Characterizing the physical conditions (density, temperature, ionization state, metallicity, etc) of the interstellar medium is critical to improving our understanding of the formation and evolution of galaxies. In this work, we present a multi-line study of the interstellar medium in the host galaxy of a quasar at z≈ 6.4, that is, when the universe was 840 Myr old. This galaxy is one of the most active and massive objects emerging from the dark ages and therefore represents a benchmark for models of the early formation of massive galaxies. We used the Atacama Large Millimeter Array to target an ensemble of tracers of ionized, neutral, and molecular gas, namely the following fine-structure lines: [O III] 88 μm, [N II] 122 μm, [C II] 158 μm, and [C I] 370 μm-as well as the rotational transitions of CO(7-6), CO(15-14), CO(16-15), and CO(19-18); OH 163.1 μm and 163.4 μm; along with H2O 3(0,3)-2(1,2), 3(3,1)-4(0,4), 3(3,1)-3(2,2), 4(0,4)-3(1,3), and 4(3,2)-4(2,3). All the targeted fine-structure lines were detected, along with half of the targeted molecular transitions. By combining the associated line luminosities with the constraints on the dust temperature from the underlying continuum emission and predictions from photoionization models of the interstellar medium, we find that the ionized phase accounts for about one-third of the total gaseous mass budget and is responsible for half of the total [C II] emission. This phase is characterized by a high density (n∼180 cm-3) that typical of HII regions. The spectral energy distribution of the photoionizing radiation is comparable to that emitted by B-type stars. Star formation also appears to be driving the excitation of the molecular medium. We find marginal evidence for outflow-related shocks in the dense molecular phase, but not in other gas phases. This study showcases the power of multi-line investigations in unveiling the properties of the star-forming medium in galaxies at cosmic dawn.

Decarli, R., Pensabene, A., Diaz-Santos, T., Ferkinhoff, C., Strauss, M., Venemans, B., et al. (2023). A comprehensive view of the interstellar medium in a quasar host galaxy at z ≈ 6.4. ASTRONOMY & ASTROPHYSICS, 673(May 2023), 1-16 [10.1051/0004-6361/202245674].

A comprehensive view of the interstellar medium in a quasar host galaxy at z ≈ 6.4

Pensabene, A;
2023

Abstract

Characterizing the physical conditions (density, temperature, ionization state, metallicity, etc) of the interstellar medium is critical to improving our understanding of the formation and evolution of galaxies. In this work, we present a multi-line study of the interstellar medium in the host galaxy of a quasar at z≈ 6.4, that is, when the universe was 840 Myr old. This galaxy is one of the most active and massive objects emerging from the dark ages and therefore represents a benchmark for models of the early formation of massive galaxies. We used the Atacama Large Millimeter Array to target an ensemble of tracers of ionized, neutral, and molecular gas, namely the following fine-structure lines: [O III] 88 μm, [N II] 122 μm, [C II] 158 μm, and [C I] 370 μm-as well as the rotational transitions of CO(7-6), CO(15-14), CO(16-15), and CO(19-18); OH 163.1 μm and 163.4 μm; along with H2O 3(0,3)-2(1,2), 3(3,1)-4(0,4), 3(3,1)-3(2,2), 4(0,4)-3(1,3), and 4(3,2)-4(2,3). All the targeted fine-structure lines were detected, along with half of the targeted molecular transitions. By combining the associated line luminosities with the constraints on the dust temperature from the underlying continuum emission and predictions from photoionization models of the interstellar medium, we find that the ionized phase accounts for about one-third of the total gaseous mass budget and is responsible for half of the total [C II] emission. This phase is characterized by a high density (n∼180 cm-3) that typical of HII regions. The spectral energy distribution of the photoionizing radiation is comparable to that emitted by B-type stars. Star formation also appears to be driving the excitation of the molecular medium. We find marginal evidence for outflow-related shocks in the dense molecular phase, but not in other gas phases. This study showcases the power of multi-line investigations in unveiling the properties of the star-forming medium in galaxies at cosmic dawn.
Articolo in rivista - Articolo scientifico
galaxies: ISM; galaxies: high-redshift; quasars: individual: PJ183+05; galaxies: star formation;
English
24-mag-2023
2023
673
May 2023
1
16
A157
open
Decarli, R., Pensabene, A., Diaz-Santos, T., Ferkinhoff, C., Strauss, M., Venemans, B., et al. (2023). A comprehensive view of the interstellar medium in a quasar host galaxy at z ≈ 6.4. ASTRONOMY & ASTROPHYSICS, 673(May 2023), 1-16 [10.1051/0004-6361/202245674].
File in questo prodotto:
File Dimensione Formato  
Decarli-2023-A&A-VoR.pdf

accesso aperto

Tipologia di allegato: Publisher’s Version (Version of Record, VoR)
Licenza: Creative Commons
Dimensione 1.12 MB
Formato Adobe PDF
1.12 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/464380
Citazioni
  • Scopus 7
  • ???jsp.display-item.citation.isi??? 6
Social impact