Observations of the Non-Thermal X-ray Emission from the Galactic Supernova Remnant G347.3-0.5

G347.3-0.5 (RX J1713.7-3946) is a member of the new class of shell-type Galactic supernova remnants (SNRs) that feature non-thermal components to their X-ray emission. We have analyzed the X-ray spectrum of this SNR over a broad energy range (0.5 to 30 keV) using archived data from observations made with two satellites, the Roentgenstaellit (ROSAT) and the Advanced Satellite for Cosmology and Astrophysics (ASCA), along with data from our own observations made with the Rossi X-ray Timing Explorer (RXTE). Using a combination of the models EQUIL and SRCUT to fit thermal and non-thermal emission, respectively, from this SNR, we find evidence for a modest thermal component to G347.3-0.5's diffuse emission with a corresponding energy of kT = 1.4 keV. We also obtain an estimate of 70 TeV for the maximum energy of the cosmic-ray electrons that have been accelerated by this SNR.Comment: 4 pages, 1 figure, to appear in "Neutron Stars in Supernova Remnants" (ASP Conference Proceedings), eds P. O. Slane and B. M. Gaensle

Radio Continuum Sources behind the Large Magellanic Cloud

We present a comprehensive multi-frequency 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 6 434 discrete radio sources in total, of which 3 789 are detected at two or more radio frequencies. We estimate the median spectral index (; where ) of = 09 and mean of 088 0.48 for 3 636 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 sources populations within our sample. We find 10 GPS candidates with peak frequencies near 5 GHz, from which we estimate their linear size. 1 866 sources from our catalogue are CSS candidates with 08.We found six candidates for High Frequency Peaker (HFP) sources, whose radio fluxes peak above 5 GHz and no sources with unconstrained peaks and ¡ 05. 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 Infrared Faint Radio Sources (IFRSs) found in this study

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) DEMS5. 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 ( ∼ 2) is indicative of non-thermal synchrotron emission as is expected from PWN–pulsar system. Finally, we detect DEMS5 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 HI cloud of ∼107 km s−1 that is possibly interacting with DEMS5. SNR DEMS5 is the first confirmed detection of a pulsar-powered bow shock nebula found outside the Galaxy

The X-ray Properties of Five Galactic Supernova Remnants Detected by the Spitzer GLIMPSE Survey

(Abbreviated) We present a study of the X-ray properties of five Galactic supernova remnants (SNRs) -- Kes 17 (G304.6$+$0.1), G311.5$-$0.3, G346.6$-$0.2, CTB 37A (G348.5$+$0.1) and G348.5$-$0.0 -- that were detected in the infrared by Reach et al. (2006) in an analysis of data from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) that was conducted by the Spitzer Space Telescope. We present and analyze archival ASCA observations of Kes 17, G311.5$-$0.3 and G346.6$-$0.2, archival XMM-Newton observations of Kes 17, CTB 37A and G348.5$-$0.0 and an archival Chandra observation of CTB 37A. All of the SNRs are clearly detected in the X-ray possibly except for G348.5$-$0.0. Our study reveals that the four detected SNRs all feature center-filled X-ray morphologies and that the observed emission from these sources is thermal in all cases. We argue that these SNRs should be classified as mixed-morphology SNRs (MM SNRs): our study strengthens the correlation between MM SNRs and SNRs interacting with molecular clouds and suggests that the origin of mixed-morphology SNRs may be due to the interactions between these SNRs and adjacent clouds. Our ASCA analysis of G311.5$-$0.3 reveals for the first time X-ray emission from this SNR: the X-ray emission is center-filled within the radio and infrared shells and thermal in nature ($kT$ $\sim$ 0.98 keV), thus motivating its classification as an MM SNR. We find considerable spectral variations in the properties associated with the plasmas of the other X-ray-detected SNRs, such as a possible overabundance of magnesium in the plasma of Kes 17. Finally, we also estimate such properties as electron density $n$$_e$, radiative age $t$$_{rad}$ and swept-up mass $M$$_X$ for each of the four X-ray-detected SNRs.Comment: 78 pages, 26 figures, Astronomical Journal, in pres

Murchison Widefield Array and XMM-Newton observations of the Galactic supernova remnant G5.9+3.1

Aims. In this paper we discuss the radio continuum and X-ray properties of the so-far poorly studied Galactic supernova remnant (SNR) G5.9 + 3.1. Methods. We present the radio spectral energy distribution (SED) of the Galactic SNR G5.9 + 3.1 obtained with the MurchisonWidefield Array (MWA). Combining these new observations with the surveys at other radio continuum frequencies, we discuss the integrated radio continuum spectrum of this particular remnant. We have also analyzed an archival XMM-Newton observation, which represents the first detection of X-ray emission from this remnant. Results. The SNR SED is very well explained by a simple power-law relation. The synchrotron radio spectral index of G5.9 + 3.1 is estimated to be 0:42 0:03 and the integrated flux density at 1 GHz to be around 2.7 Jy. Furthermore, we propose that the identified point radio source, located centrally inside the SNR shell, is most probably a compact remnant of the supernova explosion. The shell-like X-ray morphology of G5.9 + 3.1 as revealed by XMM-Newton broadly matches the spatial distribution of the radio emission, where the radio-bright eastern and western rims are also readily detected in the X-ray while the radio-weak northern and southern rims are weak or absent in the X-ray. Extracted MOS1+MOS2+PN spectra from the whole SNR as well as the north, east, and west rims of the SNR are fit successfully with an optically thin thermal plasma model in collisional ionization equilibrium with a column density NH 0:80 1022 cm2 and fitted temperatures spanning the range kT 0:14–0.23 keV for all of the regions. The derived electron number densities ne for the whole SNR and the rims are also roughly comparable (ranging from 0:20 f 1=2 to 0:40 f 1=2 cm3, where f is the volume filling factor). We also estimate the swept-up mass of the X-ray emitting plasma associated with G5.9+3.1 to be 46 f 1=2 M

X-ray emission from the mixed-morphology supernova remnant HB 9

We present the results of a spectral analysis of the central region of the mixed-morphology supernova remnant HB 9. A prior Ginga observation of this source detected a hard X-ray component above 4 keV and the origin of this particular X-ray component is still unknown. Our results demonstrate that the extracted X-ray spectra are best represented by a model consisting of a collisional ionization equilibrium plasma with a temperature of 0.1–0.2 keV (interstellar matter component) and an ionizing plasma with a temperature of 0.6–0.7 keV and an ionization timescale of \u3e1×1011 cm−3 s (ejecta component). No significant X-ray emission was found in the central region above 4 keV. The recombining plasma model reported by a previous work does not explain our spectra

ASCA and XMM-Newton Observations of the Galactic Supernova Remnant G311.5-0.3

We present an analysis of X-ray observations made with ASCA and XMM-Newton of the Galactic supernova remnant (SNR) G311.5−0.3. Prior infrared and radio observations of this SNR have revealed a shell-like morphology at both wavelengths. The spectral index of the radio emission is consistent with synchrotron emission, while the infrared colors are consistent with emission from shocked molecular hydrogen. Also previous CO observations have indicated an interaction between G311.5−0.3 and an adjacent molecular cloud. Our previous analysis of the pointed ASCA observation made of this SNR detected X-ray emission from the source for the first time but lacked the sensitivity and the angular resolution to rigorously investigate its X-ray properties. We have analyzed an archival XMM-Newton observation that included G311.5−0.3 in the field of view: this is the first time that XMM-Newton data has been used to probe the X-ray properties of this SNR. The XMM-Newton observation confirms that the X-ray emission from G311.5−0.3 is centrally concentrated and supports the classification of this source as a mixed-morphology SNR. In addition, our joint fitting of extracted ASCA and XMM-Newton spectra favor a thermal origin for the X-ray emission over a non-thermal origin. The spectral fitting parameters for our TBABS×APEC fit to the extracted spectra are N H = 4.63+1.87 −0.85×1022 cm−2 and kT = 0.68+0.20 −0.24 keV. From these fit parameters, we derive the following values for physical parameters of the SNR: ne = 0.20 cm−3, np = 0.17 cm−3, MX = 21.4 M and P/k = 3.18×106 K cm−3

Multiwavelength Study of the X-ray Bright Supernova Remnant N522-S48 in NGC 522

We present a multiwavelength examination of the supernova remnant (SNR) S26 in the nearby galaxy NGC 300 using data from Chandra X-ray Observatory, XMM-Newton X-ray Observatory, Hubble Space Telescope (HST), the Very Large Array, and the Australia Telescope Compact Array. We simultaneously fit all of the available X-ray data with a thermal plasma model and find a temperature of 0.77±0.13 keV with a hydrogen column density of (9.7+6.4 −4.8)×1020 cm−2. HST imaging allows us to measure a semimajor axis of 0.78±0.10 arcsec (7.5±1.0 pc) and a semiminor axis of 0.69+0.14 −0.12 arcsec (6.7+1.2 −1.4 pc). This precise size helps to constrain the age and velocity of the shock to be (3.3+0.7 −0.6)×103 yr and 411+275 −122 km s−1. We also fit photometry of the surrounding stars to infer the age and mass of the progenitor star to be 8±1 Myr and 25+1 −5 M. Based on measured radio properties of the source and assuming equipartition, the estimated radio luminosity of 1.7×1034 erg s−1 over the 108 to 1011 Hz frequency range results in a minimum magnetic field associated with this SNR of 0.067 mG and the minimum energy needed to power the observed synchrotron emission of 1.5× 1049 erg. The size and temperature of N300-S26 appear to be similar to the Galactic SNR G311.5–0.3 except that G311.5–0.3 has a significantly lower X-ray luminosity, is older, and has a slower shock velocity

MARCo: Solar Powered Autonomous Robotic Unmanned Surface Vehicle

Autonomous sailboats have demonstrated that a robot could potentially perform long-term ocean monitoring and traveling. However, self-operating sailboats in the past had sails, which could lead to issues caused by tipping and heeling too much, and were not fully solar powered, which leads to short power endurance issues. Energy efficient and low cost autonomous robotic unmanned surface vehicle, named MARCo (Marine Autonomous Robotic Communicator), was programmed, developed and tested throughout the year 2018 in a public, co-educational university in Morehead, Kentucky. An off-grid solar system, comprised of 3x 20-Watt 12-Volt panels and a 12-Volt charge controller, was designed, constructed, and installed on a 6ft surfboard to make it solar powered and increase power-endurance with the help of a power management algorithm written in Python. The boat is based on Raspberry Pi, a set of navigation sensors, and a ROCKBlock Iridium Modem. The project has been successful in building a solar-powered, sail-less, autonomous unmanned surface vehicle. The boat was tested in diverse marine environments (Eagle Lake, KY and an indoor pool) and the results showing the overall performance of our boat durability and energy consumption is presented. Journa

The X-ray Resolved Supernova Remnant S8 In the Dwarf Irregular Galaxy IC 1613

We conducted an observation of the nearby irregular galaxy IC 1613 with the Chandra X-ray Observatory using the S3 chip of the ACIS with an effective exposure time of 49.9 ksec. The observation primarily targeted the extensive bubble and star formation region in the northeast quadrant of the galaxy. The only known supernova remnant (SNR) in IC 1613, S8, is also the galaxy’s most luminous X-ray source (LX(0.3-8 keV) 5 − 6×1036 erg s−1). We resolve the SNR with Chandra and compare its nearly circular X-ray morphology with H and radio images. We assign an upper limit on the luminosity of any possible associated compact central object of 4×1035 erg s−1 (0.3-8 keV band) and conclude that we would detect a Crab-like pulsar but not a Cas A-like object. We infer an age for S8 of 3400-5600 years and compare it to other SNRs in the Local Group. We suggest that S8 is a young composite SNR