A QUASAR CATALOG WITH SIMULTANEOUS UV, OPTICAL, AND X-RAY OBSERVATIONS BY SWIFT

Journal Article · Wed Aug 01 04:00:00 EDT 2012 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.1088/0067-0049/201/2/10· OSTI ID:22047683

Jian, Wu; Grupe, Dirk; Koch, Scott; Gelbord, Jonathan; Schneider, Donald P; Gronwall, Caryl; Porterfield, Blair L ^[1]; Vanden Berk, Daniel; Wesolowski, Sarah ^[2]

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1. Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)
2. Department of Physics, Saint Vincent College, 300 Fraser Purchase Road, Latrobe, PA 15650 (United States)

We have compiled a catalog of optically selected quasars with simultaneous observations in UV/optical and X-ray bands by the Swift Gamma-ray Burst Explorer. Objects in this catalog are identified by matching the Swift pointings with the Sloan Digital Sky Survey Data Release 5 quasar catalog. The final catalog contains 843 objects, among which 637 have both Ultraviolet Optical Telescope (UVOT) and X-Ray Telescope (XRT) observations and 354 of which are detected by both instruments. The overall X-ray detection rate is {approx}60% which rises to {approx}85% among sources with at least 10 ks of XRT exposure time. We construct the time-averaged spectral energy distribution (SED) for each of the 354 quasars using UVOT photometric measurements and XRT spectra. From model fits to these SEDs, we find that the big blue bump contributes about {approx}0.3 dex to the quasar luminosity. We re-visit the {alpha}{sub ox}-L{sub 2500A} relation by selecting a clean sample with only Type 1 radio-quiet quasars; the dispersion of this relation is reduced by at least 15% compared with studies that use non-simultaneous UV/optical and X-ray data. We only found a weak correlation between L{sub bol}/L{sub Edd} and {alpha}{sub UV}. We do not find significant correlations between {alpha}{sub x} and {alpha}{sub ox}, {alpha}{sub ox} and {alpha}{sub UV}, and {alpha}{sub x} and log L(0.3-10 keV). The correlations between {alpha}{sub UV} and {alpha}{sub x}, {alpha}{sub ox} and {alpha}{sub x}, {alpha}{sub ox} and {alpha}{sub UV}, L{sub bol}/L{sub Edd} and {alpha}{sub x}, and L{sub bol}/L{sub Edd} and {alpha}{sub ox} are stronger among low-redshift quasars, indicating that these correlations are likely driven by the changes of SED shape with accretion state.

• OSTI ID: 22047683
• Journal Information: Astrophysical Journal, Supplement Series, Journal Name: Astrophysical Journal, Supplement Series Journal Issue: 2 Vol. 201; ISSN 0067-0049; ISSN APJSA2
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTROPHYSICS
CATALOGS
CORRELATIONS
COSMIC GAMMA BURSTS
ENERGY SPECTRA
GALAXY NUCLEI
GAMMA ASTRONOMY
KEV RANGE
LUMINOSITY
PHOTOMETRY
QUASARS
RED SHIFT
STAR ACCRETION
ULTRAVIOLET RADIATION
VISIBLE RADIATION
X-RAY DETECTION
X-RAY GALAXIES