The JWST Emission Line Survey (JELS): An untargeted search for H$α$ emission line galaxies at $z > 6$ and their physical properties
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2024
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| author | Pirie, C. A. Best, P. N. Duncan, K. J. McLeod, D. J. Cochrane, R. K. Clausen, M. Dunlop, J. S. Flury, S. R. Geach, J. E. Hale, C. L. Ibar, E. Kondapally, R. Li, Zefeng Matthee, J. McLure, R. J. Ossa-Fuentes, L. Patrick, A. L. Smail, Ian Sobral, D. Stephenson, H. M. O. Stott, J. P. Swinbank, A. M. |
| author_facet | Pirie, C. A. Best, P. N. Duncan, K. J. McLeod, D. J. Cochrane, R. K. Clausen, M. Dunlop, J. S. Flury, S. R. Geach, J. E. Hale, C. L. Ibar, E. Kondapally, R. Li, Zefeng Matthee, J. McLure, R. J. Ossa-Fuentes, L. Patrick, A. L. Smail, Ian Sobral, D. Stephenson, H. M. O. Stott, J. P. Swinbank, A. M. |
| contents | We present the first results of the JWST Emission Line Survey (JELS). Utilising the first NIRCam narrow-band imaging at 4.7$μ$m, over 63 arcmin$^{2}$ in the PRIMER/COSMOS field, we identified 609 emission line galaxy candidates. From these, we robustly selected 35 H$α$ star-forming galaxies at $z \sim 6.1$, with H$α$ star-formation rates ($\rm{SFR_{Hα}}$) $\sim0.9-15\ \rm{M_{\odot} \ yr^{-1}}$. Combining our unique H$α$ sample with the exquisite panchromatic data in the field, we explored their physical properties and star-formation histories, and compared these to a broad-band selected sample at $z\sim 6$ which offered vital new insights into the nature of high-redshift galaxies. UV-continuum slopes ($β$) were considerably redder for our H$α$ sample ($\langleβ\rangle\sim-1.92$) compared to the broad-band sample ($\langleβ\rangle\sim-2.35$). This was not due to dust attenuation as our H$α$ sample was relatively dust-poor (median $A_V=0.23$); instead, we argued the reddened slopes could be due to nebular continuum. We compared $\rm{SFR_{Hα}}$ and the UV-continuum-derived $\rm{SFR_{UV}}$ to SED-fitted measurements averaged over canonical timescales of 10 and 100 Myr ($\rm{SFR_{10}}$ and $\rm{SFR_{100}}$). We found an increase in recent SFR for our sample of H$α$ emitters, particularly at lower stellar masses ($<10^9 \ \rm{M_{\odot}}$). We also found $\rm{SFR_{Hα}}$ strongly traced SFR averaged over 10 Myr timescales, whereas the UV-continuum over-predicts SFR on 100 Myr timescales at low stellar masses. These results point to our H$α$ sample undergoing `bursty' star formation. Our F356W $z \sim 6$ sample showed a larger scatter in $\rm{SFR_{10}/SFR_{100}}$ across all stellar masses, which highlighted how narrow-band photometric selections of H$α$ emitters are key to quantifying the burstiness of star-formation activity. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2410_11808 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | The JWST Emission Line Survey (JELS): An untargeted search for H$α$ emission line galaxies at $z > 6$ and their physical properties Pirie, C. A. Best, P. N. Duncan, K. J. McLeod, D. J. Cochrane, R. K. Clausen, M. Dunlop, J. S. Flury, S. R. Geach, J. E. Hale, C. L. Ibar, E. Kondapally, R. Li, Zefeng Matthee, J. McLure, R. J. Ossa-Fuentes, L. Patrick, A. L. Smail, Ian Sobral, D. Stephenson, H. M. O. Stott, J. P. Swinbank, A. M. Astrophysics of Galaxies We present the first results of the JWST Emission Line Survey (JELS). Utilising the first NIRCam narrow-band imaging at 4.7$μ$m, over 63 arcmin$^{2}$ in the PRIMER/COSMOS field, we identified 609 emission line galaxy candidates. From these, we robustly selected 35 H$α$ star-forming galaxies at $z \sim 6.1$, with H$α$ star-formation rates ($\rm{SFR_{Hα}}$) $\sim0.9-15\ \rm{M_{\odot} \ yr^{-1}}$. Combining our unique H$α$ sample with the exquisite panchromatic data in the field, we explored their physical properties and star-formation histories, and compared these to a broad-band selected sample at $z\sim 6$ which offered vital new insights into the nature of high-redshift galaxies. UV-continuum slopes ($β$) were considerably redder for our H$α$ sample ($\langleβ\rangle\sim-1.92$) compared to the broad-band sample ($\langleβ\rangle\sim-2.35$). This was not due to dust attenuation as our H$α$ sample was relatively dust-poor (median $A_V=0.23$); instead, we argued the reddened slopes could be due to nebular continuum. We compared $\rm{SFR_{Hα}}$ and the UV-continuum-derived $\rm{SFR_{UV}}$ to SED-fitted measurements averaged over canonical timescales of 10 and 100 Myr ($\rm{SFR_{10}}$ and $\rm{SFR_{100}}$). We found an increase in recent SFR for our sample of H$α$ emitters, particularly at lower stellar masses ($<10^9 \ \rm{M_{\odot}}$). We also found $\rm{SFR_{Hα}}$ strongly traced SFR averaged over 10 Myr timescales, whereas the UV-continuum over-predicts SFR on 100 Myr timescales at low stellar masses. These results point to our H$α$ sample undergoing `bursty' star formation. Our F356W $z \sim 6$ sample showed a larger scatter in $\rm{SFR_{10}/SFR_{100}}$ across all stellar masses, which highlighted how narrow-band photometric selections of H$α$ emitters are key to quantifying the burstiness of star-formation activity. |
| title | The JWST Emission Line Survey (JELS): An untargeted search for H$α$ emission line galaxies at $z > 6$ and their physical properties |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2410.11808 |