The galaxy NGC1512 is interacting with the smaller galaxy NGC1510 and shows a peculiar morphology, characterised by two extended arms immersed in an HI disc whose size is about four times larger than the optical diameter of NGC1512. For the first time we performed a deep X-ray observation of the galaxies NGC1512 and NGC1510 with XMM-Newton to gain information on the population of X-ray sources and diffuse emission in a system of interacting galaxies. We identified and classified the sources detected in the XMM-Newton field of view by means of spectral analysis, hardness-ratios calculated with a Bayesian method, X-ray variability, and cross-correlations with catalogues in optical, infrared, and radio wavelengths. We also made use of archival Swift (X-ray) and Australia Telescope Compact Array (radio) data to better constrain the nature of the sources detected with XMM-Newton. We detected 106 sources in the energy range of 0.2-12keV, out of which 15 are located within the D_25_ regions of NGC1512 and NGC1510 and at least six sources coincide with the extended arms. We identified and classified six background objects and six foreground stars. We discussed the nature of a source within the D_25_ ellipse of NGC1512, whose properties indicate a quasi-stellar object or an intermediate ultra-luminous X-ray source. Taking into account the contribution of low-mass X-ray binaries and active galactic nuclei, the number of high-mass X-ray binaries detected within the D_25_ region of NGC1512 is consistent with the star formation rate obtained in previous works based on radio, infrared optical, and UV wavelengths. We detected diffuse X-ray emission from the interior region of NGC1512 with a plasma temperature of kT=0.68(0.31-0.87)keV and a 0.3-10keV X-ray luminosity of 1.3E+38erg/s, after correcting for unresolved discrete sources.
We present the spectral analysis of an 87ks XMM-Newton observation of Draco, a nearby dwarf spheroidal galaxy. Of the approximately 35 robust X-ray source detections, we focus our attention on the brightest of these sources, for which we report X-ray and multiwavelength parameters. While most of the sources exhibit properties consistent with active galactic nuclei, few of them possess the characteristics of low-mass X-ray binaries (LMXBs) and cataclysmic variable (CVs). Our analysis places constraints on the population of X-ray sources with LX>3x10^33^erg/s in Draco, suggesting that there are no actively accreting black hole and neutron star binaries. However, we find four sources that could be quiescent state LMXBs/CVs associated with Draco. We also place constraints on the central black hole luminosity and on a dark matter decay signal around 3.5keV.
We present results of X-ray spectroscopy for TWA 5, a member of the young TW Hydrae association, observed with XMM-Newton. TWA 5 is a multiple system which shows H{alpha} emission, a signature typical of classical T Tauri stars, but no infrared excess. From this analysis of the RGS and EPIC spectra, we have derived the emission measure distribution vs. temperature of the X-ray emitting plasma, its abundances, and the electron density.
We report a deep X-ray survey of the young (~140Myr), rich open cluster NGC 2516 obtained with the EPIC camera on board the XMM-Newton satellite. By combining data from six observations, a high sensitivity, greater than a factor of 5 with respect to recent Chandra observations, has been achieved. Kaplan-Meier estimators of the cumulative X-ray luminosity distribution are built, statistically corrected for non members contaminants and compared to those of the nearly coeval Pleiades. The EPIC spectra of the X-ray brightest stars are fitted using optically thin model plasma with one or two thermal components. We detected 431 X-ray sources and 234 of them have as optical counterparts cluster stars spanning the entire NGC 2516 Main Sequence.
We present measurements of the Galactic halo's X-ray emission for 110 XMM-Newton sight lines selected to minimize contamination from solar wind charge exchange emission. We detect emission from few million degree gas on ~4/5 of our sight lines. The temperature is fairly uniform (median = 2.22x10^6^K, interquartile range = 0.63x10^6^K), while the emission measure and intrinsic 0.5-2.0keV surface brightness vary by over an order of magnitude (~(0.4-7)x10^-3^cm^-6^pc and ~(0.5-7)x10^-12^erg/cm2/s deg^-2^, respectively, with median detections of 1.9x10^-3^cm^-6^pc and 1.5x10^-12^erg/cm2/s deg^-2^, respectively). The high-latitude sky contains a patchy distribution of few million degree gas. This gas exhibits a general increase in emission measure toward the inner Galaxy in the southern Galactic hemisphere. However, there is no tendency for our observed emission measures to decrease with increasing Galactic latitude, contrary to what is expected for a disk-like halo morphology. The measured temperatures, brightnesses, and spatial distributions of the gas can be used to place constraints on models for the dominant heating sources of the halo. We provide some discussion of such heating sources, but defer comparisons between the observations and detailed models to a later paper.
We present an X-ray spectral analysis of 126 galaxies of the 12um galaxy sample (Rush et al. 1993, Cat. VII/157). By studying this sample at X-ray wavelengths, we aim to determine the intrinsic power, continuum shape and obscuration level in these sources. We improve upon previous works by the use of superior data in the form of higher signal-to-noise ratio spectra, finer spectral resolution and a broader bandpass from XMM-Newton. We pay particular attention to Compton thick active galactic nucleus (AGN) with the help of new spectral fitting models that we have produced, which are based on Monte Carlo simulations of X-ray radiative transfer, using both a spherical and torus geometry, and taking into account Compton scattering and iron fluorescence.
The XMM-OM Serendipitous Ultra-violet Source Survey (SUSS) is a
catalog of UV sources detected serendipitously by the Optical Monitor (OM)
on-board the European Space Agency's (ESA's) XMM-Newton observatory. It has
been created at the University College London's (UCL's) Mullard Space Science
Laboratory (MSSL) on behalf of ESA and is a partner resource to the 2XMM
serendipitous X-ray source catalogue.
The catalog contains source detections drawn from 2,417 XMM-OM observations in
up to three broad band UV filters made between 2000 February 24 and 2007 March
29. All datasets included were publicly available by 2007 May 01 but note
that, due to screening criteria, not all public observations are included
in this catalog. Taking account of substantial overlaps between observations,
the net sky area covered independently is 29 - 54 square degreees, depending
on UV filter. The primary content of the catalog is filter-dependent source
positions and magnitudes, and these are accompanied by profile diagnostics
and variability statistics.
The XMM-OM SUSS catalog contains 753,578 UV source detections above a
signal-to-noise threshold limit of 3-sigma which relate to 624,049 unique
objects. A significant fraction of sources (12% - UVW2, 11% - UVM2, 11.% -
UVW1) are visited more than once during XMM operation, and a large fraction
of sources (38% - UVW2, 23% - UVM2, 22% - UVW1) are observed more than once
per filter during an individual visit. UVW2, UVM2 and UVW1 refer to the filter
bandpasses defined in the Source Properties: Filter Set section of the MSSL
documentation for this catalog:
<a href="http://www.mssl.ucl.ac.uk/~mds/XMM-OM-SUSS/SourcePropertiesFilters.shtml">http://www.mssl.ucl.ac.uk/~mds/XMM-OM-SUSS/SourcePropertiesFilters.shtml</a>.
Consequently, the scope for science based on temporal source variability on
timescales of hours to years is broad.
The positional accuracy of the catalog detections is typically 1.0 arcsec
(1-sigma confidence radius) with a median positional error of 0.67 arcsec. The
median AB magnitude of the catalog detections in the three UV bands is 19.56
(UVW2), 20.23 (UVM2) and 20.69 (UVW1). 20% of sources have AB magnitudes
fainter than 20.28 (UVW2), 20.97 (UVM2) and 21.54 (UVW1).
As part of quality evaluation for the catalog, each field has been tested
for astrometric accuracy and visually screened for cosmetic problems,
compromising aspect anomalies, stray light, large extended sources and
telemetry dropouts. Observations affected by these issues (11.2%) have been
removed from the catalog sample. Furthermore, 2% of all observations were
selected at random where each source in this sample was tested for falsehood,
spuriousness and accuracy of quality flagging. The results of this detailed
screening are included in the full documentation.
The processing used to generate the catalog is based on the SAS8.0 pipeline
developed for the pipeline reduction of all XMM observations. This version
includes a number of significant improvements over the previous data
processing system (as used by the SSC in routine processing of XMM-Newton
data on behalf of ESA). These improvements include a more robust detection
scheme for sources close to the limit of sky background, refined quality
flagging and a higher success rate (90%) for refined aspect corrections.
Ultraluminous X-ray sources (ULXs) are some of the most enigmatic X-ray bright sources known to date. It is generally accepted that they cannot host black holes as large as those associated with active galaxies, but they appear to be significantly more luminous than their better understood Galactic X-ray binary (XRB) cousins, while displaying an intriguing combination of differences and similarities with them. Through studying large, representative samples of these sources we may hope to enhance our understanding of them. To this end, we derive a large catalogue of 650 X-ray detections of 470 ULX candidates, located in 238 nearby galaxies, by cross-correlating the 2XMM Serendipitous Survey with the Third Reference Catalogue of Bright Galaxies.
In this second paper of the series, we focus on the X-ray properties of the OB star population of NGC 6231. As a tool for our analysis, we performed a literature-based census of the OB stars in the field of view. More than one hundred objects are found, among which 30% can be associated with an X-ray source. All the O-type stars are detected in the X-ray domain as soft and reasonably strong emitters. [...] Among B-type stars, the detection rate is only about 25% in the sub-type range B0-B4 and remains mostly uniform throughout the different sub-populations while it drops significantly at later sub-types. The associated X-ray spectra are harder than those of O-type stars. Our analysis points towards the emission being rather associated with a physical (in a multiple system) PMS companion. However, we still observe a correlation between the bolometric luminosity of the B stars and the measured X-ray luminosity. [...]
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