Search

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]

Aims.We present a multi-wavelength analysis of the evolved supernova remnants MCSNR J05067025 and MCSNR J0527-7104 in the Large Magellanic Cloud. Methods. We used observational data from XMM-Newton, the Australian Telescope Compact Array, and the Magellanic Cloud Emission Line Survey to study their broad-band emission and used Spitzer and Hi data to gain a picture of the environment into which the remnants are expanding. We performed a multi-wavelength morphological study and detailed radio and X-ray spectral analyses to determine their physical characteristics. Results. Both remnants were found to have bright X-ray cores, dominated by Fe L-shell emission, which is consistent with reverse shock-heated ejecta with determined Fe masses in agreement with Type Ia explosion yields. A soft X-ray shell, which is consistent with swept-up interstellar medium, was observed in MCSNR J0506-7025, suggestive of a remnant in the Sedov phase. Using the spectral fit results and the Sedov self-similar solution, we estimated the age of MCSNR J0506-7025 to be ~16-28 kyr, with an initial explosion energy of (0.07-0.84) × 1051 erg. A soft shell was absent in MCSNR J0527-7104, with only ejecta emission visible in an extremely elongated morphology that extends beyond the optical shell. We suggest that the blast wave has broken out into a low density cavity, allowing the shock heated ejecta to escape. We find that the radio spectral index of MCSNR J0506-7025 is consistent with the standard -0:5 for supernova remnants. Radio polarisation at 6 cm indicates a higher degree of polarisation along the western front and at the eastern knot with a mean fractional polarisation across the remnant of P ≅ (20 ± 6)%. Conclusions. The detection of Fe-rich ejecta in the remnants suggests that both resulted from Type Ia explosions. The newly identified Fe-rich cores in MCSNR J0506-7025 and MCSNR J0527-7104 make them members of the expanding class of evolved Fe-rich remnants in the Magellanic Clouds. [ABSTRACT FROM AUTHOR]

Aims. We present an X-ray study of the supernova remnant SNR J0533-7202 in the Large Magellanic Cloud (LMC) and determine its physical characteristics based on its X-ray emission. Methods. We observed SNR J0533-7202 with XMM-Newton (background flare-filtered exposure times of 18 ks EPIC-pn and 31 ks EPIC-MOS1, EPIC-MOS2). We produced X-ray images of the supernova remnant, performed an X-ray spectral analysis, and compared the results to multi-wavelength studies. Results. The distribution of X-ray emission is highly non-uniform, with the south-west region much brighter than the north-east. The detected X-ray emission is correlated with the radio emission from the remnant.We determine that this morphology is most likely due to the supernova remnant expanding into a non-uniform ambient medium and not an absorption e ect. We estimate the remnant size to be 53:9 (±3:4) × 43:6 (±3:4) pc, with the major axis rotated ∼64° east of north. We find no spectral signatures of ejecta emission and infer that the X-ray plasma is dominated by swept up interstellar medium. Using the spectral fit results and the Sedov self-similar solution, we estimate the age of SNR J0533-7202 to be ∼17-27 kyr, with an initial explosion energy of (0:09-0:83) × 1051 erg. We detected an X-ray source located near the centre of the remnant, namely XMMU J053348.2-720233. The source type could not be conclusively determined due to the lack of a multi-wavelength counterpart and low X-ray counts. We found that it is likely either a background active galactic nucleus or a low-mass X-ray binary in the LMC. Conclusions. We detected bright thermal X-ray emission from SNR J0533-7202 and determined that the remnant is in the Sedov phase of its evolution. The lack of ejecta emission prohibits us from typing the remnant with the X-ray data. Therefore, the likely Type Ia classification based on the local stellar population and star formation history reported in the literature cannot be improved upon. [ABSTRACT FROM AUTHOR]

Aims. We present a detailed study of the superbubble 30 Dor C and the newly identified supernova remnant MCSNR J0536-6913 in the Large Magellanic Cloud. Methods. All available XMM-Newton data (flare-filtered exposure times of 420 ks EPIC-pn, 556 ks EPIC-MOS1, 614 ks EPICMOS2) were used to characterise the thermal X-ray emission in the region. An analysis of the non-thermal X-ray emission is also presented and discussed in the context of emission mechanisms previously suggested in the literature. These data are supplemented by X-ray data from Chandra, optical data from the Magellanic Cloud Emission Line Survey, and radio data from the Australia Telescope Compact Array and the Molonglo Observatory Synthesis Telescope. Results. The brightest thermal emission towards 30 Dor C was found to be associated with a new supernova remnant, MCSNR J0536-6913. X-ray spectral analysis of MCSNR J0536-6913 suggested an ejecta-dominated remnant with lines of O, Ne, Mg, and Si, and a total 0:3-10 keV X-ray luminosity of ~8*1034 erg s-1. Based on derived ejecta abundance ratios, we determined the mass of the stellar progenitor to be either ~18 M or as high as>40 M_sun, though the spectral fits were subject to assumptions (e.g., uniform temperature and well-mixed ejecta). The thermal emission from the SB exhibited enrichment by alpha-process elements, evidence for a recent core-collapse SNR interaction with the SB shell. We detected non-thermal X-ray emission throughout 30 Dor C, with the brightest regions being highly correlated with the H-alpha and radio shells. We created a non-thermal spectral energy distribution for the north-eastern shell of 30 Dor C which was best-fit with an exponentially cut-off synchrotron model. Conclusions. Thermal X-ray emission from 30 Dor C is very complex, consisting of a large scale superbubble emission at the eastern shell wall with the brightest emission due to MCSNR J0536??6913. The fact that the non-thermal spectral energy distribution of the superbubble shell was observed to roll-off is further evidence that the non-thermal X-ray emission from 30 Dor C is synchrotron in origin. [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 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]

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]