Search

Context. X-ray observations performed with the Röntgen Satellite(ROSAT) led to the discovery of seven radio-silent isolated neutron stars (INSs) which are detected only through the relatively dim and purely thermal X-ray emission from the cooling star surface. A few of these INSs (X-ray Dim INSs, or XDINSs) have been also detected at optical wavelengths where they seem to feature thermal spectra. Optical studies of XDINSs thus play a crucial role in mapping the temperature distribution on the neutron star surface and in investigating the existence of an atmosphere around the neutron star.

Context. Short supersoft X-ray source (SSS) states (durations ≤100 days) of classical novae (CNe) indicate massive white dwarfs that are candidate progenitors of supernovae type Ia.

Context. In the past, the isolated, radio-quiet neutron star RX J0720.4-3125 showed variations in its spectral parameters (apparent radius, temperature of the emitting area and equivalent width of the absorption feature) seen in the X-ray spectra, not only during the spin period of 8.39 s, but also over time scales of years. New X-ray observations of RX J0720.4-3125 with XMM-Newton extend the coverage to about 7.5 years with the latest pointing performed in November 2007. Out of a total of fourteen available EPIC-pn datasets, eleven have been obtained with an identical instrumental setup (full frame read-out mode with a thin filter), and are best suited for a comparative investigation of the spectral and timing properties of this enigmatic X-ray pulsar.

The remarkable astrometric capabilities of the Chandra Observatory offer the possibility to measure proper motions of X-ray sources with an unprecedented accuracy in this wavelength range. We recently completed a proper motion survey of three of the seven thermally emitting radio-quiet isolated neutron stars (INSs) discovered in the ROSAT all-sky survey. These INSs (RX J0420.0-5022, RX J0806.4-4123and RX J1308.6+2127) either lack an optical counterpart or have one so faint that ground based or space born optical observations push the current possibilities of the instrumentation to the limit. Pairs of ACIS observations were acquired 3 to 5 years apart to measure the displacement of the sources on the X-ray sky using as a reference the background of extragalactic or remote Galactic X-ray sources. We derive 2σupper limits of 123 mas yr-1and 86 mas yr-1on the proper motion of RX J0420.0-5022and RX J0806.4-4123, respectively. RX J1308.6+2127exhibits a very significant displacement (~9σ) yielding μ= 220 ±25 mas yr-1, the second fastest measured among all ROSAT-discovered INSs. The source is probably moving away rapidly from the Galactic plane at a speed which precludes any significant accretion of matter from the interstellar medium. Its transverse velocity of ~740 (d/700 pc) km s-1might be the largest of all ROSAT INSs and its corresponding spatial velocity lies among the fastest recorded for neutron stars. RX J1308.6+2127is thus a middle-aged (age ~1 My) high velocity cooling neutron star. We investigate its possible origin in nearby OB associations or from a field OB star. In most cases, the flight time from birth place appears significantly shorter than the characteristic age derived from spin down rate. Overall, the distribution in transverse velocity of the ROSAT INSs is not statistically different from that of normal radio pulsars.

Aims. By measuring the gravitational redshift of spectral features in the spectrum of thermal radiation emitted from neutron stars, useful constraints for the equation of state of superdense matter can be obtained via an estimate of the mass-to-radius ratio. We searched for spectral line features in the high-resolution X-ray spectrum of the isolated neutron star RX J0720.4-3125.

Context. Only two planetary systems orbiting old ms-pulsars have been discovered. Young radio pulsars and radio-quiet neutron stars cannot be analysed by the usually-applied radio-pulse-timing technique. However, finding substellar companions orbiting these neutron stars would be of significant importance: the companion may have had an exotic formation, its observation may also enable us to study neutron-star physics.

Aims. To follow the long term evolution of Be/X-ray binaries in the Small Magellanic Cloud (SMC) we analyzed twenty-two XMM-Newton  observations towards the calibration target 1E 0102.2-7218  and seven observations towards the neighboring region around the eclipsing binary HD 5980.

Aims. We analysed eight XMM-Newton observations toward the Small Magellanic Cloud (SMC), performed between October 2006 and June 2007, to investigate high mass X-ray binary systems.

Aims. To investigate the Be/X-ray binary candidate RX J0105.9-7203 in the Small Magellanic Cloud (SMC), we analysed twenty-two archival XMM-Newton  observations around the calibration target 1E 0102.2-7218.

Aims.We present the first X-ray observations with the XMM-Newton and INTEGRAL satellites of the recently discovered cataclysmic variable 1RXS J173021.5-055933, together with simultaneous UV and coordinated optical photometry aiming at characterising its broad-band temporal and spectral properties and classifying this system as a magnetic one.

Aims.We present an extension to our XMM-Newton X-ray source catalogue of M 31containing 39 newly found sources. In order to classify and identify more of the sources we search for X-ray time variability in XMM-Newton archival data of the M 31centre field.

Context.The Be/X-ray binary pulsar AX J0058-720, discovered by ASCA, was in the field of view of the EPIC instruments during five XMM-Newton observations in the direction of the Small Magellanic Cloud (SMC).

Aims.The galactic black hole candidate XTE J1817-330was discovered in outburst by RXTE in January 2006. We present here the results of an XMM-Newton target of opportunity observation, performed on 13 March 2006 (44 days after the maximum), and an INTEGRAL observation performed on 15–18 February 2006 (18 days after the maximum).

Context.Optical novae have recently been identified as the major class of supersoft X-ray sources in M 31based on ROSAT and early XMM-Newton and Chandraobservations.

Aims.The galactic superluminal microquasar GRO J1655-40started a new outburst in February 2005, after seven years in quiescence, rising to a high/soft state in March 2005. In this paper we study the X-ray spectra during this rise.

Context.We report on XMM-Newton observations of SN 1987 Ain the Large Magellanic Cloud.

Aims.We report the discovery of the super-soft X-ray source XMMU J052016.0-692505 in the LMC with XMM-Newton.

A growing number of early Be stars exhibit X-ray luminosities that are intermediate between those typical of early type stars and those emitted by most Be/X-ray binaries in quiescence. We report on XMM-Newtonobservations of two such Be stars, SAO 49725and HD 161103, which were originally discovered in a systematic cross-correlation between the ROSAT all-sky survey and SIMBAD. The new observations confirm the X-ray luminosity excess (LX~ 1032-33erg s-1) and the hardness of their X-ray spectra, which are both unusual for normal early type stars. An iron Kαcomplex is clearly detected in HD 161103in which the H-like, He-like, and fluorescent components are resolved, while strong evidences also exist for the presence of similar features in SAO 49725. X-ray spectra can be equally well-fitted by a thermal plasma (mekal) with T~ 108K and solar abundances or by a power law+ iron linemodel with photon index ~1.5–1.8, both with a soft thermal component with T~ 107K. The intensity of the fluorescence 6.4 keV line reflects the presence of large amounts of cold material close to the X-ray sources and strongly argues against accretion onto a companion neutron star in a large orbit. On the other hand, the probable thermal origin of the X-ray emission, as supported by the ionised iron lines, disagrees with those observed in all known Be/X-ray binaries, in which a non-thermal component is always required. Remarkably, the X-ray features are similar to those of white dwarves in several cataclysmic variables. There is no evidence of high frequency pulsations in neither of the two systems. However, a large oscillation in the light curve of HD 161103with P~ 3200 s is readily detected. The X-ray light curve of SAO 49725exhibits clear variability by ~80% on time scales as short as ~1000 s. New optical observations provide updated spectral types (B0.5 III-Ve) and disclose a dense, large, and apparently stable circumstellar disc for both stars. The nature of the excess X-ray emission is discussed in light of the models proposed for γCas, magnetic disc-star interaction, or accretion onto a compact companion object – whether neutron star or white dwarf. These two new objects, added to similar cases discovered in XMM-Newtonsurveys, point to the emergence of a new class of γCas analogs.

Aims.XMM-Newton observations to determine for the first time the broad-band X-ray properties of the faint, high galactic latitude intermediate polar UU Col are presented.

Context.Recent surveys of the Local Group spiral Galaxies M 31 and M 33 with XMM-Newton yielded a large number of X-ray sources.

We report the detection and study of two faint ROSATsupersoft X-ray sources in the SMC field with XMM-Newton, RX J0059.1-7505  and RX J0059.4-7118. Due to the larger effective area of XMM-Newtonwe can constrain the X-ray spectra of both sources. RX J0059.1-7505 is optically identified with the symbiotic LIN 358 in the SMC. A ~$20~{\rm eV}$blackbody component dominates the observed spectrum. The soft blackbody component is consistent with steady nuclear burning in a shell although the spectrum is more complex than a simple blackbody continuum. RX J0059.4-7118 is not optically identified and we derive with the Optical Monitor (OM) a Vmagnitude $\ga$19.3 assuming an M0 spectral type. The X-ray spectrum is fitted with a blackbody component with a temperature of ~$90~{\rm eV}$and an additional spectrally hard component which can be reproduced with a powerlaw. The luminosity of RX J0059.4-7118 would be ~4 $\times$$10^{34}~{\rm erg}~{\rm s^{-1}}$at the distance of the SMC. This is too large for a Cataclysmic Variable (CV). The spectral appearance is not in agreement with a supersoft source in the SMC. Thus we suggest that RX J0059.4-7118 is a Galactic source. As the optical magnitude derived from the OMdata may be too faint for a normal Galactic CV we examined the possibility that RX J0059.4-7118 is a polar CV in the Galaxy, an isolated cooling neutron star (INS) at distance ~$(1{-}2)$kpc, a pulsar with a brown dwarf companion, or a Galactic quiescent low-mass X-ray binary (qLMXB). We favor the hypothesis of a Galactic CV because of variability in the EPIC-pndata with a timescale of ~1 h. A third supersoft ROSATsource, RX J0050.5-7455, is not detected with XMM-Newton.

The XMM-Newton spectra of the isolated neutron star RX J0720.4-3125obtained over 4.5 years can be described by sinusoidal variations in the inferred blackbody temperature, the size of the emitting area and the depth of the absorption line with a period of $7.1\pm0.5$years, which we suggest to be the precession period of the neutron star. Precession of a neutron star with two hot spots of different temperature and size, probably not located exactly in antipodal positions, may account for the variations in the X-ray spectra, changes in the pulsed fraction, shape of the light curve and the phase-lag between soft and hard energy bands observed from RX J0720.4-3125. An independent sinusoidal fit to published and new pulse timing residuals from a coherent analysis covering ~12 years yields a consistent period of $7.7\pm0.6$years supporting the precession model.

We present the first time resolved medium resolution optical spectroscopy of the recently identified peculiar Intermediate Polar (IP) 1RXS J154814.5-452845, which allows us to precisely determine the binary orbital period ($P_{\Omega}=9.87$±0.03 h) and the white dwarf spin period ($P_{\omega}=693.01$±0.06 s). This system is then the third just outside the purported ~6–10 h IP orbital period gap and the fifth of the small group of long period IPs, which has a relatively high degree of asynchronism. From the presence of weak red absorption features, we identify the secondary star with a spectral type K2 ±2 V, which appears to have evolved on the nuclear timescale. From the orbital radial velocities of emission and the red absorption lines a mass ratio $q=0.65$±0.12 is found. The masses of the components are estimated to be $M_{{\rm WD}} \geq 0.5~M_{\odot}$and $M_{{\rm sec}}=0.4{-}0.79~M_{\odot}$and the binary inclination $25^\circ < i \leq 58^\circ$. A distance between 540–840 pc is estimated. At this distance, the presence of peculiar absorption features surrounding Balmer emissions cannot be due to the contribution of the white dwarf photosphere and their spin modulation suggests an origin in the magnetically confined accretion flow. The white dwarf is also not accreting at a particularly high rate ($\dot M < 5$$\times$$10^{16}~{\rm g~s}^{-1}$), for its orbital period. The spin-to-orbit period ratio $P_{\omega}/P_{\Omega}$= 0.02 and the low mass accretion rate suggest that this system is far from spin equilibrium. The magnetic moment of the accreting white dwarf is found to be $\mu < 4.1$$\times$1032G cm3, indicating a low magnetic field system.

We present an analysis of the individual observations of a deep XMM-Newton survey of the Local Group spiral galaxy M 33. We detected a total of 350 sources with fluxes (in the 0.2–4.5 keV energy band) in the range 6.7 $\times$$10^{-16}{-}1.5$$\times$10-11erg s-1. This comprehensive study considers flux variability, spectral characteristics, and classification of the detected objects. Thirty-nine objects in our catalogue are new sources, while 311 were already detected in a previous analysis of most of the same data using combined images. We present improved positions of these sources and the X-ray parameters of each source in each individual observation that covers the source. We then used these parameters to systematically search for flux variability on time scales of hours to months or years. The long-term light-curves were generated for the 61 sources showing a significant variability of the (0.2–4.5) keV flux, by a factor of 1.2 to 144. The detected variability was then used to classify 8 new X-ray binary candidates in M 33. Together with the hardness ratio method and cross-correlation with optical, infrared, and radio data, we also classify or confirm previous classification of 25 supernova remnants and candidates, 2 X-ray binaries, and 11 super-soft source candidates (7 of which are new SSS candidates). In addition, we classify 13 active galactic nuclei and background galaxies, 6 stars, and 23 foreground star candidates in the direction of M 33. Further 206 objects are classified as “hard”, approximately half of which are sources intrinsic to M 33. The relative contribution of the classified XRB and SSS in M 33is now comparable to M 31. The luminosity distribution of SNRs in both spiral galaxies is almost the same, although the number of the detected SNRs in M 33remains much higher.

We searched for X-ray counterparts of optical novae detected in M 31and M 33. We combined an optical nova catalogue from the WeCAPP survey with optical novae reported in the literature and correlated them with the most recent X-ray catalogues from ROSAT, XMM-Newton, and Chandra, and – in addition – searched for nova correlations in archival data. We report 21 X-ray counterparts for novae in M 31– mostly identified as supersoft sources (SSS) by their hardness ratios – and two in M 33. Our sample more than triples the number of known optical novae with a supersoft X-ray phase. Most of the counterparts are covered in several observations allowing us to constrain their X-ray light curves. Selected brighter sources were classified by their XMM-Newton EPIC spectra. We use the well-determined start time of the SSS state in two novae to estimate the hydrogen mass ejected in the outburst to ~$10^{-5}~M_{\odot}$and ~$10^{-6}~M_{\odot}$, respectively. The supersoft X-ray phase of at least 15% of the novae starts within a year. At least one of the novae shows a SSS state lasting 6.1 years after the optical outburst. Six of the SSSs turned on between 3 and 9 years after the optical discovery of the outburst and may be interpreted as recurrent novae. If confirmed, the detection of a delayed SSS phase turn-on may be used as a new method to classify novae as recurrent. At the moment, the new method yields a ratio of recurrent novae to classical novae of 0.3, which is in agreement (within the errors) with previous works.

We present the results of a detailed temporal analysis of the bright BL Lac object Mrk 421 using the three available long timing mode observations by the EPIC PN camera. This detector mode is characterized by its long life time and is largely free of photon pile-up problems. The source was found in different intensity and variability states differing by up to more than a factor of three in count rate. A time resolved cross correlation analysis between the soft and hard energy bands revealed that the characteristics of the correlated emission, with lags of both signs, change on time scales of a few 103s. Individual spectra, resolved on time scales of ~100 s, can be quite well fitted by a broken power law and we find significant spectral variations on time scales as short as ~500–1000 s. Both the hard and the soft band spectral indices show a non-linear correlation with the source flux. A simple power law model of the form $\Gamma\propto {\mathrm {flux}}^{-a}$with $a_{\mathrm {hard}}\sim 0.13$and $a_{\mathrm {soft}}\sim 0.22$describes rather well the observed trend of decreasing Γvalues with increasing flux, which appear to “saturate” at the same limiting value of $\Gamma\sim 1.8$at the highest flux levels. A comparison of the observed light curves with numerical results from relativistic hydrodynamic computer simulations of the currently favored shock-in-jet models indicates that any determination of the jet's physical parameters from “simple” emission models must be regarded with caution: at any time we are seeing the emission from several emission regions distinct in space and time, which are connected by the complex hydrodynamic evolution of the non-uniform jet.

We report on the first pointed X-ray observations with XMM-Newtonand RXTEsatellites of the X-ray source RX J0757.0+6306 = HT Cam. We detect a strong 515 s X-ray modulation confirming the optical photometric period found in 1998, which definitively assigns this source to the intermediate polar class of magnetic cataclysmic variables. The lack of orbital sidebands in the X-rays indicates that the X-ray period is the spin period of the accreting white dwarf. Simultaneous ultraviolet and optical B-band photometry acquired with the XMM-Newton Optical Monitor and coordinated optical UBVRIphotometric data acquired at the Nordic Optical Telescope (La Palma) show that the optical pulse is in phase with the X-rays and hence originates in the magnetically-confined accretion flow. The lack of ultraviolet spin modulation suggests that accretion-induced heating on the white dwarf surface is not important in this source. Spectral analyses of XMM-Newton EPIC and RGS data show that HT Cam has a multi-temperature spectrum and, contrary to most intermediate polars, it does not suffer from strong absorption. With its 86 min orbital period, HT Cam is the third confirmed system of this class below the 2–3 h period gap accreting at a low rate.

XMM-Newton archival observations of the Be/X-ray binary candidate  revealed pulsations with a period of ~1323 s. This makes  the X-ray pulsar with the longest period known in the Small Magellanic Cloud (SMC). More than 150 X-ray observations of  by ROSAT, Chandra and XMM-Newton show flux variations by a factor of 50 on time scales of days to years. Using the accurate positions obtained from ACIS-I images, the optical counterpart is identified as a V= 14.6 mag emission line star. EPIC spectra of  above 1 keV are consistent with an absorbed power-law with column density between (6-9) $\times$1021cm-2, except during one observation when an extraordinary high value of 1.1 $\times$1023cm-2was measured which strongly attenuated the power-law emission below 3 keV. A soft excess between 0.5 and 1.0 keV is evident in the spectra which becomes best visible in the highly absorbed spectrum. The soft component can be reproduced by a thermal plasma emission model with its luminosity strongly correlated with the total intrinsic source luminosity. Including results from three other SMC Be/X-ray binaries extends the linear correlation over three orders of magnitude in source intensity, strongly suggesting that the same mechanism is responsible for the generation of the soft emission.

We searched for X-ray bursts in XMM-Newton archival data of X-ray sources in M 31globular clusters (GCs) and GC candidates. We detected two bursts simultaneously in EPIC pn and MOS detectors and some more candidates in EPIC pn. The energy distribution of the burst photons and the intrinsic luminosity during the peak of the bursts indicate that at least the strongest burst was a type I radius expansion burst. The bursts identify the sources as neutron star low mass X-ray binaries in M 31. The type I X-ray bursts in M 31are the first detected outside the Milky Way and show that with the help of XMM-Newton X-ray bursts can be used to classify neutron star low mass X-ray binaries in Local Group galaxies.

RX J0852.0-4622 is a supernova remnant discovered in the ROSATall-sky survey. Spatially coincident 1.157 MeV γ-ray line emission was detected with the COMPTELinstrument on-board CGRO. The analysis combining the X-ray and γ-ray data suggests that RX J0852.0-4622 is a close-by and young supernova remnant. Follow-up observations with ASCAshow that the two brightest sections of the limb have non-thermal spectra, which make an independent assessment of the age and distance using the Sedov equations for the evolution of the remnant almost impossible. We have observed three rim sections of RX J0852.0-4622 with XMM-Newtonand confirm the power-law type spectra measured with ASCA. We also confirm the presence of an emission-line like feature at $4.45 \pm 0.05$keV, which we suggest to be emission from Ti and Sc excited by atom/ion or ion/ion high velocity collisions. The high velocity is in agreement with the width of the 1.157 MeV γ-ray line. The X-ray line flux expected from such an interaction is consistent with the 1.157 MeV γ-ray line flux measured by COMPTEL. This consistency of the X-ray line flux and the γ-ray line flux lends further support to the existence and amounts of Ti in RX J0852.0-4622 claimed by Iyudin et al. ([CITE], Nature, 396, 142) and to the suggestion that RX J0852.0-4622 is young and nearby (Aschenbach et al. [CITE], A&A, 350, 997). Iyudin et al. ([CITE]) quote a very large broadening of the 1.157 MeV γ-ray line which would indicate a large velocity of the emitting matter of about 15 000 km s-1. Such high ejecta velocity for Ti is found only in explosion models of sub-Chandrasekhar type Ia supernovae (Woosley & Weaver [CITE], ApJ, 423, 371; Livne & Arnett [CITE], ApJ, 452, 62). In this case no compact remnant is expected. The obvious, remaining questions are what the nature and the origin of the central compact source CXOU J085201.4-461753 are and why the absorption column density apparently associated with RX J0852.0-4622 is much greater than the typical column for the Vela SNR.

We obtained deep optical imaging of the thermally emitting X-ray bright and radio-quiet isolated neutron star RX J1605.3+3249with the Subaru telescope in 1999 and 2003. Together with archival HST images acquired in 2001 these data reveal a proper motion of $\mu = 144.5\pm13.2$mas/yr. This implies a relatively high spatial velocity and indicates that the star is unlikely to be re-heated by accretion of matter from the interstellar medium. Assuming that RX J1605.3+3249is a young (10$^{5}{-}10^{6}$yr) cooling neutron star, its apparent trajectory is consistent with a birth in the nearby Sco OB2 OB association at a location close to that derived for RX J1856.5-3754and perhaps also to that of RX J0720.4-3125. This suggests that the X-ray bright part of ROSAT-discovered isolated neutron stars is dominated by the production of the Sco OB2 complex which is the closest OB association and a part of the Gould belt. The Band Rmagnitudes of the faint optical counterpart did not vary from 1999 to 2003 at $B = 27.22\pm0.10$. Its $B-R$colour index of $+0.32\pm0.17$is significantly redder than that of other isolated neutron stars and the optical flux lies a factor 11.5 above the extrapolation of the X-ray blackbody-like spectrum. The red optical colour reveals the presence of an additional emitting component in the optical regime over the main neutron star thermal emission. We also discovered a small elongated Hαnebula approximately centered on the neutron star and aligned with the direction of motion. The width of the nebula is unresolved and smaller than ~0.4´´ for a length of about 1´´. The shape of the Balmer emitting nebula around RX J1605.3+3249is very different from those seen close to other neutron stars and should be confirmed by follow-up observations. We shortly discuss the possible mechanisms which could give rise to such a geometry.

In an XMM-Newton raster observation of the bright Local Group spiral galaxy M 33we study the population of X-ray sources (X-ray binaries, supernova remnants) down to a 0.2–4.5 keV luminosity of 1035erg s-1– more than a factor of 10 deeper than earlier ROSAT observations. EPIC hardness ratios and optical and radio information are used to distinguish between different source classes. The survey detects 408 sources in an area of 0.80 square degree. We correlate these newly detected sources with earlier M 33X-ray catalogues and information from optical, infra-red and radio wavelengths. As M 33sources we detect 21 supernova remnants (SNR) and 23 SNR candidates, 5 super-soft sources and 2 X-ray binaries (XRBs). There are 267 sources classified as hard, which may either be XRBs or Crab-like SNRs in M 33or background AGN. The 44 confirmed and candidate SNRs more than double the number of X-ray detected SNRs in M 33. 16 of these are proposed as SNR candidates from the X-ray data for the first time. On the other hand, there are several sources not connected to M 33: five foreground stars, 30 foreground star candidates, 12 active galactic nucleus candidates, one background galaxy and one background galaxy candidate. Extrapolating from deep field observations we would expect 175 to 210 background sources in this field. This indicates that about half of the sources detected are within M 33.

We report on the analysis of new X-ray data obtained with XMM-Newton and Chandra from two ROSAT-discovered X-ray dim isolated neutron stars (XDINs).  was observed with XMM-Newton in April 2003, 2.5 years after the first observation. The EPIC-pn data confirm that this object is an X-ray pulsar with 11.371 s neutron star spin period. The X-ray spectrum is consistent with absorbed black-body emission with a temperature $kT = 96$eV and NH= 4$\,\times \,10^{19}$cm-2without significant changes between the two observations. Four XMM-Newton observations of  between December 2002 and July 2003 did not confirm the 22.7 s pulsations originally indicated in ROSAT data, but clearly reveal a 3.453 s period. A fit to the X-ray spectrum using an absorbed black-body model yields $kT = 45$eV, the lowest value found from the small group of XDINs and NH= 1.0$\,\times \,10^{20}$cm-2. Including a broad absorption line improves the quality of the spectral fits considerably for both objects and may indicate the presence of absorption features similar to those reported from ,  and . For both targets we derive accurate X-ray positions from the Chandra data and present an optical counterpart candidate for  with $B = 26.6\pm0.3$mag from VLT imaging.

An XMM-Newton target of opportunity observation of the field around the transient 18.37 s pulsar  in the Small Magellanic Cloud (SMC) revealed two bright, long-period X-ray pulsars in the EPIC data. A new pulsar, , with a pulse period of $701.7 \pm 0.8$s was discovered and $500.0 \pm 0.2$s pulsations were detected from   (=CXOU J005455.6–724510), confirming the period found in Chandra data. We derive X-ray positions of ${\rm RA} = 00^{\rm h}54^{\rm m}55\fs88$, ${\rm Dec} = -72\degr45\arcmin10\farcs5$and ${\rm RA} = 00^{\rm h}55^{\rm m}18\fs44$, ${\rm Dec} = -72\degr38\arcmin51\farcs8$(J2000.0) with an uncertainty of 0$\farcs$2 utilizing optical identification with OGLE stars. For both objects, the optical brightness and colours and the X-ray spectra are consistent with Be/X-ray binary systems in the SMC.

The XMM-Newton spectra of the isolated neutron star  show deviations from a Planckian energy distribution below 400 eV, similar to the spectra of RBS1223, another long-period X-ray pulsar, as reported recently by [CITE]. For a Gaussian-shaped absorption line we derive an energy of 271 eV and an equivalent width of -40 eV from the phase-averaged spectra of . We investigate the spectral variations seen in hardness ratios as function of pulse phase and find that they are best described by changes in the depth of the absorption line. The line equivalent width changes between -31 eV around intensity maximum of the pulse and -58 eV at the declining part of the pulse. Small variations (<20 eV) of the line energy with pulse phase may still be caused by statistical fluctuations. On the other hand, the black-body temperature varies significantly by 2.5 eV (statistical 90% errors typically 0.7 eV) reaching the highest value at pulse maximum. One possible interpretation for the absorption line is cyclotron resonance scattering of protons in a magnetic field with $B \simeq 5\,\times\, 10^{13}$G. This field strength is compatible with estimates inferred from recent spin down measurements of the pulsar.

We present broad-band (0.1–90 keV) spectral and temporal properties of the three Intermediate Polars, RE 0751+144 (PQ Gem), RX  J0558.0+5353 (V405 Aur) and RX  J1712.6-2414 (V2400 Oph) based on simultaneous soft and hard X-ray observations with the BeppoSAX satellite. The analysis of their spectra over the wide energy range of BeppoSAX instruments allows us to identify the soft and hard X-ray components and to determine simultaneously their temperatures. The black–body temperatures of the irradiated poles of the white dwarf atmosphere are found to be 60–100 eV, much higher than those found in their synchronous analogues, the Polars. The temperature of the optically thin post–shock plasma is well constrained in RX  J1712.6-2414 and in RE 0751+144 (13 and 17 keV) and less precisely determined in RX  J0558.0+5353. In the first two systems evidence of subsolar abundances is found, similarly to that estimated in other magnetic Cataclysmic Variables. A Compton reflection component is present in RX  J0558.0+5353 and in RE 0751+144 and it is favoured in RX J1712.6-2414. Its origin is likely at the irradiated white dwarf surface. Although these systems share common properties (a soft X-ray component and optical polarized radiation), their X-ray power spectra and light curves at different energies suggest accretion geometries that cannot be reconciled with a single and simple configuration.

Fifteen Be/X-ray binaries and candidates in the SMC were observed serendipitously with the EPIC instruments of XMM-Newton during two observations of SNR 0047–73.5 and SNR 0103–72.6 in October 2000. A total of twelve of those sources are detected. For eleven of them an accurate position and in part detection of X-ray pulsations support the proposed identification as Be/X-ray binaries. In one case the improved X-ray position excludes the previously suggested identification with an Hαemission line star found within the ROSAT error circle. The detection of pulsations (172.2 s, 320.1 s and 751 s) from three hard X-ray sources with periods known from ASCA observations confirm their proposed identifications with ROSAT sources and their optical Be star counterparts. In addition, pulsations with a period of 263.6 s were found from XMMU J004723.7-731226 = RX J0047.3-7312. For  a pulse period of $341.2\pm0.5$s was determined, continuing the large spin-up seen with ASCA, BeppoSAX and Chandra between 1996 and 1999 with a period derivative of -1.6 s yr-1covering now 4.5 years. The 0.3–10.0 keV EPIC spectra of all eleven Be/X-ray binaries and candidates are consistent with power-law energy distributions with derived photon indices strongly peaked at 1.00 with a standard deviation of 0.16. No pulsations are detected from RX J0049.2-7311 and RX J0049.5-7310 (both near the 9 s pulsar AX J0049-732) and RX J0105.1-7211 (near AX J0105-722, which may pulsate with 3.3 s), leaving the identification of the ASCA sources with ROSAT and corresponding XMM-Newton objects still unclear. We present an updated list of high-mass X-ray binaries (HMXBs) and candidates in the SMC incorporating improved X-ray positions obtained from Chandra and XMM-Newton observations. Including the results from this work and recent publications the SMC HMXB catalogue comprises 65 objects with at least 37 showing X-ray pulsations.

The eclipsing X-ray binary M 33 X-7was in the field of view during several observations of our XMM-Newton M 33survey and in the archival Chandraobservation 1730 which cover a large part of the 3.45 d orbital period. We detect emission of M 33 X-7during eclipse and a soft X-ray spectrum of the source out of eclipse that can best be described by bremsstrahlung or disk blackbody models. No significant regular pulsations of the source in the range 0.25–1000 s were found. The average source luminosity out of eclipse is 5 $\times$1037(0.5–4.5 keV). In a special analysis of DIRECT observations we identify as optical counterpart a B0I to O7I star of 18.89 mag in V which shows the ellipsoidal heating light curve of a high mass X-ray binary with the M 33 X-7binary period. The location of the X-ray eclipse and the optical minima allow us to determine an improved binary period and ephemeris of mid-eclipse as HJD $(2 \,451\,760.61\pm0.09)\pm N\times(3.45376\pm0.00021)$. The mass of the compact object derived from orbital parameters and the optical companion mass, the lack of pulsations, and the X-ray spectrum of M 33 X-7may indicate that the compact object in the system is a black hole. M 33 X-7would be the first detected eclipsing high mass black hole X-ray binary.

First results from a deep XMM-Newton observation of a field in the Large Magellanic Cloud (LMC) near the northern rim of the supergiant shell LMC 4 are presented. Spectral and temporal analyses of a sample of selected X-ray sources yielded two new candidates for supernova remnants, a supersoft X-ray source and a likely high mass X-ray binary (HMXB) pulsar. From the fourteen brightest sources ten exhibit power-law X-ray spectra with slopes compatible to those of active galactic nuclei (AGN) in the background of the LMC. Their AGN nature is further supported by the lack of optical counterparts brighter than $B\sim18$mag. From the three previously known HMXBs the Be/X-ray binary  was the brightest source in the field, allowing a more detailed analysis of its X-ray spectrum and pulse profile. During the pulse  shows eclipses of the X-ray emitting areas with increased photo-electric absorption before and after the eclipse. The detection of X-ray pulsations with a period of 69.2 s is confirmed for  and a possible period of 272 s is discovered from . The results are discussed with respect to individual sources as well as in the view of source population studies in the vicinity of the supergiant shell LMC 4.

We present the results of a detailed spectral and temporal analysis of the currently available XMM–Newton observations of the bright BL Lac object Mrk 421 using mainly the EPIC-PN data. The source was found in various intensity states differing by up to a factor of five in count rates. In general, the source is more variable and shows a harder spectrum during higher intensities than when it is in lower states. The spectrum is very complex and cannot be fitted adequately by a broken power law or a continuously curved model. We find that the flux variations on time scales of $\ga$few thousand seconds are associated with significant and sometimes very complex spectral changes. The spectral variability rate is not the same in all cases and is correlated with the source flux state: the spectral variations per unit time increase with the source flux. The Cross-Correlation analysis shows that the soft and hard band light curves are often well correlated near zero lag, in other cases the hard band variations lead the soft band variations by typically ~5 min, in two cases we find the soft band leading the hard band variations. The delays appear to be correlated to the flares' duration: the shorter the flare, the smaller the delay.