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Newton Observations (newton + observation)
Selected AbstractsThe narrow-line quasar NAB 0205 + 024 observed with XMM,NewtonMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2004L. C. Gallo ABSTRACT The XMM,Newton observation of the narrow-line quasar NAB 0205+024 reveals three striking differences since it was last observed in X-rays with ASCA. First, the 2,10 keV power law is notably steeper. Secondly, a hard X-ray flare is detected, very similar to that seen in I Zw 1. Thirdly, a strong and broad emission feature is detected with the bulk of its emission redward of 6.4 keV, and extending down to ,5 keV in the rest frame. The most likely explanation for the broad feature is neutral iron emission emitted from a narrow annulus of an accretion disc close to the black hole. The hard X-ray flare could be the mechanism that illuminates this region of the disc, allowing for the emission line to be detected. The combination of effects can be understood in terms of the ,thunder-cloud' model proposed by Merloni & Fabian. [source] An XMM,Newton observation of Ark 120: the X-ray spectrum of a ,bare' Seyfert 1 nucleusMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2004S. Vaughan ABSTRACT We report on a long (100 ks) XMM,Newton observation of the bright Seyfert 1 galaxy Arakelian 120. The source previously showed no signs of intrinsic reddening in its infrared,ultraviolet continuum and previous observations had shown no evidence for ionized absorption in either the ultraviolet or X-ray bands. The new XMM,Newton Reflection Grating Spectrometer data place tight limits on the presence of an ionized X-ray absorber and confirm that the X-ray spectrum of Ark 120 is essentially unmodified by intervening matter. Thus Ark 120 can be considered a ,bare' Seyfert 1 nucleus. This observation therefore offers a clean view of the X-ray spectrum of a ,normal' Seyfert galaxy free from absorption effects. The spectrum shows a Doppler broadened iron emission line (FWHM , 3 × 104 km s,1) and a smooth, continuous soft excess which appears to peak at an energy ,0.5 keV. This adds weight to the claim that genuine soft excesses (i.e. those due to a real steepening of the underlying continuum below ,2 keV) are ubiquitous in Seyfert 1 spectra. However, the detailed shape of the excess could not be reproduced by any of the simple models tested (power laws, blackbodies, Comptonized blackbodies, accretion disc reflection). This observation therefore demonstrates both the need to understand the soft excess (as a significant contributor to the luminosity of most Seyfert 1s) and the inability of the existing, simple models to explain it. [source] An XMM,Newton observation of Ton S180: constraints on the continuum emission in ultrasoft Seyfert galaxiesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2002S. Vaughan Abstract We present an XMM,Newton observation of the bright, narrow-line, ultrasoft type 1 Seyfert galaxy Ton S180. The 0.3,10 keV X-ray spectrum is steep and curved, showing a steep slope above 2.5 keV (,, 2.3) and a smooth, featureless excess of emission at lower energies. The spectrum can be adequately parametrized using a simple double power-law model. The source is strongly variable over the course of the observation but shows only weak spectral variability, with the fractional variability amplitude remaining approximately constant over more than a decade in energy. The curved continuum shape and weak spectral variability are discussed in terms of various physical models for the soft X-ray excess emission, including reflection off the surface of an ionized accretion disc, inverse Compton scattering of soft disc photons by thermal electrons, and Comptonization by electrons with a hybrid thermal/non-thermal distribution. We emphasize the possibility that the strong soft excess may be produced by dissipation of accretion energy in the hot, upper atmosphere of the putative accretion disc. [source] A systematic study of low-mass X-ray binaries in the M31 globular cluster systemMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2010Mark B. Peacock ABSTRACT We investigate low-mass X-ray binaries (LMXBs) in the M31 globular cluster (GC) system using data from the 2XMMi catalogue. These X-ray data are based on all publicly available XMM,Newton observations of the galaxy. This new survey provides the most complete and homogeneous X-ray survey of M31's GCs to date, covering >80 per cent of the confirmed old clusters in the galaxy. We associate 41 X-ray sources with confirmed old clusters in the recent M31 cluster catalogue of Peacock et al. Comparing these data with previous surveys of M31, it is found that three of these clusters are newly identified, including a bright transient source in the cluster B128. Four additional clusters, that are not detected in these 2XMMi data, have previously been associated with X-ray sources from Chandra or ROSAT observations. Including these clusters, we identify 45 clusters in M31 which are associated with X-ray emission. By considering the latest optical GC catalogues, we identify that three of the previously proposed X-ray clusters are likely to be background galaxies and two have stellar profiles. We consider the properties of LMXB hosting clusters and confirm significant trends between the presence of an LMXB and the metallicity, luminosity and stellar collision rate of a cluster. We consider the relationship between the luminosity and stellar collision rate of a cluster and note that LMXB hosting clusters have higher than average stellar collision rates for their mass. Our findings strongly suggest that the stellar collision rate is the dominant parameter related to the presence of LMXBs. This is consistent with the formation of LMXBs in GCs through dynamical interactions. [source] The impact of mergers on relaxed X-ray clusters , III.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2008Effects on compact cool cores ABSTRACT We use the simulations presented in Poole et al. to examine the effects of mergers on the properties of cool cores in X-ray clusters. Motivated by recent Chandra and XMM,Newton observations, we propose a scheme for classifying the morphology of clusters based on their surface brightness and entropy profiles. Three dominant morphologies emerge: two hosting compact cores and central temperatures which are cool [CCC (compact cool core) systems] or warm [CWC (compact warm core) systems] and one hosting extended cores which are warm [EWC (extended warm core) systems]. In the cases we have studied, CCC states are disrupted only after direct collisions with merging cluster cores. This can happen in head-on collisions or during second pericentric passage in off-axis mergers. By the time they are relaxed, our remnant cores have generally been heated to warm core (CWC or EWC) states but subsequently recover CCC states by the end of the simulation. The only case resulting in a long-lived EWC state is a slightly off-axis 3:1 merger for which the majority of shock heating occurs during the accretion of a low-entropy stream formed from the disruption of the secondary's cool core. Since tdyn,tcool for all our relaxing merger remnant cores, compression prevents their core temperatures from falling until after they relax to the compact states allowed by their remnant central entropies. This naturally explains the population of relaxed CWC systems observed in recent Chandra and XMM,Newton observations with no need to invoke active galactic nuclei feedback. The morphological segregation in the Lx,Tx scaling relation noted by McCarthy et al. is qualitatively reflected in the results of our mergers as well. However, none of the cases we have studied produces systems with sufficiently high central entropies to account for the most underluminous EWC systems observed. Lastly, mergers do not efficiently mix the intracluster medium in our simulations. As a result, merging systems which initially host central metallicity gradients do not yield merger remnants with flat metallicity profiles. Taken together, these results suggest that once formed, compact core systems are remarkably stable against disruption from mergers. It remains to be demonstrated exactly how the sizable observed population of extended core systems was formed. [source] Constraints on decaying dark matter from XMM,Newton observations of M31MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2008Alexey Boyarsky ABSTRACT We derive constraints on the parameters of the radiatively decaying dark matter (DM) particle, using the XMM,Newton EPIC spectra of the Andromeda galaxy (M31). Using the observations of the outer (5,13 arcmin) parts of M31, we improve the existing constraints. For the case of sterile neutrino DM, combining our constraints with the latest computation of abundances of sterile neutrinos in the Dodelson,Widrow (DW) scenario, we obtain the lower mass limit ms < 4 keV, which is stronger than the previous one ms < 6 keV, obtained recently by Asaka, Laine & Shaposhnikov. Comparing this limit with the most recent results on Lyman , forest analysis of Viel et al. (ms > 5.6 keV), we argue that the scenario in which all the DM is produced via the DW mechanism is ruled out. We discuss, however, other production mechanisms and note that the sterile neutrino remains a viable candidate for DM, either warm or cold. [source] XMM,Newton observations of UW CrB: detection of X-ray bursts and evidence for accretion disc evolutionMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2005Pasi Hakala ABSTRACT UW CrB (MS 1603+2600) is a peculiar short-period X-ray binary that exhibits extraordinary optical behaviour. The shape of the optical light curve of the system changes drastically from night to night, without any changes in overall brightness. Here we report X-ray observations of UW CrB obtained with XMM,Newton. We find evidence for several X-ray bursts, confirming a neutron star primary. This considerably strengthens the case that UW CrB is an accretion disc corona system located at a distance of at least 5,7 kpc (3,5 kpc above the Galactic plane). The X-ray and Optical Monitor (ultraviolet,optical) light curves show remarkable shape variation from one observing run to another, which we suggest are due to large-scale variations in the accretion disc shape resulting from a warp that periodically obscures the optical and soft X-ray emission. This is also supported by the changes in phase-resolved X-ray spectra. [source] XMM,Newton observations of warm absorbers in PG quasarsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2004C. E. Ashton ABSTRACT We present XMM,Newton European Photon Imaging Camera observations of warm absorbers in the quasars PG 1114+445 and PG 1309+355, both of which exhibit evidence for absorption by warm material in the line of sight. We find the absorption in PG 1114+445 to be in two phases, a ,hot' phase with a log ionization parameter, ,, of 2.57, and a ,cooler' phase with log ,= 0.83; an unresolved transition array (UTA) of M-shell iron is observed in the cooler phase. The absorption in this quasar is similar to that observed in the Seyfert 1 NGC 3783. The absorption in PG 1309+355 consists of a single phase, with log ,= 1.87. The absorbing gas lies at distances of 1018,1022 cm from the continuum radiation sources in these active galactic nuclei (AGN), which suggests that it could originate in a wind emanating from a molecular torus. We derive distances assuming that these X-ray warm absorbers have the same velocity as the ultraviolet warm absorbers observed in these quasars. The distances to the warm absorbers from the central continuum source scale approximately with the square root of the AGN ionizing luminosity, a result consistent with the warm absorber originating as a torus wind. The kinetic luminosities of these outflowing absorbers represent insignificant fractions (<10,3) of the energy budgets of the AGN. [source] XMM,Newton observations of GB B1428+4217: confirmation of intrinsic soft X-ray absorptionMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2004M. A. Worsley ABSTRACT We report the results of XMM,Newton observations of the X-ray bright, radio-loud blazar GB B1428+4217 at a redshift of z= 4.72. We confirm the presence of soft X-ray spectral flattening at energies ,0.7 keV as reported in previous ROSAT and BeppoSAX observations. At hard X-ray energies, the spectrum is consistent with a power law, although we find that the spectral slope varied between both XMM,Newton observations and it is also significantly different from that reported previously. Whilst we cannot rule out intrinsic cold absorption to explain the spectral depression, we favour a dust-free warm absorber. Cold absorption requires a column density ,1.4,1.6 × 1022 cm,2, whilst a warm absorber could have up to ,1023 cm,2 and an ionization parameter ,102. The spectrum of GB B1428+4217 shows remarkable parallels with that of the z= 4.4 blazar PMN J0525,3343, in which the available evidence is also most consistent with a warm absorber model. [source] Detection of type 2 quasars in the radio galaxies B3 0731+438 and 3C 257MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2003P. M. Derry ABSTRACT We present XMM,Newton observations and spectral fitting of two high-redshift, [O iii]-luminous, narrow-line radio galaxies, B3 0731+438 and 3C 257. Their X-ray continua are well fitted by a partial covering model with intrinsically unabsorbed and absorbed power-law components. The spectral models indicate that both objects harbour highly obscured nuclei, with NH, 0.5,2 × 1023 cm,2. Correcting for this absorption we find large intrinsic luminosities in the range LX, 0.2,1 × 1045 erg s,1. Thus, both sources are type 2 quasars. [source] Hard X,ray observations of Extremely Red ObjectsASTRONOMISCHE NACHRICHTEN, Issue 1-2 2003M. Brusa Abstract Extremely Red Objects (EROs, R,K>5) constitute a heterogeneous class of extragalactic sources including high redshift elliptical galaxies, dusty star,forming systems and heavily obscured AGNs. Hard X-ray observations provide an unique and powerful tool to uncover obscured nuclear or star,forming activity. We present the results of XMM,Newton observations of the largest sample of EROs available to date (about 450 objects over a contiguous area of 700 arcmin2). Five of the 46 hard X,ray selected sources brighter than 3 × 10,15 cgs in the 2,10 keV band, are associated with EROs. All of the X-ray detected EROs show rather extreme X,ray,to,optical flux ratios, suggesting the presence of highly obscured AGN activity. We also report on the X,ray stacking analysis of spectroscopically identified EROs in the Chandra Deep Field South. [source] | ||||||||||