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http://hdl.handle.net/20.500.12386/26075
Titolo: | High-energy sources at low radio frequency: the Murchison Widefield Array view of Fermi blazars | Autori: | GIROLETTI, MARCELLO MASSARO, Francesco D'Abrusco, R. Lico, R. Burlon, D. Hurley-Walker, N. Johnston-Hollitt, M. Morgan, J. Pavlidou, V. Bell, M. BERNARDI, GIANNI Bhat, R. Bowman, J. D. Briggs, F. Cappallo, R. J. Corey, B. E. Deshpande, A. A. Ewall-Rice, A. Emrich, D. Gaensler, B. M. Goeke, R. Greenhill, L. J. Hazelton, B. J. Hindson, L. Kaplan, D. L. Kasper, J. C. Kratzenberg, E. Feng, L. Jacobs, D. Kudryavtseva, N. Lenc, E. Lonsdale, C. J. Lynch, M. J. McKinley, B. McWhirter, S. R. Mitchell, D. A. Morales, M. F. Morgan, E. Oberoi, D. Offringa, A. R. Ord, S. M. Pindor, B. Prabu, T. Procopio, P. Riding, J. Rogers, A. E. E. Roshi, A. Udaya Shankar, N. Srivani, K. S. Subrahmanyan, R. Tingay, S. J. Waterson, M. Wayth, R. B. Webster, R. L. Whitney, A. R. Williams, A. Williams, C. L. |
Data pubblicazione: | 2016 | Rivista: | ASTRONOMY & ASTROPHYSICS | Numero: | 588 | Da pagina:: | A141 | Abstract: | Context. Low-frequency radio arrays are opening a new window for the study of the sky, both to study new phenomena and to better characterize known source classes. Being flat-spectrum sources, blazars are so far poorly studied at low radio frequencies. <BR /> Aims: We characterize the spectral properties of the blazar population at low radio frequency, compare the radio and high-energy properties of the gamma-ray blazar population, and search for radio counterparts of unidentified gamma-ray sources. <BR /> Methods: We cross-correlated the 6100 deg<SUP>2</SUP> Murchison Widefield Array Commissioning Survey catalogue with the Roma blazar catalogue, the third catalogue of active galactic nuclei detected by Fermi-LAT, and the unidentified members of the entire third catalogue of gamma-ray sources detected by Fermi-LAT. When available, we also added high-frequency radio data from the Australia Telescope 20 GHz catalogue. <BR /> Results: We find low-frequency counterparts for 186 out of 517 (36%) blazars, 79 out of 174 (45%) gamma-ray blazars, and 8 out of 73 (11%) gamma-ray blazar candidates. The mean low-frequency (120-180 MHz) blazar spectral index is ⟨α<SUB>low</SUB>⟩ = 0.57 ± 0.02: blazar spectra are flatter than the rest of the population of low-frequency sources, but are steeper than at ~GHz frequencies. Low-frequency radio flux density and gamma-ray energy flux display a mildly significant and broadly scattered correlation. Ten unidentified gamma-ray sources have a (probably fortuitous) positional match with low radio frequency sources. <BR /> Conclusions: Low-frequency radio astronomy provides important information about sources with a flat radio spectrum and high energy. However, the relatively low sensitivity of the present surveys still misses a significant fraction of these objects. Upcoming deeper surveys, such as the GaLactic and Extragalactic All-Sky MWA (GLEAM) survey, will provide further insight into this population. Tables 5-7 are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A141">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A141 | URI: | http://hdl.handle.net/20.500.12386/26075 | URL: | http://arxiv.org/abs/1602.08869v1 https://www.aanda.org/articles/aa/abs/2016/04/aa27817-15/aa27817-15.html |
ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/201527817 | Bibcode ADS: | 2016A&A...588A.141G | Fulltext: | open |
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