Evencio Mediavilla

The Influence of Gravitational Microlensing on the Broad Emission Lines of Quasars

We discuss the effects of microlensing on the broad emission lines (BELs) of QSOs in the light of recent determinations of the size of the broad-line region (BLR) and its scaling with QSO luminosity. Microlensing by star-sized objects can produce significant amplifications in the BEL of some multiple-imaged QSOs, and could be very relevant for high-ionization lines. We have identified a group of 10 gravitational lens systems (~30% of the selected sample) in which microlensing could be observed. Using standard kinematic models for active galactic nuclei, we have studied the changes induced in the line profile by a microlens located at different positions with respect to the center of the BLR. We found that microlensing could produce important effects such as the relative enhancement of different parts of the line profile or the displacement of the peak of the line. The study of BEL profiles of different ionization in a microlensed QSO image could be an alternative method for probing the BLR structure and size.

Detection of the 2175 Å Extinction Feature at z = 0.83

We determine the extinction curve in the z_l=0.83 lens galaxy of the gravitational lens SBS0909+532 from the wavelength dependence of the flux ratio between the lensed quasar images (z_s=1.38) from 3400 to 9200\AA. It is the first measurement of an extinction curve at a cosmological distance of comparable quality to those obtained within the Galaxy. The extinction curve has a strong 2175\AA feature, a noteworthy fact because it has been weak or non-existent in most estimates of extinction curves outside the Galaxy. The extinction curve is fitted well by a standard

Contribution of the disk emission to the broad emission lines in AGNs: Two-component model

R_V=2.1\pm0.9

The Nature and Size of the Optical Continuum Source in QSO 2237+0305

Galactic extinction curve. If we assume standard Galactic extinction laws, the estimated dust redshift of

Integral field spectroscopy of the luminous infrared galaxy arp 299 (IC 694 + NGC 3690)

z=0.88\pm0.02

The Extinction Law in High-Redshift Galaxies*

is in good agreement with the spectroscopic redshift of the lens galaxy. The widespread assumption that SMC extinction curves are more appropriate models for cosmological dust may be incorrect.

Stellar and Ionized-Gas Kinematics of the Seyfert 1 Galaxy NGC 3516

We present an investigation of the structure of the emission line region in a sample of 12 single-peaked Active Galactic Nuclei (AGNs). Using the high resolution Hβ and Hα line profiles observed with the Isaac Newton Telescope (La Palma) we study the substructure in the lines (such as shoulders or bumps) which can indicate a disk or disk-like emission in Broad Line Regions (BLRs). Applying Gaussian analysis we found that both kinds of emission regions, BLR and NLR, are complex. In this sample the narrow (OIII) lines are composites of two components; NLR1 which have random velocities from ∼200 to 500 km s −1 and systematic velocities toward the blue from 20 to 350 km s −1 , and NLR2 with smaller random velocities (∼100−200 km s −1 ) and a redshift corresponding to the cosmological one. The BLR also have complex structure and we apply a two-component model assuming that the line wings originate in a very broad line region (VBLR) and the line core in an intermediate line region (ILR). The VBLR is assumed to be an accretion disk and the ILR a spherical emission region. The model fits very well the Hα and Hβ line profiles of the AGNs.

QSO 2237+0305 VR Light Curves from Gravitational LensES International Time Project Optical Monitoring

From the peak of a gravitational microlensing high-magnification event in the A component of QSO 2237+0305, which was accurately monitored by the Gravitational Lenses International Time Project collaboration, we derived new information on the nature and size of the optical V-band and R-band sources in the distant quasar. If the microlensing peak is caused by a microcaustic crossing, we first obtain that the standard accretion disk is a scenario more reliable/feasible than other typical axially symmetric models. Moreover, the standard scenario fits both the V-band and R-band observations with reduced χ2 values very close to 1. Taking into account all these results, a standard accretion disk around a supermassive black hole is a good candidate for the optical continuum main source in QSO 2237+0305. Second, using the standard source model and a robust upper limit on the transverse galactic velocity, we infer that 90% of the V-band and R-band luminosities are emitted from a region with a radial size less than 1.2 × 10-2 pc (=3.7 × 1016 cm, at a 2 σ confidence level).

A Study of the Correlation between the Amplification of the Fe Kα Line and the X-Ray Continuum of Quasars due to Microlensing

The luminous infrared galaxy Arp 299 (IC 694 + NGC 3690) is studied using optical integral field spectroscopy obtained with the INTEGRAL system, together with archival Hubble Space Telescope WFPC2 and NICMOS images. The stellar and ionized gas morphology shows ?-dependent variations due to the combined effects of the dust internal extinction and the nature and spatial distribution of the different ionizing sources. The two-dimensional ionization maps have revealed an off-nuclear conical structure of about 4 kpc in length, characterized by high-excitation conditions and a radial gradient in the gas electron density. The apex of this structure coincides with B1 region of NGC 3690, which in turn presents Seyfert-like ionization, high extinction, and a high velocity dispersion. These results strongly support the hypothesis that B1 is the true nucleus of NGC 3690, where an AGN is located. In the circumnuclear regions H II-like ionization dominates, while LINER-like ionization is found elsewhere. The H?-emitting sources with ages from 3.3 to 7.2 ? 106 yr, have masses of between 6 and 680 ? 106 M? and contribute about 45% to the bolometric luminosity (extinction corrected). The ionized (H?) and neutral (Na D) gas velocity fields show similar structure on scales of several hundred to about 1 kpc, indicating that these gas components are kinematically coupled. The kinematic structure is complex and on scales of about 0.2 kpc does not appear to be dominated by the presence of ordered, rotational motions. The large velocity dispersion measured in NGC 3690 indicates that this galaxy is the most massive of the system. The low velocity amplitude and dispersion of the interface suggest that the ionized gas is slowly rotating or in a close to quiescent phase.

DETECTION OF CHROMATIC MICROLENSING IN Q 2237 + 0305 A

We estimate the dust extinction laws in two intermediate-redshift galaxies. The dust in the lens galaxy of LBQS 1009-0252, which has an estimated lens redshift of zl 0.88, appears to be similar to that of the SMC, with no significant feature at 2175 A. Only if the lens galaxy is at a redshift of zl 0.3, which is completely inconsistent with the galaxy colors, luminosity, and location on the fundamental plane, can the data be fitted with a normal Galactic extinction curve. The dust in the zl = 0.68 lens galaxy for B028+357, whose reddened image lies behind a molecular cloud, requires a very flat ultraviolet extinction curve with (formally) RV = 12 ± 2. Both lens systems seem to have unusual extinction curves by Galactic standards.