Local photoionization feedback effects on galaxies

Obreja, Aura; Macciò, Andrea V.; Moster, Benjamin P.; Udrescu, Silviu M.; Buck, Tobias; Kannan, Rahul; Dutton, Aaron A.; Blank, Marvin

doi:10.1093/mnras/stz2639

Cited by 17 publications

(8 citation statements)

References 119 publications

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“…The deviations of H 2 abundances from equilibrium in cosmic environments highlight the need to follow a time-dependent non-equilibrium approach to obtain reliable molecular fractions (as stressed lately by Hu et al 2017Hu et al , 2021, and as done throughout work). Other popular hydrodynamic simulations (such as Owls or Eagle; Schaye et al 2015, and references therein) adopt UV rates similar to the ones used here (HM), but employ low-density thresholds for star formation and do not partition hydrogen into its ionised, neutral, and molecular components (as also done in the NIHAO project; Obreja et al 2019). Post-processing assumptions on how to distribute these species are therefore needed (Blitz & Rosolowsky 2006or Gnedin & Kravtsov 2011.…”

Section: Discussionmentioning

confidence: 99%

Atomic and molecular gas from the epoch of reionisation down to redshift 2

Maio

Péroux

Ciardi

2022

A&A

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Context. Cosmic gas makes up about 90% of the baryonic matter in the Universe and H2 molecule is the most tightly linked to star formation. Aims. In this work we study cold neutral gas, its H2 component at different epochs, and corresponding depletion times. Methods. We perform state-of-the-art hydrodynamic simulations that include time-dependent atomic and molecular non-equilibrium chemistry coupled to star formation, feedback effects, different UV backgrounds presented in the recent literature and a number of additional processes occurring during structure formation (COLDSIM). We predict gas evolution and contrast the mass density parameters and gas depletion timescales. We also investigate their relation to cosmic expansion in light of the latest infrared and (sub)millimetre observations in the redshift range 2 ≲ z ≲ 7. Results. By performing updated non-equilibrium chemistry calculations we are able to broadly reproduce the latest HI and H2 observations. We find neutral-gas mass density parameters Ωneutral ≃ 10−3 and increasing from lower to higher redshift, in agreement with available HI data. Because of the typically low metallicities during the epoch of reionisation, time-dependent H2 formation is mainly led by the H− channel in self-shielded gas, while H2 grain catalysis becomes important in locally enriched sites at any redshift. Ultraviolet (UV) radiation provides free electrons and facilitates H2 build-up while heating cold metal-poor environments. Resulting H2 fractions can be as high as ∼50% of the cold gas mass at z ∼ 4–8, in line with the latest measurements from high-redshift galaxies. The H2 mass density parameter increases with time until a plateau of ΩH2 ≃ 10−4 is reached. Quantitatively, we find agreement between the derived ΩH2 values and the observations up to z ∼ 7 and both HI and H2 trends are better reproduced by our non-equilibrium H2-based star formation modelling. The predicted gas depletion timescales decrease at lower z in the whole time interval considered, with H2 depletion times remaining below the Hubble time and comparable to the dynamical time at all z. This implies that non-equilibrium molecular cooling is efficient at driving cold-gas collapse in a broad variety of environments and has done so since very early cosmic epochs. While the evolution of chemical species is clearly affected by the details of the UV background and gas self shielding, the assumptions on the adopted initial mass function, different parameterizations of H2 dust grain catalysis, photoelectric heating, and cosmic-ray heating can affect the results in a non-trivial way. In the Appendix, we show detailed analyses of individual processes, as well as simple numerical parameterizations and fits to account for them. Conclusions. Our findings suggest that, in addition to HI, non-equilibrium H2 observations are pivotal probes for assessing cold-gas cosmic abundances and the role of UV background radiation at different epochs.

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Section: Discussionmentioning

confidence: 99%

Atomic and molecular gas from the epoch of reionisation down to redshift 2

Maio

Péroux

Ciardi

2022

A&A

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“…The deviations of H 2 abundances from equilibrium in cosmic environments highlight the need to follow a time-dependent non-equilibrium approach to obtain reliable molecular fractions (as stressed lately by Hu et al 2017Hu et al , 2021, and as done throughout this work). Other popular hydrodynamic simulations (such as Owls or Eagle; Schaye et al 2015, and references therein) adopt UV rates similar to the ones used here (HM), but employ low-density thresholds for star formation and do not partition hydrogen into its ionised, neutral and molecular components (as also done in the NIHAO project; Obreja et al 2019). So, post-processing assumptions on how to distribute these species are needed (Blitz & Rosolowsky 2006or Gnedin & Kravtsov 2011.…”

Section: Discussionmentioning

confidence: 99%

Atomic and molecular gas from the epoch of reionization down to redshift 2

Maio,

Péroux,

Ciardi

2021

Preprint

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Cosmic gas makes up about 90% of baryonic matter in the Universe and H 2 is the closest molecule to star formation. In this work we study cold neutral gas and its H 2 component at different epochs, exploiting state-of-the-art hydrodynamic simulations that include time-dependent atomic and molecular non-equilibrium chemistry coupled to star formation, feedback effects, different UV backgrounds presented in the recent literature and a number of additional processes occurring during structure formation (ColdSIM). We predict gas evolution and contrast the mass density parameters and gas depletion timescales, as well as their relation to cosmic expansion, in light of the latest IR and (sub-)mm observations in the redshift range 2 z 7. By performing updated non-equilibrium chemistry calculations we are able to broadly reproduce the latest HI and H 2 observations. We find neutral-gas mass density parameters Ω neutral ≃ 10 −3 and increasing from lower to higher redshift, in agreement with available HI data. Because of the typically low metallicities during the epoch of reionization, time-dependent H 2 formation is mainly led by the H − channel in self-shielded gas, while H 2 grain catalysis becomes important in locally enriched sites at any redshift. UV radiation provides free electrons and facilitates H 2 build-up while heating cold metal-poor environments. Resulting H 2 fractions can be as high as ∼ 50% of the cold gas mass at z ∼ 4-8, in line with the latest measurements from high-redshift galaxies. The H 2 mass density parameter increases with time until a plateau of Ω H 2 ≃ 10 −4 is reached. Quantitatively, we find an agreement between the derived Ω H 2 values and the observations up to z ∼ 7 and both HI and H 2 trends are better reproduced by our non-equilibrium H 2based star formation modelling. The predicted gas depletion timescales decrease at lower z in the whole time interval considered, with H 2 depletion times remaining below the Hubble time and comparable to the dynamical time at all z. This implies that nonequilibrium molecular cooling is efficient at driving cold-gas collapse in a broad variety of environments and since the very early cosmic epochs. While the evolution of chemical species is clearly affected by the details of the UV background and gas self-shielding, the assumptions on the adopted initial mass function, different parameterizations of H 2 dust grain catalysis, photoelectric heating and cosmic-ray heating can affect the results in a non-trivial way. In appendix, we show detailed analyses of individual processes, as well as simple numerical parameterizations and fits to account for them. Our findings suggest that, in addition to HI, non-equilibrium H 2 observations are pivotal probes for assessing cold-gas cosmic abundances and the role of UV background radiation at different epochs.

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“…Wiersma et al 2009;Gnedin & Hollon 2012;Sarkar et al 2021;Robinson et al 2021), and therefore on its thermal energy balance as well as on the the equilibrium between the ionized, atomic, and molecular phases (e.g. Obreja et al 2019). This, in turn, has profound implications on all the processes that take place within the galaxy, including star formation and feedback, or the growth and destruction of dust grains.…”

Section: Introductionmentioning

confidence: 99%

“…Millán-Irigoyen et al 2020) and numerical hydrodynamical simulations (e.g. Gnedin & Abel 2001;Petkova & Springel 2009;Wise & Abel 2011;Rosdahl et al 2013;Obreja et al 2019;Kannan et al 2019;Grond et al 2019;Wünsch et al 2021) use different approximations in an attempt to track the number of photons that can ionize (or dissociate) the atomic (molecular) gas, but solving the full radiative transfer problem, coupled with chemical evolution and hydrodynamics in a cosmological context, is still beyond current technical capabilities.…”

Section: Introductionmentioning

confidence: 99%

Predicting interstellar radiation fields from chemical evolution models

Romero¹,

Corcho-Caballero²,

Millán-Irigoyen³

et al. 2022

Preprint

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We present a new method to obtain the interstellar radiation field (ISRF) of regions that contain stars, dust and gas. Starting from stellar spectra, we first run the radiative transfer code Skirt to compute the mean intensity field due to the stellar component alone. Then, we import that result to the photoionisation code Cloudy to compute the emissivity and opacity of the given mixture of gas and dust as a function of wavelength. Finally, we ask Skirt again to compute the mean intensity field, adding the total contribution of stars, gas and dust. This process is repeated iteratively, calling both codes sequentially in order to obtain increasingly accurate estimates. We have designed a first test, reminiscent of an Hii region, that consists of a B star, approximated as a black-body, surrounded by a spherical shell of gas and dust with uniform density. We find that the results of our three-dimensional radiative transfer method are in excellent agreement with a spherically symmetric Cloudy simulation. As a realistic scientific application, we calculate the interstellar radiation field of a Milky Way-like galaxy based on two different chemical evolution models. Both of them give results broadly consistent with previous ones reported in the literature for the interstellar radiation field of our Galaxy, albeit they systematically underestimate the mid-infrared emission, with significant differences in this range, as well as in the ultraviolet, stemming from the input stellar and ISM properties. These results show the feasibility of our method to incorporate radiative transfer to chemical evolution models, increasing their predictive power and using this interstellar radiation field to further constrain their parameters. Python source code to implement our method is publicly available at https://github.com/MarioRomeroC/Mixclask.

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Local photoionization feedback effects on galaxies

Cited by 17 publications

References 119 publications

Atomic and molecular gas from the epoch of reionisation down to redshift 2

Atomic and molecular gas from the epoch of reionisation down to redshift 2

Atomic and molecular gas from the epoch of reionization down to redshift 2

Predicting interstellar radiation fields from chemical evolution models

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