dorsal/arxiv
View SchemaAstroSat UV Deep Field IV. An Extended UV disk around a massive spiral galaxy at z=0.67
| Authors | Pushpak Pandey, Kanak Saha, Sanchayeeta Borthakur |
|---|---|
| Categories | |
| ArXiv ID | 2601.06581vv1 |
| URL | https://arxiv.org/abs/2601.06581 |
| License | http://creativecommons.org/licenses/by/4.0/ |
Abstract
Extended ultraviolet (XUV) emission in nearby disk galaxies supports the inside-out growth scenario through low-efficiency star formation in their outer regions. However, such detections have largely been limited to the local Universe (z ~ 0) due to the need for deep, high-resolution UV imaging. We report the detection of a clumpy XUV disk in a massive, isolated spiral galaxy $(log(M_*/M_\odot) \approx 11.04)$ at z=0.67, observed with AstroSat/UVIT. The intrinsic rest frame FUV surface brightness profile, corrected for the instrument PSF, shows a more extended disk than its optical and IR counterparts. The XUV disk reaches nearly twice the optical radius and includes a large UV-bright low surface brightness (LSB) region $(S_{LSB}/S_{K80}\approx9.3, \mu_{FUV}-\mu_K\approx 1)$, consistent with the Type II XUV definition. Additionally, the detection of UV clumps without optical counterparts supports a Type I classification, suggesting gravitational instabilities and recent star formation. These features point to recent cold gas accretion onto the outer disk. From the asymmetric light profile, we estimate a gas accretion rate of $\sim 11 M_\odot$ $yr^{-1}$, providing evidence of active disk growth at intermediate redshift.
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"abstract": "Extended ultraviolet (XUV) emission in nearby disk galaxies supports the inside-out growth scenario through low-efficiency star formation in their outer regions. However, such detections have largely been limited to the local Universe (z ~ 0) due to the need for deep, high-resolution UV imaging. We report the detection of a clumpy XUV disk in a massive, isolated spiral galaxy $(log(M_*/M_\\odot) \\approx 11.04)$ at z=0.67, observed with AstroSat/UVIT. The intrinsic rest frame FUV surface brightness profile, corrected for the instrument PSF, shows a more extended disk than its optical and IR counterparts. The XUV disk reaches nearly twice the optical radius and includes a large UV-bright low surface brightness (LSB) region $(S_{LSB}/S_{K80}\\approx9.3, \\mu_{FUV}-\\mu_K\\approx 1)$, consistent with the Type II XUV definition. Additionally, the detection of UV clumps without optical counterparts supports a Type I classification, suggesting gravitational instabilities and recent star formation. These features point to recent cold gas accretion onto the outer disk. From the asymmetric light profile, we estimate a gas accretion rate of $\\sim 11 M_\\odot$ $yr^{-1}$, providing evidence of active disk growth at intermediate redshift.",
"arxiv_id": "2601.06581",
"authors": [
"Pushpak Pandey",
"Kanak Saha",
"Sanchayeeta Borthakur"
],
"categories": [
"astro-ph.GA"
],
"license": "http://creativecommons.org/licenses/by/4.0/",
"title": "AstroSat UV Deep Field IV. An Extended UV disk around a massive spiral galaxy at z=0.67",
"url": "https://arxiv.org/abs/2601.06581",
"version": "v1"
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