A. M. Read

The XMM-Newton Serendipitous Survey - I. The role of XMM-Newton Survey Science Centre

This paper describes the performance of XMM-Newton for serendipitous surveys and summarises the scope and potential of the XMM-Newton Serendipitous Survey. The role of the Survey Science Centre (SSC) in the XMM-Newton project is outlined. The SSCs follow-up and identification programme for the XMM-Newton serendipitous survey is described together with the presentation of some of the first results.

XMM-Newton observations of NGC 253: Resolving the emission components in the disk and nuclear area

We describe the rst XMM-Newton observations of the starburst galaxy NGC 253. As known from previous X-ray observations, NGC 253 shows a mixture of extended (disk and halo) and point-source emission. The high XMM-Newton throughput allows a detailed investigation of the spatial, spectral and variability properties of these components simultaneously. We characterize the brightest sources by their hardness ratios, detect a bright X-ray transient70 00 SSW of the nucleus, and show the spectrum and light curve of the brightest point source (30 00 S of the nucleus, most likely a black-hole X-ray binary, BHXRB). The unresolved emission of two disk regions can be modeled by two thin thermal plasma components (temperatures of0.13 and 0.4 keV) plus residual harder emission, with the lower temperature component originating from above the disk. The nuclear spectrum can be modeled by a three temperature plasma (0.6, 0.9, and 6 keV) with the higher temperatures increasingly absorbed. The high temperature component most likely originates from the starburst nucleus, as no non-thermal component, that would point at a signicant contribution from an active nucleus (AGN), is needed. Assuming that type IIa supernova remnants (SNRs) are mostly responsible for the E> 4 keV emission, the detection with EPIC of the 6.7 keV line allows us to estimate a supernova rate within the nuclear starburst of 0.2 yr 1 . The unprecedented combination of RGS and EPIC also sheds new light on the emission of the complex nuclear region, the X-ray plume and the disk diuse emission. In particular, EPIC images reveal that the limb- brightening of the plume is mostly seen in higher ionization emission lines, while in the lower ionization lines, and below 0.5 keV, the plume is more homogeneously structured. The plume spectrum can again be modeled by a three temperature thermal plasma containing the two low temperature nuclear components (though less absorbed) plus an unabsorbed 0.15 keV component similar to the disk spectra. This points to new interpretations as to the make up of the starburst-driven outflow.

The second ROSAT PSPC survey of M 31 and the complete ROSAT PSPC source list

This paper reports the results of the analysis of the second ROSAT PSPC survey of M 31 performed in summer 1992. We compare our results with those of the rst survey, already published in Supper et al. (1997). Within the10: 7d eg 2 eld of view, 396 individual X-ray sources are detected in the second survey data, of which 164 are new detections. When combined with the rst survey, this result in a total of 560 X-ray sources in the eld of M 31. Their (0.1 keV{2.0 keV) fluxes range from 7 10 15 erg cm 2 s 1 to 7:6 10 12 erg cm 2 s 1 , and of these 560 sources, 55 are tentatively identied with foreground stars, 33 with globular clusters, 16 with supernova remnants, and 10 with radio sources and galaxies (including M 32). A comparison with the results of the Einstein M 31 survey reveals 491 newly detected sources, 11 long term variable sources, and 7 possible transient sources. Comparing the two ROSAT surveys, we come up with 34 long term variable sources and 8 transient candidates. For the M 31 sources, the observed luminosities range from 4 10 35 erg s 1 to 4 10 38 erg s 1 . The total (0.1 keV{2.0 keV) luminosity of M 31 is (3:4 0:3) 10 39 erg s 1 , distributed approximately equally between the bulge and disk. Within the bulge region, the luminosity of a possible diuse component combined with faint sources below the detection threshold is (2:0 0:5) 10 38 erg s 1 . An explanation in terms of hot gaseous emission leads to a maximum total gas mass of (1:0 0:3) 10 6 M.

The central region of M 31 observed with XMM-Newton. I. Group properties and diffuse emission

We present the results of a study based on an XMM-Newton Performance Verification observation of the central 30 arcmin of the nearby spiral galaxy M31. In the 34-ks European Photon Imaging Camera (EPIC) exposure, we detect 116 sources down to a limiting luminosity of 6 x 10^35 erg/s (0.3--12 keV, d = 760 kpc). The luminosity distribution of the sources detected with XMM-Newton flattens at luminosities below ~ 2.5 x 10^37 erg/s. We make use of hardness ratios for the detected sources in order to distinguish between classes of objects such as super-soft sources and intrinsically hard or highly absorbed sources. We demonstrate that the spectrum of the unresolved emission in the bulge of M31 contains a soft excess which can be fitted with a ~ 0.35-keV optically-thin thermal-plasma component clearly distinct from the composite point-source spectrum. We suggest that this may represent diffuse gas in the centre of M31, and we illustrate its extent in a wavelet-deconvolved image.We present the results of a study based on an XMM-Newton Performance Verification observation of the central 30´of the nearby spiral galaxy M 31. In the 34-ks European Photon Imaging Camera (EPIC) exposure, we detect 116 sources down to a limiting luminosity of #1 10#2 erg s-1 (0.3-12 keV, d=760 kpc). The luminosity distribution of the sources detected with XMM-Newton flattens at luminosities below

The extended X-ray halo of the Crab-like SNR G21.5-0.9

\sim

X-ray emission from the Sculptor galaxy NGC 300

2.5 1037 erg s-1 . We make use of hardness ratios for the detected sources in order to distinguish between classes of objects such as super-soft sources and intrinsically hard or highly absorbed sources. We demonstrate that the spectrum of the unresolved emission in the bulge of M 31 contains a soft excess which can be fitted with a

XMM-Newton survey of the low-metallicity open cluster NGC 2516

\sim

An X-ray view of the active nucleus in NGC 4258

0.35-keV optically-thin thermal-plasma component clearly distinct from the composite point-source spectrum. We suggest that this may represent diffuse gas in the centre of M 31, and we illustrate its extent in a wavelet-deconvolved image.

Radio jets and diffuse X-ray emission around the peculiar galaxy pair ESO 295-IG022

Recent XMM-Newton observations reveal an extended (r ≈ 150′′) low-surface brightness X-ray halo in the supernova remnant G21.5-0.9. The near circular symmetry, the lack of any limb brightening and the nonthermal spectral form, all favour an interpretation of this outer halo as an extension of the central synchrotron nebula rather than as a shell formed by the supernova blast wave and ejecta. The X-ray spectrum of the nebula exhibits a marked spectral softening with radius, with the power-law spectral index varying from Γ = 1.63± 0.04 in the core to Γ = 2.45±0.06 at the edge of the halo. Similar spectral trends are seen in other Crab-like remnants and reflect the impact of the synchrotron radiation losses on very high energy electrons as they diffuse out from the inner nebula. A preliminary timing analysis provides no evidence for any pulsed X-ray emission from the core

X-ray and radio observations of supernova remnants in NGC 300

We report here the results of a full analysis of all the ROSAT PSPC spectral imaging observations and all the ROSAT HRI high resolution imaging observations of the very nearby (D =2 :1 Mpc) Sculptor galaxy, NGC 300. Many point sources are detected within the eld, several of them showing evidence for variability, and we present full source lists detailing their X-ray properties, and attempt to classify them on the basis of their temporal, spectral and multi-wavelength characteristics. A black hole X-ray binary candidate, a supersoft source and several supernova remnants and H ii regions are detected in X-rays, as is unresolved, possibly diuse emission, accounting for perhaps20% of the total NGC 300 X-ray (0.1 2.4 keV) luminosity (5:8 10 38 erg s 1 ). We compare the X-ray source luminosity distribution of NGC 300 with that of other nearby galaxies, and we also compare NGC 300 with its Sculptor neighbours, concluding that it is a quite an unremarkable system, showing no unusual X-ray (or other multi-wavelength) properties. It may be one of the best examples of a completely typical normal quiescent late-type spiral galaxy.