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Cosmological Evolution of the Hard X-Ray Active Galactic Nucleus Luminosity Function and the Origin of the Hard X-Ray Background
Ueda, Yoshihiro; Ohta, Kouji; Akiyama, Masayuki +1 more
We investigate the cosmological evolution of the hard X-ray luminosity function (HXLF) of active galactic nuclei (AGNs) in the 2-10 keV luminosity range of 1041.5-1046.5 ergs s-1 as a function of redshift up to 3. From a combination of surveys conducted at photon energies above 2 keV with HEAO 1, ASCA, and Chandra,…
A Quantitative Comparison of the Small Magellanic Cloud, Large Magellanic Cloud, and Milky Way Ultraviolet to Near-Infrared Extinction Curves
Gordon, Karl D.; Clayton, Geoffrey C.; Misselt, K. A. +2 more
We present an exhaustive quantitative comparison of all the known extinction curves in the Small and Large Magellanic Clouds (SMC and LMC) with our understanding of the general behavior of Milky Way extinction curves. The RV-dependent CCM relationship of Cardelli, Clayton, and Mathis and the sample of extinction curves used to derive th…
An extended upper atmosphere around the extrasolar planet HD209458b
Lecavelier des Etangs, A.; Ferlet, R.; Vidal-Madjar, A. +4 more
The planet in the system HD209458 is the first one for which repeated transits across the stellar disk have been observed. Together with radial velocity measurements, this has led to a determination of the planet's radius and mass, confirming it to be a gas giant. But despite numerous searches for an atmospheric signature, only the dense lower atm…
On characterizing the variability properties of X-ray light curves from active galaxies
Vaughan, S.; Uttley, P.; Warwick, R. S. +1 more
We review some practical aspects of measuring the amplitude of variability in `red noise' light curves typical of those from active galactic nuclei (AGN). The quantities commonly used to estimate the variability amplitude in AGN light curves, such as the fractional rms variability amplitude, Fvar, and excess variance, σ2…
IBIS: The Imager on-board INTEGRAL
Di Cocco, G.; Vigroux, L.; Bird, A. J. +17 more
The IBIS telescope is the high angular resolution gamma-ray imager on-board the INTEGRAL Observatory, successfully launched from Baikonur (Kazakhstan) the 17{th} of October 2002. This medium size ESA project, planned for a 2 year mission with possible extension to 5, is devoted to the observation of the gamma-ray sky in the energy range from 3 keV…
Astrometric Calibration of the Sloan Digital Sky Survey
Hennessy, G. S.; Munn, Jeffrey A.; Ivezić, Željko +4 more
The astrometric calibration of the Sloan Digital Sky Survey is described. For point sources brighter than r~20, the astrometric accuracy is 45 mas rms per coordinate when reduced against the USNO CCD Astrograph Catalog and 75 mas rms when reduced against Tycho-2, with an additional 20-30 mas systematic error in both cases. The rms errors are domin…
The Galactic Disk Mass Function: Reconciliation of the Hubble Space Telescope and Nearby Determinations
Chabrier, Gilles
We derive and parameterize the Galactic mass function (MF) below 1 Msolar characteristic of both single objects and binary systems. We resolve the long-standing discrepancy between the MFs derived from the Hubble Space Telescope (HST) and from the nearby luminosity functions, respectively. We show that this discrepancy stemmed from two …
A Survey of z>5.7 Quasars in the Sloan Digital Sky Survey. II. Discovery of Three Additional Quasars at z>6
Pentericci, Laura; White, Richard L.; Grebel, Eva K. +28 more
We present the discovery of three new quasars at z>6 in ~ 1300 deg2 of Sloan Digital Sky Survey imaging data, J114816.64+525150.3 (z=6.43), J104845.05+463718.3 (z=6.23), and J163033.90+401209.6 (z=6.05). The first two objects have weak Lyα emission lines; their redshifts are determined from the positions of the Lyman break. They are …
Estimating Star Formation Rates from Infrared and Radio Luminosities: The Origin of the Radio-Infrared Correlation
Bell, Eric F.
I have assembled a diverse sample of galaxies from the literature with far-ultraviolet (FUV), optical, infrared (IR), and radio luminosities to explore the calibration of radio-derived and IR-derived star formation (SF) rates and the origin of the radio-IR correlation. By comparing the 8-1000 µm IR, which samples dust-reprocessed starlight, …
The Relationship between Stellar Light Distributions of Galaxies and Their Formation Histories
Conselice, Christopher J.
A major problem in extragalactic astronomy is the inability to distinguish in a robust, physical, and model-independent way how galaxy populations are physically related to each other and to their formation histories. A similar, but distinct, and also long-standing question is whether the structural appearances of galaxies, as seen through their s…