Anatomy of a z=6 Lyman-α emitter down to parsec scales: extreme UV slopes, metal-poor regions and possibly leaking star clusters

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Hauptverfasser: Messa, Matteo, Vanzella, E., Loiacono, F., Bergamini, P., Castellano, M., Sun, B., Willott, C., Windhorst, R. A., Yan, H., Angora, G., Rosati, P., Adamo, A., Annibali, F., Bolamperti, A., Bradač, M., Bradley, L. D., Calura, F., Claeyssens, A., Comastri, A., Conselice, C. J., D'Silva, J. C. J., Dickinson, M., Frye, B. L., Grillo, C., Grogin, N. A., Gruppioni, C., Koekemoer, A. M., Meneghetti, M., Meštrić, U., Pascale, R., Ravindranath, S., Ricotti, M., Summers, J., Zanella, A.
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Veröffentlicht: 2024
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author Messa, Matteo
Vanzella, E.
Loiacono, F.
Bergamini, P.
Castellano, M.
Sun, B.
Willott, C.
Windhorst, R. A.
Yan, H.
Angora, G.
Rosati, P.
Adamo, A.
Annibali, F.
Bolamperti, A.
Bradač, M.
Bradley, L. D.
Calura, F.
Claeyssens, A.
Comastri, A.
Conselice, C. J.
D'Silva, J. C. J.
Dickinson, M.
Frye, B. L.
Grillo, C.
Grogin, N. A.
Gruppioni, C.
Koekemoer, A. M.
Meneghetti, M.
Meštrić, U.
Pascale, R.
Ravindranath, S.
Ricotti, M.
Summers, J.
Zanella, A.
author_facet Messa, Matteo
Vanzella, E.
Loiacono, F.
Bergamini, P.
Castellano, M.
Sun, B.
Willott, C.
Windhorst, R. A.
Yan, H.
Angora, G.
Rosati, P.
Adamo, A.
Annibali, F.
Bolamperti, A.
Bradač, M.
Bradley, L. D.
Calura, F.
Claeyssens, A.
Comastri, A.
Conselice, C. J.
D'Silva, J. C. J.
Dickinson, M.
Frye, B. L.
Grillo, C.
Grogin, N. A.
Gruppioni, C.
Koekemoer, A. M.
Meneghetti, M.
Meštrić, U.
Pascale, R.
Ravindranath, S.
Ricotti, M.
Summers, J.
Zanella, A.
contents We present a detailed JWST/NIRSpec and NIRCam analysis of a gravitationally-lensed galaxy ($\rm μ=17-21$) at redshift 6.14 magnified by the Hubble Frontier Field galaxy cluster MACS J0416. The target galaxy is overall a typical compact and UV-faint ($\rm M_{UV}=-17.8$) Lyman-$α$ emitter, yet the large magnification allows the detailed characterization of structures on sub-galactic scales (down to a few parsecs). Prominent optical $\rm Hα$, $\rm Hβ$ and [OIII]$λ\lambda4959,5007$ lines are spatially resolved with the high spectral resolution grating (G395H, R~2700), with large equivalent widths, EW($\rm Hβ$+[OIII])$\gtrsim1000$ Å, and elevated ionising photon production efficiencies $\rm log(ξ_{ion}/erg^{-1}Hz)=25.2-25.7$. NIRCam deep imaging reveals the presence of compact rest-UV bright regions along with individual star clusters of $\rm R_{eff}=3-8~pc$ in size and $\rm M\sim2\cdot10^5-5\cdot10^{6}~M_\odot$ in mass. These clusters are characterised by steep UV slopes, $\rmβ_{UV}\lesssim-2.5$, which in some cases are associated with a dearth of line emission, indicating possible leaking of the ionizing radiation, as also supported by a Lyman-$\rm α$ emission peaking at $\rm \sim100~km~s^{-1}$ from the systemic redshift. While the entire system is characterised by low-metallicity, $\sim0.1~Z_\odot$, the NIRSpec-IFU map also reveals the presence of a low-luminosity, metal-poor region with $\rm Z\lesssim2\%~Z_\odot$, barely detected in NIRCam imaging; this region is displaced by $\rm >200~pc$ from one of the brightest structures of the system in UV, and would have been too faint to detect if not for the large magnification of the system.
format Preprint
id arxiv_https___arxiv_org_abs_2407_20331
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Anatomy of a z=6 Lyman-α emitter down to parsec scales: extreme UV slopes, metal-poor regions and possibly leaking star clusters
Messa, Matteo
Vanzella, E.
Loiacono, F.
Bergamini, P.
Castellano, M.
Sun, B.
Willott, C.
Windhorst, R. A.
Yan, H.
Angora, G.
Rosati, P.
Adamo, A.
Annibali, F.
Bolamperti, A.
Bradač, M.
Bradley, L. D.
Calura, F.
Claeyssens, A.
Comastri, A.
Conselice, C. J.
D'Silva, J. C. J.
Dickinson, M.
Frye, B. L.
Grillo, C.
Grogin, N. A.
Gruppioni, C.
Koekemoer, A. M.
Meneghetti, M.
Meštrić, U.
Pascale, R.
Ravindranath, S.
Ricotti, M.
Summers, J.
Zanella, A.
Astrophysics of Galaxies
We present a detailed JWST/NIRSpec and NIRCam analysis of a gravitationally-lensed galaxy ($\rm μ=17-21$) at redshift 6.14 magnified by the Hubble Frontier Field galaxy cluster MACS J0416. The target galaxy is overall a typical compact and UV-faint ($\rm M_{UV}=-17.8$) Lyman-$α$ emitter, yet the large magnification allows the detailed characterization of structures on sub-galactic scales (down to a few parsecs). Prominent optical $\rm Hα$, $\rm Hβ$ and [OIII]$λ\lambda4959,5007$ lines are spatially resolved with the high spectral resolution grating (G395H, R~2700), with large equivalent widths, EW($\rm Hβ$+[OIII])$\gtrsim1000$ Å, and elevated ionising photon production efficiencies $\rm log(ξ_{ion}/erg^{-1}Hz)=25.2-25.7$. NIRCam deep imaging reveals the presence of compact rest-UV bright regions along with individual star clusters of $\rm R_{eff}=3-8~pc$ in size and $\rm M\sim2\cdot10^5-5\cdot10^{6}~M_\odot$ in mass. These clusters are characterised by steep UV slopes, $\rmβ_{UV}\lesssim-2.5$, which in some cases are associated with a dearth of line emission, indicating possible leaking of the ionizing radiation, as also supported by a Lyman-$\rm α$ emission peaking at $\rm \sim100~km~s^{-1}$ from the systemic redshift. While the entire system is characterised by low-metallicity, $\sim0.1~Z_\odot$, the NIRSpec-IFU map also reveals the presence of a low-luminosity, metal-poor region with $\rm Z\lesssim2\%~Z_\odot$, barely detected in NIRCam imaging; this region is displaced by $\rm >200~pc$ from one of the brightest structures of the system in UV, and would have been too faint to detect if not for the large magnification of the system.
title Anatomy of a z=6 Lyman-α emitter down to parsec scales: extreme UV slopes, metal-poor regions and possibly leaking star clusters
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2407.20331