LOFAR MSSSCitation formats

  • External authors:
  • K. T. Chyzy
  • W. Jurusik
  • J. Piotrowska
  • B. Nikiel-Wroczyński
  • V. Heesen
  • V. Vacca
  • N. Nowak
  • R. Paladino
  • P. Surma
  • S. S. Sridhar
  • G. Heald
  • R. Beck
  • J. Conway
  • K. Sendlinger
  • M. Curyło
  • D. Mulcahy
  • J. W. Broderick
  • M. J. Hardcastle
  • J. R. Callingham
  • G. Gürkan
  • M. Iacobelli
  • H. J.A. Röttgering
  • B. Adebahr
  • A. Shulevski
  • R. J. Dettmar
  • A. O. Clarke
  • J. S. Farnes
  • E. Orrú
  • V. N. Pandey
  • M. Pandey-Pommier
  • R. Pizzo
  • C. J. Riseley
  • A. Rowlinson
  • A. J. Stewart
  • A. J. Van Der Horst
  • R. J. Van Weeren

Standard

LOFAR MSSS : Flattening low-frequency radio continuum spectra of nearby galaxies. / Chyzy, K. T.; Jurusik, W.; Piotrowska, J.; Nikiel-Wroczyński, B.; Heesen, V.; Vacca, V.; Nowak, N.; Paladino, R.; Surma, P.; Sridhar, S. S.; Heald, G.; Beck, R.; Conway, J.; Sendlinger, K.; Curyło, M.; Mulcahy, D.; Broderick, J. W.; Hardcastle, M. J.; Callingham, J. R.; Gürkan, G.; Iacobelli, M.; Röttgering, H. J.A.; Adebahr, B.; Shulevski, A.; Dettmar, R. J.; Breton, R. P.; Clarke, A. O.; Farnes, J. S.; Orrú, E.; Pandey, V. N.; Pandey-Pommier, M.; Pizzo, R.; Riseley, C. J.; Rowlinson, A.; Scaife, A. M.M.; Stewart, A. J.; Van Der Horst, A. J.; Van Weeren, R. J.

In: Astronomy and Astrophysics, Vol. 619, A36, 11.2018.

Research output: Contribution to journalArticle

Harvard

Chyzy, KT, Jurusik, W, Piotrowska, J, Nikiel-Wroczyński, B, Heesen, V, Vacca, V, Nowak, N, Paladino, R, Surma, P, Sridhar, SS, Heald, G, Beck, R, Conway, J, Sendlinger, K, Curyło, M, Mulcahy, D, Broderick, JW, Hardcastle, MJ, Callingham, JR, Gürkan, G, Iacobelli, M, Röttgering, HJA, Adebahr, B, Shulevski, A, Dettmar, RJ, Breton, RP, Clarke, AO, Farnes, JS, Orrú, E, Pandey, VN, Pandey-Pommier, M, Pizzo, R, Riseley, CJ, Rowlinson, A, Scaife, AMM, Stewart, AJ, Van Der Horst, AJ & Van Weeren, RJ 2018, 'LOFAR MSSS: Flattening low-frequency radio continuum spectra of nearby galaxies', Astronomy and Astrophysics, vol. 619, A36. https://doi.org/10.1051/0004-6361/201833133

APA

Chyzy, K. T., Jurusik, W., Piotrowska, J., Nikiel-Wroczyński, B., Heesen, V., Vacca, V., ... Van Weeren, R. J. (2018). LOFAR MSSS: Flattening low-frequency radio continuum spectra of nearby galaxies. Astronomy and Astrophysics, 619, [A36]. https://doi.org/10.1051/0004-6361/201833133

Vancouver

Chyzy KT, Jurusik W, Piotrowska J, Nikiel-Wroczyński B, Heesen V, Vacca V et al. LOFAR MSSS: Flattening low-frequency radio continuum spectra of nearby galaxies. Astronomy and Astrophysics. 2018 Nov;619. A36. https://doi.org/10.1051/0004-6361/201833133

Author

Chyzy, K. T. ; Jurusik, W. ; Piotrowska, J. ; Nikiel-Wroczyński, B. ; Heesen, V. ; Vacca, V. ; Nowak, N. ; Paladino, R. ; Surma, P. ; Sridhar, S. S. ; Heald, G. ; Beck, R. ; Conway, J. ; Sendlinger, K. ; Curyło, M. ; Mulcahy, D. ; Broderick, J. W. ; Hardcastle, M. J. ; Callingham, J. R. ; Gürkan, G. ; Iacobelli, M. ; Röttgering, H. J.A. ; Adebahr, B. ; Shulevski, A. ; Dettmar, R. J. ; Breton, R. P. ; Clarke, A. O. ; Farnes, J. S. ; Orrú, E. ; Pandey, V. N. ; Pandey-Pommier, M. ; Pizzo, R. ; Riseley, C. J. ; Rowlinson, A. ; Scaife, A. M.M. ; Stewart, A. J. ; Van Der Horst, A. J. ; Van Weeren, R. J. / LOFAR MSSS : Flattening low-frequency radio continuum spectra of nearby galaxies. In: Astronomy and Astrophysics. 2018 ; Vol. 619.

Bibtex

@article{1684383ac50b48cb9afddc86de83e162,
title = "LOFAR MSSS: Flattening low-frequency radio continuum spectra of nearby galaxies",
abstract = "Aims. The shape of low-frequency radio continuum spectra of normal galaxies is not well understood, the key question being the role of physical processes such as thermal absorption in shaping them. In this work we take advantage of the LOFAR Multifrequency Snapshot Sky Survey (MSSS) to investigate such spectra for a large sample of nearby star-forming galaxies. Methods. Using the measured 150 MHz flux densities from the LOFAR MSSS survey and literature flux densities at various frequencies we have obtained integrated radio spectra for 106 galaxies characterised by different morphology and star formation rate. The spectra are explained through the use of a three-dimensional model of galaxy radio emission, and radiation transfer dependent on the galaxy viewing angle and absorption processes. Results. Our galaxies' spectra are generally flatter at lower compared to higher frequencies: the median spectral index αlow measured between ≈ 50 MHz and 1.5 GHz is -0.57 ± 0.01 while the high-frequency one αhigh, calculated between 1.3 GHz and 5 GHz, is -0.77 ± 0.03. As there is no tendency for the highly inclined galaxies to have more flattened low-frequency spectra, we argue that the observed flattening is not due to thermal absorption, contradicting the suggestion of Israel & Mahoney (1990, ApJ, 352, 30). According to our modelled radio maps for M 51-like galaxies, the free-free absorption effects can be seen only below 30 MHz and in the global spectra just below 20 MHz, while in the spectra of starburst galaxies, like M 82, the flattening due to absorption is instead visible up to higher frequencies of about 150 MHz. Starbursts are however scarce in the local Universe, in accordance with the weak spectral curvature seen in the galaxies of our sample. Locally, within galactic disks, the absorption effects are distinctly visible in M 51-like galaxies as spectral flattening around 100-200 MHz in the face-on objects, and as turnovers in the edge-on ones, while in M 82-like galaxies there are strong turnovers at frequencies above 700 MHz, regardless of viewing angle. Conclusions. Our modelling of galaxy spectra suggests that the weak spectral flattening observed in the nearby galaxies studied here results principally from synchrotron spectral curvature due to cosmic ray energy losses and propagation effects. We predict much stronger effects of thermal absorption in more distant galaxies with high star formation rates. Some influence exerted by the Milky Way's foreground on the spectra of all external galaxies is also expected at very low frequencies.",
keywords = "Galaxies: evolution, Galaxies: statistics, Radio continuum: galaxies",
author = "Chyzy, {K. T.} and W. Jurusik and J. Piotrowska and B. Nikiel-Wroczyński and V. Heesen and V. Vacca and N. Nowak and R. Paladino and P. Surma and Sridhar, {S. S.} and G. Heald and R. Beck and J. Conway and K. Sendlinger and M. Curyło and D. Mulcahy and Broderick, {J. W.} and Hardcastle, {M. J.} and Callingham, {J. R.} and G. G{\"u}rkan and M. Iacobelli and R{\"o}ttgering, {H. J.A.} and B. Adebahr and A. Shulevski and Dettmar, {R. J.} and Breton, {R. P.} and Clarke, {A. O.} and Farnes, {J. S.} and E. Orr{\'u} and Pandey, {V. N.} and M. Pandey-Pommier and R. Pizzo and Riseley, {C. J.} and A. Rowlinson and Scaife, {A. M.M.} and Stewart, {A. J.} and {Van Der Horst}, {A. J.} and {Van Weeren}, {R. J.}",
year = "2018",
month = "11",
doi = "10.1051/0004-6361/201833133",
language = "English",
volume = "619",
journal = "Astronomy & Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",

}

RIS

TY - JOUR

T1 - LOFAR MSSS

T2 - Flattening low-frequency radio continuum spectra of nearby galaxies

AU - Chyzy, K. T.

AU - Jurusik, W.

AU - Piotrowska, J.

AU - Nikiel-Wroczyński, B.

AU - Heesen, V.

AU - Vacca, V.

AU - Nowak, N.

AU - Paladino, R.

AU - Surma, P.

AU - Sridhar, S. S.

AU - Heald, G.

AU - Beck, R.

AU - Conway, J.

AU - Sendlinger, K.

AU - Curyło, M.

AU - Mulcahy, D.

AU - Broderick, J. W.

AU - Hardcastle, M. J.

AU - Callingham, J. R.

AU - Gürkan, G.

AU - Iacobelli, M.

AU - Röttgering, H. J.A.

AU - Adebahr, B.

AU - Shulevski, A.

AU - Dettmar, R. J.

AU - Breton, R. P.

AU - Clarke, A. O.

AU - Farnes, J. S.

AU - Orrú, E.

AU - Pandey, V. N.

AU - Pandey-Pommier, M.

AU - Pizzo, R.

AU - Riseley, C. J.

AU - Rowlinson, A.

AU - Scaife, A. M.M.

AU - Stewart, A. J.

AU - Van Der Horst, A. J.

AU - Van Weeren, R. J.

PY - 2018/11

Y1 - 2018/11

N2 - Aims. The shape of low-frequency radio continuum spectra of normal galaxies is not well understood, the key question being the role of physical processes such as thermal absorption in shaping them. In this work we take advantage of the LOFAR Multifrequency Snapshot Sky Survey (MSSS) to investigate such spectra for a large sample of nearby star-forming galaxies. Methods. Using the measured 150 MHz flux densities from the LOFAR MSSS survey and literature flux densities at various frequencies we have obtained integrated radio spectra for 106 galaxies characterised by different morphology and star formation rate. The spectra are explained through the use of a three-dimensional model of galaxy radio emission, and radiation transfer dependent on the galaxy viewing angle and absorption processes. Results. Our galaxies' spectra are generally flatter at lower compared to higher frequencies: the median spectral index αlow measured between ≈ 50 MHz and 1.5 GHz is -0.57 ± 0.01 while the high-frequency one αhigh, calculated between 1.3 GHz and 5 GHz, is -0.77 ± 0.03. As there is no tendency for the highly inclined galaxies to have more flattened low-frequency spectra, we argue that the observed flattening is not due to thermal absorption, contradicting the suggestion of Israel & Mahoney (1990, ApJ, 352, 30). According to our modelled radio maps for M 51-like galaxies, the free-free absorption effects can be seen only below 30 MHz and in the global spectra just below 20 MHz, while in the spectra of starburst galaxies, like M 82, the flattening due to absorption is instead visible up to higher frequencies of about 150 MHz. Starbursts are however scarce in the local Universe, in accordance with the weak spectral curvature seen in the galaxies of our sample. Locally, within galactic disks, the absorption effects are distinctly visible in M 51-like galaxies as spectral flattening around 100-200 MHz in the face-on objects, and as turnovers in the edge-on ones, while in M 82-like galaxies there are strong turnovers at frequencies above 700 MHz, regardless of viewing angle. Conclusions. Our modelling of galaxy spectra suggests that the weak spectral flattening observed in the nearby galaxies studied here results principally from synchrotron spectral curvature due to cosmic ray energy losses and propagation effects. We predict much stronger effects of thermal absorption in more distant galaxies with high star formation rates. Some influence exerted by the Milky Way's foreground on the spectra of all external galaxies is also expected at very low frequencies.

AB - Aims. The shape of low-frequency radio continuum spectra of normal galaxies is not well understood, the key question being the role of physical processes such as thermal absorption in shaping them. In this work we take advantage of the LOFAR Multifrequency Snapshot Sky Survey (MSSS) to investigate such spectra for a large sample of nearby star-forming galaxies. Methods. Using the measured 150 MHz flux densities from the LOFAR MSSS survey and literature flux densities at various frequencies we have obtained integrated radio spectra for 106 galaxies characterised by different morphology and star formation rate. The spectra are explained through the use of a three-dimensional model of galaxy radio emission, and radiation transfer dependent on the galaxy viewing angle and absorption processes. Results. Our galaxies' spectra are generally flatter at lower compared to higher frequencies: the median spectral index αlow measured between ≈ 50 MHz and 1.5 GHz is -0.57 ± 0.01 while the high-frequency one αhigh, calculated between 1.3 GHz and 5 GHz, is -0.77 ± 0.03. As there is no tendency for the highly inclined galaxies to have more flattened low-frequency spectra, we argue that the observed flattening is not due to thermal absorption, contradicting the suggestion of Israel & Mahoney (1990, ApJ, 352, 30). According to our modelled radio maps for M 51-like galaxies, the free-free absorption effects can be seen only below 30 MHz and in the global spectra just below 20 MHz, while in the spectra of starburst galaxies, like M 82, the flattening due to absorption is instead visible up to higher frequencies of about 150 MHz. Starbursts are however scarce in the local Universe, in accordance with the weak spectral curvature seen in the galaxies of our sample. Locally, within galactic disks, the absorption effects are distinctly visible in M 51-like galaxies as spectral flattening around 100-200 MHz in the face-on objects, and as turnovers in the edge-on ones, while in M 82-like galaxies there are strong turnovers at frequencies above 700 MHz, regardless of viewing angle. Conclusions. Our modelling of galaxy spectra suggests that the weak spectral flattening observed in the nearby galaxies studied here results principally from synchrotron spectral curvature due to cosmic ray energy losses and propagation effects. We predict much stronger effects of thermal absorption in more distant galaxies with high star formation rates. Some influence exerted by the Milky Way's foreground on the spectra of all external galaxies is also expected at very low frequencies.

KW - Galaxies: evolution

KW - Galaxies: statistics

KW - Radio continuum: galaxies

UR - http://www.scopus.com/inward/record.url?scp=85056557047&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/201833133

DO - 10.1051/0004-6361/201833133

M3 - Article

VL - 619

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

M1 - A36

ER -