skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Suppression of H2-cooling in protogalaxies aided by trapped Lyα cooling radiation
ABSTRACT We study the thermal evolution of UV-irradiated atomic cooling haloes using high-resolution three-dimensional hydrodynamic simulations. We consider the effect of H− photodetachment by Lyα cooling radiation trapped in the optically-thick cores of three such haloes, a process that has not been included in previous simulations. Because H− is a precursor of molecular hydrogen, its destruction can diminish the H2 abundance and cooling. We find that the critical UV flux for suppressing H2-cooling is decreased by ∼15–50 per cent in our fiducial models. Previous one-zone modelling found a larger effect, with Jcrit reduced by a factor of a few; we show that adopting a constant halo mass to determine the trapped Lyα energy density, as is done in the one-zone models, yields a larger reduction in Jcrit, consistent with their findings. Our results nevertheless suggest that Lyα radiation may have an important effect on the thermal evolution of UV-irradiated haloes, and therefore on the potential for massive black hole formation.  more » « less
Award ID(s):
2006176
PAR ID:
10269137
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Monthly Notices of the Royal Astronomical Society
Volume:
500
Issue:
1
ISSN:
0035-8711
Page Range / eLocation ID:
138 to 144
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; (, ArXivorg)
    We study the thermal evolution of UV-irradiated atomic cooling haloes using high-resolution three-dimensional hydrodynamic simulations. We consider the effect of H^- photodetachment by Ly{\alpha} cooling radiation trapped in the optically-thick cores of three such haloes, a process which has not been included in previous simulations. H^- is a precursor of molecular hydrogen, and therefore, its destruction can diminish the H2 abundance and cooling. Using a simple high-end estimate for the trapped Ly{\alpha} energy density, we find that H^- photodetachment by Ly{\alpha} decreases the critical UV flux for suppressing H2-cooling by up to a factor of \approx 5. With a more conservative estimate of the Ly{\alpha} energy density, we find the critical flux is decreased only by ~15-50 percent. Our results suggest that Ly{\alpha} radiation may have an important effect on the thermal evolution of UV-irradiated haloes, and therefore on the potential for massive black hole formation. 
    more » « less
  2. ; ; (, Monthly Notices of the Royal Astronomical Society)
    null (Ed.)
    ABSTRACT Recent three-dimensional cosmological simulations of protogalaxy formation have suggested that supermassive stars (SMSs) can form in gas clouds in which H2 cooling is suppressed by dynamical heating prior to the activation of atomic cooling, but they stopped short of the following growth of a central protostar. Here, we examine whether accretion on the protostellar core in this cloud is sufficiently rapid, in the face of the radiation feedback, to produce an SMS. We perform one-dimensional radiation-hydrodynamical simulations of the hot collapsing cloud with non-equilibrium chemical reactions directly adopting the cloud properties from Wise et al. as an initial condition. We find that the stellar Lyman–Werner (LW) radiation from the SMS dissociates H2 in the inner regions of the gas flow, increasing gas temperature and thermal pressure, and temporarily stopping the accretion. However, this negative feedback ceases when the self-gravity and inward ram pressure force on larger scales push the gas inwards. The central protostar is unable to expand an H ii region due to the high density, and grows to a mass of $${\gtrsim}10^5\, {\rm M}_{\odot }$$. Our results suggests the successful formation of SMSs, and resulting massive ($${\sim}10^5\, {\rm M}_{\odot }$$) remnant black holes in the clouds, but need to be confirmed in two- or three-dimensional simulations. 
    more » « less
  3. ; ; ; ; ; (, Monthly Notices of the Royal Astronomical Society)
    ABSTRACT The circumgalactic medium (CGM) in $$\gtrsim 10^{12}\ \mathrm{M}_{\odot }$$ haloes is dominated by a hot phase ($$T \gtrsim 10^{6}$$ K). While many models exist for the hot gas structure, there is as yet no consensus. We compare cooling flow models, in which the hot CGM flows inwards due to radiative cooling, to the CGM of $$\sim 10^{12}{\,\rm to\,}10^{13}\ \mathrm{M}_{\odot }$$ haloes in galaxy formation simulations from the Feedback in Realistic Environments (FIRE) project at $$z\sim 0$$. The simulations include realistic cosmological evolution and feedback from stars but neglect AGN feedback. At both mass scales, CGM inflows are typically dominated by the hot phase rather than by the ‘precipitation’ of cold gas. Despite being highly idealized, we find that cooling flows describe $$\sim 10^{13}\ \mathrm{M}_{\odot }$$ haloes very well, with median agreement in the density and temperature profiles of $$\sim 20{{\ \rm per\ cent}}$$ and $$\sim 10{{\ \rm per\ cent}}$$, respectively. This indicates that stellar feedback has little impact on CGM scales in those haloes. For $$\sim 10^{12}\ \mathrm{M}_{\odot }$$ haloes, the thermodynamic profiles are also accurately reproduced in the outer CGM. For some of these lower-mass haloes, cooling flows significantly overpredict the hot gas density in the inner CGM. This could be due to multidimensional angular momentum effects not well captured by our one-dimensional cooling flow models and/or to the larger cold gas fractions in these regions. Turbulence, which contributes $$\sim 10{\!-\!}40{{\ \rm per\ cent}}$$ of the total pressure, must be included to accurately reproduce the temperature profiles. Overall, cooling flows predict entropy profiles in better agreement with the FIRE simulations than other idealized models in the literature. 
    more » « less
  4. ; ; ; ; ; ; ; ; (, Monthly Notices of the Royal Astronomical Society)
    ABSTRACT The observability of Lyα emitting galaxies (LAEs) during the Epoch of Reionization can provide a sensitive probe of the evolving neutral hydrogen gas distribution, thus setting valuable constraints to distinguish different reionization models. In this study, we utilize the new thesan suite of large-volume ($$L_\text{box} = 95.5\, \text{cMpc}$$) cosmological radiation-hydrodynamic simulations to directly model the Lyα emission from individual galaxies and the subsequent transmission through the intergalactic medium. thesan combines the arepo-rt radiation-hydrodynamic solver with the IllustrisTNG galaxy formation model and includes high- and medium-resolution simulations designed to investigate the impacts of halo-mass-dependent escape fractions, alternative dark matter models, and numerical convergence. We find important differences in the Lyα transmission based on reionization history, bubble morphology, frequency offset from line centre, and galaxy brightness. For a given global neutral fraction, Lyα transmission reduces when low-mass haloes dominate reionization over high-mass haloes. Furthermore, the variation across sightlines for a single galaxy is greater than the variation across all galaxies. This collectively affects the visibility of LAEs, directly impacting observed Lyα luminosity functions (LFs). We employ Gaussian Process Regression using SWIFTEmulator to rapidly constrain an empirical model for dust escape fractions and emergent spectral-line profiles to match observed LFs. We find that dust strongly impacts the Lyα transmission and covering fractions of MUV ≲ −19 galaxies in $$M_\text{vir} \gtrsim 10^{11}\, \text{M}_{\bigodot }$$ haloes, such that the dominant mode of removing Lyα photons in non-LAEs changes from low-IGM transmission to high dust absorption around z ∼ 7. 
    more » « less
  5. ; ; ; (, Monthly Notices of the Royal Astronomical Society)
    ABSTRACT Gas in the central regions of cool-core clusters and other massive haloes has a short cooling time (≲1 Gyr). Theoretical models predict that this gas is susceptible to multiphase condensation, in which cold gas is expected to condense out of the hot phase if the ratio of the thermal instability growth time-scale (tti) to the free-fall time (tff) is tti/tff ≲ 10. The turbulent mixing time tmix is another important time-scale: if tmix is short enough, the fluctuations are mixed before they can cool. In this study, we perform high-resolution (5122 × 768–10242 × 1536 resolution elements) hydrodynamic simulations of turbulence in a stratified medium, including radiative cooling of the gas. We explore the parameter space of tti/tff and tti/tmix relevant to galaxy and cluster haloes. We also study the effect of the steepness of the entropy profile, the strength of turbulent forcing and the nature of turbulent forcing (natural mixture versus compressive modes) on multiphase gas condensation. We find that larger values of tti/tff or tti/tmix generally imply stability against multiphase gas condensation, whereas larger density fluctuations (e.g. due to compressible turbulence) promote multiphase gas condensation. We propose a new criterion min (tti/min (tmix, tff)) ≲ c2 × exp (c1σs) for when the halo becomes multiphase, where σs denotes the amplitude of logarithmic density fluctuations and c1 ≃ 6, c2 ≃ 1.8 from an empirical fit to our results. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email