A Relation between Supermassive Black Hole Mass and Quasar Metallicity?

Abstract

We analyze spectra for a large sample of 578 active galactic nuclei to examine the relationships between broad emission line properties and central supermassive black hole (SMBH) mass. We estimate SMBH masses by applying the virial theorem to the C iv 1549 broad emission line. Although the FWHMs of C iv and H appear nearly unrelated in individual objects, these FWHMs are well correlated when averaged over subsamples in our database. Therefore, the lines are equally valid indicators of the average SMBH mass in quasar samples. Our sample spans 5 orders of magnitude in SMBH mass, 6 orders of magnitude in luminosity, and a redshift range of 0 z 5. Most lines diminish in equivalent width with increasing black hole mass (the usual '' Baldwin effect ''), and there are no trends with redshift. Recent studies indicate that there is a relationship between SMBH mass and the overall bulge/spheroidal component mass of the surrounding galaxy. This relation, together with the well-known mass-metallicity relationship among galaxies, predicts a relationship between SMBH mass and quasar metallicity. We estimate the metallicity in the broad emission line region by comparing several line ratios involving nitrogen to theoretical predictions. We find that the data are consistent with a trend between SMBH mass and metallicity, with some line ratios indicating a very strong trend, but the uncertainties in several other important line ratios are too large to confirm or test this correlation.

Determining Central Black Hole Masses in Distant Active Galaxies and Quasars. II. Improved Optical and UV Scaling Relationships

“…Table 1 of Baskin & Laor (2005) Baskin & Laor (2005) caution against the use of the C iv emission line for estimating black hole masses through mass scaling relationships of the type derived in this paper. As their conclusion was contrary to that reached in Paper I and by Warner et al (2003) and Vestergaard (2004), we felt that is was important for us to examine the same data as Baskin & Laor (2005) and attempt to understand the origin of these different results.…”

“…[7]), as argued in Paper I and by Warner et al (2003) and Vestergaard (2004). It has been argued, however, that C iv may be an inappropriate choice for this application on the grounds that the dynamics of the C iv-emitting gas may not be determined primarily by gravitation; in particular, it has been suggested that (1) the line profiles might be affected by obscuration within the line-emitting region and (2) there are reasons to believe that a significant fraction of the C iv line arises in an outflowing wind.…”

J004457+4123 (Sharov 21): not a remarkable nova in M 31 but a background quasar with a spectacular UV flare

“…Significant progress has been achieved over the last years with the calibration of the R-L relation (Vestergaard 2002(Vestergaard , 2009Corbett et al 2003;Warner et al 2003;Peterson et al 2004;Vestergaard & Peterson 2006).…”

Supermassive black holes in the early universe

“…We analyzed these quasar spectra using a multi-component fit approach (power-law continuum, FeII emission, Balmer continuum emission). We applied the equations given by Kaspi et al (2000), McLure & Jarvis (2002), Vestergaard (2002), and Warner et al (2003) to estimate the black hole mass and to compare, for the first time, results based on CIV, MgII, and Hβ. While CIV is a high-ionization line, Hβ and MgII are low-ionization lines but it can be assumed that the low and high ionization broad line gas are in gravitationally dominated motion (Onken & Peterson 2002).…”