Variations of the ultraviolet Fe II and Balmer continuum emission in the Seyfert galaxy NGC 5548

Kochanek

et al. 2010

ApJ

345

484

We use the microlensing variability observed for 11 gravitationally lensed quasars to show that the accretion disk size at a rest-frame wavelength of 2500 Å is related to the black hole mass by log(R 2500 /cm) = (15.78 ± 0.12) + (0.80 ± 0.17) log(M BH /10 9 M ). This scaling is consistent with the expectation from thin-disk theory (R ∝ M 2/3 BH ), but when interpreted in terms of the standard thin-disk model (T ∝ R −3/4 ), it implies that black holes radiate with very low efficiency, log(η) = −1.77 ± 0.29 + log(L/L E ), where η = L/(Ṁc 2 ). Only by making the maximum reasonable shifts in the average inclination, Eddington factors, and black hole masses can we raise the efficiency estimate to be marginally consistent with typical efficiency estimates (η ≈ 10%). With one exception, these sizes are larger by a factor of ∼4 than the size needed to produce the observed 0.8 μm quasar flux by thermal radiation from a thin disk with the same T ∝ R −3/4 temperature profile. While scattering a significant fraction of the disk emission on large scales or including a large fraction of contaminating line emission can reduce the size discrepancy, resolving it also appears to require that accretion disks have flatter temperature/surface brightness profiles.

Section: Discussionmentioning

confidence: 99%

The Quasar Accretion Disk Size-Black Hole Mass Relation

Kochanek

et al. 2010

ApJ

345

484

“…Note that for limited wavelength fitting range (i.e., λ < 3646 Å), the Balmer continuum cannot be well constrained and is degenerate with the PL and Fe ii components (e.g., Maoz et al 1993;Wang et al 2009) and is generally not fitted (e.g., Shen et al 2011). In the case of global fits, a single PL continuum is required to simultaneously fit the region from C iv to Hα, providing some additional constraints on the Balmer continuum; however even in this case, the Balmer continuum may still be poorly constrained in a few cases, which will lead to uncertainties in the PL continuum luminosity estimates.…”

Section: Pseudo-continuum Fitmentioning

confidence: 99%

Comparing Single-Epoch Virial Black Hole Mass Estimators for Luminous Quasars

Shen¹,

Liu²

2012

ApJ

258

428

Single-epoch virial black hole (BH) mass estimators utilizing broad emission lines have been routinely applied to high-redshift quasars to estimate their BH masses. Depending on the redshift, different line estimators (Hα, Hβ, Mg ii λ2798, C iv λ1549) are often used with optical/near-infrared spectroscopy. Here, we use a homogeneous sample of 60 intermediate-redshift (z ∼ 1.5-2.2) Sloan Digital Sky Survey quasars with optical and near-infrared spectra covering C iv through Hα to investigate the consistency between different single-epoch virial BH mass estimators. We critically compare rest-frame UV line estimators (C iv λ1549, C iii] λ1908, and Mg ii λ2798) with optical estimators (Hβ and Hα) in terms of correlations between line widths and between continuum/line luminosities, for the high-luminosity regime (L 5100 > 10 45.4 erg s −1 ) probed by our sample. The continuum luminosities of L 1350 and L 3000 , and the broad-line luminosities are well correlated with L 5100 , reflecting the homogeneity of quasar spectra in the rest-frame UV-optical, among which L 1350 and the line luminosities for C iv and C iii] have the largest scatter in the correlation with L 5100 . We found that the Mg ii FWHM correlates well with the FWHMs of the Balmer lines and that the Mg ii line estimator can be calibrated to yield consistent virial mass estimates with those based on the Hβ/Hα estimators, thus extending earlier results on less luminous objects. The C iv FWHM is poorly correlated with the Balmer line FWHMs, and the scatter between the C iv and Hβ FWHMs consists of an irreducible part (∼0.12 dex), and a part that correlates with the blueshift of the C iv centroid relative to that of Hβ, similar to earlier studies comparing C iv with Mg ii. The C iii] FWHM is found to correlate with the C iv FWHM, and hence is also poorly correlated with the Hβ FWHM. While the C iv and C iii] lines can be calibrated to yield consistent virial mass estimates as Hβ on average, the scatter is substantially larger than Mg ii, and the usage of C iv/C iii] FWHM in the mass estimators does not improve the agreement with the Hβ estimator. We discuss controversial claims in the literature on the correlation between C iv and Hβ FWHMs, and suggest that the reported correlation is either a result based on small samples or only valid for low-luminosity objects.

“…This program has provided data with good temporal frequency and coverage for a number of selected Seyfert galaxies: NGC 5548 (Clavel et al 1991;Peterson et al 1991Peterson et al , 1993Peterson et al , 1994Peterson et al , 1999Maoz et al 1993;Dietrich et al 1993;Korista et al 1995;Chiang et al 2000); NGC 3783 (Reichert et al 1994;Stirpe et al 1994;Alloin et al 1995); NGC 4151 (Crenshaw et al 1996;Kaspi et al 1996;Warwick et al 1996;Edelson et al 1996); Fairall 9 (Rodriguez-Pascual et al 1997;SantosLleo et al 1997); NGC 7469 (Wanders et al 1997;Collier et al 1998) and 3C 390.3 Dietrich et al 1998;O'Brien et al 1998). It has been found that a significant part of the BLR variability can be associated with a region located within some light weeks from the central source.…”

Section: Introductionmentioning

confidence: 99%

Intermediate resolution H$\mathsf{\beta}$ spectroscopy and photometric monitoring of 3C 390.3

Shapovalova¹,

Burenkov

Carrasco

et al. 2001

A&A

Self Cite

117

Abstract. We have monitored the AGN 3C 390.3 between 1995 and 2000. A historical B-band light curve dating back to 1966 shows a large increase in brightness during 1970-1971, followed by a gradual decrease down to a minimum in 1982. During the 1995-2000 lapse the broad Hβ emission and the continuum flux varied by a factor of ≈3. Two large amplitude outbursts, of different duration, in continuum and Hβ light were observed i.e.: in October 1994 a brighter flare that lasted ≈1000 days and in July 1997 another one that lasted ≈700 days were detected. The response time lag of the emission lines relative to flux changes of the continuum has been found to vary with time i.e. during 1995-1997 a lag of about 100 days is evident, while during 1998-1999 a double valued lag of ≈100 days and ≈35 days is present in our data. The flux in the Hβ wings and line core vary simultaneously, a behavior indicative of predominantly circular motions in the BLR. Important changes of the Hβ emission profiles were detected: at times, we found profiles with prominent asymmetric wings, like those normaly seen in Sy1s, while at other times, we observe profiles with weak, almost symmetrical wings, similar to those of Sy1.8s. We further dismiss the hypothesis that the double peaked Hβ profiles in this object originate in a massive binary BH. Instead, we found that the radial velocity difference between the red and blue bumps is anticorrelated with the light curves of Hβ and continuum radiation. This implies that the zone that contributes most of the energy to the emitted line changes in radius within the disk. The velocity difference increases, corresponding to smaller radii, as the continuum flux decreases. When the continuum flux increases the hump velocity difference decreases. These transient phenomena are expected to result from the variable accretion rate close to the central source. The optical continuum and the Hβ flux variations might be related to changes in X-ray emission modulated by a variable accretion rate, changing the surface temperature of the disk, as a result of a variable X-ray irradiation (Ulrich 2000). Theoretical Hβ profiles were computed for an accretion disk, the observed profiles are best reproduced by an inclined disk (25• ) whose region of maximum emission is located roughly at 200 Rg. The mass of the black hole in 3C 390.3, estimated from the reverberation analysis is Mrev ≈ 2.1 × 10 9 M , 5 times larger than previous estimates (Wandel et al. 1999).