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| Format: | Preprint |
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2023
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2306.08605 |
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| _version_ | 1866912999512473600 |
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| author | Calabrò, Antonello Pentericci, Laura Feltre, Anna Haro, Pablo Arrabal Radovich, Mario Seillé, Lise Marie Oliva, Ernesto Daddi, Emanuele Amorín, Ricardo Bagley, Micaela B. Bisigello, Laura Buat, Véronique Castellano, Marco Cleri, Nikko Dickinson, Mark Fernández, Vital Finkelstein, Steven Giavalisco, Mauro Grazian, Andrea Hathi, Nimish Hirschmann, Michaela Juneau, Stéphanie Kartaltepe, Jeyhan S. Koekemoer, Anton Lucas, Ray A. Papovich, Casey Pérez-González, Pablo Pirzkal, Nor Santini, Paola Trump, Jonathan de la Vega, Alexander Wilkins, Stephen Yung, L. Y. Aaron Cassata, Paolo Gobat, Raphael Mascia, Sara Napolitano, Lorenzo Vulcani, Benedetta |
| author_facet | Calabrò, Antonello Pentericci, Laura Feltre, Anna Haro, Pablo Arrabal Radovich, Mario Seillé, Lise Marie Oliva, Ernesto Daddi, Emanuele Amorín, Ricardo Bagley, Micaela B. Bisigello, Laura Buat, Véronique Castellano, Marco Cleri, Nikko Dickinson, Mark Fernández, Vital Finkelstein, Steven Giavalisco, Mauro Grazian, Andrea Hathi, Nimish Hirschmann, Michaela Juneau, Stéphanie Kartaltepe, Jeyhan S. Koekemoer, Anton Lucas, Ray A. Papovich, Casey Pérez-González, Pablo Pirzkal, Nor Santini, Paola Trump, Jonathan de la Vega, Alexander Wilkins, Stephen Yung, L. Y. Aaron Cassata, Paolo Gobat, Raphael Mascia, Sara Napolitano, Lorenzo Vulcani, Benedetta |
| contents | Optical rest-frame spectroscopic diagnostics are usually employed to distinguish between star formation and AGN-powered emission. However, this method is biased against dusty sources, hampering a complete census of the AGN population across cosmic epochs. To mitigate this effect, it is crucial to observe at longer wavelengths in the rest-frame near-infrared (near-IR), which is less affected by dust attenuation and can thus provide a better description of the intrinsic properties of galaxies. AGN diagnostics in this regime have not been fully exploited so far, due to the scarcity of near-IR observations of both AGNs and star-forming galaxies, especially at redshifts higher than 0.5. Using Cloudy photoionization models, we identify new AGN - star formation diagnostics based on the ratio of bright near-infrared emission lines, namely [SIII] 9530 Angstrom, [CI] 9850 Angstrom, [PII] 1.188 $μm$, [FeII] $1.257 μm$, and [FeII] $1.64 μm$ to Paschen lines (either Pa$γ$ or Pa$β$), providing simple, analytical classification criteria. We apply these diagnostics to a sample of 64 star-forming galaxies and AGNs at 0 < z < 1, and 65 sources at 1 < z < 3 recently observed with JWST-NIRSpec in CEERS. We find that the classification inferred from the near-infrared is broadly consistent with the optical one based on the BPT and the [SII]/H$α$ ratio. However, in the near-infrared, we find $\sim 60 \%$ more AGNs than in the optical (13 instead of 8), with 5 sources classified as 'hidden' AGNs, showing a larger AGN contribution at longer wavelengths, possibly due to the presence of optically thick dust. The diagnostics we present provide a promising tool to find and characterize AGNs from z=0 to z=3 with low and medium-resolution near-IR spectrographs in future surveys. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2306_08605 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Near-infrared emission line diagnostics for AGN from the local Universe to redshift 3 Calabrò, Antonello Pentericci, Laura Feltre, Anna Haro, Pablo Arrabal Radovich, Mario Seillé, Lise Marie Oliva, Ernesto Daddi, Emanuele Amorín, Ricardo Bagley, Micaela B. Bisigello, Laura Buat, Véronique Castellano, Marco Cleri, Nikko Dickinson, Mark Fernández, Vital Finkelstein, Steven Giavalisco, Mauro Grazian, Andrea Hathi, Nimish Hirschmann, Michaela Juneau, Stéphanie Kartaltepe, Jeyhan S. Koekemoer, Anton Lucas, Ray A. Papovich, Casey Pérez-González, Pablo Pirzkal, Nor Santini, Paola Trump, Jonathan de la Vega, Alexander Wilkins, Stephen Yung, L. Y. Aaron Cassata, Paolo Gobat, Raphael Mascia, Sara Napolitano, Lorenzo Vulcani, Benedetta Astrophysics of Galaxies Optical rest-frame spectroscopic diagnostics are usually employed to distinguish between star formation and AGN-powered emission. However, this method is biased against dusty sources, hampering a complete census of the AGN population across cosmic epochs. To mitigate this effect, it is crucial to observe at longer wavelengths in the rest-frame near-infrared (near-IR), which is less affected by dust attenuation and can thus provide a better description of the intrinsic properties of galaxies. AGN diagnostics in this regime have not been fully exploited so far, due to the scarcity of near-IR observations of both AGNs and star-forming galaxies, especially at redshifts higher than 0.5. Using Cloudy photoionization models, we identify new AGN - star formation diagnostics based on the ratio of bright near-infrared emission lines, namely [SIII] 9530 Angstrom, [CI] 9850 Angstrom, [PII] 1.188 $μm$, [FeII] $1.257 μm$, and [FeII] $1.64 μm$ to Paschen lines (either Pa$γ$ or Pa$β$), providing simple, analytical classification criteria. We apply these diagnostics to a sample of 64 star-forming galaxies and AGNs at 0 < z < 1, and 65 sources at 1 < z < 3 recently observed with JWST-NIRSpec in CEERS. We find that the classification inferred from the near-infrared is broadly consistent with the optical one based on the BPT and the [SII]/H$α$ ratio. However, in the near-infrared, we find $\sim 60 \%$ more AGNs than in the optical (13 instead of 8), with 5 sources classified as 'hidden' AGNs, showing a larger AGN contribution at longer wavelengths, possibly due to the presence of optically thick dust. The diagnostics we present provide a promising tool to find and characterize AGNs from z=0 to z=3 with low and medium-resolution near-IR spectrographs in future surveys. |
| title | Near-infrared emission line diagnostics for AGN from the local Universe to redshift 3 |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2306.08605 |