J/AJ/135/10 SDSS-DR4/RASS source matching (Parejko+, 2008)
Source matching in the SDSS and RASS: which galaxies are really X-ray sources?
Parejko J.K., Constantin A., Vogeley M.S., Hoyle F.
<Astron. J., 135, 10-19 (2008)>
=2008AJ....135...10P 2008AJ....135...10P
ADC_Keywords: Surveys ; Galaxy catalogs ; X-ray sources ; Cross identifications
Keywords: galaxies: active - quasars: general - X-rays: galaxies -
X-rays: general
Abstract:
The current view of galaxy formation holds that all massive galaxies
harbor a massive black hole at their center, but that these black
holes are not always in an actively accreting phase. X-ray emission is
often used to identify accreting sources, but for galaxies that are
not harboring quasars (low-luminosity active galaxies), the X-ray flux
may be weak, or obscured by dust. To aid in the understanding of
weakly accreting black holes in the local universe, a large sample of
galaxies with X-ray detections is needed. We cross-match the ROSAT All
Sky Survey (RASS) with galaxies from the Sloan Digital Sky Survey Data
Release 4 (SDSS DR4) to create such a sample. Because of the high SDSS
source density and large RASS positional errors, the cross-matched
catalog is highly contaminated by random associations. We investigate
the overlap of these surveys and provide a statistical test of the
validity of RASS-SDSS galaxy cross-matches.
Description:
This study employs data from the Sloan Digital Sky Survey Data Release
4 (SDSS DR4), an optical imaging and spectroscopic survey with
spectroscopic coverage of ∼16% of the sky as described in York et
al. (2000AJ....120.1579Y 2000AJ....120.1579Y) and Adelman-McCarthy et al. (2006, cat.
II/267).
ROSAT data are form the RASS Faint Source Catalog (FSC; Voges et al.
2000, Cat. IX/29) and RASS Bright Source Catalog (BSC; Voges et al.
1999, Cat. IX/10).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 106 2278 Catalog of SDSS-DR4/RASS matching sources
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See also:
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
IX/29 : ROSAT All-Sky Survey Faint Source Catalog (Voges+ 2000)
II/267 : The SDSS Photometric Catalog, Release 4 (Adelman-McCarthy+, 2006)
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
6- 24 A19 --- SDSS The SDSS object identification,
JHHMMSS.ss+DDMMSS.s
26- 43 A18 --- SpecObjID Unique SDSS extracted SDSS spectrum
identifier
45- 48 A4 --- --- [1RXS]
50- 65 A16 --- 1RXS The RASS object identification,
HHMMSS.s+DDMMSS
67- 72 F6.3 arcsec Sep Separation between RASS and SDSS source
positions
74- 77 F4.1 arcsec ePos Positional error of RASS measurement (1)
79- 84 F6.4 --- Match Probability RASS/SDSS match is real
86-106 A21 --- Class Object spectroscopic classification (2)
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Note (1): As described at the end of Section 2.2, and plotted in Figure 2.
Note (2): see Fig.1 for the regions in the diagram. The classes are:
emission = emission-line galaxies;
h2 = HII region;
liner = low-ionisation nuclear emission-line region;
passive = no emission (Hα, Hβ, [OIII]);
seyfert = Seyfert galaxies;
unclassifiable = galaxies showing some but no all emission lines
transition = in transition region of the diagram of Fig.1
unclassified_emission = incompatible locations in the diagrams
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 11-Feb-2011