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List of accepted poster contributions
Jason Gofford, Keele University
The highly ionized outflows of MR2251-178 and 3C445
Since its original detection in an EINSTEIN spectra of MR2251-178, the soft X-ray warm absorber has typically become regarded as an almost ubiquitous component of most AGN spectra. Over the last decade or so evidence has been mounting for the presence of additional highly ionized, high velocity, outflows in the Fe K band of several objects. Here, we present our recent results from analysis of Suzaku/Swift BAT spectra from MR2251-178, a radio-quiet quasar, and 3C445, a broad-line radio galaxy. In both objects we detect high velocity outflows in the Fe_K band from H- and/or He-like iron with outflow velocities of ~0.1c and ~0.05c, respectively. We comparatively discuss the properties of the absorbing gas in each object and, in light of their differing classifications, also discuss how they fit into the unified AGN model.
Victoria Heard, University of Leicester
The X-ray Source Population in the Galactic Centre Region
The obscuration of the Galactic Centre (GC) by interstellar gas and dust means that constraining the nature of the GC source population is a significant challenge. We use archive XMM-Newton observations to investigate the X-ray properties of a sample of 877 sources within a 5 x 5 degree region around the GC. The spatial and flux distributions of the sample suggest that many of the sources are associated with the old stellar population and are most likely accreting X-ray binaries. The spectral properties support this scenario and indicate that the majority of bright sources are low-mass X-ray binaries (LMXB) and the fainter sources are cataclysmic variables (CV) and quiescent LMXBs. We cross-correlated our XMM-Newton selected sample with Chandra data to investigate the long-term variability history of the sources and discover that the faint and bright populations behave in a similar manner. This implies that the fainter sources are the less-luminous counterparts to the brighter ones.
Sarah Hutton, Durham University
Constraining the SEDs of AGN to find Super-Eddington objects
The aim is to study AGN whose accretion disc component can be well constrained by optical/UV and X-ray data. We have constructed SEDs of 192 SDSS AGN which have XMM-Newton spectra. Out of this sample, 52 objects also had XMM-Optical Monitor (OM) data which extends the SDSS optical coverage into the UV. We develop a new model to explain the origins of the X-ray soft excess linking this to upscattered photons from the disc. The new model allows investigation of the accretion disc's dependency on the black hole mass. The MBH is constrained from measurements of the H-beta line FWHM and the continuum at 5100 Angstroms, combined with the BLR Size-Luminosity relationship. This results in a range of 2x10^5 to 3x10^9 Msun. This model is capable of modeling a wide variety of SEDs without introducing additional components.
Sean Farrell, University of Leicester
Exploring the Nature of the Brightest Hyper-luminous X-ray Source
Ultra-luminous X-ray sources (ULXs) are non-nuclear extragalactic objects with luminosities in excess of the Eddington limit for stellar mass black holes, implying black hole masses in the intermediate range (i.e. ~100 - 10,000 Msun). However, various theories can account for the extreme luminosities without a particularly massive compact object. The recent discovery of the most luminous ULX with a record breaking luminosity of ~1E42 erg/s cannot be easily explained using alternative methods, and is the current front runner for establishing the existence of intermediate mass black holes. I will present here a review of the current state of knowledge on this intriguing source, and will outline the results of the latest multi-wavelength follow-up data that we have acquired, which continue to suggest a black hole in excess of 500 Msun.
Andrew Sutton, Durham University
The most extreme ULXs
We present a sample of 10 nearby (D < 100 Mpc) extreme luminosity candidate ultraluminous X-ray sources (ULXs, with L(x) > 5e40erg/s), identified from a cross-correlation of the RC3 catalogue of galaxies with the 2XMM catalogue. Six of the sample have also been observed by Chandra. Of the 10 sources, six reside in the arms of spiral galaxies, one in the disc of an edge on spiral galaxy and the remaining three close to large elliptical galaxies. Five of the sources were initially identified as candidate hyperluminous X-ray sources (HLXs), including all three sources in elliptical galaxies. However, three of these candidates are rejected as HLXs. Two have optical counterparts indicating a high likelihood they are AGNs; the third is resolved into multiple objects by an archival Chandra observation. The sample is characterised by X-ray spectra that appear slightly harder than average for less-luminous ULXs, and temporal variability on timescales of months - years is seen in all sources with multiple observations. We discuss the implications for the nature of these sources.
Kian Momtahan, University of Bristol
The effects of warm absorbers on IRAS 13349+2438
The radio quiet quasar IRAS 13349+2438 was observed on two separate occasions by XMM-Newton in 2000 and 2006. Analysis of the former observations (Sako el al) highlighted the existence of a number of absorption features which could be characterized by two distinct zones of absorption by warm ionized gas clouds (warm absorbers) close to the Active Galactic Nucleus (AGN). We have analyzed the RGS observation using XSTAR warm absorber models in order obtain a detailed picture of the absorber properties around the AGN. These observations provide additional insight into the ionization and velocity structure of the absorber, and its variability
Veronica Taipe Sidoti, University of Leicester
The Host Galaxies of X-ray selected AGN
We study the properties of the host galaxies of X-ray selected AGN using a large sample drawn from the XMM-Newton 2XMMi catalogue which have statistically secure counterparts in SDSS DR7. The carefully-constructed sample consists of 3846 sources with galaxy morphology in SDSS and with X-ray to optical flux ratios characteristic of AGN. SDSS photometric redshifts are used to estimate absolute magnitudes, rest frame colours and luminosities. The sample has median redshift z~0.35. We find that the population of galaxies harbouring an AGN have have a significantly different observed frame colour distribution to that of a representative field galaxy sample. In the rest frame we find that this effect is due to our AGN galaxy sample having intrinsically bluer colours and a significant bias towards higher galaxy masses. The shift towards bluer colours can be related to enhanced star formation, or to an unobscured AGN contribution. We use near-IR data from UKIDSS LAS and 2MASS, available for 40% of the sample, to constrain the AGN contribution. We also investigate how the main AGN parameters (i.e. X-ray luminosity and hardness ratios) relate to the properties of the host galaxies.
Mari Kolehmainen, Durham University
High mass accretion rate spectra and the spin of GX 339-4
We analyse quasi-simultaneous XMM-Newton and RXTE high mass accretion rate spectra from the black hole binary (BHB) GX 339-4 in both the soft intermediate state (SIMS) and the soft, disc dominated state. We compare these observed disc spectra with the best current theoretical models (BHSPEC: Davis et al. 2006) to constrain the black hole spin as well as giving some constraints on the vertical structure of the disc. We show that the extremely broad iron line seen in the SIMS depends very strongly on the assumed continuum and absorption column. Allowing the absorption column to be free gives a much narrower line, making the spin derived from the iron line consistent with that obtained from disc spectral fitting.
Floyd Jackson, Durham University
The Ultraluminous X-ray Source Population in M82: Scouting for ULXs with GNOM82ES
M82 is an X-ray bright star forming galaxy in the local universe, situated at a distance of 3.89 Mpc. Within M82 lie a number of bright X-ray point sources, some of which are known and studied ULXs. The most well studied of these is M82 X-1, the brightest ULX in the local universe, with luminosities reaching 10^41 erg s^-1. A number of less bright ULXs and ULX candidates also lie withing the galaxy. With the use of NASA's CHANDRA observatory, the Great NASA Obersvatories M82 Extended Survey (GNOM82ES) has recently yielded four 120 ks X-ray observations of M82. Within this data, the brightest of the ULXs present the major caveat of pile-up. In this poster, I will present the analysis of the CHANDRA data, and the subsequent spectral and timing result of the X-ray visible ULXs and ULX candidates in M82. I will also describe the methods used to overcome the effects of pile-up.
Andrew Lobban, Keele University
Results of a Deep, Contemporaneous Chandra HETG and Broad-band Suzaku observation of NGC 4051
We present the results of a deep Chandra HETG observation (~300 ks) of the highly variable narrow-line Seyfert 1 NGC 4051. The HETG spectrum reveals > 30 significant photo-ionised lines in both emission and absorption requiring four distinct ionisation absorbing zones for the gas, all outflowing with velocities < 1000 km/s. A selection of the strongest lines appear to be resolved with FWHM of ~600 km/s. The kinematics and location of the outflowing zones in relation to past studies of this source will be discussed. We also present the results of a quasi-simultaneous 350 ks broad-band Suzaku observation of NGC 4051 where we focus on the Fe K line profile which reveals significant detections of H-like and He-like Fe (including two further zones of highly ionised absorbing gas) plus additional significant emission at ~5.4 and ~5.9 keV. The details of the long-term variability of this source will also be discussed.
Rhaana Starling, University of Leicester
The discovery of a gamma-ray burst with an associated supernova
We report the discovery of nearby long, soft GRB 100316D, and the subsequent unveiling of its host galaxy and associated supernova. We study the extremely unusual prompt emission with time-resolved gamma-ray to X-ray spectrsoscopy and find that a thermal component in addition to the synchrotron spectrum is required. The host galaxy is a bright, blue galaxy with a highly disturbed morphology. We compare and contrast the X-ray emission and hosts for a subsample of GRBs with associated supernovae. GRB 100316D is an important addition to the current sparse sample of spectroscopically confirmed GRB-SNe, from which a better understanding of long GRB progenitors and the GRB-SN connection can be gleaned.