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J/ApJ/685/773       X-ray-UV relations in SDSS DR5 QSOs      (Gibson+, 2008)

Are optically selected quasars universally X-ray luminous? X-ray-UV relations in Sloan Digital Sky Survey quasars. Gibson R.R., Brandt W.N., Schneider D.P. <Astrophys. J., 685, 773-786 (2008)> =2008ApJ...685..773G
ADC_Keywords: Surveys ; QSOs ; X-ray sources ; Ultraviolet ; Redshifts Keywords: galaxies: active - galaxies: nuclei - quasars: absorption lines - quasars: emission lines - X-rays: general Abstract: We analyze archived Chandra and XMM-Newton X-ray observations of 536 Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5) quasars (QSOs) at 1.7≤z≤2.7 in order to characterize the relative UV and X-ray spectral properties of QSOs that do not have broad UV absorption lines (BALs). We constrain the fraction of X-ray-weak, non-BAL QSOs and find that such objects are rare; for example, sources underluminous by a factor of 10 comprise ≲2% of optically selected SDSS QSOs. X-ray luminosities vary with respect to UV emission by a factor of ≲2 over several years for most sources. UV continuum reddening and the presence of narrow-line absorbing systems are not strongly associated with X-ray weakness in our sample. X-ray brightness is significantly correlated with UV emission-line properties, so that relatively X-ray-weak, non-BAL QSOs generally have weaker, blueshifted CIV λ1549 emission and broader CIII] λ1909 lines. The CIV emission-line strength depends on both UV and X-ray luminosity, suggesting that the physical mechanism driving the global Baldwin effect is also associated with X-ray emission. Description: In this study we consider the 536 SDSS QSOs at redshifts 1.7≤z≤2.7 that have been observed with Chandra or XMM-Newton. The lower limit on redshift ensures that the SDSS spectrum reaches to ∼1400Å allowing good coverage of any potential high-velocity CIV absorption, up to ~-30000km/s. The upper redshift limit ensures that the 2500Å continuum is in view so that we can determine the UV continuum flux accurately. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 111 536 Source information table2.dat 55 536 UV emission line measurements
See also: VII/252 : SDSS-DR5 quasar catalog (Schneider+, 2007) J/AJ/133/313 : AGN from RASS and SDSS DR5 (Anderson+, 2007) http://www.sdss.org : SDSS Home Page Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 19 A19 --- SDSS SDSS source name JHHMMSS.ss+DDMMSS.s 21- 24 F4.2 --- z Spectroscopic redshift 26- 35 I10 --- ObsId Chandra or XMM observation identification number (1) 37- 41 F5.1 ks Expo X-ray exposure time (2) 43- 46 I4 ct Scts Observed-frame soft (0.5-2keV) counts in source region 48- 50 I3 ct Hcts Observed-frame hard (2-8keV) counts in source region 52 I1 --- X [0/1] X-ray detected? (1=yes) 54 I1 --- B [0/1] Source in sample B? (1=yes) 56 A1 --- l_logR* Limit flag on logR* 58- 62 F5.2 [-] logR* Radio-loudness parameter (5) 64- 68 I5 km/s CIV.0 Rest-frame balnicity index for CIV absorption (6) 70 I1 --- Mg Number of narrow Mg II absorption systems (7) 72- 76 F5.2 [10-7W/Hz] L1400 Log of monochromatic luminosity at 1400Å (8) 78- 82 F5.2 [10-7W/Hz] L2500 Log of monochromatic luminosity at 2500Å (8) 84 A1 --- l_L2keV Limit flag on log2keV 86- 90 F5.2 [10-7W/Hz] L2keV Log of monochromatic luminosity at 2keV (8) 92 A1 --- l_a.OX Limit flag on a.OX 94- 98 F5.2 --- a.OX X-ray/optical spectral index (9) 100-103 F4.2 --- e_a.OX ? Uncertainty in a.OX (10) 105 A1 --- l_Da.OX Limit flag on Da.OX 107-111 F5.2 --- Da.OX Relative X-ray brightness (11)
Note (1): The Chandra or XMM-Newton observation identification number. Ten-digit numbers correspond to XMM-Newton observations, while shorter numbers correspond to Chandra observations. Note (2): Reported by the CIAO or SAS toolchains for the extraction of the source region. Note (5): Where log(R*)=log[Lν(5GHz)/Lν(2500Å)]. We classify sources with log(R*)≥1 as "radio-loud" and all other sources as "radio-quiet". Note (6): Similar to the traditional "balnicity index", BI, of Weymann et al. (1991ApJ...373...23W), except that it is integrated from velocity offsets -25000km/s to 0km/s from the QSO rest frame. Note (7): Found using the method described in Section 2.2. Note (8): Where the luminosity is in units of erg/s/Hz. Note (9): Where a.OX = αOX = 0.3838*log(L(2keV)/L(2500Å)). Note (10): Errors assumed to be dominated by the error on X-ray luminosity. Note (11): Relative to "ordinary" QSOs. Where Da.OX = ΔαOX = αOX - (-0.217±0.036)*log(L2500Å)+(5.075±1.118). (for instance, a value of -0.5 corresponds to X-ray weakness by a factor of ∼20 compared to QSOs with the same UV luminosity)
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 19 A19 --- SDSS SDSS source identification, JHHMMSS.ss+DDMMSS.s 21- 25 F5.1 0.1nm C4EW Equivalent width of CIV (1549Å) 27- 32 F6.1 0.1nm C4Wave Central wavelength of CIV (1549Å) 34- 37 F4.1 0.1nm C4FWHM Full-Width at Half-Maximum of CIV (1549Å) 39- 42 F4.1 0.1nm C3EW ? Equivalent width of CIII] (1909AA) (1) 44- 49 F6.1 0.1nm C3Wave ? Central wavelength of CIII] (1909AA) (1) 51- 55 F5.1 0.1nm C3FWHM ? Full-Width at Half-Maximum of CIII] (1909Å) (1)
Note (1): Blank entries indicate that the C III] emission line could not be fit because the spectrum was bad in that region.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 03-Sep-2009
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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