Emission-line galaxies at $z\sim1$ from near-IR HST Slitless Spectroscopy: metallicities, star formation rates and redshift confirmations from VLT/FORS2 spectroscopy
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| Autores principales: | , , , , , , , , , , , , , , , , |
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| Formato: | Preprint |
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2024
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| author | Boyett, K. Bunker, A. J. Chevallard, J Battisti, A. J. Henry, A. L. Wilkins, S. Malkan, M. A. Caruana, J. Atek, H. Baronchelli, I. Colbert, J. Dai, Y. S. Gardner, Jonathan. P. Rafelski, M. Scarlata, C. Teplitz, H. I. Wang, X. |
| author_facet | Boyett, K. Bunker, A. J. Chevallard, J Battisti, A. J. Henry, A. L. Wilkins, S. Malkan, M. A. Caruana, J. Atek, H. Baronchelli, I. Colbert, J. Dai, Y. S. Gardner, Jonathan. P. Rafelski, M. Scarlata, C. Teplitz, H. I. Wang, X. |
| contents | We follow up emission line galaxies identified through the near-infrared slitless HST/WFC3 WISP survey with VLT/FORS2 optical spectroscopy. Over 4 WISP fields, we targetted 85 of 138 line emission objects at $0.4<z<2$ identified in WFC3 spectroscopy. Half the galaxies are fainter than $H_{AB}=24$mag, and would not have been included in many well-known surveys based on broad-band magnitude selection. We confirm 95% of the initial WFC3 grism redshifts in the 38 cases where we detect lines in FORS2 spectroscopy. However, for targets which exhibited a single emission line in WFC3, up to 65% at $z<1.28$ did not have expected emission lines detected in FORS2 and hence may be spurious (although this false-detection rate improves to 33% using the latest public WISP emission line catalogue). From the Balmer decrement the extinction of the WISP galaxies is consistent with $A($H$α)=1$mag. From SED fits to multi-band photometry including Spitzer $3.6μ$m, we find a median stellar mass of $\log_{10}(M/M_{\odot})=8.94$. Our emission-line-selected galaxies tend to lie above the star-forming main sequence (i.e. higher specific star formation rates). Using [OIII], [OII] and H$β$ lines to derive gas-phase metallicities, we find typically sub-solar metallicities, decreasing with redshift. Our WISP galaxies lie below the $z=0$ mass-metallicity relation, and galaxies with higher star formation rates tend to have lower metallicity. Finally, we find a strong increase with redshift of the H$α$ rest-frame equivalent width in this emission-line selected sample, with higher $EW_0$ galaxies having larger [OIII]/H$β$ and O32 ratios on average, suggesting lower metallicity or higher ionisation parameter in these extreme emission line galaxies. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2404_07497 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Emission-line galaxies at $z\sim1$ from near-IR HST Slitless Spectroscopy: metallicities, star formation rates and redshift confirmations from VLT/FORS2 spectroscopy Boyett, K. Bunker, A. J. Chevallard, J Battisti, A. J. Henry, A. L. Wilkins, S. Malkan, M. A. Caruana, J. Atek, H. Baronchelli, I. Colbert, J. Dai, Y. S. Gardner, Jonathan. P. Rafelski, M. Scarlata, C. Teplitz, H. I. Wang, X. Astrophysics of Galaxies We follow up emission line galaxies identified through the near-infrared slitless HST/WFC3 WISP survey with VLT/FORS2 optical spectroscopy. Over 4 WISP fields, we targetted 85 of 138 line emission objects at $0.4<z<2$ identified in WFC3 spectroscopy. Half the galaxies are fainter than $H_{AB}=24$mag, and would not have been included in many well-known surveys based on broad-band magnitude selection. We confirm 95% of the initial WFC3 grism redshifts in the 38 cases where we detect lines in FORS2 spectroscopy. However, for targets which exhibited a single emission line in WFC3, up to 65% at $z<1.28$ did not have expected emission lines detected in FORS2 and hence may be spurious (although this false-detection rate improves to 33% using the latest public WISP emission line catalogue). From the Balmer decrement the extinction of the WISP galaxies is consistent with $A($H$α)=1$mag. From SED fits to multi-band photometry including Spitzer $3.6μ$m, we find a median stellar mass of $\log_{10}(M/M_{\odot})=8.94$. Our emission-line-selected galaxies tend to lie above the star-forming main sequence (i.e. higher specific star formation rates). Using [OIII], [OII] and H$β$ lines to derive gas-phase metallicities, we find typically sub-solar metallicities, decreasing with redshift. Our WISP galaxies lie below the $z=0$ mass-metallicity relation, and galaxies with higher star formation rates tend to have lower metallicity. Finally, we find a strong increase with redshift of the H$α$ rest-frame equivalent width in this emission-line selected sample, with higher $EW_0$ galaxies having larger [OIII]/H$β$ and O32 ratios on average, suggesting lower metallicity or higher ionisation parameter in these extreme emission line galaxies. |
| title | Emission-line galaxies at $z\sim1$ from near-IR HST Slitless Spectroscopy: metallicities, star formation rates and redshift confirmations from VLT/FORS2 spectroscopy |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2404.07497 |