The Black Hole Mass - Galaxy Bulge Relationship for QSOs in the SDSS DR3

We investigate the relationship between black hole mass and host galaxy velocity dispersion for QSOs in Data Release 3 of the Sloan Digital Sky Survey. We derive black hole mass from the broad Hbeta line width and continuum luminosity, and the bulge stellar velocity dispersion from the [OIII] narrow line width. At higher redshifts, we use MgII and [OII] in place of Hbeta and [OIII]. For redshifts z < 0.5, our results agree with the black hole mass - bulge velocity dispersion relationship for nearby galaxies. For 0.5 < z < 1.2, this relationship appears to show evolution with redshift in the sense that the bulges are too small for their black holes. However, we find that part of this apparent trend can be attributed to observational biases, including a Malmquist bias involving the QSO luminosity. Accounting for these biases, we find ~0.2 dex evolution in the black hole mass-bulge velocity dispersion relationship between now and redshift z ~ 1.Comment: Accepted by ApJ, 15 pages, 9 figure

Consistent simulation of bromine chemistry from the marine boundary layer to the stratosphere – Part 2: Bromocarbons

In this second part of a series of articles dedicated to a detailed analysis of bromine chemistry in the atmosphere we address one (out of two) dominant natural sources of reactive bromine. The two main source categories are the release of bromine from sea salt and the decomposition of bromocarbons by photolysis and reaction with OH. Here, we focus on C&lt;sub&gt;1&lt;/sub&gt;-bromocarbons. We show that the atmospheric chemistry general circulation model ECHAM5/MESSy realistically simulates their emission, transport and decomposition from the boundary layer up to the mesosphere. We included oceanic emission fluxes of the short-lived bromocarbons CH&lt;sub&gt;2&lt;/sub&gt;Br&lt;sub&gt;2&lt;/sub&gt;, CH&lt;sub&gt;2&lt;/sub&gt;ClBr, CHClBr&lt;sub&gt;2&lt;/sub&gt;, CHCl&lt;sub&gt;2&lt;/sub&gt;Br, CHBr&lt;sub&gt;3&lt;/sub&gt; and of CH&lt;sub&gt;3&lt;/sub&gt;Br. The vertical profiles and the surface mixing ratios of the bromocarbons are in general agreement with the (few available) observations, especially in view of the limited information available and the consequent coarseness of the emission fields. For CHBr&lt;sub&gt;3&lt;/sub&gt;, CHCl&lt;sub&gt;2&lt;/sub&gt;Br and CHClBr&lt;sub&gt;2&lt;/sub&gt; photolysis is the most important degradation process in the troposphere. In contrast to this, tropospheric CH&lt;sub&gt;2&lt;/sub&gt;Br&lt;sub&gt;2&lt;/sub&gt;, CH&lt;sub&gt;3&lt;/sub&gt;Br and CH&lt;sub&gt;2&lt;/sub&gt;ClBr are more efficiently decomposed by reaction with OH. In the free troposphere approximately 40% of the C&lt;sub&gt;1&lt;/sub&gt;-bromocarbons decompose by reaction with OH. Our results indicate that bromoform contributes substantial amounts of reactive bromine to the lower stratosphere and thus should not be neglected in stratospheric simulations

Deep Photometry in a Remote M31 Major Axis Field Near G1

We present photometry from Hubble Space Telescope (HST)/Wide Field Planetary Camera 2 parallel imagery of a remote M31 field at a projected distance of about 34 kpc from the nucleus near the SW major axis. This field is near the globular cluster G1, and near one of the candidate tidal plumes identified by Ferguson et al. (2002). The F606W (V) and F814W (I) images were obtained in parallel with Space Telescope Imaging Spectrograph spectroscopy of G1 (GO-9099) and total 7.11 hours of integration time -- the deepest HST field in the outer disk of M31 to date, reaching to V ~ 28. The color-magnitude diagram of the field shows a clearly-defined red clump at V = 25.25 and a red giant branch consistent with [Fe/H] ~ -0.7. The lack of a blue horizontal branch contrasts with other M31 halo fields, the Andromeda dwarf spheroidals, and with the nearby globular cluster G1. Comparing the observed luminosity function to the Padova models, we find that at least some of the stellar population must be younger than 6 - 8 Gyr. The outermost detected neutral hydrogen gas disk of M31 lies only 2 kpc in projection from our field. The finding that some giants in the field have radial velocities close to that of the neutral hydrogen gas (Reitzel, Guhathakurta, & Rich 2003) leads us to conclude that our field samples the old, low-surface-brightness disk rather than the true Population II spheroid.Comment: 15 pages, 3 figures. accepted for publication in the A

State transition and electrocaloric effect of BaZrx_{x}Ti1−x_{1-x}O3_3: simulation and experiment

The electrocaloric effect (ECE) of BaZr$_{x}$Ti$_{1-x}$O$_3$ (BZT) is closely related to the relaxor state transition of the materials. This work presents a systematic study on the ECE and the state transition of the BZT, using a combined canonical and microcanonical Monte Carlo simulations based a lattice-based on a Ginzburg-Landau-type Hamiltonian. For comparison and verification, experimental measurements have been carried on BTO and BZT ($x=0.12$ and $0.2$) samples, including the ECE at various temperatures, domain patterns by Piezoresponse Force Microscopy at room temperature, and the P-E loops at various temperatures. Results show that the dependency of BZT behavior of the Zr-concentration can be classified into three different stages. In the composition range of $0 \leq x \leq 0.2$, ferroelectric domains are visible, but ECE peak drops with increasing Zr-concentration harshly. In the range of $0.3 \leq x \leq 0.7$, relaxor features become prominent, and the decrease of ECE with Zr-concentration is moderate. In the high concentration range of $x \geq 0.8$, the material is almost nonpolar, and there is no ECE peak visible. Results suggest that BZT with certain low range of Zr-concentration around $x=0.12 \sim 0.3$ can be a good candidate with relatively high ECE and simutaneously wide temperature application range at rather low temperature

A possible bias on the estimate of Lbol/Ledd in AGN as a function of luminosity and redshift

The BH mass (and the related Eddington ratio) in broad line AGN is usually evaluated by combining estimates (often indirect) of the BLR radius and of the FWHM of the broad lines, under the assumption that the BLR clouds are in Keplerian motion around the BH. Such an evaluation depends on the geometry of the BLR. There are two major options for the BLR configuration: spherically symmetric or ``flattened''. In the latter case the inclination to the line of sight becomes a relevant parameter. This paper is devoted to evaluate the bias on the estimate of the Eddington ratio when a spherical geometry is assumed (more generally when inclination effects are ignored), while the actual configuration is ``flattened'', as some evidence suggests. This is done as a function of luminosity and redshift, on the basis of recent results which show the existence of a correlation between the fraction of obscured AGN and these two parameters up to at least z=2.5. The assumed BLR velocity field is akin to the ``generalized thick disk'' proposed by Collin et al. (2006). Assuming an isotropic orientation in the sky, the mean value of the bias is calculated as a function of luminosity and redshift. It is demonstrated that, on average, the Eddington ratio obtained assuming a spherical geometry is underestimated for high luminosities, and overestimated for low luminosities. This bias converges for all luminosities at z about 2.7, while nothing can be said on this bias at larger redshifts due to the lack of data. The effects of the bias, averaged over the luminosity function of broad line AGN, have been calculated. The results imply that the bias associated with the a-sphericity of the BLR make even worse the discrepancy between the observations and the predictions of evolutionary models.Comment: 6 pages, 3 figures, accepted for publication in A&

Supermassive Black Holes and the Evolution of Galaxies

Black holes, an extreme consequence of the mathematics of General Relativity, have long been suspected of being the prime movers of quasars, which emit more energy than any other objects in the Universe. Recent evidence indicates that supermassive black holes, which are probably quasar remnants, reside at the centers of most galaxies. As our knowledge of the demographics of these relics of a violent earlier Universe improve, we see tantalizing clues that they participated intimately in the formation of galaxies and have strongly influenced their present-day structure.Comment: 20 pages, - This is a near-duplicate of the paper in Nature 395, A14, 1998 (Oct 1

Accretion Disk Temperatures and Continuum Colors in QSOs

Accretion disks around supermassive black holes are widely believed to be the dominant source of the optical-ultraviolet continuum in many classes of active galactic nuclei (AGN). We study here the relationship between the continuum colors of AGN and the characteristic accretion disk temperature (T_max). Based on NLTE models of accrection disks in AGN computed as described by Hubeny et al. (2000), we find that continuum intensity ratios for several pairs of wavelengths between 1350 and 5100 A should show a trend of bluer colors for higher T_max, notwithstanding random disk inclinations. We compare this theoretical expectation with observed colors of QSOs in the Sloan Digital Sky Survey,deriving black hole mass and thence T_max from the width of the Mg II broad emission line. The observed colors generally do not show the expected trend and in some cases show a reverse trend of redder colors with increasing T_max. The cause of this discrepancy does not appear to be dust reddening or galaxy contamination but may relate to the accretion rate, as the offset objects are accreting above ~30 % of the Eddington limit. The derived disk temperature depends primarily on line width, with little or no dependence on luminosity.Comment: 7 pages, 7 figures, accepted for publication in ApJ, uses emulateapj.cl