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We report new radio timing solutions from a 3-yr observing campaign conducted with the MeerKAT and Murriyang telescopes for nine Small Magellanic Cloud pulsars, increasing the number of characterized rotation-powered extragalactic pulsars by 40 per cent. We can infer from our determined parameters that the pulsars are seemingly all isolated, that six are ordinary pulsars, and that three of the recent MeerKAT discoveries have a young characteristic age of under 100 kyr and have undergone a spin-up glitch. Two of the sources, PSRs J0040 |$-$| 7337 and J0048 |$-$| 7317, are energetic young pulsars with spin-down luminosities of the order of 10 |$^{36}$|  erg s |$^{-1}$|⁠. They both experienced a large glitch, with a change in frequency of about 30  |$\mu$| Hz, and a frequency derivative change of order |$-10^{-14}$|  Hz s |$^{-1}$|⁠. These glitches, the inferred glitch rate, and the properties of these pulsars (including potentially high inter-glitch braking indices) suggest these neutron stars might be Vela-like repeating glitchers and should be closely monitored in the future. The position and energetics of PSR J0048 |$-$| 7317 confirm it is powering a new pulsar wind nebula (PWN) detected as a radio continuum source; and similarly the association of PSR J0040 |$-$| 7337 with the PWN of supernova remnant (SNR) DEM S5 (for which we present a new Chandra image) is strengthened. Finally, PSR J0040 |$-$| 7335 is also contained within the same SNR but is a chance superposition. It has also been seen to glitch with a change of frequency of |$10^{-2}$|   |$\mu$| Hz. This work more than doubles the characterized population of SMC radio pulsars. [ABSTRACT FROM AUTHOR]

We present new radio continuum images and a source catalogue from the MeerKAT survey in the direction of the Small Magellanic Cloud. The observations, at a central frequency of 1.3 GHz across a bandwidth of 0.8 GHz, encompass a field of view ∼7° × 7° and result in images with resolution of 8 arcsec. The median broad-band Stokes I image Root Mean Squared noise value is ∼11  μ Jy beam−1. The catalogue produced from these images contains 108 330 point sources and 517 compact extended sources. We also describe a UHF (544–1088 MHz) single pointing observation. We report the detection of a new confirmed Supernova Remnant (SNR; MCSNR J0100–7211) with an X-ray magnetar at its centre and 10 new SNR candidates. This is in addition to the detection of 21 previously confirmed SNRs and two previously noted SNR candidates. Our new SNR candidates have typical surface brightness an order of magnitude below those previously known, and on the whole they are larger. The high sensitivity of the MeerKAT survey also enabled us to detect the bright end of the SMC Planetary Nebulae (PNe) sample – point-like radio emission is associated with 38 of 102 optically known PNe, of which 19 are new detections. Lastly, we present the detection of three foreground radio stars amidst 11 circularly polarized sources, and a few examples of morphologically interesting background radio galaxies from which the radio ring galaxy ESO 029–G034 may represent a new type of radio object. [ABSTRACT FROM AUTHOR]

We present new and archival Australia Telescope Compact Array and Atacama Large Millimeter/submillimeter Array data of the Small Magellanic Cloud supernova remnant 1E 0102.2–7219 at 2100, 5500, 9000, and 108 000 MHz; as well as H  i data provided by the Australian Square Kilometre Array Pathfinder. The remnant shows a ring-like morphology with a mean radius of 6.2 pc. The 5500 MHz image reveals a bridge-like structure, seen for the first time in a radio image. This structure is also visible in both optical and X-ray images. In the 9000 MHz image, we detect a central feature that has a flux density of 4.3 mJy but rule out a pulsar wind nebula origin, due to the lack of significant polarization towards the central feature with an upper limit of 4  per cent. The mean fractional polarization for 1E 0102.2–7219 is 7 ± 1 and 12 ± 2  per cent for 5500 and 9000 MHz, respectively. The spectral index for the entire remnant is −0.61 ± 0.01. We estimate the line-of-sight magnetic field strength in the direction of 1E 0102.2–7219 of ∼44 µG with an equipartition field of |$65\pm 5\, \mu$| G. This latter model uses the minimum energy of the sum of the magnetic field and cosmic ray electrons only. We detect an H  i cloud towards this remnant at the velocity range of ∼160–180 km s−1 and a cavity-like structure at the velocity of 163.7–167.6 km s−1. We do not detect CO emission towards 1E 0102.2–7219. [ABSTRACT FROM AUTHOR]

During a systematic search for new X-ray pulsators in the XMM–Newton archive, we discovered a high amplitude (⁠|$PF\simeq 86~{{\ \rm per\ cent}}$|⁠) periodic (⁠|$P\simeq 7.25\, \mathrm{s}$|⁠) modulation in the X-ray flux of 4XMM J045626.3–694723 (J0456 hereafter), a previously unclassified source in the Large Magellanic Cloud (LMC). The period of the modulation is strongly suggestive of a spinning neutron star (NS). The source was detected only during one out of six observations in 2018–2022. Based on an absorbed power-law spectral model with photon slope of Γ ≃ 1.9, we derive a 0.3–10 keV luminosity of |$L_\mathrm{X}\simeq 2.7\times 10^{34}\, \mathrm{erg}\, \mathrm{s}^{-1}$| for a distance of 50 kpc. The X-ray properties of J0456 are at variance with those of variable LMC X-ray pulsars hosted in high-mass X-ray binary systems with a Be-star companion. Based on Southern African Large Telescope (SALT) spectroscopic observations of the only optical object that matches the X-ray uncertainty region, we cannot completely rule out that J0456 is an NS accreting from a late-type (G8-K3) star, an as-yet-unobserved binary evolutionary outcome in the Magellanic Clouds (MCs). We show that the source properties are in better agreement with those of magnetars. J0456 may thus be the second known magnetar in the LMC after SGR 0526–66. [ABSTRACT FROM AUTHOR]

We present a new Australian Square Kilometre Array Pathfinder (ASKAP) sample of 14 radio supernova remnants (SNR) candidates in the Large Magellanic Cloud (LMC). This new sample is a significant increase to the known number of older, larger, and low surface brightness LMC SNRs. We employ a multifrequency search for each object and found possible traces of optical and occasionally X-ray emission in several of these 14 SNR candidates. One of these 14 SNR candidates (MCSNR J0522 – 6543) has multifrequency properties that strongly indicate a bona fide SNR. We also investigate a sample of 20 previously suggested LMC SNR candidates and confirm the SNR nature of MCSNR J0506 – 6815. We detect lower surface brightness SNR candidates which were likely formed by a combination of shock waves and strong stellar winds from massive progenitors (and possibly surrounding OB stars). Some of our new SNR candidates are also found in lower density environments in which SNe type Ia explode inside a previously excavated interstellar medium. [ABSTRACT FROM AUTHOR]

The Large Magellanic Cloud (LMC) hosts a rich population of supernova remnants (SNRs), our knowledge of which is the most complete of any galaxy. However, there remain many candidate SNRs, identified through optical and radio observations where additional X-ray data can confirm their SNR nature and provide details on their physical properties. In this paper, we present XMM–Newton observations that provide the first deep X-ray coverage of ten objects, comprising eight candidates and two previously confirmed SNRs. We perform multifrequency studies using additional data from the Magellanic Cloud Emission Line Survey (MCELS) to investigate their broad-band emission and used Spitzer data to understand the environment in which the objects are evolving. We confirm seven of the eight candidates as bona-fide SNRs. We used a multifrequency morphological study to determine the position and size of the remnants. We identify two new members of the class of evolved Fe-rich remnants in the Magellanic Clouds (MCs), several SNRs well into their Sedov-phase, one SNR likely projected towards a H  ii region, and a faint, evolved SNR with a hard X-ray core which could indicate a pulsar wind nebula. Overall, the seven newly confirmed SNRs represent a ∼10-per cent increase in the number of LMC remnants, bringing the total number to 71, and provide further insight into the fainter population of X-ray SNRs. [ABSTRACT FROM AUTHOR]

We present a comprehensive multifrequency catalogue of radio sources behind the Large Magellanic Cloud (LMC) between 0.2 and 20 GHz, gathered from a combination of new and legacy radio continuum surveys. This catalogue covers an area of ∼144 deg2 at angular resolutions from 45 arcsec to ∼3 arcmin. We find 6434 discrete radio sources in total, of which 3789 are detected at two or more radio frequencies. We estimate the median spectral index (α; where Sv ∼ ν α) of α = −0.89 and mean of −0.88 ± 0.48 for 3636 sources detected exclusively at two frequencies (0.843 and 1.384 GHz) with similar resolution [full width at half-maximum (FWHM) ∼40–45 arcsec]. The large frequency range of the surveys makes it an effective tool to investigate Gigahertz Peak Spectrum (GPS), Compact Steep Spectrum (CSS), and Infrared Faint Radio Source (IFRS) populations within our sample. We find 10 GPS candidates with peak frequencies near 5 GHz, from which we estimate their linear size. 1866 sources from our catalogue are CSS candidates with α  < −0.8. We found six candidates for High Frequency Peaker (HFP) sources, whose radio fluxes peak above 5 GHz and no sources with unconstrained peaks and α  > 0.5. We found optical counterparts for 343 of the radio continuum sources, of which 128 have a redshift measurement. Finally, we investigate the population of 123 IFRSs found in this study. [ABSTRACT FROM AUTHOR]

We report here on the discovery with XMM–Newton of pulsations at 22 ms from the central compact source associated with IKT 16, a supernova remnant in the Small Magellanic Cloud (SMC). The measured spin period and spin period derivative correspond to 21.7661076(2) ms and 2.9(3) × 10−14 s s−1, respectively. Assuming standard spin-down by magnetic dipole radiation, the spin-down power corresponds to 1.1 × 1038 erg s−1 implying a Crab-like pulsar. This makes it the most energetic pulsar discovered in the SMC so far and a close analogue of PSR J0537–6910, a Crab-like pulsar in the Large Magellanic Cloud. The characteristic age of the pulsar is 12 kyr. Having for the first time a period measure for this source, we also searched for the signal in archival data collected in radio with the Parkes telescope and in γ-rays with the Fermi /LAT, but no evidence for pulsation was found in these energy bands. [ABSTRACT FROM AUTHOR]

We report the discovery of a new high-mass X-ray binary pulsar, XMMU J050722.1−684758, possibly associated with the supernova remnant (SNR) MCSNR J0507−6847 in the Large Magellanic Cloud, using XMM–Newton X-ray observations. Pulsations with a periodicity of 570 s are discovered from the Be X-ray binary XMMU J050722.1−684758 confirming its nature as a HMXB pulsar. The HMXB is located near the geometric centre of the SNR MCSNR J0507−6847(0.9 arcmin from the centre) which supports the XRB-SNR association. The estimated age of the SNR is 43–63 kyr years which points to a middle aged to old SNR. The large diameter of the SNR combined with the lack of distinctive shell counterparts in optical and radio indicates that the SNR is expanding into the tenuous environment of the superbubble N103. The estimated magnetic field strength of the neutron star is B ≳ 1014 G assuming a spin equilibrium condition which is expected from the estimated age of the parent remnant and assuming that the measured mass-accretion rate remained constant throughout. [ABSTRACT FROM AUTHOR]

We report the results of eROSITA and NICER observations of the 2020 June outburst of the Be/X-ray binary pulsar RX J0529.8−6556 in the Large Magellanic Cloud, along with the analysis of archival X-ray and optical data from this source. We find two anomalous features in the system's behaviour. First, the pulse profile observed by NICER during maximum luminosity is similar to that observed by XMM–Newton in 2000, despite the fact that the X-ray luminosity was different by two orders of magnitude. In contrast, a modest decrease in luminosity in the 2020 observations generated a significant change in pulse profile. Secondly, we find that the historical optical outbursts are not strictly periodic, as would be expected if the outbursts were triggered by periastron passage, as is generally assumed. The optical peaks are also not coincident with the X-ray outbursts. We suggest that this behaviour may result from a misalignment of the Be star disc and the orbital plane, which might cause changes in the timing of the passage of the neutron star through the disc as it precesses. We conclude that the orbital period of the source remains unclear. [ABSTRACT FROM AUTHOR]

Supersoft X-ray sources (SSS) have been identified as white dwarfs accreting from binary companions and undergoing nuclear burning of the accreted material on their surface. Although expected to be a relatively numerous population from both binary evolution models and their identification as type Ia supernova progenitor candidates, given the very soft spectrum of SSSs relatively few are known. Here we report on the X-ray and optical properties of 1RXS J050526.3−684628, a previously unidentified accreting nuclear-burning white dwarf located in the Large Magellanic Cloud (LMC). XMM–Newton observations enabled us to study its X-ray spectrum and measure for the first time short-period oscillations of ∼170 s. By analysing newly obtained X-ray data by eROSITA , together with Swift observations and archival ROSAT data, we have followed its long-term evolution over the last 3 decades. We identify 1RXS J050526.3−684628 as a slowly evolving post-nova SSS undergoing residual surface nuclear burning, which finally reached its peak in 2013 and is now declining. Though long expected on theoretical grounds, such long-lived residual-burning objects had not yet been found. By comparison with existing models, we find that the effective temperature and luminosity evolution are consistent with an ∼0.7 M⊙ carbon–oxygen white dwarf accreting |${\sim} 10^{-9}~\rm {M}_{\odot }$|  yr−1. Our results suggest that there may be many more undiscovered SSSs and 'missed' novae awaiting dedicated deep X-ray searches in the LMC and elsewhere. [ABSTRACT FROM AUTHOR]

The application of standard accretion theory to observations of X-ray binaries provides valuable insights into neutron star (NS) properties, such as their spin period and magnetic field. However, most studies concentrate on relatively old systems, where the NS is in its late propeller, accretor, or nearly spin equilibrium phase. Here, we use an analytic model from standard accretion theory to illustrate the evolution of high-mass X-ray binaries (HMXBs) early in their life. We show that a young NS is unlikely to be an accretor because of the long duration of ejector and propeller phases. We apply the model to the recently discovered ∼4000 yr old HMXB XMMU J051342.6−672412 and find that the system's NS, with a tentative spin period of 4.4 s, cannot be in the accretor phase and has a magnetic field B > a few × 1013 G, which is comparable to the magnetic field of many older HMXBs and is much higher than the spin equilibrium inferred value of a few × 1011 G. The observed X-ray luminosity could be the result of thermal emission from a young cooling magnetic NS or a small amount of accretion that can occur in the propeller phase. [ABSTRACT FROM AUTHOR]

We report the discovery of a very young high-mass X-ray binary (HMXB) system associated with the supernova remnant (SNR) MCSNR J0513-6724 in the Large Magellanic Cloud (LMC), using XMM–Newton X-ray observations. The HMXB is located at the geometrical centre of extended soft X-ray emission, which we confirm as an SNR. The HMXB spectrum is consistent with an absorbed power law with spectral index ∼1.6 and a luminosity of 7 × 1033 erg s−1 (0.2–12 keV). Tentative X-ray pulsations are observed with a periodicity of 4.4 s and the OGLE I -band light curve of the optical counterpart from more than 17.5 yr reveals a period of 2.2324 ± 0.0003 d, which we interpret as the orbital period of the binary system. The X-ray spectrum of the SNR is consistent with non-equilibrium shock models as expected for young/less evolved SNRs. From the derived ionization time-scale we estimate the age of the SNR to be <6 kyr. The association of the HMXB with the SNR makes it the youngest HMXB, in the earliest evolutionary stage known to date. An HMXB as young as this can switch on as an accreting pulsar only when the spin period has reached a critical value. Under this assumption, we obtain an upper limit to the magnetic field of <5 × 1011 G. This implies several interesting possibilities including magnetic field burial, possibly by an episode of post-supernova hyper-critical accretion. Since these fields are expected to diffuse out on a time-scale of 103–104 yr, the discovery of a very young HMXB can provide us the unique opportunity to observe the evolution of the observable magnetic field for the first time in X-ray binaries. [ABSTRACT FROM AUTHOR]

NGC 300 ULX1 is an ultraluminous X-ray pulsar, showing an unprecedented spin evolution, from about 126 s to less than 20 s in only 4 yr, consistent with steady mass accretion rate. Following its discovery we have been monitoring the system with Swift and NICER to further study its properties. We found that even though the observed flux of the system dropped by a factor of ≳20, the spin-up rate remained almost constant. A possible explanation is that the decrease in the observed flux is a result of increased absorption of obscuring material due to outflows or a precessing accretion disc. [ABSTRACT FROM AUTHOR]

We report the discovery of a new Small Magellanic Cloud pulsar wind nebula (PWN) at the edge of the supernova remnant (SNR) DEM S5. The pulsar powered object has a cometary morphology similar to the Galactic PWN analogues PSR B1951+32 and 'the mouse'. It is travelling supersonically through the interstellar medium. We estimate the pulsar kick velocity to be in the range of 700–2000 km s−1 for an age between 28 and 10 kyr. The radio spectral index for this SNR–PWN–pulsar system is flat (–0.29 ± 0.01) consistent with other similar objects. We infer that the putative pulsar has a radio spectral index of –1.8, which is typical for Galactic pulsars. We searched for dispersion measures up to 1000 cm−3 pc but found no convincing candidates with an S/N greater than 8. We produce a polarization map for this PWN at 5500 MHz and find a mean fractional polarization of P  ∼ 23 per cent. The X-ray power-law spectrum (Γ ∼ 2) is indicative of non-thermal synchrotron emission as is expected from PWN–pulsar system. Finally, we detect DEM S5 in infrared (IR) bands. Our IR photometric measurements strongly indicate the presence of shocked gas that is expected for SNRs. However, it is unusual to detect such IR emission in an SNR with a supersonic bow shock PWN. We also find a low-velocity H  i cloud of ∼107 km s−1 that is possibly interacting with DEM S5. SNR DEM S5 is the first confirmed detection of a pulsar-powered bow shock nebula found outside the Galaxy. [ABSTRACT FROM AUTHOR]

We report the results of AstroSat and NuSTAR observations of the Be/X-ray binary pulsar SXP 15.3 in the Small Magellanic Cloud during its outburst in late 2017, when the source reached a luminosity level of ∼1038 erg s−1, close to the Eddington limit. The unprecedented broad-band coverage of the source allowed us to perform timing and spectral analysis between 3 and 80 keV. The pulse profile exhibits a significant energy dependence, and morphs from a double-peaked profile to a single broad pulse at energies >15 keV. This can be explained by a spectral hardening during an intensity dip seen between the two peaks of the pulse profile. We detect a Cyclotron Resonance Scattering Feature at ∼5 keV in the X-ray spectrum, independent of the choice of the continuum model. This indicates a magnetic field strength of 6 × 1011 G for the neutron star. [ABSTRACT FROM AUTHOR]

The Large Magellanic Cloud (LMC) currently hosts around 23 high-mass X-ray binaries (HMXBs) of which most are Be/X-ray binaries. The LMC XMM-Newton survey provided follow-up observations of previously known X-ray sources that were likely HMXBs, as well as identifying newHMXBcandidates. In total, 19 candidate HMXBs were selected based on their X-ray hardness ratios. In this paper we present red and blue optical spectroscopy, obtained with Southern African Large Telescope and the South African Astronomical Observatory 1.9-m telescope, plus a timing analysis of the long-term optical light curves from OGLE to confirm the nature of these candidates. We find that nine of the candidates are new Be/X-ray binaries, substantially increasing the LMC Be/X-ray binary population. Furthermore, we present the optical properties of these new systems, both individually and as a group of all the BeXBs identified by the XMM-Newton survey of the LMC. [ABSTRACT FROM AUTHOR]

SXP 1062 is a Be X-ray binary (BeXB) located in the Small Magellanic Cloud. It hosts a longperiodX- ray pulsar and is likely associated with the supernova remnant MCSNRJ0127-7332. In this work we present a multiwavelength view on SXP 1062 in different luminosity regimes. We consider monitoring campaigns in optical (OGLE survey) and X-ray (Swift telescope). During these campaigns a tight coincidence of X-ray and optical outbursts is observed. We interpret this as typical Type I outbursts as often detected in BeXBs at periastron passage of the neutron star (NS). To study different X-ray luminosity regimes in depth, during the source quiescence we observed it with XMM-Newton while Chandra observations followed an X-ray outburst. Nearly simultaneously with Chandra observations in X-rays, in optical the RSS/SALT telescope obtained spectra of SXP 1062. On the basis of our multiwavelength campaign we propose a simple scenario where the disc of the Be star is observed face-on, while the orbit of the NS is inclined with respect to the disc. According to the model of quasi-spherical settling accretion our estimation of the magnetic field of the pulsar in SXP 1062 does not require an extremely strong magnetic field at the present time. [ABSTRACT FROM AUTHOR]

We report on the X-ray and optical properties of two high-mass X-ray binary systems located in the Large Magellanic Cloud (LMC). Based on the obtained optical spectra, we classify the massive companion as a supergiant star in both systems. Timing analysis of the X-ray events collected by XMM-Newton revealed the presence of coherent pulsations (spin period∼2013 s) for XMMUJ053108.3-690923 and fast flaring behaviour for XMMUJ053320.8-684122. The X-ray spectra of both systems can be modelled sufficiently well by an absorbed power law, yielding hard spectra and high intrinsic absorption from the environment of the systems. Due to their combined X-ray and optical properties, we classify both systems as SgXRBs: the 19th confirmed X-ray pulsar and a probable supergiant fast X-ray transient in the LMC, the second such candidate outside our Galaxy. [ABSTRACT FROM AUTHOR]

We report on a detailed study of the spectral and temporal properties of the neutron star low-mass X-ray binary SLX 1737-282, which is located only ~1° away from Sgr A*. The system is expected to have a short orbital period, even within the ultracompact regime, given its persistent nature at low X-ray luminosities and the long duration thermonuclear burst that it has displayed. We have analysed a Suzaku (18 ks) observation and an XMM-Newton (39 ks) observation taken 7 yr apart. We infer (0.5-10 keV) X-ray luminosities in the range of 3-6 × 1035ergs-1, in agreement with previous findings. The spectra are well described by a relatively cool (kTbb = 0.5 keV) blackbody component plus a Comptonized emission component with Г ~ 1.5-1.7. These values are consistent with the source being in a faint hard state, as confirmed by the ~20 per cent fractional root-mean-square amplitude of the fast variability (0.1-7 Hz) inferred from the XMM-Newton data. The electron temperature of the corona is ≳7 keV for the Suzaku observation, but it is measured to be as low as ~2 keV in the XMM-Newton data at higher flux. The latter is significantly lower than expected for systems in the hard state. We searched for X-ray pulsations and imposed an upper limit to their semiamplitude of 2 per cent (0.001-7 Hz). Finally, we investigated the origin of the low-frequency variability emission present in the XMM-Newton data and ruled out an absorption dip origin. This constraint the orbital inclination of the system to ≲65° unless the orbital period is longer than 11 h (i.e. the length of the XMM-Newton observation). [ABSTRACT FROM AUTHOR]

We report on the X-ray spectral and temporal properties of the Be/X-ray binary system XMMUJ004855.5-734946 located in the Small Magellanic Cloud. The system was monitored by Swift/XRT during a moderate outburst in 2016 July, while an unanticipated Chandra target of opportunity observation was triggered when the luminosity of the system was greater than 1036 erg s-1 allowing a detailed study of X-ray properties of the systems. Specifically, its X-ray spectrum, as observed during the outburst, is well modelled by an absorbed power law (T = 0.58). Timing analysis of the collected photon events revealed coherent X-ray pulsations with a period of ~15.64 s, thus confirming XMMU J004855.5-734946 as a high-mass X-ray binary pulsar. By analysing archival XMM-Newton observations, we determined the longterm spin period evolution of the neutron star, showing that the compact star has spun-up by Ṗ ~ -0.0028 s yr-1. By modelling the X-ray pulsed emission as detected by Chandra, we set constraints on the inclination of the magnetic and rotation axis of the neutron star, as well to its compactness (i.e. (M/M☉)/(R/km) = 0.095 ± 0.007). [ABSTRACT FROM AUTHOR]

The transient IGR J01217-7257 in the Small Magellanic Cloud was found to be in a new outburst during INTEGRALobservations. We triggered anXMM-Newton target of opportunity observation near outburst maximum, which lead to the discovery of X-ray pulsations with a period of 2.165 s. This period is very similar to that detected from XTE J0119-731, suggesting that both sources are identical. The pulse profile obtained from the EPIC-pn instrument is complex and highly energy dependent. Pulse-phase spectroscopy reveals variations in the spectral slope correlated with the changes in flux during the pulse, with the harder X-ray spectrum at pulse maximum and softer during minimum. Analysis of XMM-Newton reflection grating spectra reveals the presence of emission lines that suggest the presence of ionized material around the neutron star. By monitoring the system during its outburst with Swift/XRT we detected a possible transition from the accretor to the propeller stage. [ABSTRACT FROM AUTHOR]

The X-ray binary population of the Small Magellanic Cloud (SMC) contains a large number of massive X-ray binaries and the recent survey of the SMC by XMM-Newton has resulted in almost 50 more tentative high-mass X-ray binary (HMXB) candidates. Using probability parameters from Haberl and Sturm together with the optical spectra and timing in this work, we confirm six new massive X-ray binaries in the SMC. We also report two very probable binary periods of 36.4 d in XMM 1859 and of 72.2 d in XMM 2300. These Be X-ray binaries are likely part of the general SMC population, which rarely undergoes an X-ray outburst. [ABSTRACT FROM AUTHOR]

NGC 7793 P13 is a variable (luminosity range ∼100) ultraluminous X-ray source proposed to host a stellar-mass black hole of less than 15 M⊙ in a binary system with orbital period of 64 d and a 18–23 M⊙ B9Ia companion. Within the EXTraS (Exploring the X-ray Transient and variable Sky) project, we discovered pulsations at a period of ∼0.42 s in two XMM–Newton observations of NGC 7793 P13, during which the source was detected at LX ∼ 2.1 × 1039 and 5 × 1039 erg s−1 (0.3–10 keV band). These findings unambiguously demonstrate that the compact object in NGC 7793 P13 is a neutron star accreting at super-Eddington rates. While standard accretion models face difficulties accounting for the pulsar X-ray luminosity, the presence of a multipolar magnetic field with B ∼ few × 1013 G close to the base of the accretion column appears to be in agreement with the properties of the system. [ABSTRACT FROM AUTHOR]

We report on the identification of the new Galactic Centre (GC) transient Swift J174540.7-290015 as a likely low-mass X-ray binary located at only 16 arcsec from Sgr A*. This transient was detected on 2016 February 6, during the Swift GC monitoring, and it showed long-term spectral variations compatible with a hard- to soft-state transition. We observed the field with XMM-Newton on February 26 for 35 ks, detecting the source in the soft state, characterized by a low level of variability and a soft X-ray thermal spectrum with a high energy tail (detected by INTEGRAL up to ~50 keV), typical of either accreting neutron stars or black holes. We observed: (i) a high column density of neutral absorbing material, suggesting that Swift J174540.7-290015 is located near or beyond the GC and; (ii) a sub-Solar iron abundance, therefore we argue that iron is depleted into dust grains. The lack of detection of Fe K absorption lines, eclipses or dipping suggests that the accretion disc is observed at a low inclination angle. Radio (Very Large Array) observations did not detect any radio counterpart to Swift J174540.7-290015. No evidence for X-ray or radio periodicity is found. The location of the transient was observed also in the near-infrared (near-IR) with gamma-ray burst optical near-IR detector at MPG/European Southern Observatory La Silla 2.2 m telescope and VLT/NaCo pre- and post-outburst. Within the Chandra error region, we find multiple objects that display no significant variations. [ABSTRACT FROM AUTHOR]

We report on the results of a ~40-d multi-wavelength monitoring of the Be X-ray binary system IGR J05007-7047 (LXP 38.55). During that period the system was monitored in the X-rays using the Swift telescope and in the optical with multiple instruments. When the X-ray luminosity exceeded 1036 erg s-1 we triggered an XMM-Newton ToO observation. Timing analysis of the photon events collected during the XMM-Newton observation reveals coherent X-ray pulsations with a period of 38.551(3) s (1σ), making it the 17th known high-mass X-ray binary pulsar in the LMC. During the outburst, the X-ray spectrum is fitted best with a model composed of an absorbed power law (Γ = 0.63) plus a high-temperature blackbody (kT ~2 keV) component. By analysing ~12 yr of available OGLE optical data we derived a 30.776(5) d optical period, confirming the previously reported X-ray period of the system as its orbital period. During our X-ray monitoring the system showed limited optical variability while its IR flux varied in phase with the X-ray luminosity, which implies the presence of a disc-like component adding cooler light to the spectral energy distribution of the system. [ABSTRACT FROM AUTHOR]

The deepest XMM-Newton mosaic map of the central 1°.5 of the Galaxy is presented, including a total of about 1.5 Ms of EPIC-pn cleaned exposures in the central 15 arcsec and about 200 ks outside. This compendium presents broad-band X-ray continuum maps, soft X-ray intensity maps, a decomposition into spectral components and a comparison of the X-ray maps with emission at other wavelengths. Newly discovered extended features, such as supernova remnants (SNRs), superbubbles and X-ray filaments are reported. We provide an atlas of extended features within ±1° of Sgr A*. We discover the presence of a coherent X-rayemitting region peaking around G0.1-0.1 and surrounded by the ring of cold, mid-IR-emitting material known from previous work as the 'Radio Arc Bubble' and with the addition of the X-ray data now appears to be a candidate superbubble. Sgr A's bipolar lobes show sharp edges, suggesting that they could be the remnant, collimated by the circumnuclear disc, of an SN explosion that created the recently discovered magnetar, SGR J1745-2900. Soft X-ray features, most probably from SNRs, are observed to fill holes in the dust distribution, and to indicate a direct interaction between SN explosions and Galactic centre (GC) molecular clouds. We also discover warm plasma at high Galactic latitude, showing a sharp edge to its distribution that correlates with the location of known radio/mid-IR features such as the 'GC Lobe'. These features might be associated with an inhomogeneous hot 'atmosphere' over the GC, perhaps fed by continuous or episodic outflows of mass and energy from the GC region. [ABSTRACT FROM AUTHOR]

On MJD 56590-1 (2013 Oct 25–26), observations of the Magellanic Clouds by the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observatory discovered a previously unreported bright, flaring X-ray source. This source was initially given the identification IGR J00569-7226. Subsequent multiwavelength observations identified the system as new Be/X-ray binary system in the Small Magellanic Cloud (SMC). Follow-up X-ray observations by Swift and XMM–Newton revealed an X-ray pulse period of 5.05 s and that the system underwent regular occultation/eclipse behaviour every 17 d. This is the first reported eclipsing Be/X-ray binary system in the SMC, and only the second such system known to date. Furthermore, the nature of the occultation makes it possible to use the neutron star to ‘X-ray’ the circumstellar disc, thereby, for the first time, revealing direct observational evidence for its size and clumpy structure. Swift timing measurements allowed for the binary solution to be calculated from the Doppler-shifted X-ray pulsations. This solution suggests this is a low-eccentricity binary relative to others measured in the SMC. Finally, it is interesting to note that the mass determined from this dynamical method for the Be star (∼13.0 M⊙) is significantly different from that inferred from the spectroscopic classification of B0.2Ve (∼16.0 M⊙) – an effect that has been noted for some other high mass X-ray binary systems. [ABSTRACT FROM AUTHOR]

We identify a new candidate for a Be/X-ray binary in the XMM–Newton slew survey and archival Swift observations that is located in the transition region of the Wing of the Small Magellanic Cloud and the Magellanic Bridge. We investigated and classified this source with follow-up XMM–Newton and optical observations. We model the X-ray spectra and search for periodicities and variability in the X-ray observations and the Optical Gravitational Lensing Experiment I-band light curve. The optical counterpart has been classified spectroscopically, with data obtained at the South African Astronomical Observatory 1.9 m telescope, and photometrically, with data obtained using the Gamma-ray Burst Optical Near-ir Detector at the MPG 2.2 m telescope. The X-ray spectrum is typical of a high-mass X-ray binary with an accreting neutron star. We detect X-ray pulsations, which reveal a neutron-star spin period of Ps = (264.516 ± 0.014) s. The source likely shows a persistent X-ray luminosity of a few 1035 erg s−1 and in addition type-I outbursts that indicate an orbital period of ∼146 d. A periodicity of 0.867 d, found in the optical light curve, can be explained by non-radial pulsations of the Be star. We identify the optical counterpart and classify it as a B1-2II-IVe star. This confirms SXP 265 as a new Be/X-ray binary pulsar originating in the tidal structure between the Magellanic Clouds. [ABSTRACT FROM AUTHOR]

We present new optical spectroscopy of 20 candidate counterparts of 17 X-ray sources in the direction of the M31 disc. By comparing the X-ray catalogue from the XMM–Newton survey of M31 with star catalogues from the Local Group Galaxy Survey, we chose counterpart candidates based on optical colour and X-ray hardness. We have discovered 17 counterpart candidates with spectra containing stellar features. Eight of these are early-type stars of O or B type in M31, with hard X-ray spectra, making them good high-mass X-ray binary (HMXB) candidates. Three of these eight exhibit emission lines, which we consider to be the strongest HMXB candidates. In addition, our spectra reveal two likely Galactic cataclysmic variables, one foreground M star, two probable low-mass X-ray binaries related to M31 globular clusters, one emission-line region with an embedded Wolf–Rayet star and one newly discovered supernova remnant. Finally, two of the sources have stellar spectra with no features indicative of association with an X-ray source. [ABSTRACT FROM PUBLISHER]

ABSTRACT In the course of the XMM-Newton survey of the Small Magellanic Cloud (SMC), two new bright X-ray sources were discovered exhibiting the spectral characteristics of high-mass X-ray binaries - but revealing only weak evidence for pulsations in just one of the objects (at 153 s in XMMU J010743.1−715953). The accurate X-ray source locations permit the identification of these X-ray sources with Be stars, thereby strongly suggesting that these systems are new Be/X-ray binaries. From blue spectra the proposed classification for XMMU J010633.1−731543 is B0.5-1Ve and for XMMU J010743.1−715953 it is B2IV-Ve. [ABSTRACT FROM AUTHOR]

ABSTRACT In the course of the XMM-Newton survey of the Small Magellanic Cloud (SMC), two new bright X-ray sources were discovered exhibiting the spectral characteristics of high-mass X-ray binaries - but revealing only weak evidence for pulsations in just one of the objects (at 153 s in XMMU J010743.1−715953). The accurate X-ray source locations permit the identification of these X-ray sources with Be stars, thereby strongly suggesting that these systems are new Be/X-ray binaries. From blue spectra the proposed classification for XMMU J010633.1−731543 is B0.5-1Ve and for XMMU J010743.1−715953 it is B2IV-Ve. [ABSTRACT FROM AUTHOR]

ABSTRACT RX J0720.4−3125 is the most peculiar object among a group of seven isolated X-ray pulsars (the so-called Magnificent Seven), since it shows long-term variations of its spectral and temporal properties on time-scales of years. This behaviour was explained by different authors either by free precession (with a 7 or 14 yr period) or possibly a glitch that occurred around MJD = 528 66 ± 73 d. We analysed our most recent XMM-Newton and Chandra observations in order to further monitor the behaviour of this neutron star. With the new data sets, the timing behaviour of RX J0720.4−3125 suggests a single (sudden) event (e.g. a glitch) rather than a cyclic pattern as expected by free precession. The spectral parameters changed significantly around the proposed glitch time, but more gradual variations occurred already before the (putative) event. Since MJD ≈ 530 00 d the spectra indicate a very slow cooling by ∼2 eV over 7 yr. [ABSTRACT FROM AUTHOR]

ABSTRACT We report on the first X-ray images of the Phoenix dwarf galaxy, taken with XMM-Newton in 2009 July. This Local Group dwarf galaxy shares similarities with the Small Magellanic Cloud (SMC) including a burst of star formation ∼50 Myr ago. The SMC has an abundance of high-mass X-ray binaries (HMXBs) and so we have investigated the possibility of an HMXB population in Phoenix with the intention of furthering the understanding of the HMXB-star formation rate relation. The data from the combined European Photon Imaging Cameras (EPIC) were used to distinguish between different source classes [foreground stars, background galaxies, active galactic nuclei (AGN) and supernova remnants] using EPIC hardness ratios and correlations with optical and radio catalogues. Of the 81 X-ray sources in the field of view, six are foreground stars, four are galaxies and one is an AGN. The remaining sources with optical counterparts have log( fX/ fopt) consistent with AGN in the local Universe. Further investigation of five sources in the field of view suggests that they are all background AGN. Their position behind the gas cloud associated with Phoenix makes them a possible tool for further probing the metallicity of this region. We find no evidence for any HMXBs in Phoenix at this time. This rules out the existence of the X-ray persistent supergiant X-ray binary systems. However, the transient nature of the Be/X-ray binaries means we cannot rule out a population of these sources but can conclude that it is not extensive. [ABSTRACT FROM AUTHOR]

ABSTRACT We present fast timing photometric observations of the intermediate polar V2069 Cygni (RX J2123.7+4217) using the Optical Timing Analyzer (OPTIMA) at the 1.3-m telescope of Skinakas Observatory. The optical (450-950 nm) light curve of V2069 Cygni was measured with sub-second resolution for the first time during 2009 July and revealed a double-peaked pulsation with a period of 743.38 ± 0.25 s. A similar double-peaked modulation was found in the simultaneous Swift satellite observations. We suggest that this period represents the spin of the white dwarf accretor. Moreover, we present results from a detailed analysis of the XMM-Newton observation, which also shows a double-peaked modulation, however shifted in phase, with a period of 742.35 ± 0.23 s. The X-ray spectra obtained from the XMM-Newton European Photon Imaging Camera (EPIC) instruments were modelled by a plasma emission and a soft blackbody component with a partial covering photoelectric absorption model with a covering fraction of 0.65. An additional Gaussian emission line at 6.385 keV with an equivalent width of 243 eV is required to account for fluorescent emission from neutral iron. The iron fluorescence (∼6.4 keV) and Fe xxvi lines (∼6.95 keV) are clearly resolved in the EPIC spectra. In the Porb- Pspin diagram of intermediate polars, V2069 Cyg shows a low spin-to-orbit ratio of ∼0.0276 in comparison with ∼0.1 for other intermediate polars. [ABSTRACT FROM AUTHOR]

ABSTRACT We report the Australia Telescope Compact Array (ATCA) and ROSAT detection of supernova remnant (SNR) J0529−6653 in the Large Magellanic Cloud (LMC) which is positioned in the projected vicinity of the known radio pulsar PSR B0529−66. In the radio continuum frequencies, this LMC object follows a typical SNR structure of a shell morphology with brightened regions in the south-west. It exhibits an almost circular shape of D= 33 × 31 pc (1-pc uncertainty in each direction) and radio spectral index of α=−0.68 ± 0.03 - typical for mid-age SNRs. We also report detection of polarized regions with a peak value of ∼17 ± 7 per cent at 6 cm. An investigation of ROSAT images produced from merged Position Sensitive Proportional Counter (PSPC) data reveals the presence of extended X-ray emission coincident with the radio emission of the SNR. In X-rays, the brightest part is in the north-east. We discuss various scenarios with regard to the SNR-pulsar association with emphasis on the large age difference, lack of a pulsar trail and no prominent point-like radio or X-ray source. [ABSTRACT FROM AUTHOR]

ABSTRACT We co-added the available XMM-Newton Reflection Grating Spectrometer (RGS) spectra for each of the isolated X-ray pulsars RX J0720.4−3125, RX J1308.6+2127 (RBS1223), RX J1605.3+3249 and RX J1856.4−3754 (four members of the 'Magnificent Seven') and the 'Three Musketeers' Geminga, PSR B0656+14 and PSR B1055−52. We confirm the detection of a narrow absorption feature at 0.57 keV in the co-added RGS spectra of RX J0720.4−3125 and RX J1605.3+3249 (including most recent observations). In addition, we found similar absorption features in the spectra of RX J1308.6+2127 (at 0.53 keV) and maybe PSR B1055−52 (at 0.56 keV). The absorption feature in the spectra of RX J1308.6+2127 is broader than the feature e.g. in RX J0720.4−3125. The narrow absorption features are detected with 2-5.6σ significance. Although very bright and frequently observed, there are no absorption features visible in the spectra of RX J1856.4−3754 and PSR B0656+14, while the co-added XMM-Newton RGS spectrum of Geminga has not enough counts to detect such a feature. We discuss a possible origin of these absorption features as lines caused by the presence of highly ionized oxygen (in particular O vii and/or O vi at 0.57 keV) in the interstellar medium and absorption in the neutron star atmosphere, namely the absorption features at 0.57 keV as gravitational redshifted ( gr= 1.17) O viii. [ABSTRACT FROM AUTHOR]

BSTRACT [ABSTRACT FROM AUTHOR]

We present an optical and X-ray study of four Be/X-ray binaries located in the Small Magellanic Cloud (SMC). OGLE I-band data of up to 11 years of semicontinuous monitoring has been analysed for SMC X-2, SXP172 and SXP202B, providing both a measurement of the orbital period ( and 229.9 d for the pulsars, respectively) and a detailed optical orbital profile for each pulsar. For SXP172 this has allowed a direct comparison of the optical and X-ray emission seen through regular RXTE monitoring, revealing that the X-ray outbursts precede the optical by around 7 d. Recent X-ray studies by XMM-Newton have identified a new source in the vicinity of SXP15.3 raising doubt on the identification of the optical counterpart to this X-ray pulsar. Here we present a discussion of the observations that led to the proposal of the original counterpart and a detailed optical analysis of the counterpart to the new X-ray source, identifying a 21.7 d periodicity in the OGLE I-band data. The optical characteristics of this star are consistent with that of a SMC Be/X-ray binary. However, this star was rejected as the counterpart to SXP15.3 in previous studies due to the lack of Hα emission. [ABSTRACT FROM AUTHOR]

We report on the results of a multi-wavelength study of the compact object candidate 1RXS J141256.0+792204 (Calvera). Calvera was observed in the X-rays with XMM-Newton/EPIC twice for a total exposure time of ks. The source spectrum is thermal and well reproduced by a two-component model composed of either two (absorbed) hydrogen atmosphere models or two blackbodies with temperatures eV, eV, respectively (as measured at infinity). Evidence was found for an absorption feature at keV while no power-law high-energy tail is statistically required. Using pn and MOS data we discovered pulsations in the X-ray emission at a period ms. The detection is highly significant , and unambiguously confirms the neutron star nature of Calvera. The pulse profile is nearly sinusoidal, with a pulsed fraction of per cent. We looked for the timing signature of Calvera in the Fermi Large Area Telescope (LAT) data base and found a significant pulsed signal at a period coincident with the X-ray value. The gamma-ray timing analysis yielded a tight upper limit on the period derivative, s s ( erg s, G for magneto-dipolar spin-down). Radio searches at 1.36 GHz with the 100-m Effelsberg radio telescope yielded negative results, with a deep upper limit on the pulsed flux of mJy. Diffuse, soft keV) X-ray emission about 13 arcmin west of the Calvera position is present both in our pointed observations and in archive ROSAT all-sky survey images, but is unlikely associated with the X-ray pulsar. Its spectrum is compatible with an old supernova remnant (SNR); no evidence for diffuse emission in the radio and optical bands was found. The most likely interpretations are that Calvera is either a central compact object escaped from a SNR or a mildly recycled pulsar; in both cases the source would be the first ever member of the class detected at gamma-ray energies. [ABSTRACT FROM AUTHOR]

ABSTRACT We present X-ray and optical data on the Be/X-ray binary (BeXRB) pulsar IGR J 01054−7253= SXP11.5 in the Small Magellanic Cloud (SMC). Rossi X-ray Timing Explorer ( RXTE) observations of this source in a large X-ray outburst reveal an 11.483 ± 0.002 s pulse period and show both the accretion-driven spin-up of the neutron star and the motion of the neutron star around the companion through Doppler shifting of the spin period. Model fits to these data suggest an orbital period of 36.3 ± 0.4 d and of (4.7 ± 0.3) × 10−10 seconds s−1. We present an orbital solution for this system, making it one of the best-described BeXRB systems in the SMC. The observed pulse period, spin-up and X-ray luminosity of SXP11.5 in this outburst are found to agree with the predictions of neutron star accretion theory. Timing analysis of the long-term optical light curve reveals a periodicity of 36.70 ± 0.03 d, in agreement with the orbital period found from the model fit to the X-ray data. Using blue-end spectroscopic observations we determine the spectral type of the counterpart to be O9.5-B0 IV-V. This luminosity class is supported by the observed V-band magnitude. Using optical and near-infrared photometry and spectroscopy, we study the circumstellar environment of the counterpart in the months after the X-ray outburst. [ABSTRACT FROM AUTHOR]

Deep observations of the Small Magellanic Cloud (SMC) and region were carried out in the hard X-ray band by the INTEGRAL observatory in 2008–2009. The field of view of the instrument permitted simultaneous coverage of the entire SMC and the eastern end of the Magellanic Bridge. In total, INTEGRAL detected seven sources in the SMC and five in the Magellanic Bridge; the majority of the sources were previously unknown systems. Several of the new sources were detected undergoing bright X-ray outbursts and all the sources exhibited transient behaviour except the supergiant system SMC X-1. They are all thought to be high-mass X-ray binary systems in which the compact object is a neutron star. [ABSTRACT FROM AUTHOR]

The Small Magellanic Cloud (SMC) Be/X-ray binary pulsar SXP6.85 = XTE underwent a large Type II outburst beginning on 2008 August 10. The source was consistently seen for the following 20 weeks (MJD = 54688–54830). We present X-ray timing and spectroscopic analysis of the source as a part of our ongoing Rossi X-ray Timing Explorer (RXTE) monitoring campaign and INTEGRAL key programme monitoring the SMC and 47 Tuc. A comparison with the Optical Gravitational Lensing Experiment (OGLE) III light curve of the Be counterpart shows the X-ray outbursts from this source coincide with times of optical maximum. We attribute this to the circumstellar disc increasing in size, causing mass accretion on to the neutron star. Ground based infrared photometry and Hα spectroscopy obtained during the outburst are used as a measure of the size of the circumstellar disc and lend support to this picture. In addition, folded RXTE light curves seem to indicate complex changes in the geometry of the accretion regions on the surface of the neutron star, which may be indicative of an inhomogeneous density distribution in the circumstellar material causing a variable accretion rate on to the neutron star. Finally, the assumed inclination of the system and Hα equivalent width measurements are used to make a simplistic estimate of the size of the circumstellar disc. [ABSTRACT FROM AUTHOR]

INTEGRAL observations of the Small Magellanic Cloud region have resulted in the serendipitous detection of two transient hard X-ray sources in the Magellanic Bridge. In this paper, we present the timing and spectral characteristics of these sources across the 2–100 keV energy range, which, in conjunction with their optical counterparts, demonstrate that they are high-mass X-ray binaries (HMXBs) in the Magellanic Bridge. Together with one previously known HMXB system, and three candidates, these sources represent an emerging population of X-ray binaries in the Bridge, probably initiated by tidally induced star formation as a result of the gravitational interaction between the Large and Small Magellanic Clouds. [ABSTRACT FROM AUTHOR]

On 2006 August 30, SXP18.3 a high-mass X-ray binary (HMXB) in the Small Magellanic Cloud (SMC) with an 18.3 s pulse period was observed by Rossi X-ray Timing Explorer ( RXTE). The source was seen continuously for the following 36 weeks. This is the longest type II outburst ever seen from a HMXB in the SMC. During the outburst, SXP18.3 was located from serendipitous XMM–Newton observations. The identification of the optical counterpart has allowed SXP18.3 to be classified as a Be/X-ray binary. This paper will report on the analysis of the optical and weekly RXTE X-ray data that span the last 10 yr. The extreme length of this outburst has for the first time enabled us to perform an extensive study of the pulse timing of a SMC Be/X-ray binary. We present a possible full orbital solution from the pulse timing data. An orbital period of 17.79 d is proposed from the analysis of the Optical Gravitational Lensing Experiment (OGLE) III light curve placing SXP18.3 on the boundary of known sources in the Corbet diagram. [ABSTRACT FROM AUTHOR]

Here we report on the first XMM–Newton observation of the anomalous X-ray pulsar 1RXS J170849.0–400910. The source was observed in 2003 August, and was found at a flux level factor of about 2 lower than previous observations. Moreover, a significant spectral evolution appears to be present, the source exhibiting a much softer spectrum than in the past. Comparison of the present properties of 1RXS J170849.0–400910 with those from archival data shows a clear correlation between the X-ray flux and the spectral hardness. In particular, the flux and the spectral hardness reached a maximum level close to the two glitches the source experienced in 1999 and 2001, and successively decreased. Although the excellent XMM–Newton spectral resolution should in principle allow us to detect the absorption line reported in a phase-resolved spectrum with BeppoSAX, and interpreted as a cyclotron feature, we found no absorption features, neither in the phase-averaged spectrum nor in the phase-resolved spectra. We discuss in detail both the possibilities that the feature in the BeppoSAX data may have resulted from a spurious detection and that it is real and intrinsically variable. We then discuss a possible explanation for the glitches and for the softening of the source emission that followed the flux decrease, in the framework of the magnetar model. [ABSTRACT FROM AUTHOR]

We present a combined analysis of XMM–Newton, Chandra and ROSAT observations of the isolated neutron star RX J0720.4-3125, spanning a total period of ∼7 yr. We develop a maximum likelihood periodogram for our analysis based on the ΔC statistic and the maximum likelihood method, which are appropriate for the treatment of sparse event lists. Our results have been checked a posteriori by folding a further BeppoSAX data set with the period predicted at the time of that observation: the phase is found to be consistent. The study of the spin history and the measure of the spin-down rate are of extreme importance in discriminating between the possible mechanisms suggested for the nature of the X-ray emission. The value of P·, here measured for the first time, is ≈10[sup -14] s s[sup -1]. This value cannot be explained in terms of torque from a fossil disc. When interpreted in terms of dipolar losses, it gives a magnetic field of B≈10[sup 13] G, making it also implausible that the source is accreting from the underdense surroundings. On the other hand, we also find it unlikely that the field decayed from a much larger value (B≈10 [sup 15] G , as expected for a magnetar powered by dissipation of a superstrong field) since this scenario predicts a source age of ≈10 [sup 4] yr, too young to match the observed X-ray luminosity. The observed properties are more compatible with a scenario in which the source is ≈10 [sup 6] yr old, and its magnetic field has not changed substantially over the lifetime. [ABSTRACT FROM AUTHOR]