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

Abstract

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. In this paper, 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. We cross-correlated the 6100 deg 2 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. 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-raymore » 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. 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. Finally, upcoming deeper surveys, such as the GaLactic and Extragalactic All-Sky MWA (GLEAM) survey, will provide further insight into this population.« less

Authors:
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Publication Date:
Research Org.:
National Inst. for Astrophysics (INAF), Bologna (Italy); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org.:
USDOE; National Inst. for Astrophysics (INAF) (Italy)
Contributing Org.:
Fermi-LAT Collaboration
OSTI Identifier:
1355690
Grant/Contract Number:  
PRIN-INAF-2011
Resource Type:
Accepted Manuscript
Journal Name:
Astronomy and Astrophysics
Additional Journal Information:
Journal Volume: 588; Journal ID: ISSN 0004-6361
Publisher:
EDP Sciences
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; BL Lacertae objects; catalogs; gamma rays: galaxies; quasars; non-thermal radiation mechanisms; radio continuum: galaxies

Citation Formats

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. 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., and Williams, C. L. High-energy sources at low radio frequency: the Murchison Widefield Array view of Fermi blazars. United States: N. p., 2016. Web. doi: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. 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. High-energy sources at low radio frequency: the Murchison Widefield Array view of Fermi blazars. United States. doi: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. 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., and Williams, C. L. Fri . "High-energy sources at low radio frequency: the Murchison Widefield Array view of Fermi blazars". United States. doi:10.1051/0004-6361/201527817. https://www.osti.gov/servlets/purl/1355690.
@article{osti_1355690,
title = {High-energy sources at low radio frequency: the Murchison Widefield Array view of Fermi blazars},
author = {Giroletti, M. and Massaro, F. and D’Abrusco, R. and Lico, R. and Burlon, D. and Hurley-Walker, N. and Johnston-Hollitt, M. and Morgan, J. and Pavlidou, V. and Bell, M. and Bernardi, G. and Bhat, R. and Bowman, J. D. and Briggs, F. and Cappallo, R. J. and Corey, B. E. and Deshpande, A. A. and Ewall-Rice, A. and Emrich, D. and Gaensler, B. M. and Goeke, R. and Greenhill, L. J. and Hazelton, B. J. and Hindson, L. and Kaplan, D. L. and Kasper, J. C. and Kratzenberg, E. and Feng, L. and Jacobs, D. and Kudryavtseva, N. and Lenc, E. and Lonsdale, C. J. and Lynch, M. J. and McKinley, B. and McWhirter, S. R. and Mitchell, D. A. and Morales, M. F. and Morgan, E. and Oberoi, D. and Offringa, A. R. and Ord, S. M. and Pindor, B. and Prabu, T. and Procopio, P. and Riding, J. and Rogers, A. E. E. and Roshi, A. and Udaya Shankar, N. and Srivani, K. S. and Subrahmanyan, R. and Tingay, S. J. and Waterson, M. and Wayth, R. B. and Webster, R. L. and Whitney, A. R. and Williams, A. and Williams, C. L.},
abstractNote = {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. In this paper, 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. 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. 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. 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. Finally, upcoming deeper surveys, such as the GaLactic and Extragalactic All-Sky MWA (GLEAM) survey, will provide further insight into this population.},
doi = {10.1051/0004-6361/201527817},
journal = {Astronomy and Astrophysics},
number = ,
volume = 588,
place = {United States},
year = {2016},
month = {4}
}

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Cited by: 6 works
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Works referenced in this record:

SUMSS: A Wide-Field Radio Imaging Survey of the Southern Sky. I. Science Goals, Survey Design, and Instrumentation
journal, March 1999

  • Bock, D. C. -J.; Large, M. I.; Sadler, Elaine M.
  • The Astronomical Journal, Vol. 117, Issue 3
  • DOI: 10.1086/300786

A simplified view of blazars: contribution to the X-ray and γ-ray extragalactic backgrounds
journal, May 2015

  • Giommi, P.; Padovani, P.
  • Monthly Notices of the Royal Astronomical Society, Vol. 450, Issue 3
  • DOI: 10.1093/mnras/stv793

FERMI LARGE AREA TELESCOPE THIRD SOURCE CATALOG
journal, June 2015

  • Acero, F.; Ackermann, M.; Ajello, M.
  • The Astrophysical Journal Supplement Series, Vol. 218, Issue 2
  • DOI: 10.1088/0067-0049/218/2/23

Unified Schemes for Radio-Loud Active Galactic Nuclei
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Assessing the Significance of Apparent Correlations Between Radio and Gamma-Ray Blazar Fluxes
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From the Blazar Sequence to the Blazar Envelope: Revisiting the Relativistic jet Dichotomy in Radio-Loud Active Galactic Nuclei
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The radio-γ-ray connection in Fermi blazars: γ-ray-radio flux correlation in blazars
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LOFAR: The LOw-Frequency ARray
journal, July 2013


The Australia Telescope 20 GHz Survey: the source catalogue
journal, March 2010


The Murchison Widefield Array: The Square Kilometre Array Precursor at Low Radio Frequencies
journal, January 2013

  • Tingay, S. J.; Goeke, R.; Bowman, J. D.
  • Publications of the Astronomical Society of Australia, Vol. 30
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GLEAM: The GaLactic and Extragalactic All-Sky MWA Survey
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THE SECOND CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE
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THE RADIO/GAMMA-RAY CONNECTION IN ACTIVE GALACTIC NUCLEI IN THE ERA OF THE FERMI LARGE AREA TELESCOPE
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THE THIRD CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE
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Correlation of Fermi Large Area Telescope sources with the 20-GHz Australia Telescope Compact Array radio survey: AT20G-1FGL
journal, July 2010


FERMI LARGE AREA TELESCOPE FIRST SOURCE CATALOG
journal, May 2010

  • Abdo, A. A.; Ackermann, M.; Ajello, M.
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HIGH-FREQUENCY RADIO PROPERTIES OF SOURCES IN THE FERMI -LAT 1 YEAR POINT SOURCE CATALOG
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Synchrotron and inverse-Compton emission from blazar jets – IV. BL Lac type blazars and the physical basis for the blazar sequence
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Spectral properties and the effect on redshift cut-off of compact active galactic nuclei from the AT20G survey: Spectral properties and z cut-off of AGNs
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The VLA Low-Frequency Sky Survey
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The NRAO VLA Sky Survey
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FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG
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The LOFAR Multifrequency Snapshot Sky Survey (MSSS): I. Survey description and first results
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SUMSS: a wide-field radio imaging survey of the southern sky - II. The source catalogue
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The Planck –ATCA Co-eval Observations project: analysis of radio source properties between 5 and 217 GHz
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Roma-BZCAT: a multifrequency catalogue of blazars
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The Low-Frequency Radio Catalog of Flat-Spectrum Sources
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FIVE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE OBSERVATIONS: COSMOLOGICAL INTERPRETATION
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BLAZAR SPECTRAL PROPERTIES AT 74 MHz
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The Murchison Widefield Array Commissioning Survey: A Low-Frequency Catalogue of 14 110 Compact Radio Sources over 6 100 Square Degrees
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Unveiling the Nature of the Unidentified Gamma-Ray Sources. iii. Gamma-Ray Blazar-Like Counterparts at low Radio Frequencies
journal, June 2013

  • Massaro, F.; D'Abrusco, R.; Giroletti, M.
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The 5th edition of the Roma-BZCAT. A short presentation
journal, April 2015


A unifying view of the spectral energy distributions of blazars
journal, September 1998


Unveiling the Nature of Unidentified γ-Ray Sources. vi. γ-Ray Blazar Candidates in the wish Survey and Their Radio Properties
journal, April 2014

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    Works referencing / citing this record:

    The 5th edition of the Roma-BZCAT. A short presentation
    journal, April 2015


    The Murchison Widefield Array: The Square Kilometre Array Precursor at Low Radio Frequencies
    journal, January 2013

    • Tingay, S. J.; Goeke, R.; Bowman, J. D.
    • Publications of the Astronomical Society of Australia, Vol. 30
    • DOI: 10.1017/pasa.2012.007

    The Murchison Widefield Array Commissioning Survey: A Low-Frequency Catalogue of 14 110 Compact Radio Sources over 6 100 Square Degrees
    journal, January 2014

    • Hurley-Walker, Natasha; Morgan, John; Wayth, Randall B.
    • Publications of the Astronomical Society of Australia, Vol. 31
    • DOI: 10.1017/pasa.2014.40

    GLEAM: The GaLactic and Extragalactic All-Sky MWA Survey
    journal, January 2015

    • Wayth, R. B.; Lenc, E.; Bell, M. E.
    • Publications of the Astronomical Society of Australia, Vol. 32
    • DOI: 10.1017/pasa.2015.26

    A unifying view of the spectral energy distributions of blazars
    journal, September 1998


    SUMSS: a wide-field radio imaging survey of the southern sky - II. The source catalogue
    journal, July 2003


    LOFAR: The LOw-Frequency ARray
    journal, July 2013


    The LOFAR Multifrequency Snapshot Sky Survey (MSSS): I. Survey description and first results
    journal, October 2015


    Roma-BZCAT: a multifrequency catalogue of blazars
    journal, December 2008


    Unified Schemes for Radio-Loud Active Galactic Nuclei
    journal, June 1995

    • Urry, C. Megan; Padovani, Paolo
    • Publications of the Astronomical Society of the Pacific, Vol. 107
    • DOI: 10.1086/133630

    The NRAO VLA Sky Survey
    journal, May 1998

    • Condon, J. J.; Cotton, W. D.; Greisen, E. W.
    • The Astronomical Journal, Vol. 115, Issue 5
    • DOI: 10.1086/300337

    SUMSS: A Wide-Field Radio Imaging Survey of the Southern Sky. I. Science Goals, Survey Design, and Instrumentation
    journal, March 1999

    • Bock, D. C. -J.; Large, M. I.; Sadler, Elaine M.
    • The Astronomical Journal, Vol. 117, Issue 3
    • DOI: 10.1086/300786

    The VLA Low-Frequency Sky Survey
    journal, July 2007

    • Cohen, A. S.; Lane, W. M.; Cotton, W. D.
    • The Astronomical Journal, Vol. 134, Issue 3
    • DOI: 10.1086/520719

    FIVE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE OBSERVATIONS: COSMOLOGICAL INTERPRETATION
    journal, February 2009

    • Komatsu, E.; Dunkley, J.; Nolta, M. R.
    • The Astrophysical Journal Supplement Series, Vol. 180, Issue 2
    • DOI: 10.1088/0067-0049/180/2/330

    FERMI LARGE AREA TELESCOPE FIRST SOURCE CATALOG
    journal, May 2010

    • Abdo, A. A.; Ackermann, M.; Ajello, M.
    • The Astrophysical Journal Supplement Series, Vol. 188, Issue 2
    • DOI: 10.1088/0067-0049/188/2/405

    FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG
    journal, March 2012

    • Nolan, P. L.; Abdo, A. A.; Ackermann, M.
    • The Astrophysical Journal Supplement Series, Vol. 199, Issue 2
    • DOI: 10.1088/0067-0049/199/2/31

    Unveiling the Nature of the Unidentified Gamma-Ray Sources. iii. Gamma-Ray Blazar-Like Counterparts at low Radio Frequencies
    journal, June 2013

    • Massaro, F.; D'Abrusco, R.; Giroletti, M.
    • The Astrophysical Journal Supplement Series, Vol. 207, Issue 1
    • DOI: 10.1088/0067-0049/207/1/4

    BLAZAR SPECTRAL PROPERTIES AT 74 MHz
    journal, September 2013

    • Massaro, F.; Giroletti, M.; Paggi, A.
    • The Astrophysical Journal Supplement Series, Vol. 208, Issue 2
    • DOI: 10.1088/0067-0049/208/2/15

    Unveiling the Nature of Unidentified γ-Ray Sources. vi. γ-Ray Blazar Candidates in the wish Survey and Their Radio Properties
    journal, April 2014

    • Nori, M.; Giroletti, M.; Massaro, F.
    • The Astrophysical Journal Supplement Series, Vol. 212, Issue 1
    • DOI: 10.1088/0067-0049/212/1/3

    The Low-Frequency Radio Catalog of Flat-Spectrum Sources
    journal, June 2014

    • Massaro, F.; Giroletti, M.; D'Abrusco, R.
    • The Astrophysical Journal Supplement Series, Vol. 213, Issue 1
    • DOI: 10.1088/0067-0049/213/1/3

    FERMI LARGE AREA TELESCOPE THIRD SOURCE CATALOG
    journal, June 2015

    • Acero, F.; Ackermann, M.; Ajello, M.
    • The Astrophysical Journal Supplement Series, Vol. 218, Issue 2
    • DOI: 10.1088/0067-0049/218/2/23

    Synchrotron and inverse-Compton emission from blazar jets – IV. BL Lac type blazars and the physical basis for the blazar sequence
    journal, October 2013

    • Potter, William J.; Cotter, Garret
    • Monthly Notices of the Royal Astronomical Society, Vol. 436, Issue 1
    • DOI: 10.1093/mnras/stt1569

    The Planck –ATCA Co-eval Observations project: analysis of radio source properties between 5 and 217 GHz
    journal, November 2015

    • Massardi, Marcella; Bonaldi, Anna; Bonavera, Laura
    • Monthly Notices of the Royal Astronomical Society, Vol. 455, Issue 3
    • DOI: 10.1093/mnras/stv2561

    A simplified view of blazars: contribution to the X-ray and γ-ray extragalactic backgrounds
    journal, May 2015

    • Giommi, P.; Padovani, P.
    • Monthly Notices of the Royal Astronomical Society, Vol. 450, Issue 3
    • DOI: 10.1093/mnras/stv793

    The Australia Telescope 20 GHz Survey: the source catalogue
    journal, March 2010


    Correlation of Fermi Large Area Telescope sources with the 20-GHz Australia Telescope Compact Array radio survey: AT20G-1FGL
    journal, July 2010


    The radio-γ-ray connection in Fermi blazars: γ-ray-radio flux correlation in blazars
    journal, March 2011


    Spectral properties and the effect on redshift cut-off of compact active galactic nuclei from the AT20G survey: Spectral properties and z cut-off of AGNs
    journal, April 2012