Low-redshift Lyman Continuum Survey: Radio continuum properties of low-$z$ Lyman continuum emitters
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2023
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| author | Bait, Omkar Borthakur, Sanchayeeta Schaerer, Daniel Momjian, Emmanuel Sebastian, Biny Saldana-Lopez, Alberto Flury, Sophia R. Chisholm, John Marques-Chaves, Rui Jaskot, Anne E. Ferguson, Harry C. Worseck, Gabor Ji, Zhiyuan Komarova, Lena Trebitsch, Maxime Hayes, Matthew J. Pentericci, Laura Ostlin, Goran Thuan, Trinh Amorín, Ricardo O. Wang, Bingjie Xu, Xinfeng Sargent, Mark T. |
| author_facet | Bait, Omkar Borthakur, Sanchayeeta Schaerer, Daniel Momjian, Emmanuel Sebastian, Biny Saldana-Lopez, Alberto Flury, Sophia R. Chisholm, John Marques-Chaves, Rui Jaskot, Anne E. Ferguson, Harry C. Worseck, Gabor Ji, Zhiyuan Komarova, Lena Trebitsch, Maxime Hayes, Matthew J. Pentericci, Laura Ostlin, Goran Thuan, Trinh Amorín, Ricardo O. Wang, Bingjie Xu, Xinfeng Sargent, Mark T. |
| contents | Sources that leak Lyman-continuum (LyC) photons and lead to the reionisation of the universe are intensely studied using multiple observing facilities. Recently, the Low-redshift LyC Survey (LzLCS) has found the first large sample of LyC emitting galaxies at low redshift ($z\sim 0.3$) with the Hubble Space Telescope/Cosmic Origins Spectrograph. The LzLCS sample contains a robust estimate of the LyC escape fraction ($f_\mathrm{esc}^\mathrm{LyC}$) for 66 galaxies spanning a wide range of $f_\mathrm{esc}^\mathrm{LyC}$. Here we, for the first time, aim to study the radio continuum (RC) properties of LzLCS sources and their dependence on $f_\mathrm{esc}^\mathrm{LyC}$. We present Karl G. Jansky Very Large Array RC observations at C (4-8 GHz), S (2-4 GHz) and L (1-2 GHz) bands for a sub-sample of the LzLCS sources. The radio spectral index ($α^{\mathrm{3GHz}}_\mathrm{6GHz}$) spans a wide range from being flat ( $\geq -0.1$) to very steep ($\leq -1.0$). The strongest leakers in our sample show flat $α^{\mathrm{3GHz}}_\mathrm{6GHz}$, weak leakers have $α^{\mathrm{3GHz}}_\mathrm{6GHz}$ close to normal star-forming galaxies, and non-leakers are characterized by steep $α^{\mathrm{3GHz}}_\mathrm{6GHz}$. We argue that a combination of young ages, free-free absorption, and a flat cosmic-ray energy spectrum can altogether lead to a flat $α^{\mathrm{3GHz}}_\mathrm{6GHz}$ for strong leakers. Non-leakers are characterized by steep spectra which can arise due to break/cutoff at high frequencies. Such a cutoff in the spectrum can arise in a single injection model of CRs characteristic of galaxies which have recently stopped star formation. Such a relation between $α^{\mathrm{3GHz}}_\mathrm{6GHz}$ and $f_\mathrm{esc}^\mathrm{LyC}$ hints at the interesting role of supernovae, CRs, and magnetic fields in facilitating the escape ( and/or the lack) of LyC photons. (Abridged) |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2310_18817 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Low-redshift Lyman Continuum Survey: Radio continuum properties of low-$z$ Lyman continuum emitters Bait, Omkar Borthakur, Sanchayeeta Schaerer, Daniel Momjian, Emmanuel Sebastian, Biny Saldana-Lopez, Alberto Flury, Sophia R. Chisholm, John Marques-Chaves, Rui Jaskot, Anne E. Ferguson, Harry C. Worseck, Gabor Ji, Zhiyuan Komarova, Lena Trebitsch, Maxime Hayes, Matthew J. Pentericci, Laura Ostlin, Goran Thuan, Trinh Amorín, Ricardo O. Wang, Bingjie Xu, Xinfeng Sargent, Mark T. Astrophysics of Galaxies Sources that leak Lyman-continuum (LyC) photons and lead to the reionisation of the universe are intensely studied using multiple observing facilities. Recently, the Low-redshift LyC Survey (LzLCS) has found the first large sample of LyC emitting galaxies at low redshift ($z\sim 0.3$) with the Hubble Space Telescope/Cosmic Origins Spectrograph. The LzLCS sample contains a robust estimate of the LyC escape fraction ($f_\mathrm{esc}^\mathrm{LyC}$) for 66 galaxies spanning a wide range of $f_\mathrm{esc}^\mathrm{LyC}$. Here we, for the first time, aim to study the radio continuum (RC) properties of LzLCS sources and their dependence on $f_\mathrm{esc}^\mathrm{LyC}$. We present Karl G. Jansky Very Large Array RC observations at C (4-8 GHz), S (2-4 GHz) and L (1-2 GHz) bands for a sub-sample of the LzLCS sources. The radio spectral index ($α^{\mathrm{3GHz}}_\mathrm{6GHz}$) spans a wide range from being flat ( $\geq -0.1$) to very steep ($\leq -1.0$). The strongest leakers in our sample show flat $α^{\mathrm{3GHz}}_\mathrm{6GHz}$, weak leakers have $α^{\mathrm{3GHz}}_\mathrm{6GHz}$ close to normal star-forming galaxies, and non-leakers are characterized by steep $α^{\mathrm{3GHz}}_\mathrm{6GHz}$. We argue that a combination of young ages, free-free absorption, and a flat cosmic-ray energy spectrum can altogether lead to a flat $α^{\mathrm{3GHz}}_\mathrm{6GHz}$ for strong leakers. Non-leakers are characterized by steep spectra which can arise due to break/cutoff at high frequencies. Such a cutoff in the spectrum can arise in a single injection model of CRs characteristic of galaxies which have recently stopped star formation. Such a relation between $α^{\mathrm{3GHz}}_\mathrm{6GHz}$ and $f_\mathrm{esc}^\mathrm{LyC}$ hints at the interesting role of supernovae, CRs, and magnetic fields in facilitating the escape ( and/or the lack) of LyC photons. (Abridged) |
| title | Low-redshift Lyman Continuum Survey: Radio continuum properties of low-$z$ Lyman continuum emitters |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2310.18817 |