 3783 which shows a strong, non-varying X-ray warm absorber and physically related and kinematically varying UV absorption. We compare our new observations to high-resolution, high signal-to-noise archival data from 2001, allowing a unique investigation into the long-term variations of the absorption over a...
Topics: High Energy Astrophysical Phenomena, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1410.4569
56
56
Sep 22, 2013
09/13
by
A. Eckart; F. K. Baganoff; M. Morris; M. W. Bautz; W. N. Brandt; G. P. Garmire; R. Genzel; T. Ott; G. R. Ricker; C. Straubmeier; T. Viehmann; R. Schödel
texts
eye 56
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We report on the first simultaneous near-infrared/X-ray detection of the Sgr A* counterpart which is associated with the massive black hole at the center of the Milky Way. The observations have been carried out using the NACO adaptive optics (AO) instrument at the European Southern Observatory's Very Large Telescope and the ACIS-I instrument aboard the Chandra X-ray Observatory. We also report on quasi-simultaneous observations at a wavelength of 3.4 mm using the Berkeley-Illinois-Maryland...
Source: http://arxiv.org/abs/astro-ph/0403577v2
52
52
Sep 23, 2013
09/13
by
A. Eckart; F. K. Baganoff; M. R. Morris; D. Kunneriath; M. Zamaninasab; G. Witzel; R. Schödel; M. García-Marín; L. Meyer; G. C. Bower; D. Marrone; M. W. Bautz; W. N. Brandt; G. P. Garmire; G. R. Ricker; C. Straubmeier; D. A. Roberts; K. Muzic; J. Mauerhan; A. Zensus
texts
eye 52
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We report on new modeling results based on the mm- to X-ray emission of the SgrA* counterpart associated with the massive black hole at the Galactic Center. Our modeling is based on simultaneous observations carried out on 07 July, 2004, using the ESO NACO adaptive optics instrument and the ACIS-I instrument aboard the Chandra X-ray Observatory as well as the SMA and the VLA. The observations revealed several flare events in all wavelength domains. Here we show that a combined synchrotron...
Source: http://arxiv.org/abs/0904.2460v1
41
41
Sep 21, 2013
09/13
by
A. Eckart; F. K. Baganoff; M. Zamaninasab; M. Morris; R. Schoedel; L. Meyer; K. Muzic; M. W. Bautz; W. N. Brandt; G. P. Garmire; G. R. Ricker; D. Kunneriath; C. Straubmeier; W. Duschl; M. Dovciak; V. Karas; S. Markoff; F. Najarro; J. Mauerhan; J. Moultaka; A. Zensus
texts
eye 41
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Stellar dynamics indicate the presence of a super massive 3-4x10^6 Msun solm black hole at the Galactic Center. It is associated with the variable radio, near-infrared, and X-ray counterpart Sagittarius A* (SgrA*). The goal is the investigation and understanding of the physical processes responsible for the variable emission from SgrA*. The observations have been carried out using the NACO adaptive optics (AO) instrument at the European Southern Observatory's Very Large Telescope (July 2005,...
Source: http://arxiv.org/abs/0712.3165v2
9
9.0
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 9
favorite 0
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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
16
16
Jun 28, 2018
06/18
by
A. Georgakakis; J. Aird; J. Buchner; M. Salvato; M. -L. Menzel; W. N. Brandt; I. D. McGreer; T. Dwelly; G. Mountrichas; K. Koki; I. Georgantopoulos; L. -T. Hsu; A. Merloni; Z. Liu; K. Nandra; N. P. Ross
texts
eye 16
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We combine deep X-ray survey data from the Chandra observatory and the wide-area/shallow XMM-XXL field to estimate the AGN X-ray luminosity function in the redshift range z=3-5. The sample consists of nearly 340 sources with either photometric (212) or spectroscopic (128) redshift in the above range. The combination of deep and shallow survey fields provides a luminosity baseline of three orders of magnitude, Lx(2-10keV)~1e43-1e46erg/s at z>3. We follow a Bayesian approach to determine the...
Topics: High Energy Astrophysical Phenomena, Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1507.07558
111
111
Jul 20, 2013
07/13
by
A. J. Barger; L. L. Cowie; A. T. Steffen; A. E. Hornschemeier; W. N. Brandt; G. P. Garmire
texts
eye 111
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We present submillimeter observations for 136 of the 370 X-ray sources detected in the 1 Ms exposure of the Chandra Deep Field North. Ten of the X-ray sources are significantly detected in the submillimeter. The average X-ray source in the sample has a significant 850 micron flux of 1.69+/-0.27 mJy. This value shows little dependence on the 2-8 keV flux from 5e-16 erg/cm^2/s to 1e-14 erg/cm^2/s. The ensemble of X-ray sources contribute about 10% of the extragalactic background light at 850...
Source: http://arxiv.org/abs/astro-ph/0107252v1
49
49
Sep 22, 2013
09/13
by
A. J. Barger; L. L. Cowie; M. W. Bautz; W. N. Brandt; G. P. Garmire; A. E. Hornschemeier; R. J. Ivison; F. N. Owen
texts
eye 49
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We describe the optical, near-infrared, and radio properties of a sample of hard (2-7 keV) X-ray sources detected in a deep Chandra observation of the field surrounding the Abell 370 cluster. We combine these data with similar observations of the Chandra Deep Field-North and the Hawaii Survey Field SSA13 to obtain a sample of 69 hard X-ray sources (45 are spectroscopically identified) with extremely deep 20 cm observations. We find that about 4% of the >Lstar galaxy population is X-ray...
Source: http://arxiv.org/abs/astro-ph/0106219v1
40
40
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 40
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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
42
42
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
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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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57
Sep 19, 2013
09/13
by
A. J. Barger; L. L. Cowie; W. N. Brandt; P. Capak; G. P. Garmire; A. E. Hornschemier; A. T. Steffen; E. H. Wehner
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eye 57
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We present the optical, near-infrared, submillimeter, and radio follow-up catalog of the X-ray selected sources from the 1 Ms Chandra observation of the Hubble Deep Field North region. We have B, V, R, I, and z' magnitudes for the 370 X-ray point sources, HK' magnitudes for 276, and spectroscopic redshifts for 182. We present high-quality spectra for 175 of these. The redshift distribution shows indications of structures at z=0.843 and z=1.0175 (also detected in optical surveys) which could...
Source: http://arxiv.org/abs/astro-ph/0206370v1
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41
Sep 18, 2013
09/13
by
A. J. Young; C. S. Crawford; A. C. Fabian; W. N. Brandt; P. T. O'Brien
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eye 41
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We report on a short optical monitoring programme of the narrow-line Seyfert 1 Galaxy IRAS 13224-3809. Previous X-ray observations of this object have shown persistent giant variability. The degree of variability at other wavelengths may then be used to constrain the conditions and emission processes within the nucleus. Optical variability is expected if the electron population responsible for the soft X-ray emission is changing rapidly and Compton-upscattering infrared photons in the nucleus,...
Source: http://arxiv.org/abs/astro-ph/9903133v1
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43
Sep 22, 2013
09/13
by
A. Laor; W. N. Brandt
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eye 43
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We describe the results of a survey of the UV absorption properties of the Boroson & Green sample of AGN, which extends from the Seyfert (M_V ~ -21) to the luminous quasar (M_V ~ -27) level. The survey is based mostly on HST archival data available for >~ 1/2 of the 87 sample objects. Our main result is that soft X-ray weak quasars (SXWQs, 10 AGN with alpha_ox
Source: http://arxiv.org/abs/astro-ph/0201038v1
6
6.0
Jun 28, 2018
06/18
by
A. Marinucci; S. Bianchi; G. Matt; D. M. Alexander; M. Balokovic; F. E. Bauer; W. N. Brandt; P. Gandhi; M. Guainazzi; F. A. Harrison; K. Iwasawa; M. Koss; K. K. Madsen; F. Nicastro; S. Puccetti; C. Ricci; D. Stern; D. J. Walton
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eye 6
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We present a NuSTAR and XMM-Newton monitoring campaign in 2014/2015 of the Compton-thick Seyfert 2 galaxy, NGC 1068. During the August 2014 observation, we detect with NuSTAR a flux excess above 20 keV ($32\pm6 \%$) with respect to the December 2012 observation and to a later observation performed in February 2015. We do not detect any spectral variation below 10 keV in the XMM-Newton data. The transient excess can be explained by a temporary decrease of the column density of the obscuring...
Topics: Astrophysics, High Energy Astrophysical Phenomena
Source: http://arxiv.org/abs/1511.03503
3
3.0
Jun 29, 2018
06/18
by
A. Masini; A. Comastri; M. Baloković; I. Zaw; S. Puccetti; D. R. Ballantyne; F. E. Bauer; S. E. Boggs; W. N. Brandt; M. Brightman; F. E. Christensen; W. W. Craig; P. Gandhi; C. J. Hailey; F. A. Harrison; M. J. Koss; G. Madejski; C. Ricci; E. Rivers; D. Stern; W. W. Zhang
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eye 3
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Aims. Study the connection between the masing disk and obscuring torus in Seyfert 2 galaxies. Methods. We present a uniform X-ray spectral analysis of the high energy properties of 14 nearby megamaser Active Galactic Nuclei observed by NuSTAR. We use a simple analytical model to localize the maser disk and understand its connection with the torus by combining NuSTAR spectral parameters with available physical quantities from VLBI mapping. Results. Most of the sources analyzed are heavily...
Topics: Astrophysics, High Energy Astrophysical Phenomena, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1602.03185
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4.0
Jun 30, 2018
06/18
by
A. P. Thomson; R. J. Ivison; J. M. Simpson; A. M. Swinbank; Ian Smail; V. Arumugam; D. M. Alexander; A. Beelen; W. N. Brandt; I. Chandra; H. Dannerbauer; T. R. Greve; J. A. Hodge; E. Ibar; A. Karim; E. J. Murphy; E. Schinnerer; S. Sirothia; F. Walter; J. L. Wardlow; P. van der Werf
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eye 4
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We present a study of the radio properties of 870$\mu$m-selected submillimetre galaxies (SMGs), observed at high resolution with ALMA in the Extended Chandra Deep Field South. From our initial sample of 76 ALMA SMGs, we detect 52 SMGs at $>3\sigma$ significance in VLA 1400MHz imaging, of which 35 are also detected at $>3\sigma$ in new 610MHz GMRT imaging. Within this sample of radio-detected SMGs, we measure a median radio spectral index $\alpha_{610}^{1400} = -0.79 \pm 0.06$, (with...
Topics: Astrophysics of Galaxies, Astrophysics, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1404.7128
55
55
Sep 21, 2013
09/13
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A. T. Steffen; I. Strateva; W. N. Brandt; D. M. Alexander; A. M. Koekemoer; B. D. Lehmer; D. P. Schneider; C. Vignali
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eye 55
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We present partial-correlation analyses that examine the strengths of the relationships between L_UV, L_X, Alpha_OX, and redshift for optically-selected AGNs. We extend the work of Strateva et al. (2005), that analyzed optically-selected AGNs from the Sloan Digital Sky Survey (SDSS), by including 52 moderate-luminosity, optically-selected AGNs from the COMBO-17 survey with corresponding deep (~250 ks to 1 Ms) X-ray observations from the Extended Chandra Deep Field-South. The COMBO-17 survey...
Source: http://arxiv.org/abs/astro-ph/0602407v1
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64
Sep 18, 2013
09/13
by
A. T. Steffen; W. N. Brandt; D. M. Alexander; S. C. Gallagher; B. D. Lehmer
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eye 64
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We employ X-ray stacking techniques to examine the contribution from X-ray undetected, mid-infrared-selected sources to the unresolved, hard (6-8 keV) cosmic X-ray background (CXB). We use the publicly available, 24 micron Spitzer Space Telescope MIPS catalogs from the Great Observatories Origins Deep Survey (GOODS) - North and South fields, which are centered on the 2 Ms Chandra Deep Field-North and the 1 Ms Chandra Deep Field-South, to identify bright (S_24 > 80 microJy) mid-infrared...
Source: http://arxiv.org/abs/0705.2213v1
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37
Sep 19, 2013
09/13
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A. Weiss; A. Kovacs; K. Coppin; T. R. Greve; F. Walter; Ian Smail; J. S. Dunlop; K. K. Knudsen; D. M. Alexander; F. Bertoldi; W. N. Brandt; S. C. Chapman; P. Cox; H. Dannerbauer; C. De Breuck; E. Gawiser; R. J. Ivison; D. Lutz; K. M. Menten; A. M. Koekemoer; E. Kreysa; P. Kurczynski; H. -W. Rix; E. Schinnerer; P. P. van der Werf
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eye 37
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We present a sensitive 870 micron survey of the Extended Chandra Deep Field South (ECDFS) using LABOCA on the APEX telescope. The LABOCA ECDFS Submillimetre Survey (LESS) covers the full 30' x 30' field size of the ECDFS and has a uniform noise level of 1.2 mJy/beam. LESS is thus the largest contiguous deep submillimetre survey undertaken to date. The noise properties of our map show clear evidence that we are beginning to be affected by confusion noise. We present a catalog of 126 SMGs...
Source: http://arxiv.org/abs/0910.2821v1
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50
Sep 23, 2013
09/13
by
Aleksandar M. Diamond-Stanic; Xiaohui Fan; W. N. Brandt; Ohad Shemmer; Michael A. Strauss; Scott F. Anderson; Christopher L. Carilli; Robert R. Gibson; Linhua Jiang; J. Serena Kim; Gordon T. Richards; Gary D. Schmidt; Donald P. Schneider; Yue Shen; Paul S. Smith; Marianne Vestergaard; Jason E. Young
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eye 50
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We identify a sample of 74 high-redshift quasars (z>3) with weak emission lines from the Fifth Data Release of the Sloan Digital Sky Survey and present infrared, optical, and radio observations of a subsample of four objects at z>4. These weak emission-line quasars (WLQs) constitute a prominent tail of the Lya+NV equivalent width distribution, and we compare them to quasars with more typical emission-line properties and to low-redshift active galactic nuclei with weak/absent emission...
Source: http://arxiv.org/abs/0904.2181v2
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52
Sep 22, 2013
09/13
by
Antara R. Basu-Zych; Bret D. Lehmer; Ann E. Hornschemeier; Rychard J. Bouwens; Tassos Fragos; Pascal A. Oesch; Krzysztof Belczynski; W. N. Brandt; Vassiliki Kalogera; Bin Luo; Neal Miller; James R. Mullaney; Panayiotis Tzanavaris; Yongquan Xue; Andreas Zezas
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eye 52
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We present results from deep X-ray stacking of >4000 high redshift galaxies from z~1 to 8 using the 4 Ms Chandra Deep Field South (CDF-S) data, the deepest X-ray survey of the extragalactic sky to date. The galaxy samples were selected using the Lyman break technique based primarily on recent HST ACS and WFC3 observations. Based on such high specific star formation rates (sSFRs): log SFR/M* > -8.7, we expect that the observed properties of these LBGs are dominated by young stellar...
Source: http://arxiv.org/abs/1210.3357v1
66
66
Sep 18, 2013
09/13
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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
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eye 66
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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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7.0
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 7
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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
2
2.0
Jun 29, 2018
06/18
by
B. D. Lehmer; A. R. Basu-Zych; S. Mineo; W. N. Brandt; R. T. Eufrasio; T. Fragos; A. E. Hornschemeier; B. Luo; Y. Q. Xue; F. E. Bauer; M. Gilfanov; P. Ranalli; D. P. Schneider; O. Shemmer; P. Tozzi; J. R. Trump; C. Vignali; J. -X. Wang; M. Yukita; A. Zezas
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eye 2
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We present measurements of the evolution of normal-galaxy X-ray emission from $z \approx$ 0-7 using local galaxies and galaxy samples in the 6 Ms Chandra Deep Field-South (CDF-S) survey. The majority of the CDF-S galaxies are observed at rest-frame energies above 2 keV, where the emission is expected to be dominated by X-ray binary (XRB) populations; however, hot gas is expected to provide small contributions to the observed- frame < 1 keV emission at $z < 1$. We show that a single...
Topics: Astrophysics, Cosmology and Nongalactic Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1604.06461
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39
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
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eye 39
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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
50
50
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 50
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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
47
47
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 47
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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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47
Sep 20, 2013
09/13
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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 47
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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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60
Sep 22, 2013
09/13
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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 60
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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
