arXiv subjects

M. D. Filipović

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

94 records · Page 6Linked to original sources

arXiv2009

Radio Detection of 18 Rass BL Lac Objects

We present the radio detection of 18 BL Lac objects from our survey of over 575 square degrees of sky. These 18 objects are located within 20 arcsec of the X-ray position, of which 11 have a measured red-shift. All candidates are radio emitters above ~1 mJy and fall within the range of existing samples on the two colour, alpha_ro vs alpha_ox, diagram with a transitional population of three (3) evident. Two unusual sources have been identified, a candidate radio quiet BL Lac, RX J0140.9-4130, and an extreme HBL, RX J0109.9-4020, with Log(nu_peak)~19.2. The BL Lac Log(N)-Log(S) relation is consistent with other samples and indicates the ROSAT All Sky Survey (RASS) could contain (2000+-400) BL Lac objects.

astro-ph.CO↗

arXiv2009

Radio Planetary Nebulae in the Magellanic Clouds

We report the extragalactic radio-continuum detection of 15 planetary nebulae (PNe) in the Magellanic Clouds (MCs) from recent Australia Telescope Compact Array+Parkes mosaic surveys. These detections were supplemented by new and high resolution radio, optical and IR observations which helped to resolve the true nature of the objects. Four of the PNe are located in the Small Magellanic Cloud (SMC) and 11 are located in the Large Magellanic Cloud (LMC). Based on Galactic PNe the expected radio flux densities at the distance of the LMC/SMC are up to ~2.5 mJy and ~2.0 mJy at 1.4 GHz, respectively. We find that one of our new radio PNe in the SMC has a flux density of 5.1 mJy at 1.4 GHz, several times higher than expected. We suggest that the most luminous radio PN in the SMC (N S68) may represent the upper limit to radio peak luminosity because it is ~3 times more luminous than NGC 7027, the most luminous known Galactic PN. We note that the optical diameters of these 15 MCs PNe vary from very small (~0.08 pc or 0.32"; SMP L47) to very large (~1 pc or 4"; SMP L83). Their flux densities peak at different frequencies, suggesting that they may be in different stages of evolution. We briefly discuss mechanisms that may explain their unusually high radio-continuum flux densities. We argue that these detections may help solve the "missing mass problem" in PNe whose central stars were originally 1-8 Msun. We explore the possible link between ionised halos ejected by the central stars in their late evolution and extended radio emission. Because of their higher than expected flux densities we tentatively call this PNe (sub)sample - "Super PNe".

astro-ph.CO↗

arXiv2008

Radio Continuum Study of Supernova Remnants in the Large Magellanic Cloud - SNR J0519-6926

We present the results of new high resolution ATCA observations of SNR J0519-6926. We found that this SNR exhibits a typical "horseshoe" appearance with alpha = -0.55 +- 0.08 and D=28+-1 pc. No polarization (or magnetic fields) are detected to a level of 1%. This is probably due to a relatively poor sampling of the uv plane caused be observing in "snap-shot" mode.

astro-ph↗

arXiv2008

Optical Spectra of Radio Planetary Nebulae in the Small Magellanic Cloud

We present preliminary results from spectral observations of four candidate radio sources co-identified with known planetary nebulae (PNe) in the Small Magellanic Cloud (SMC). These were made using the Radcliffe 1.9-meter telescope in Sutherland, South Africa. These radio PNe were originally found in Australia Telescope Compact Array (ATCA) surveys of the SMC at 1.42 and 2.37 GHz, and were further confirmed by new high resolution ATCA images at 6 and 3 cm (4"/2"). Optical PNe and radio candidates are within 2" and may represent a subpopulation of selected radio bright objects. Nebular ionized masses of these objects may be 2.6 MSol or greater, supporting the existence of PNe progenitor central stars with masses up to 8 MSol.

astro-ph↗