PROBING THE ORIGINS OF THE C IV AND Fe K{alpha} BALDWIN EFFECTS

Journal Article · Tue Sep 01 04:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/702/1/767; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21333802

Jian, Wu; Vanden Berk, Daniel E; Brandt, W N; Schneider, Donald P; Gibson, Robert R

We use UV/optical and X-ray observations of 272 radio-quiet Type 1 active galactic nuclei and quasars to investigate the C IV Baldwin Effect (BEff). The UV/optical spectra are drawn from the Hubble Space Telescope, International Ultraviolet Explorer and Sloan Digital Sky Survey archives. The X-ray spectra are from the Chandra and XMM-Newton archives. We apply correlation and partial-correlation analyses to the equivalent widths (EWs), continuum monochromatic luminosities, and {alpha}{sub ox}, which characterizes the relative X-ray to UV brightness. The EW of the C IV {lambda}1549 emission line is correlated with both {alpha}{sub ox} and luminosity. We find that by regressing l{sub {nu}}(2500 A) with EW(C IV) and {alpha}{sub ox}, we can obtain tighter correlations than by regressing l{sub {nu}}(2500 A) with only EW(C IV). Both correlation and regression analyses imply that l{sub {nu}}(2500 A) is not the only factor controlling the changes of EW(C IV); {alpha}{sub ox} (or, equivalently, the soft X-ray emission) plays a fundamental role in the formation and variation of C IV. Variability contributes at least 60% of the scatter of the EW(C IV)-l{sub {nu}}(2500 A) relation and at least 75% of the scatter of the of the EW(C IV)-{alpha}{sub ox} relation. In our sample, narrow Fe K{alpha} 6.4 keV emission lines are detected in 50 objects. Although narrow Fe K{alpha} exhibits a BEff similar to that of C IV, its EW has almost no dependence on either {alpha}{sub ox} or EW(C IV). This suggests that the majority of narrow Fe K{alpha} emission is unlikely to be produced in the broad emission-line region. We do find suggestive correlations between the emission-line luminosities of C IV and Fe K{alpha}, which could be potentially used to estimate the detectability of the Fe K{alpha} line of quasars from rest-frame UV spectroscopic observations.

• OSTI ID: 21333802
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 702; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BRIGHTNESS
EMISSION
GALAXY NUCLEI
LUMINOSITY
MONOCHROMATIC RADIATION
QUASARS
REGRESSION ANALYSIS
SOFT X RADIATION
TELESCOPES
ULTRAVIOLET RADIATION
X-RAY SPECTRA