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A Radio Continuum Study of Dwarf Galaxies: 6 cm imaging of Little Things

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A Radio Continuum Study of Dwarf Galaxies : 6 cm imaging of Little Things. / Hindson, Luke; Kitchener, Ged; Brinks, Elias; Heesen, Volker; Westcott, Jonathan; Hunter, Deidre; Zhang, Hong-Xin; Rupen, Michael; Rau, Urvashi.

In: Astrophysical Journal, Supplement Series, Vol. 234, No. 2, 29, 01.02.2018.

Research output: Contribution to journalArticlepeer-review

Harvard

Hindson, L, Kitchener, G, Brinks, E, Heesen, V, Westcott, J, Hunter, D, Zhang, H-X, Rupen, M & Rau, U 2018, 'A Radio Continuum Study of Dwarf Galaxies: 6 cm imaging of Little Things', Astrophysical Journal, Supplement Series, vol. 234, no. 2, 29. https://doi.org/10.3847/1538-4365/aaa42c

APA

Hindson, L., Kitchener, G., Brinks, E., Heesen, V., Westcott, J., Hunter, D., Zhang, H-X., Rupen, M., & Rau, U. (2018). A Radio Continuum Study of Dwarf Galaxies: 6 cm imaging of Little Things. Astrophysical Journal, Supplement Series, 234(2), [29]. https://doi.org/10.3847/1538-4365/aaa42c

Vancouver

Author

Hindson, Luke ; Kitchener, Ged ; Brinks, Elias ; Heesen, Volker ; Westcott, Jonathan ; Hunter, Deidre ; Zhang, Hong-Xin ; Rupen, Michael ; Rau, Urvashi. / A Radio Continuum Study of Dwarf Galaxies : 6 cm imaging of Little Things. In: Astrophysical Journal, Supplement Series. 2018 ; Vol. 234, No. 2.

Bibtex

@article{4bf9262460e94c1783245a154fbeea9b,
title = "A Radio Continuum Study of Dwarf Galaxies: 6 cm imaging of Little Things",
abstract = "In this paper, we examine to what extent the radio continuum can be used as an extinction-free probe of star formation in dwarf galaxies. To that aim, we observe 40 nearby dwarf galaxies with the Very Large Array at 6 cm (4-8 GHz) in C-configuration. We obtained images with 3″-8″ resolution and noise levels of 3-15 μJy beam -1. We detected emission associated with 22 of the 40 dwarf galaxies, eight of which are new detections. The general picture is that of an interstellar medium largely devoid of radio continuum emission, interspersed by isolated pockets of emission associated with star formation. We find an average thermal fraction of ∼50%-70% and an average magnetic field strength of ∼5-8 μG, only slightly lower than that found in larger, spiral galaxies. At 100 pc scales, we find surprisingly high values for the average magnetic field strength of up to 50 μG. We find that dwarf galaxies follow the theoretical predictions of the radio continuum-star formation rate relation within regions of significant radio continuum emission but that the nonthermal radio continuum is suppressed relative to the star formation rate when considering the entire optical disk. We examine the far-infrared-star formation rate relation for our sample and find that the far-infrared is suppressed compared to the expected star formation rate. We discuss explanations for these observed relations and the impact of our findings on the radio continuum-far-infrared relation. We conclude that radio continuum emission at centimeter wavelengths has the promise of being a largely extinction-free star formation rate indicator. We find that star formation rates of gas-rich, low-mass galaxies can be estimated with an uncertainty of ± 0.2 dex between the values of 2 × 10 -4 and 0.1 M o yr -1. ",
keywords = "galaxies: dwarf, galaxies: magnetic fields, galaxies: star formation, radio continuum: galaxies, radio continuum: ISM",
author = "Luke Hindson and Ged Kitchener and Elias Brinks and Volker Heesen and Jonathan Westcott and Deidre Hunter and Hong-Xin Zhang and Michael Rupen and Urvashi Rau",
note = "Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.",
year = "2018",
month = feb,
day = "1",
doi = "10.3847/1538-4365/aaa42c",
language = "English",
volume = "234",
journal = "Astrophysical Journal, Supplement Series",
issn = "0067-0049",
publisher = "IOP Publishing Ltd.",
number = "2",

}

RIS

TY - JOUR

T1 - A Radio Continuum Study of Dwarf Galaxies

T2 - 6 cm imaging of Little Things

AU - Hindson, Luke

AU - Kitchener, Ged

AU - Brinks, Elias

AU - Heesen, Volker

AU - Westcott, Jonathan

AU - Hunter, Deidre

AU - Zhang, Hong-Xin

AU - Rupen, Michael

AU - Rau, Urvashi

N1 - Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

PY - 2018/2/1

Y1 - 2018/2/1

N2 - In this paper, we examine to what extent the radio continuum can be used as an extinction-free probe of star formation in dwarf galaxies. To that aim, we observe 40 nearby dwarf galaxies with the Very Large Array at 6 cm (4-8 GHz) in C-configuration. We obtained images with 3″-8″ resolution and noise levels of 3-15 μJy beam -1. We detected emission associated with 22 of the 40 dwarf galaxies, eight of which are new detections. The general picture is that of an interstellar medium largely devoid of radio continuum emission, interspersed by isolated pockets of emission associated with star formation. We find an average thermal fraction of ∼50%-70% and an average magnetic field strength of ∼5-8 μG, only slightly lower than that found in larger, spiral galaxies. At 100 pc scales, we find surprisingly high values for the average magnetic field strength of up to 50 μG. We find that dwarf galaxies follow the theoretical predictions of the radio continuum-star formation rate relation within regions of significant radio continuum emission but that the nonthermal radio continuum is suppressed relative to the star formation rate when considering the entire optical disk. We examine the far-infrared-star formation rate relation for our sample and find that the far-infrared is suppressed compared to the expected star formation rate. We discuss explanations for these observed relations and the impact of our findings on the radio continuum-far-infrared relation. We conclude that radio continuum emission at centimeter wavelengths has the promise of being a largely extinction-free star formation rate indicator. We find that star formation rates of gas-rich, low-mass galaxies can be estimated with an uncertainty of ± 0.2 dex between the values of 2 × 10 -4 and 0.1 M o yr -1.

AB - In this paper, we examine to what extent the radio continuum can be used as an extinction-free probe of star formation in dwarf galaxies. To that aim, we observe 40 nearby dwarf galaxies with the Very Large Array at 6 cm (4-8 GHz) in C-configuration. We obtained images with 3″-8″ resolution and noise levels of 3-15 μJy beam -1. We detected emission associated with 22 of the 40 dwarf galaxies, eight of which are new detections. The general picture is that of an interstellar medium largely devoid of radio continuum emission, interspersed by isolated pockets of emission associated with star formation. We find an average thermal fraction of ∼50%-70% and an average magnetic field strength of ∼5-8 μG, only slightly lower than that found in larger, spiral galaxies. At 100 pc scales, we find surprisingly high values for the average magnetic field strength of up to 50 μG. We find that dwarf galaxies follow the theoretical predictions of the radio continuum-star formation rate relation within regions of significant radio continuum emission but that the nonthermal radio continuum is suppressed relative to the star formation rate when considering the entire optical disk. We examine the far-infrared-star formation rate relation for our sample and find that the far-infrared is suppressed compared to the expected star formation rate. We discuss explanations for these observed relations and the impact of our findings on the radio continuum-far-infrared relation. We conclude that radio continuum emission at centimeter wavelengths has the promise of being a largely extinction-free star formation rate indicator. We find that star formation rates of gas-rich, low-mass galaxies can be estimated with an uncertainty of ± 0.2 dex between the values of 2 × 10 -4 and 0.1 M o yr -1.

KW - galaxies: dwarf

KW - galaxies: magnetic fields

KW - galaxies: star formation

KW - radio continuum: galaxies

KW - radio continuum: ISM

UR - http://www.scopus.com/inward/record.url?scp=85042522959&partnerID=8YFLogxK

U2 - 10.3847/1538-4365/aaa42c

DO - 10.3847/1538-4365/aaa42c

M3 - Article

VL - 234

JO - Astrophysical Journal, Supplement Series

JF - Astrophysical Journal, Supplement Series

SN - 0067-0049

IS - 2

M1 - 29

ER -