Matthew A. Malkan

Ultraviolet variability of NGC 5548 - Dynamics of the continuum production region and geometry of the broad-line region

Data from the 1989-1990 IUE monitoring of the Seyfert galaxy NGC 5548 are used here to analyze the continuum variability properties of the galaxy and to derive the structure or its emission-line region. The mean shape of the UV continuum is well fit by an accretion disk model with a given black hole mass and an additional component required to reproduce the observed soft X-ray flux. The continuum fluctuation power spectrum is very steep, with most of the variance coming from about 1 yr time scales. The entire optical/UV continuum rises and falls almost simultaneously, so that the logarithmic slope of the power spectrum is nearly the same for all bands, but the flux at higher photon frequencies varies with larger amplitude. The emission-line material around the nucleus may best be described by a highly ionized inner zone of high and nearly constant pressure that stretches about 4-14 light-days from the center and an outer, more weakly ionized zone of considerably lower ionization at least 20-30 light-days out. 44 refs.

Luminosity dependent covering factor of the dust torus around AGN viewed with AKARI and WISE

Yoshiki Toba∗1,2, Shinki Oyabu3, Hideo Matsuhara2, Matthew A. Malkan4, Daisuke Ishihara3, Takehiko Wada2, Youichi Ohyama5, Satoshi Takita2, and Chisato Yamauchi6 1The Graduate University for Advanced Studies (SOKENDAI), Japan 2Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Japan 3Graduate School of Science, Nagoya University, Japan 4Department of Physics and Astronomy, University of California, USA 5Institute of Astronomy and Astrophysics, Taiwan 6Astronomy Data Center, National Astronomical Observatory of Japan, Japan

The NICMOS parallel program: Grism survey results and emission-line candidates

In its parallel pointings, NICMOS has given us a unique window on the evolving Universe. We have analyzed the deep parallel NICMOS grism observations, covering more than 60 square arcminutes and down to continuum H1.6=22 in the deepest fields. With this slitless grism spectroscopy, NICMOS reveals 33 new line-emitting galaxies. In most cases, the single emission line is likely to be Hα at 0.7<z<1.9, and their volume density is comparable to that of the brighter galaxies selected by the Lyman break method. Our first Keck LRIS spectrum of one of these galaxies confirms this identification. The inferred star formation rates for the emission-line galaxies are 2–480M./year. We present the details of the grism survey and our analysis so far.