Black Holes and Host Galaxies of NLS1s

Recently, reliable mass estimates for the central black holes in AGN became feasible due to emission-line reverberation techniques. Using this method as a calibrator, it is possible to determine black hole masses for a wide range of AGN, in particular NLS1s. Do NLS1s have smaller black holes than ordinary Seyfert 1 galaxies? Are their black holes smaller compared to the sizes of their host galaxies? Do they have larger L/M ratios? Do NLS1s have hotter accretion disks? I confront these questions with accretion disk theory and with the data, showing that the above may well be the case.Comment: Contributed talk presented at the Joint MPE,AIP,ESO workshop on NLS1s, Bad Honnef, Dec. 1999, to appear in New Astronomy Reviews; also available at http://wave.xray.mpe.mpg.de/conferences/nls1-worksho

On the Baldwin Effect in Active Galactic Nuclei: II. Intrinsic Spectral Evolution

We suggest that the growth of the central black hole in active galactic nuclei (AGN) due to the matter accreted over the AGN lifetime causes an evolution of the luminosity and spectrum. In a previous paper we have shown that the effective temperature of the UV continuum spectrum and the emission-line equivalent width are anti-correlated with the black-hole mass. Here we estimate the change in the equivalent width of the emission lines due to the growth of the black hole mass caused by the accreted material and show that for several plausible accretion scenarios and effective-temperature models the evolving equivalent width is anti-correlated with continuum luminosity, implying that intrinsic evolution could contribute to the Baldwin effect.Comment: 14 pages Latex, 2 figures. Accepted for publication in the Astrophysical Journa

The Black Hole to Bulge Mass Relation in Active Galactic Nuclei

The masses of the central black holes in Active Galactic Nuclei (AGNs) can be estimated using the broad emission-lines as a probe of the virial mass. Using reverberation mapping to determine the size of the Broad Line Region (BLR) and the width of the variable component of the line profile H$\beta$ line it is possible to find quite accurate virial mass estimates for AGNs with adequate data. Compiling a sample of AGNs with reliable central masses and bulge magnitudes we find an average black-hole-to-bulge mass ratio of 0.0003, a factor of 20 less than the value found for normal galaxies and for bright quasars. This lower ratio is more consistent with the back hole mass density predicted from quasar light, and is similar to the central black hole/bulge mass ratio in our Galaxy. We argue that the black hole/bulge mass ratio actually has a significantly larger range than indicated by mssive black holes detected in normal galaxies (using stellar dynamics) and in bright quasars, which may be biased towards large black holes. We derive a scenario of black hole growth that explains the observed distribution.Comment: 12 pages LaTeX, including 2 revised figures, revised table. Revised version to be published in the Astrophysical Journal (Letters) Ap.J.Lett. 51

Cosmic rays in the 10(16) to 10(19) eV range from pulsars

The flux is calculated of cosmic rays (CRs) produced by a distribution of pulsars that are: (1) born with rapid rotation rates, (2) slow down as they evolve, and (3) produce energetic nuclei with a characteristic energy proportional to their rotation rates. It is found that, for energy independent escape from the disk of the galaxy, the predicted spectrum will be essentially what is observed between approx 10 to the 16th power to 10 to the 19 power eV if the slow down law as inferred for radio pulsars can be extrapolated to young pulsars with shorter periods

Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei: I. Comparing the Photoionization and Reverberation Techniques

The masses and emission-line region sizes of Active Galactic Nuclei (AGNs) can be measured by ``reverberation-mapping'' (measuring the lag of the emission-line luminosity after changes in the continuum). We use tis technique to calibrate similar size and mass estimates made by photoionization models of the AGN line-emitting regions. We compile a sample of 19 AGNs with reliable reverberation and spectroscopy data, twice the number available previously. The data provide strong evidence that the BLR size and the emission-line width measure directly the central mass. Two methods are used to estimate the distance of the broad emission-line region (BLR) from the ionizing source: the photoionization method (available for many AGNs but has large intrinsic uncertainties), and the reverberation method (gives very reliable distances, but available for only a few objects). The distance estimate is combined with the velocity dispersion, derived from the broad Hb line profile, to estimate the virial mass. Comparing the central masses calculated with the reverberation method to those calculated using a photoionization model, we find a highly significant, nearly linear correlation. This provides a calibration of the photoionization method on the objects with presently available reverberation data, which should enable mass estimates for all AGNs with measured Hb line width. Comparing the BLR sizes given by the two methods also enables us to estimate the ionizing EUV luminosity which is directly unobservable. We find it to be typically ten times the visible (monochromatic luminosity at 5100A). The inferred Eddington ratio of the individual objects in our sample are 0.001-0.03 (visible luminosity) and 0.01-0.3 (ionizing luminosity).Comment: 27 pages Latex, 8 figures. Accepted for publication in the Astrophysical Journa

X-ray variability and spectral scaling: a measure of BLR sizes in AGN

We apply a new method of determination of the size of the broad emission-line region (BLR) in active galactic nuclei. This method relates the radius of the broad-line region of AGN to the soft X-ray luminosity and spectral index. Comparing the BLR distances calculated from our photoionization scaling model to the BLR distances determined by reverberation mapping shows that the scaling law agrees with the $R\sim L^{1/2}$ empirical relation. We investigate a complimentary method of estimating the BLR distance - based on the Keplerian broadening of the emission lines and the central mass estimated from X-ray variability.Comment: 4 page latex file, 2 figs. Complete uuencoded compressed PS file is also available at ftp://saba.fiz.huji.ac.il/~pub/wandel/blrx_ts.uu or at http://shum.cc.huji.ac.il/~amri/papers/blrx_ts(tex,ps) to appear in Proc. of Astronomical Time Serie

On the Baldwin Effect in Active Galactic Nuclei: I. The Continuum-Spectrum - Mass Relationship

We suggest that the Baldwin Effect is a result of the spectral dependence of the line-driving ionizing continuum on the black hole mass. We derive a relationship between the mass of the central black hole and the broad emission line luminosity in active galactic nuclei (AGN). Assuming the UV spectrum of AGN is emitted from an optically thick medium we find an expression for the characteristic energy of the ``UV bump'' in terms of the observable luminosity and emission-line width. We show empirically and analytically that the bump energy is anti-correlated with the black-hole mass and with the continuum luminosity. Our model reproduces the observed inverse correlation between equivalent width and continuum luminosity, yielding an explanation of the Baldwin effect from first principles. The model gives a good fit to the Baldwin Effect of the CIV line for a mean quasar EUV spectrum (Zheng et al. 1997) and for several model spectra. The model also predicts a correlation between the strength of the Baldwin Effect (the slope of the equivalent width as a function of luminosity) and the ionization potential, consistent with recent data.Comment: 19 pages Latex, 2 figures. Accepted for publication in the Astrophysical Journa

Hybrid binomial Langevin-multiple mapping conditioning modeling of a reacting mixing layer

A novel, stochastic, hybrid binomial Langevin-multiple mapping conditioning (MMC) model—that utilizes the strengths of each component—has been developed for inhomogeneous flows. The implementation has the advantage of naturally incorporating velocity-scalar interactions through the binomial Langevin model and using this joint probability density function (PDF) to define a reference variable for the MMC part of the model. The approach has the advantage that the difficulties encountered with the binomial Langevin model in modeling scalars with nonelementary bounds are removed. The formulation of the closure leads to locality in scalar space and permits the use of simple approaches (e.g., the modified Curl’s model) for transport in the reference space. The overall closure was evaluated through application to a chemically reacting mixing layer. The results show encouraging comparisons with experimental data for the first two moments of the PDF and plausible results for higher moments at a relatively modest computational cost

Supermassive Black Holes in Active Galactic Nuclei. I. The Consistency of Black Hole Masses in Quiescent and Active Galaxies

We report the first results of a program to measure accurate stellar velocity dispersions in the bulges of the host galaxies of active galactic nuclei (AGNs) for which accurate black hole (BH) masses have been determined via reverberation mapping. We find good agreement between BH masses obtained from reverberation mapping, and from the M(BH) - sigma relation as defined by quiescent galaxies, indicating a common relationship between active and quiescent black holes and their large-scale environments.Comment: Submitted to ApJ