5 research outputs found
Discovery of a pulsar-powered bow shock nebula in the Small Magellanic Cloud supernova remnant DEMS5
We report the discovery of a new Small Magellanic Cloud pulsar wind nebula (PWN) at the edge of the supernova remnant (SNR) DEMâS5. The pulsar powered object has a cometary morphology similar to the Galactic PWN analogues PSRâB1951+32 and âthe mouseâ. It is travelling supersonically through the interstellar medium. We estimate the pulsar kick velocity to be in the range of 700â2000âkmâsâ1 for an age between 28 and 10âkyr. The radio spectral index for this SNRâPWNâpulsar system is flat (â0.29 ± 0.01) consistent with other similar objects. We infer that the putative pulsar has a radio spectral index of â1.8, which is typical for Galactic pulsars. We searched for dispersion measures up to 1000âcmâ3âpc 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 perâcent. The X-ray power-law spectrum (Π⌠2) is indicative of non-thermal synchrotron emission as is expected from PWNâpulsar system. Finally, we detect DEMâS5 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 Hâi cloud of âŒ107âkmâsâ1 that is possibly interacting with DEMâS5. SNR DEMâS5 is the first confirmed detection of a pulsar-powered bow shock nebula found outside the Galaxy.Rami Z. E. Alsaberi, C. Maitra, M. D. FilipoviÄ, L. M. Bozzetto, F. Haberl ... Gavin P Rowell .. et al
Radio continuum sources behind the Large Magellanic Cloud
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 âŒ144 deg(2) at angular resolutions from 45 arcsec to âŒ3 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 S(v) ⌠Μ(α)) of α = â0.89 and mean of â0.88 ± 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) âŒ40â45 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 < â0.8. 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.M D FilipoviÄ âŠ G. Rowell ⊠et al