The soft X-ray excess AGN RE J2248-511

We model the spectral energy distribution of the ultrasoft broad-line AGN RE J2248-511 with Comptonised accretion disc models. These are able to reproduce the steep optical and ultrasoft X-ray slopes, and the derived black hole mass is consistent with independent mass estimates. This AGN displays properties of both broad and narrow line Seyfert 1 galaxies, but we conclude that it is intrinsically a `normal' Seyfert 1 viewed at high inclination angle.Comment: 4 pages, 1 figure. MG10 Proceeding

The Reddest DR3 SDSS/XMM Quasars

We have cross-correlated the SDSS DR3 Schneider et al. (2005) quasar catalog with the XMM-Newton archive. Color and redshift selections (g - r > 0.5 and 0.9 z < 2.1) result in a sample of 17 red, moderate redshift quasars. The redshift selection minimizes possible contamination due to host galaxy emission and Lyalpha forest absorption. Both optical and X-ray information are required to distinguish between the two likely remaining causes of the red colors: 1) dust-reddening and 2) an intrinsically red continuum. We find that 7 of 17 quasars can be classified as probable `intrinsically red' objects. These 7 quasars have unusually broad MgII emission lines (=10,500 km s^{-1}), moderately flat, but unabsorbed X-ray spectra =1.66+/-0.08), and low accretion rates (mdot/mdot_{Edd}} ~ 0.01). We suggest low accretion rates as a possible physical explanation for quasars with intrinsically red optical continua. We find that 8 of 17 quasars can be classified as dust-reddened. Three of these have upper-limits on the absorption column from X-ray spectral fits of N_H = 3-13 x 10^{22} cm^2, while the other five quasars must be absorbed by at least N_H = 10^{23} cm^2 in order to be consistent with a comparably selected alpha_{ox}-l_{uv} distribution. Two objects in the sample are unclassified.Comment: 20 pages, 12 figures, Accepted for publication in Ap

X-ray selected active galactic nuclei with red optical continua

We discuss the properties of X-ray selected `red' AGN from the RIXOS sample. These are Seyfert 1 galaxies and quasars whose optical continua are relatively soft, ie. with an energy index, alpha_opt>2. There are 14 objects in the RIXOS sample which satisfy this criterion and they cover a range in redshift from z=0.08 to 1.27. Of these, two have characteristics which suggest that the continuum is intrinsically red, ie. an optical continuum which does not appear to have been significantly reddened by dust or to have contaminating light from the host galaxy. A further three objects show evidence of being absorbed by cold gas and dust with columns of up to 1e22 cm-2. The data are inconclusive on the remaining AGN.Comment: 9 pages, 3 figures, accepted for publication in the Monthly Notices of the Royal Astronomical Society. Also available from http://www.mssl.ucl.ac.uk/www_astro/preprints/preprints.htm

Constraining the black hole mass and accretion rate in the narrow-line Seyfert 1 RE J1034+396

We present a comprehensive study of the spectrum of the narrow-line Seyfert 1 galaxy RE J1034+396, summarizing the information obtained from the optical to X-rays with observations from the William Herschel 4.2m Telescope (WHT), the Hubble Space Telescope, the Extreme UltraViolet Explorer, ROSAT, ASCA and BeppoSAX. The BeppoSAX spectra reveal a soft component which is well-represented by two blackbodies with kT of about 60 eV and 160 eV, mimicking that expected from a hot, optically-thick accretion disc around a low-mass black hole. This is borne out by our modeling of the optical to X-ray nuclear continuum, which constrains the physical parameters of a NLS1 for the first time. The models demonstrate that RE J1034+396 is likely to be a system with a nearly edge-on accretion disk (60 to 75 degrees from the disk axis), accreting at nearly Eddington rates (0.3 to 0.7 L_edd) onto a low mass (about 2 million solar masses) black hole (abridged).Comment: ApJ accepte

RE J2248-511 - Not all variable, ultrasoft, X-ray AGN have narrow Balmer lines

We present ASCA data on RE J2248-511, extending existing optical and soft X-ray coverage to 10 keV, and monitoring the soft component. These data show that, despite a very strong ultrasoft X-ray excess below 0.3 keV and a soft 0.3--2 keV spectral index in earlier ROSAT data, the hard X-ray spectrum (alpha~ -0.8; 0.6-10 keV) is typical of type 1 AGN, and the soft component has since disappeared. Optical data taken at two different epochs show that the big blue bump is also highly variable. The strength of the ultrasoft X-ray component and the extreme variability in RE J2248-511 are reminiscent of the behaviour observed in many narrow line Seyfert 1s (NLS1s). However, the high energy end of the ROSAT spectrum, the ASCA spectrum and the Balmer line full widths at half maximum of ~3000 km/s in RE J2248-511, are typical of normal Seyfert 1 AGN. The change in the soft X-ray spectrum as observed in the ROSAT and ASCA data is consistent with the behaviour of Galactic Black Hole Candidates (GBHCs) as they move from a high to a low state, ie. a fall in the ultrasoft component and a hardening of the X-ray continuum. This GBHC analogy has also been proposed for NLS1s. Alternatively, the variability may be caused by opacity changes in a hot, optically-thin corona which surrounds a cold, dense accretion disc; this was first suggested by Guainazzi et al. for 1H0419-577, an object which shows remarkably similar properties to RE J2248-511.Comment: 10 pages, 4 figures. Accepted for Monthly Notices of RA