Alessandro Pizzella

TL;DR: Deharveng et al. as discussed by the authors presented the optical spectroscopic follow-up of 31 z = 0.3 Lyα emitters, and found that 17% of them have line ratios that require the hard ionizing continuum produced by an active galactic nucleus.

Abstract: Black hole masses are tightly correlated with the stellar velocity dispersions of the bulges which surround them, and slightly less-well correlated with the bulge luminosity It is common to use these correlations to estimate the expected abundance of massive black holes This is usually done by starting from an observed distribution of velocity dispersions or luminosities and then changing variables This procedure neglects the fact that there is intrinsic scatter in these black hole mass--observable correlations Accounting for this scatter results in estimates of black hole abundances which are larger by almost an order of magnitude at masses >10^9 M_sun Including this scatter is particularly important for models which seek to infer quasar lifetimes and duty cycles from the local black hole mass function However, even when scatter has been accounted for, the M_bh-sigma relation predicts fewer massive black holes than does the M_bh-L relation This is because the sigma-L relation in the black hole samples currently available is inconsistent with that in the SDSS sample from which the distributions of L or sigma are based: the black hole samples have smaller L for a given sigma, or larger sigma for a given L The sigma-L relation in the black hole samples is similarly discrepant with that in other samples of nearby early-type galaxies This suggests that current black hole samples are biased: if this is a selection rather than physical effect, then the M_bh-sigma and M_bh-L relations currently in the literature are also biased from their true values

Abstract: Black hole masses are tightly correlated with the stellar velocity dispersions of the bulges which surround them and slightly less well correlated with the bulge luminosity. It is common to use these correlations to estimate the expected abundance of massive black holes. This is usually done by starting from an observed distribution of velocity dispersions or luminosities and then changing variables. This procedure neglects the fact that there is intrinsic scatter in these black hole mass-observable correlations. Accounting for this scatter results in estimates of black hole abundances which are larger by almost an order of magnitude at masses >109 M☉. Including this scatter is particularly important for models which seek to infer quasar lifetimes and duty cycles from the local black hole mass function. However, even when scatter has been accounted for, the M•-σ relation predicts fewer massive black holes than does the M•-L relation. This is because the σ-L relation in the black hole samples currently available is inconsistent with that in the SDSS sample from which the distributions of L or σ are based: the black hole samples have smaller L for a given σ, or larger σ for a given L. The σ-L relation in the black hole samples is similarly discrepant with that in other samples of nearby early-type galaxies. This suggests that current black hole samples are biased: if this is a selection rather than a physical effect, then the M•-σ and M•-L relations currently in the literature are also biased from their true values.

TL;DR: In this article, an optical spectroscopic monitoring program targeting NGC 5548 as part of a larger multi-wavelength reverberation mapping campaign was presented, which spanned 6 months and achieved an almost daily cadence with observations from five ground-based telescopes.

TL;DR: In this paper, a compilation of UBV RIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986 to 2003 is presented, where the photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars.