Turbulent Gas in Lensed Planck-selected Starbursts at z ∼ 1-3.5
Abstract
Dusty star-forming galaxies at high redshift (1 < z < 3) represent the most intense star-forming regions in the universe. Key aspects to these processes are the gas heating and cooling mechanisms, and although it is well known that these galaxies are gas-rich, little is known about the gas excitation conditions. Only a few detailed radiative transfer studies have been carried out owing to a lack of multiple line detections per galaxy. Here we examine these processes in a sample of 24 strongly lensed star-forming galaxies identified by the Planck satellite (LPs) at z ∼ 1.1-3.5. We analyze 162 CO rotational transitions (ranging from Jup = 1 to 12) and 37 atomic carbon fine-structure lines ([C I]) in order to characterize the physical conditions of the gas in the sample of LPs. We simultaneously fit the CO and [C I] lines and the dust continuum emission, using two different non-LTE, radiative transfer models. The first model represents a two-component gas density, while the second assumes a turbulence-driven lognormal gas density distribution. These LPs are among the most gas-rich, IR-luminous galaxies ever observed (μL ${L}_{\mathrm{IR}(8-1000\mu {\rm{m}})}\sim {10}^{13-14.6}$ L⊙; $\langle $ μLMISM $\rangle $ = (2.7 ± 1.2) × 1012 M⊙, with μL ∼ 10-30 the average lens magnification factor). Our results suggest that the turbulent interstellar medium present in the LPs can be well characterized by a high turbulent velocity dispersion ( $\langle $ ΔVturb $\rangle $ ∼ 100 km s-1) and ratios of gas kinetic temperature to dust temperature $\langle $ Tkin/Td $\rangle $ ∼ 2.5, sustained on scales larger than a few kiloparsecs. We speculate that the average surface density of the molecular gas mass and IR luminosity, ${{\rm{\Sigma }}}_{{M}_{\mathrm{ISM}}}$ ∼ 103-4 M⊙ pc-2 and ${{\rm{\Sigma }}}_{{L}_{\mathrm{IR}}}$ ∼ 1011-12 L⊙ kpc-2, arise from both stellar mechanical feedback and a steady momentum injection from the accretion of intergalactic gas.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2021
- DOI:
- 10.3847/1538-4357/abcc01
- arXiv:
- arXiv:2010.16231
- Bibcode:
- 2021ApJ...908...95H
- Keywords:
-
- Starburst galaxies;
- Strong gravitational lensing;
- High-redshift galaxies;
- Interstellar medium;
- 1570;
- 1643;
- 734;
- 847;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 54 pages, 18 figures. Accepted for publication in The Astrophysical Journal (as of Oct. 30, 2020). Please feel free to view the supplementary figures here (which can later be found online in the ApJ after the full publication procedure): https://drive.google.com/drive/folders/1CN3rqlUDcNi5JSDH2GhFk_SLSlo10han?usp=sharing