On the relativistic iron line and soft excess in the Seyfert 1 galaxy Markarian 335

We report on a 133 ks XMM-Newton observation of the Seyfert 1 galaxy Markarian 335. The 0.4-12 keV spectrum contains an underlying power law continuum, a soft excess below 2 keV, and a double-peaked iron emission feature in the 6-7 keV range. We investigate the possibility that the double-peaked emission might represent the characteristic signature of the accretion disc. Detailed investigations show that a moderately broad, accretion disc line is most likely present, but that the peaks may be owing to narrower components from more distant material. The peaks at 6.4 and 7 keV can be identified, respectively, with the molecular torus in active galactic nucleus unification schemes, and very highly ionized, optically thin gas filling the torus. The X-ray variability spectra on both long (~100 ks) and short (~1 ks) timescales disfavour the recent suggestion that the soft excess is an artifact of variable, moderately ionized absorption.Comment: 6 pages, 2 figures, accepted for publication in MNRA

What is on Tap? The Role of Spin in Compact Objects and Relativistic Jets

We examine the role of spin in launching jets from compact objects across the mass scale. Our work includes a total of 37 Seyferts, 11 stellar-mass black holes, and 13 neutron stars. We find that when the Seyfert reflection lines are modeled with Gaussian line features (a crude proxy for inner disk radius and therefore spin), only a slight inverse correlation is found between the Doppler-corrected radio luminosity at 5 GHz (a proxy for jet power) and line width. When the Seyfert reflection features are fit with relativistically-blurred disk reflection models that measure spin, there is a tentative positive correlation between the Doppler-corrected radio luminosity and the spin measurement. Further, when we include stellar-mass black holes in the sample, to examine the effects across the mass scale, we find a slightly stronger correlation with radio luminosity per unit mass and spin, at a marginal significance (2.3 sigma confidence level). Finally, when we include neutron stars, in order to probe lower spin values, we find a positive correlation (3.3 sigma confidence level) between radio luminosity per unit mass and spin. Although tentative, these results suggest that spin may have a role in determining the jet luminosity. In addition, we find a slightly more significant correlation (4.4 sigma confidence level) between radio luminosity per Bolometric luminosity and spin, using our entire sample of black holes and neutrons stars. Again, although tentative, these relations point to the possibility that the mass accretion rate, i.e. Bolometric luminosity, is also important in determining the jet luminosity, in addition to spin. Our analysis suggests that mass accretion rate and disk or coronal magnetic field strength may be the "throttle" in these compact systems, to which the Eddington limit and spin may set the maximum jet luminosity that can be achieved.Comment: 14 pages, 13 Figures, ApJ Accepte

The relationship between X-ray variability amplitude and black hole mass in active galactic nuclei

We have investigated the relationship between the 2-10 keV X-ray variability amplitude and black hole mass for a sample of 46 radio-quiet active galactic nuclei observed by ASCA. Thirty-three of the objects in our sample exhibited variability over a time-scale of ~40 ks, and we found a significant anti-correlation between excess variance and mass. Unlike most previous studies, we have quantified the variability using nearly the same time-scale for all objects. Moreover, we provide a prescription for estimating the uncertainties in excess variance which accounts both for measurement uncertainties and for the stochastic nature of the variability. We also present an analytical method to predict the excess variance from a model power spectrum accounting for binning, sampling and windowing effects. Using this, we modelled the variance-mass relation assuming all objects have a universal twice-broken power spectrum, with the position of the breaks being dependent on mass. This accounts for the general form of the relationship but there is considerable scatter. We investigated this scatter as a function of the X-ray photon index, luminosity and Eddington ratio. After accounting for the dependence of excess variance on mass, we find no significant correlation with either luminosity or X-ray spectral slope. We do find an anti-correlation between excess variance and the Eddington ratio, although this relation might be an artifact owing to the uncertainties in the mass measurements. It remains to be established that enhanced X-ray variability is a property of objects with steep X-ray slopes or large Eddington ratios.Comment: 13 pages, 5 figures, accepted for publication in MNRA

The Microchannel X-ray Telescope for the Gamma-Ray Burst mission SVOM

We present the Microchannel X-ray Telescope, a new light and compact focussing telescope that will be flying on the Sino-French SVOM mission dedicated to Gamma-Ray Burst science. The MXT design is based on the coupling of square pore micro-channel plates with a low noise pnCCD. MXT will provide an effective area of about 50 cmsq, and its point spread function is expected to be better than 3.7 arc min (FWHM) on axis. The estimated sensitivity is adequate to detect all the afterglows of the SVOM GRBs, and to localize them to better then 60 arc sec after five minutes of observation.Comment: 12 pages, 8 figures, to be published in SPIE Astronomical Telescopes + Instrumentation, Montreal, June 201

Intensive HST, RXTE and ASCA Monitoring of NGC 3516: Evidence Against Thermal Reprocessing

During 1998 April 13-16, NGC 3516 was monitored almost continuously with HST for 10.3 hr in the UV and 2.8 d in the optical, and simultaneous RXTE and ASCA monitoring covered the same period. The X-rays were strongly variable with the soft (0.5-2 keV) showing stronger variations (~65% peak-to-peak) than the hard (2-10 keV; ~50% peak-to-peak). The optical continuum showed much smaller but highly significant variations: a slow ~2.5% rise followed by a faster ~3.5% decline. The short UV observation did not show significant variability. The soft and hard X-ray light curves were strongly correlated with no significant lag. Likewise, the optical continuum bands (3590 and 5510 A) were also strongly correlated with no measurable lag above limits of <0.15 d. However no significant correlation or simple relationship could be found for the optical and X-ray light curves. These results appear difficult to reconcile with previous reports of correlations between X-ray and optical variations and of measurable lags within the optical band for some other Seyfert 1s. These results also present serious problems for "reprocessing" models in which the X-ray source heats a stratified accretion disk which then reemits in the optical/ultraviolet: the synchronous variations within the optical would suggest that the emitting region is <0.3 lt-d across, while the lack of correlation between X-ray and optical variations would indicate, in the context of this model, that any reprocessing region must be >1 lt-d in size. It may be possible to resolve this conflict by invoking anisotropic emission or special geometry, but the most natural explanation appears to be that the bulk of the optical luminosity is generated by some other mechanism than reprocessing.Comment: 23 pages including 6 figures, accepted for publication in Ap

An X-ray Bright Nucleus in the Low Surface Brightness Galaxy UGC 6614

We report a study of the X-ray emission from the nuclear region of the low surface brightness (LSB) galaxy UGC 6614. Very little is known about the central objects in LSB galaxies especially their X-ray properties and X-ray spectra. In this study we have used XMM-Newton archival data to study the characteristics of the X-ray spectrum and the X-ray flux variability of the AGN in the LSB galaxy UGC 6614. The nucleus of UGC 6614 is very bright in X-ray emission with an absorption corrected 0.2-10.0 keV luminosity of ~1.1 x 10^{42} erg s^{-1}. The X-ray spectrum is found to be power-law type with a moderate column density. A short time scale of intensity variation and large X-ray flux is indicative of the presence of a black hole at the centre of this galaxy. Using the method of excess variance, we have determined the black hole mass to be ~0.12 x 10^{6} solar mass. The X-ray spectral properties are similar to that of the Seyfert I type AGNs. Our study thus demonstrates that although LSB galaxies are poor in star formation, they may harbour AGNs with X-ray properties comparable to that seen in more luminous spiral galaxies.Comment: 5 pages, 4 figures, Accepted for publication in MNRA

Discovery of Water Maser Emission in Five AGN and a Possible Correlation Between Water Maser and Nuclear 2-10 keV Luminosities

We report the discovery of water maser emission in five active galactic nuclei (AGN) with the 100-m Green Bank Telescope (GBT). The positions of the newly discovered masers, measured with the VLA, are consistent with the optical positions of the host nuclei to within 1 sigma (0.3 arcsec radio and 1.3 arcsec optical) and most likely mark the locations of the embedded central engines. The spectra of three sources, 2MASX J08362280+3327383, NGC 6264, and UGC 09618 NED02, display the characteristic spectral signature of emission from an edge-on accretion disk with maximum orbital velocity of ~700, ~800, and ~1300 km s^-1, respectively. We also present a GBT spectrum of a previously known source MRK 0034 and interpret the narrow Doppler components reported here as indirect evidence that the emission originates in an edge-on accretion disk with orbital velocity of ~500 km s^-1. We obtained a detection rate of 12 percent (5 out of 41) among Seyfert 2 and LINER systems with 10000 km s^-1 < v_sys < 15000 km s^-1. For the 30 nuclear water masers with available hard X-ray data, we report a possible relationship between unabsorbed X-ray luminosity (2-10 keV) and total isotropic water maser luminosity, L_{2-10} proportional to L_{H2O}^{0.5+-0.1}, consistent with the model proposed by Neufeld and Maloney in which X-ray irradiation and heating of molecular accretion disk gas by the central engine excites the maser emission.Comment: 16 pages, 5 tables, 3 figures, to appear in the November 10, 2006, v651n2 issue of the Astrophysical Journa

Hard X-ray spectral variability of the brightest Seyfert AGN in the Swift/BAT sample

Aims: We used data from the 58 month long, continuous Swift/Burst Alert Telescope (BAT) observations of the five brightest Seyfert galaxies at hard X-rays, to study their flux and spectral variability in the 20-100 keV energy band. The column density in these objects is less than 10^24 cm-2, which implies that the Swift/BAT data allow us to study the "true" variability of the central source. Results: All objects show significant variations, with an amplitude which is similar to the AGN variability amplitude at energies below 10 keV. We found evidence for an anti-correlation between variability amplitude and black hole mass. The light curves in both bands are well correlated, with no significant delays on time scales as short as 2 days. NGC 4151 and NGC 2110 do not show spectral variability, but we found a significant anti-correlation between hardness ratios and source flux in NGC 4388 (and NGC 4945, IC 4329, to a lesser extent). This "softer when brighter" behaviour is similar to what has been observed at energies below 10 keV, and cannot be explained if the continuum varies only in flux; the intrinsic shape should also steepen with increasing flux. Conclusions: The presence of significant flux variations indicate that the central source in these objects is intrinsically variable on time scales as short as 1-2 days. The intrinsic slope of the continuum varies with the flux (at least in NGC 4388). The positive "spectral slope-flux" correlation can be explained if the temperature of the hot corona decreases with increasing flux. The lack of spectral variations in two objects, could be due to the fact that they may operate in a different "state", as their accretion rate is less than 1% of the Eddington limit (significantly smaller than the rate of the other three objects in the sample).Comment: Accepted (29/10/11) for publication in A&A (12 pages, containing 14 figures and 2 tables). (Abstract shortened --see link for the complete one

The Sloan Digital Sky Survey Reverberation Mapping Project: the XMM-Newton X-ray source catalog and multi-band counterparts

The XMM-RM project was designed to provide X-ray coverage of the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) field. 41 XMM-Newton exposures, placed surrounding the Chandra AEGIS field, were taken, covering an area of 6.13 deg^2 and reaching a nominal exposure depth of ~15 ks. We present an X-ray catalog of 3553 sources detected in these data, using a PSF-fitting algorithm and a sample selection threshold that produces a ~5% fraction of spurious sources. In addition to the PSF-fitting likelihood, we calculate a second source reliability measure based on Poisson theory using source and background counts within an aperture. Using the Poissonian likelihood, we select a sub-sample with a high purity and find that it has similar number count profiles to previous X-ray surveys. The Bayesian method "NWAY" was employed to identify counterparts of the X-ray sources from the optical Legacy and the IR unWISE catalogs, using a 2-dimensional unWISE magnitude-color prior created from optical/IR counterparts of Chandra X-ray sources. A significant number of the optical/IR counterparts correspond to sources with low detection likelihoods, proving the value of retaining the low-likelihood detections in the catalog. 932 of the XMM-RM sources are covered by SDSS spectroscopic observations. 89% of them are classified as AGN, and 71% of these AGN are in the SDSS-RM quasar catalog. Among the SDSS-RM quasars, 80% are detectable at the depth of the XMM observations.Comment: ApJS accepted. 20 pages, 16 figure