What controls the C iv line profile in active galactic nuclei

By A. Baskin, Ari Laor. 2004

206 citations recorded by the source corpus.

The high-ionization lines in active galactic nuclei (AGN), such as C IV, tend to be blueshifted with respect to the lower-ionization lines, such as Hβ, and often show a strong blue excess asymmetry not seen in the low-ionization lines. There is accumulating evidence that the Hβ profile is dominated by gravity, and thus provides a useful estimate of the black hole mass in AGN. The shift and asymmetry commonly seen in C IV suggest that non-gravitational effects, such as obscuration and radiation pressure, may affect the line profile. We explore the relation between the Hβ and C IV profiles using the ultraviolet (UV) spectra available for 81 of the 87 z ≤ 0.5 PG quasars in the Boroson & Green sample. We find the following. (1) Narrow C IV lines (full width at half-maximum, FWHM 4000 km s -1 . This argues against the view that C IV generally originates closer to the centre, compared with Hβ. (3) C IV appears to provide a significantly less accurate, and possibly biased estimate of the black hole mass in AGN, compared with Hβ. (4) All objects where C IV is strongly blueshifted and asymmetric have a high L/L○ Edd , but the reverse is not true. This suggests that a high L/L Edd is a necessary but not sufficient condition for generating a blueshifted asymmetric C iv emission. (5) We also find indications for dust reddening and scattering in 'normal' AGN. In particular, PG quasars with a redder optical-UV continuum slope show weaker C iv emission, stronger C IV absorption and a higher optical continuum polarization.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/52f4fdfe0547bea1b9c68fd962cad6d8819c207f

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Citations in the corpus

The first ultraviolet quasar-stacked spectrum at z ≃ 2.4 from WFC3 (2015, background): “See equations 3– 5 and table 1 in Laor & Davis (2011) for a more accurate approach. reliability of utilizing the C IV line is controversial, since C IV can be severely affected by non-virial motions such as outflows, winds, and strong absorption (e.g. Baskin & Laor 2005; Shen et al. 2008).”
The Relationship between Luminosity and Broad-Line Region Size in Active Galactic Nuclei (2005, background): “While important progress has been made, there are still a number of potential problems that need to be addressed (e.g., Maoz 2002; Shemmer et al. 2004; Baskin & Laor 2005).”
On the origin of radio emission in radio-quiet quasars (2008, background): “However, a more comprehensive study of the C IV line profile of 81 of the 87 BG92 objects, including lower quality UV spectra (Baskin & Laor 2005) indicates there are no other objects with strong C IV absorption.”
Discovery of extreme [O III] λ5007 Å outflows in high-redshift red quasars (2015, background): “For a more typical density of 103 cm−3 (Baskin & Laor 2005), the nominal emitting size is 14 kpc. Radiation-pressure-dominated models (Dopita et al. 2002; Stern et al. 2014b) suggest somewhat higher ionization parameters, between U = 0.01 and 0.1, but even in this case the emitting size is between…”
Cosmic Evolution of Mass Accretion Rate and Metallicity in Active Galactic Nuclei (2006, methodology): “…in numerous papers to obtain a “single epoch” estimate of the black hole (BH) mass by combining the derived BLR size with a measure of the gas velocity obtained from emission line widths, e.g. FWHM(Hβ ) (e.g. Netzer 2003; Vestergaard 2004; Shemmer et al. 2004, hereafter S04; Baskin and Laor 2005).”
COMPARING SINGLE-EPOCH VIRIAL BLACK HOLE MASS ESTIMATORS FOR LUMINOUS QUASARS (2012, methodology): “On the other hand, we confirm the poor correlation between CIV FWHM and Hβ FWHM reported earlier (e.g., Baskin & Laor 2005; Netzer et al. 2007), which was also inferred from the comparison between CIV and MgII using SDSS quasars (e.g., Shen et al. 2008).”
Simultaneous X-ray/optical/UV snapshots of active galactic nuclei from XMM–Newton: spectral energy distributions for the reverberation mapped sample (2008, methodology): “…for the overlapping sources in VF07 were obtained from the previous reverberation mapping catalogue of Kaspi et al. (2000) and the single-epoch virial mass measurements of Baskin & Laor (2005), along with a few objects with masses from Peterson et al. (2004) (NGC 3227, NGC 3516, NGC 4593, Mrk 279).”
Probing the Coevolution of Supermassive Black Holes and Galaxies Using Gravitationally Lensed Quasar Hosts (2006, background): “Netzer (2003), Vestergaard (2004) and Baskin & Laor (2005) discuss why they should be applicable to luminous quasars and the potential caveats.”
Piecing together the X-ray background : bolometric corrections for active galactic nuclei (2007, methodology): “Optical points were taken primarily from the study of Baskin & Laor (2005) and NASA/IPAC Extragalactic Database (NED) photometry.”
Reverberation Mapping of High-Luminosity Quasars: First Results (2006, result): “The high Eddington ratio that we obtain is similar to that found for many other quasars (e.g., Shemmer et al. 2004; Baskin & Laor 2005).”
C IV λ1549 as an Eigenvector 1 Parameter for Active Galactic Nuclei (2007, methodology): “Baskin & Laor 2005 assume that the width and strength of C iv k1549NC and [O iii] k5007 are correlated.”
Hot graphite dust and the infrared spectral energy distribution of active galactic nuclei (2011, background): “Similar to the relation with the AGN luminosity, Netzeret al. (2004) and Baskin & Laor (2005) found that the equivalent width of the broad Hβ and CIV lines also anti-correlates withL/LEdd.”
A Systematic Analysis of Fe II Emission in Quasars: Evidence for Inflow to the Central Black Hole (2008, background): “2 of Baskin & Laor 2005; Fig.”
Active galactic nuclei: what’s in a name? (2017, methodology): “…have been made to calibrate C iv to produce BH mass estimates, though it is becoming clear that the winds discussed above can significantly bias the estimates for high-redshift quasars which rely on the C iv emission line (Baskin and Laor 2005; Richards et al. 2011; Denney 2012; Shen 2013).”
The Mass Relations between Supermassive Black Holes and Their Host Galaxies at 1 < z < 2 with HST-WFC3 (2019, background): “…(or MgII) line that may have unknown systematics, such as a nongravitational component of the gas dynamics of the broad-line region (BLR), when compared to local samples with masses based on broad Balmer lines(i.e., Hα and Hβ; Baskin & Laor 2005; Trakhtenbrot & Netzer 2012; Schulze et al. 2018).”
Biases in Virial Black Hole Masses: An SDSS Perspective (2007, methodology): “Our measured distributions of FWHMs are consistent with other investigations (e.g., Baskin & Laor 2005; Salviander et al. 2007), with similar widths and a∼ 0.1 dex difference in the mean values6 (which might be caused by small differences in the techniques to determine FWHMs).”
UNIFICATION OF LUMINOUS TYPE 1 QUASARS THROUGH C iv EMISSION (2010, background): “For example, the Hβ line tends to be redshifted when C iv is close to systemic and that Hβ has little shift (red or blue) when C iv is blueshifted (e.g., Marziani et al. 1996; Baskin & Laor 2005).”
The evolution of the broad-line region among SDSS quasars (2005, background): “A simple Gaussian or Lorentzian profile does not work since the broad emission lines of quasars generally show asymmetric velocity profiles (e.g., Corbin 1997; Vanden Berk et al. 2001; Baskin & Laor 2005).”