SHORES II: Multi-frequency Characterisation of the Sub-mJy Radio Population in FIR-selected Fields
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| Format: | Preprint |
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2025
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| _version_ | 1866915657759588352 |
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| author | Behiri, Meriem Massardi, Marcella Galluzzi, Vincenzo Giulietti, Marika Gururajan, Gayathri Prandoni, Isabella Lapi, Andrea |
| author_facet | Behiri, Meriem Massardi, Marcella Galluzzi, Vincenzo Giulietti, Marika Gururajan, Gayathri Prandoni, Isabella Lapi, Andrea |
| contents | We present a new deep multi-frequency radio survey of two extragalactic fields observed with the Australia Telescope Compact Array (ATCA) as part of the SHORES project (Serendipitous H-ATLAS fields Observations of Radio Extragalactic Sources). The observations, centred at 2.1, 5.5, and 9 GHz, cover the central 0.5 deg$^2$ of two Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) fields down to rms sensitivities of 9-17 $μ$Jy$/$beam at 2.1 GHz, 28-39 $μ$Jy/beam at 5.5 GHz and 38-61 $μ$Jy/beam at 9 GHz. This setup allows us to investigate the spectral energy distributions (SEDs) of faint radio sources and probe the nature of the sub-mJy population. We extract and validate a robust catalogue of 489 sources at 2.1 GHz, 101 of which are also detected at 5.5 GHz. We perform a multi-frequency analysis of the radio number counts and derive the spectral indices of sources in the deep fields. The spectral index distribution of our sources peaks around $α\sim -0.7$, consistent with synchrotron emission from the faint radio population. The number counts at 2.1 GHz are consistent with previous deep surveys and theoretical models, and provide a lower limit on the star-forming galaxy population, which is expected to dominate the faint end. The 5.5 GHz data offer new, direct constraints on the sub-mJy radio sky at higher frequencies. By cross-matching with the H-ATLAS catalogue, we identify a sample of sources with far-infrared (FIR) counterparts and explore the far-infrared-radio correlation (FIRRC). The sources with $q_{FIR} \geq 1.69$ exhibit radio spectral indices typical of star-forming galaxies. Furthermore, we identify a population of radio-only sources with similar indices that may correspond to high-redshift SFGs, lacking counterparts in the FIR survey due to its limited resolution and sensitivity. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2512_06089 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | SHORES II: Multi-frequency Characterisation of the Sub-mJy Radio Population in FIR-selected Fields Behiri, Meriem Massardi, Marcella Galluzzi, Vincenzo Giulietti, Marika Gururajan, Gayathri Prandoni, Isabella Lapi, Andrea Astrophysics of Galaxies We present a new deep multi-frequency radio survey of two extragalactic fields observed with the Australia Telescope Compact Array (ATCA) as part of the SHORES project (Serendipitous H-ATLAS fields Observations of Radio Extragalactic Sources). The observations, centred at 2.1, 5.5, and 9 GHz, cover the central 0.5 deg$^2$ of two Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) fields down to rms sensitivities of 9-17 $μ$Jy$/$beam at 2.1 GHz, 28-39 $μ$Jy/beam at 5.5 GHz and 38-61 $μ$Jy/beam at 9 GHz. This setup allows us to investigate the spectral energy distributions (SEDs) of faint radio sources and probe the nature of the sub-mJy population. We extract and validate a robust catalogue of 489 sources at 2.1 GHz, 101 of which are also detected at 5.5 GHz. We perform a multi-frequency analysis of the radio number counts and derive the spectral indices of sources in the deep fields. The spectral index distribution of our sources peaks around $α\sim -0.7$, consistent with synchrotron emission from the faint radio population. The number counts at 2.1 GHz are consistent with previous deep surveys and theoretical models, and provide a lower limit on the star-forming galaxy population, which is expected to dominate the faint end. The 5.5 GHz data offer new, direct constraints on the sub-mJy radio sky at higher frequencies. By cross-matching with the H-ATLAS catalogue, we identify a sample of sources with far-infrared (FIR) counterparts and explore the far-infrared-radio correlation (FIRRC). The sources with $q_{FIR} \geq 1.69$ exhibit radio spectral indices typical of star-forming galaxies. Furthermore, we identify a population of radio-only sources with similar indices that may correspond to high-redshift SFGs, lacking counterparts in the FIR survey due to its limited resolution and sensitivity. |
| title | SHORES II: Multi-frequency Characterisation of the Sub-mJy Radio Population in FIR-selected Fields |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2512.06089 |