arXiv subjects

M. D. Filipović

Publications and source records attributed to M. D. Filipović.

At least 91 records · Page 5Linked to original sources

arXiv2012

Radio-Continuum Observations Of Small, Radially Polarised Supernova Remnant J0519-6902 In The Large Magellanic Cloud

We report on new Australian Telescope Compact Array (ATCA) observations of SNR J0519-6902. The Supernova Remnant (SNR) is small in size (~8 pc) and exhibits a typical SNR spectrum of alpha = -0.53 +- 0.07, with steeper spectral indices found towards the northern limb of the remnant. SNR J0519-6902 contains a low level of radially orientated polarisation at wavelengths of 3 & 6 cm, which is characteristic of younger SNRs. A fairly strong magnetic field was estimated of ~171 microG. The remnant appears to be the result of a typical Type Ia supernovae, sharing many properties as another small and young Type Ia LMC SNR, J0509-6731.

astro-ph.GA↗

arXiv2012

The Physical Parameters of the Micro-quasar S26 in the Sculptor Group Galaxy NGC 7793

NGC 7793 - S26 is an extended source (350 pc $\times$ 185 pc) previously studied in the radio, optical and x-ray domains. It has been identified as a micro-quasar which has inflated a super bubble. We used Integral Field Spectra from the Wide Field Spectrograph on the ANU 2.3 m telescope to analyse spectra between 3600--7000 Å. This allowed us to derive fluxes and line ratios for selected nebular lines. Applying radiative shock model diagnostics, we estimate shock velocities, densities, radiative ages and pressures across the object. We show that S26 is just entering its radiative phase, and that the northern and western regions are dominated by partially-radiative shocks due to a lower density ISM in these directions. We determine a velocity of expansion along the jet of 330 km s$^{-1}$, and a velocity of expansion of the bubble in the minor axis direction of 132 km s$^{-1}$. We determine the age of the structure to be $4.1\times10^5$ yr, and the jet energy flux to be $ (4-10)\times10^{40}$ erg s$^{-1}$ The jet appears to be collimated within $\sim0.25$ deg, and to undergo very little precession. If the relativistic $β\sim 1/3$, then some 4 M$_{\odot}$ of relativistic matter has already been processed through the jet. We conclude that the central object in S26 is probably a Black Hole with a mass typical of the ultra-luminous X-ray source population which is currently consuming a fairly massive companion through Roche Lobe accretion.

astro-ph.HE↗

arXiv2012

Multi-frequency study of supernova remnants in the Large Magellanic Cloud. Confirmation of the supernova remnant status of DEM L205

We present new X-ray and radio data of the LMC SNR candidate DEM L205, obtained by XMM-Newton and ATCA, along with archival optical and infrared observations. We use data at various wavelengths to study this object and its complex neighbourhood, in particular in the context of the star formation activity, past and present, around the source. We analyse the X-ray spectrum to derive some remnant's properties, such as age and explosion energy. Supernova remnant features are detected at all observed wavelengths: soft and extended X-ray emission is observed, arising from a thermal plasma with a temperature kT between 0.2 keV and 0.3 keV. Optical line emission is characterised by an enhanced [SII]/Halpha ratio and a shell-like morphology, correlating with the X-ray emission. The source is not or only tentatively detected at near-infrared wavelengths (< 10 microns), but there is a detection of arc-like emission at mid and far-infrared wavelengths (24 and 70 micron) that can be unambiguously associated with the remnant. We suggest that thermal emission from dust heated by stellar radiation and shock waves is the main contributor to the infrared emission. Finally, an extended and faint non-thermal radio emission correlates with the remnant at other wavelengths and we find a radio spectral index between -0.7 and -0.9, within the range for SNRs. The size of the remnant is ~79x64 pc and we estimate a dynamical age of about 35000 years. We definitely confirm DEM L205 as a new SNR. This object ranks amongst the largest remnants known in the LMC. The numerous massive stars and the recent outburst in star formation around the source strongly suggest that a core-collapse supernova is the progenitor of this remnant. (abridged)

astro-ph.HE↗

arXiv2012

Multifrequency radio observations of SNR J0536-6735 (N 59B) with associated pulsar

We present a study of new Australian Telescope Compact Array (ATCA) observations of supernova remnant, SNR J0536-6735. This remnant appears to follow a shell morphology with a diameter of D=36x29 pc (with 1 pc uncertainty in each direction). There is an embedded Hii region on the northern limb of the remnant which made various analysis and measurements (such as flux density, spectral index and polarisation) difficult. The radio-continuum emission followed the same structure as the optical emission, allowing for extent and flux density estimates at 20 cm. We estimate a surface brightness for the SNR at 1 GHz of 2.55x10^-21 W m^-2 Hz^-1 sr^-1. Also, we detect a distinctive radio-continuum point source which confirms the previous suggestion of this remnant being associated with a pulsar wind nebulae (PWN). The tail of this remnant isn't seen in the radio-continuum images and is only seen in the optical and X-ray images.

astro-ph.HE↗

arXiv2012

20 cm VLA Radio-Continuum Study of M31 - Images and Point Source Catalogues

We present a series of new high-sensitivity and high-resolution radio-continuum images of M31 at λ=20 cm (ν=1.4 GHz). These new images were produced by merging archived 20 cm radio-continuum observations from the Very Large Array (VLA) telescope. Images presented here are sensitive to rms=60 μJy and feature high angular resolution (<10"). A complete sample of discrete radio sources have been catalogued and analysed across 17 individual VLA projects. We identified a total of 864 unique discrete radio sources across the field of M31. One of the most prominent regions in M31 is the ring feature for which we estimated total integrated flux of 706 mJy at λ=20 cm. We compare here, detected sources to those listed in Gelfand et al. (2004) at λ=92 cm and find 118 sources in common to both surveys. The majority (61%) of these sources exhibit a spectral index of α<-0.6 indicating that their emission is predominantly non-thermal in nature. That is more typical for background objects.

astro-ph.GA↗

arXiv2012

New 6 and 3-cm radio-continuum maps of the Small Magellanic Cloud: Part II - Point source catalogue

We present two new catalogues of radio-continuum sources in the field of the Small Magellanic Cloud (SMC). These catalogues contain sources found at 4800 MHz (lambda=6 cm) and 8640 MHz (lambda=3 cm). Some 457 sources have been detected at 3 cm with 601 sources at 6 cm created from new high-sensitivity and resolution radio-continuum images of the SMC from Crawford et al. (2011).

astro-ph.CO↗

arXiv2012

Periodic Emission from the Gamma-ray Binary 1FGL J1018.6-5856

Gamma-ray binaries are stellar systems containing a neutron star or black hole with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation with a 16.6 day period. We identified a variable X-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGL J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.

astro-ph.HE↗

arXiv2012

Multi-Frequency Study of Supernova Remnants in the Large Magellanic Cloud. The case of LMC SNR J0530-7007

Context: The Supernova Remnants (SNRs) known in the Large Magellanic Cloud (LMC) show a variety of morphological structures in the different wavelength bands. This variety is the product of the conditions in the surrounding medium with which the remnant interacts and the inherent circumstances of the supernova event itself. Aims: This paper performs a multi-frequency study of the LMC SNR J0530-7007 by combining Australia Telescope Compact Array (ATCA), Molonglo Observatory Synthesis Telescope (MOST), Röntgensatellit (ROSAT) and Magellanic Clouds Emission Line Survey (MCELS) observations. Methods: We analysed radio-continuum, X-ray and optical data and present a multi-wavelength morphological study of LMC SNR J0530-7007. Results We find that this object has a shell-type morphology with a size of 215"x180" (52 pc x 44 pc); a radio spectral index (alpha=-0.85+-0.13); with [Sii]/Halpha > 0.4 in the optical; and the presence of non-thermal radio and X-ray emission. Conclusions: We confirmed this object as a bona-fide shell-type SNR which is probably a result of a Type Ia supernova.

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arXiv2011

Multi-frequency study of the Large Magellanic Cloud Supernova Remnant J0529-6653 near Pulsar B0529-66

We report the 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 x 31 pc (1 pc uncertainty in each direction) and radio spectral index of alpha=-0.68$+-$0.03 - typical for mid-age SNRs. We also report detection of polarised regions with a peak value of 17+-7% at 6 cm. An investigation of ROSAT images produced from merged 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 in regards to the SNR-PSR association with emphasis on the large age difference, lack of a pulsar trail and no prominent point-like radio or X-ray source.

astro-ph.HE↗

arXiv2011

New 20-CM Radio-Continuum Study of The Small Magellanic Cloud: Part II - Point Sources Catalogue

We present a new catalogue of radio-continuum sources in the field of the Small Magellanic Cloud (SMC). This catalogue contains sources previously not found in 2370 MHz (λ=13 cm) with sources found at 1400 MHz (λ=20 cm) and 843 MHz (λ=36 cm). 45 sources have been detected at 13 cm, with 1560 sources at 20 cm created from new high sensitivity and resolution radio-continuum images of the SMC at 20 cm from Paper I . We also created a 36 cm catalogue to which we listed 1689 radio-continuum sources.

astro-ph.CO↗

arXiv2011

New 6 and 3-cm Radio-Continuum Maps of the Small Magellanic Cloud. Part I - The Maps

We present new 6 and 3-cm radio-continuum maps of the Small Magellanic Cloud (SMC), created with the "peeling" technique and a joint deconvolution. The maps have resolutions of 30" and 20" and r.m.s. noise of 0.7 and 0.8 mJy/beam at 6 and 3 cm, respectively. These maps will be used for future studies of the SMC's radio source population and overall extended structure.

astro-ph.CO↗

arXiv2011

Radio continuum observations of LMC SNR J0550-6823

We report on new Australia Telescope Compact Array (ATCA) observations of the Large Magellanic Cloud (LMC) supernova remnant (SNR) J0550-6823 (DEM L328). This object is a typical horseshoe SNR with a diameter of 373" x 282" +- 4" (90 x 68 +- 1), making it one of the largest known SNRs in the Local Group. We estimate a relatively steep radio spectral index of alpha = -0.79 +- 0.27. However, its stronger than expected polarisation of 50% +- 10% is atypical for older and more evolved SNRs. We also note a strong correlation between [Oiii] and radio images, classifying this SNR as oxygen dominant.

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arXiv2011

A pilot study of the radio-continuum emission from MASH planetary nebulae

We report an Australia Telescope Compact Array (ATCA) radio-continuum observations of 26 planetary nebulae (PNe) at wavelengths of 3 and 6 cm. This sample of 26 PNe were taken from the Macquarie/AAO/Strasbourg Halpha PNe (MASH) catalogue and previous lists. We investigate radio detection quality including measured and derived parameters for all detected or marginally detected PNe from this combined sample. Some 11 objects from the observed sample have been successfully detected and parametrized. Except for one, all detected PNe have very low radio surface brightnesses. We use a statistical distance scale method to calculate distances and ionised masses of the detected objects. Nebulae from this sample are found to be large (>0.2 pc in diameter) and highly diluted which indicates old age. For 21 PNe from this sample we list integrated Halpha fluxes and interstellar extinction coefficients, either taken from the literature or derived here from the Balmer decrement and radio to Halpha ratio methods. Finally, our detected fraction of the MASH pilot sample is relatively low compared to the non-MASH sub-sample. We conclude that future radio surveys of the MASH sample must involve deeper observations with better uv coverage in order to increase the fraction of detected objects and improve the quality of the derived parameters.

astro-ph.SR↗

arXiv2011

New 20-cm radio-continuum study of the small Magellanic cloud: Part I - Images

We present and discuss new high-sensitivity and resolution radio-continuum images of the Small Magellanic Cloud (SMC) at lambda=20 cm (nu=1.4 GHz). The new images were created by merging 20-cm radiocontinuum archival data, from the Australian Telescope Compact Array and the Parkes radio-telescope. Our images span from ~10'' to ~150'' in resolution and sensitivity of r.m.s.>=0.5 mJy/beam. These images will be used in future studies of the SMC's intrinsic sources and its overall extended structure.

astro-ph.CO↗

arXiv2010

The XMM-Newton survey of the Small Magellanic Cloud: Discovery of the 11.866 s Be/X-ray binary pulsar XMMUJ004814.0-732204 (SXP11.87)

One of the goals of the XMM-Newton survey of the Small Magellanic Cloud is the study of the Be/X-ray binary population. During one of our first survey observations a bright new transient - XMMUJ004814.0-732204 - was discovered. We present the analysis of the EPIC X-ray data together with optical observations, to investigate the spectral and temporal characteristics of XMMUJ004814.0-732204. We found coherent X-ray pulsations in the EPIC data with a period of (11.86642 +/- 0.00017) s. The X-ray spectrum can be modelled by an absorbed power-law with indication for a soft excess. Depending on the modelling of the soft X-ray spectrum, the photon index ranges between 0.53 and 0.66. We identify the optical counterpart as a B = 14.9mag star which was monitored during the MACHO and OGLE-III projects. The optical light curves show regular outbursts by ~0.5 mag in B and R and up to 0.9 mag in I which repeat with a time scale of about 1000 days. The OGLE-III optical colours of the star are consistent with an early B spectral type. An optical spectrum obtained at the 1.9 m telescope of the South African Astronomical Observatory in December 2009 shows H_alpha emission with an equivalent width of 3.5 +/- 0.6 A. The X-ray spectrum and the detection of pulsations suggest that XMMUJ004814.0-732204 is a new high mass X-ray binary pulsar in the SMC. The long term variability and the H_alpha emission line in the spectrum of the optical counterpart identify it as a Be/X-ray binary system.

astro-ph.HE↗

arXiv2010

Radio-continuum jets around the peculiar galaxy pair ESO 295-IG022

We report new radio-continuum observations with the Australia Telescope Compact Array (ATCA) of the region surrounding the peculiar galaxy pair ESO 295-IG022, at the centre of the poor cluster Abell S0102. We observed this cluster at wavelengths of lambda=20/13 and 6/3 cm with the ATCA 6 km array. With these configurations, we achieved a resolution of ~2" at 3 cm which is sufficient to resolve the jet-like structure of ~3' length detected at 20 cm. From our new high resolution images at 6 and 3 cm we confirm the presence of a double jet structure, most likely originating from the northern galaxy (ESO295-IG022-N), bent and twisted towards the south. We found the spectral index of the jet to be very steep (alpha=-1.32). No point source was detected that could be associated with the core of ESO 295-IG022-N. On the other hand, ESO 295-IG022-S does not show any jet structure, but does show a point radio source. This source has variable flux and spectral index, and appears to be superposed on the line-of-sight of the jets (seen at 20-cm) originating from the northern galaxy ESO 295-IG022-N. Finally, regions of very high and somewhat well ordered polarisation were detected at the level of 70%.

astro-ph.CO↗

arXiv2010

Multifrequency Radio Observations of a SNR in the LMC. The Case of SNR J0527-6549 (DEM l204)

We present a detailed study and results of new Australia Telescope Compact Array (ATCA) observations of supernova remnant, SNR J0527-6549. This Large Magellanic Cloud (LMC) ob ject follows a typical supernova remnant (SNR) horseshoe morphology with a diameter of D=(66x58)+-1 pc which is among the largest SNRs in the LMC. Its relatively large size indicates older age while a steeper than expected radio spectral index of aplha=-0.92+-0.11 is more typical for younger and energetic SNRs. Also, we report detections of regions with a high order of polarization at a peak value of ~54+-17% at 6 cm.

astro-ph.CO↗

arXiv2009

Multifrequency Observations of One of the Largest Supernova Remnants in the Local Group of Galaxies, LMC - SNR J0450-709

We present the results of new Australia Telescope Compact Array (ATCA) observations of one of the largest supernova remnants, SNR J0450-709, in the Local Group of galaxies. We found that this Large Magellanic Cloud (LMC) ob ject exhibits a typical morphology of an old supernova remnant (SNR) with diameter D=102x75+-1 pc and radio spectral index alpha=-0.43+-0.06. Regions of high polarisation were detected with peak value of ~40%.

astro-ph.CO↗