High-energy sources at low radio frequency: The Murchison Widefield Array view of Fermi blazars

M. Giroletti; F. Massaro; R. D'Abrusco; R. Lico; D. Burlon; N. Hurley-Walker; M. Johnston-Hollitt; J. Morgan; V. Pavlidou; M. Bell; G. Bernardi; R. Bhat; Judd Bowman; F. Briggs; R. J. Cappallo; B. E. Corey; A. A. Deshpande; A. Ewall-Rice; D. Emrich; B. M. Gaensler; R. Goeke; L. J. Greenhill; B. J. Hazelton; L. Hindson; D. L. Kaplan; J. C. Kasper; E. Kratzenberg; L. Feng; Daniel Jacobs; N. Kudryavtseva; E. Lenc; C. J. Lonsdale; M. J. Lynch; B. McKinley; S. R. McWhirter; D. A. Mitchell; M. F. Morales; E. Morgan; D. Oberoi; A. R. Offringa; S. M. Ord; B. Pindor; T. Prabu; P. Procopio; J. Riding; A. E E Rogers; A. Roshi; N. Udaya Shankar; K. S. Srivani; R. Subrahmanyan; S. J. Tingay; M. Waterson; R. B. Wayth; R. L. Webster; A. R. Whitney; A. Williams; C. L. Williams

doi:10.1051/0004-6361/201527817

High-energy sources at low radio frequency: The Murchison Widefield Array view of Fermi blazars

M. Giroletti, F. Massaro, R. D'Abrusco, R. Lico, D. Burlon, N. Hurley-Walker, M. Johnston-Hollitt, J. Morgan, V. Pavlidou, M. Bell, G. Bernardi, R. Bhat, Judd Bowman, F. Briggs, R. J. Cappallo, B. E. Corey, A. A. Deshpande, A. Ewall-Rice, D. Emrich, B. M. GaenslerR. Goeke, L. J. Greenhill, B. J. Hazelton, L. Hindson, D. L. Kaplan, J. C. Kasper, E. Kratzenberg, L. Feng, Daniel Jacobs, N. Kudryavtseva, E. Lenc, C. J. Lonsdale, M. J. Lynch, B. McKinley, S. R. McWhirter, D. A. Mitchell, M. F. Morales, E. Morgan, D. Oberoi, A. R. Offringa, S. M. Ord, B. Pindor, T. Prabu, P. Procopio, J. Riding, A. E E Rogers, A. Roshi, N. Udaya Shankar, K. S. Srivani, R. Subrahmanyan, S. J. Tingay, M. Waterson, R. B. Wayth, R. L. Webster, A. R. Whitney, A. Williams, C. L. Williams

Earth and Space Exploration, School of (SESE)

Research output: Contribution to journal › Article › peer-review

29 Scopus citations

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. 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. Methods. We cross-correlated the 6100 deg² 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. 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_low) = 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. 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.

Original language	English (US)
Article number	A141
Journal	Astronomy and Astrophysics
Volume	588
DOIs	https://doi.org/10.1051/0004-6361/201527817
State	Published - Apr 1 2016

Keywords

BL Lacertae objects: general
Catalogs
Gamma rays: galaxies
Quasars: general
Radiation mechanisms: non-thermal
Radio continuum: galaxies

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.1051/0004-6361/201527817

Cite this

Giroletti, M., Massaro, F., D'Abrusco, R., Lico, R., Burlon, D., Hurley-Walker, N., Johnston-Hollitt, M., Morgan, J., Pavlidou, V., Bell, M., Bernardi, G., Bhat, R., Bowman, J., Briggs, F., Cappallo, R. J., Corey, B. E., Deshpande, A. A., Ewall-Rice, A., Emrich, D., ... Williams, C. L. (2016). High-energy sources at low radio frequency: The Murchison Widefield Array view of Fermi blazars. Astronomy and Astrophysics, 588, [A141]. https://doi.org/10.1051/0004-6361/201527817

Giroletti, M, Massaro, F, D'Abrusco, R, Lico, R, Burlon, D, Hurley-Walker, N, Johnston-Hollitt, M, Morgan, J, Pavlidou, V, Bell, M, Bernardi, G, Bhat, R, Bowman, J, Briggs, F, Cappallo, RJ, Corey, BE, Deshpande, AA, Ewall-Rice, A, Emrich, D, Gaensler, BM, Goeke, R, Greenhill, LJ, Hazelton, BJ, Hindson, L, Kaplan, DL, Kasper, JC, Kratzenberg, E, Feng, L, Jacobs, D, Kudryavtseva, N, Lenc, E, Lonsdale, CJ, Lynch, MJ, McKinley, B, McWhirter, SR, Mitchell, DA, Morales, MF, Morgan, E, Oberoi, D, Offringa, AR, Ord, SM, Pindor, B, Prabu, T, Procopio, P, Riding, J, Rogers, AEE, Roshi, A, Udaya Shankar, N, Srivani, KS, Subrahmanyan, R, Tingay, SJ, Waterson, M, Wayth, RB, Webster, RL, Whitney, AR, Williams, A & Williams, CL 2016, 'High-energy sources at low radio frequency: The Murchison Widefield Array view of Fermi blazars', Astronomy and Astrophysics, vol. 588, A141. https://doi.org/10.1051/0004-6361/201527817

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title = "High-energy sources at low radio frequency: The Murchison Widefield Array view of Fermi blazars",

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. 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. Methods. We cross-correlated the 6100 deg2 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. 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 (αlow) = 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. 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.",

keywords = "BL Lacertae objects: general, Catalogs, Gamma rays: galaxies, Quasars: general, Radiation mechanisms: non-thermal, Radio continuum: galaxies",

author = "M. Giroletti and F. Massaro and R. D'Abrusco and R. Lico and D. Burlon and N. Hurley-Walker and M. Johnston-Hollitt and J. Morgan and V. Pavlidou and M. Bell and G. Bernardi and R. Bhat and Judd Bowman and F. Briggs and Cappallo, {R. J.} and Corey, {B. E.} and Deshpande, {A. A.} and A. Ewall-Rice and D. Emrich and Gaensler, {B. M.} and R. Goeke and Greenhill, {L. J.} and Hazelton, {B. J.} and L. Hindson and Kaplan, {D. L.} and Kasper, {J. C.} and E. Kratzenberg and L. Feng and Daniel Jacobs and N. Kudryavtseva and E. Lenc and Lonsdale, {C. J.} and Lynch, {M. J.} and B. McKinley and McWhirter, {S. R.} and Mitchell, {D. A.} and Morales, {M. F.} and E. Morgan and D. Oberoi and Offringa, {A. R.} and Ord, {S. M.} and B. Pindor and T. Prabu and P. Procopio and J. Riding and Rogers, {A. E E} and A. Roshi and {Udaya Shankar}, N. and Srivani, {K. S.} and R. Subrahmanyan and Tingay, {S. J.} and M. Waterson and Wayth, {R. B.} and Webster, {R. L.} and Whitney, {A. R.} and A. Williams and Williams, {C. L.}",

note = "Publisher Copyright: {\textcopyright} ESO 2016.",

year = "2016",

month = apr,

day = "1",

doi = "10.1051/0004-6361/201527817",

language = "English (US)",

volume = "588",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

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TY - JOUR

T1 - High-energy sources at low radio frequency

T2 - The Murchison Widefield Array view of Fermi blazars

AU - Giroletti, M.

AU - Massaro, F.

AU - D'Abrusco, R.

AU - Lico, R.

AU - Burlon, D.

AU - Hurley-Walker, N.

AU - Johnston-Hollitt, M.

AU - Morgan, J.

AU - Pavlidou, V.

AU - Bell, M.

AU - Bernardi, G.

AU - Bhat, R.

AU - Bowman, Judd

AU - Briggs, F.

AU - Cappallo, R. J.

AU - Corey, B. E.

AU - Deshpande, A. A.

AU - Ewall-Rice, A.

AU - Emrich, D.

AU - Gaensler, B. M.

AU - Goeke, R.

AU - Greenhill, L. J.

AU - Hazelton, B. J.

AU - Hindson, L.

AU - Kaplan, D. L.

AU - Kasper, J. C.

AU - Kratzenberg, E.

AU - Feng, L.

AU - Jacobs, Daniel

AU - Kudryavtseva, N.

AU - Lenc, E.

AU - Lonsdale, C. J.

AU - Lynch, M. J.

AU - McKinley, B.

AU - McWhirter, S. R.

AU - Mitchell, D. A.

AU - Morales, M. F.

AU - Morgan, E.

AU - Oberoi, D.

AU - Offringa, A. R.

AU - Ord, S. M.

AU - Pindor, B.

AU - Prabu, T.

AU - Procopio, P.

AU - Riding, J.

AU - Rogers, A. E E

AU - Roshi, A.

AU - Udaya Shankar, N.

AU - Srivani, K. S.

AU - Subrahmanyan, R.

AU - Tingay, S. J.

AU - Waterson, M.

AU - Wayth, R. B.

AU - Webster, R. L.

AU - Whitney, A. R.

AU - Williams, A.

AU - Williams, C. L.

PY - 2016/4/1

Y1 - 2016/4/1

N2 - 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. 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. Methods. We cross-correlated the 6100 deg2 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. 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 (αlow) = 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. 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.

AB - 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. 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. Methods. We cross-correlated the 6100 deg2 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. 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 (αlow) = 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. 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.

KW - BL Lacertae objects: general

KW - Catalogs

KW - Gamma rays: galaxies

KW - Quasars: general

KW - Radiation mechanisms: non-thermal

KW - Radio continuum: galaxies

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DO - 10.1051/0004-6361/201527817

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JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

M1 - A141

ER -

High-energy sources at low radio frequency: The Murchison Widefield Array view of Fermi blazars

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High-energy sources at low radio frequency: The Murchison Widefield Array view of Fermi blazars

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ASJC Scopus subject areas

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