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Title: Giant Ly α Nebulae in the Illustris Simulation

Abstract

Several “giant” Ly α nebulae with an extent ≳300 kpc and observed Ly α luminosity of ≳10{sup 44} erg s{sup −1} cm{sup −2} arcsec{sup −2} have recently been detected, and it has been speculated that their presence hints at a substantial cold gas reservoir in small cool clumps not resolved in modern hydrodynamical simulations. We use the Illustris simulation to predict the Ly α emission emerging from large halos ( M > 10{sup 11.5} M {sub ⊙}) at z ∼ 2 and thus test this model. We consider both active galactic nucleus (AGN) and star driven ionization, and compare the simulated surface brightness maps, profiles, and Ly α spectra to a model where most gas is clumped below the simulation resolution scale. We find that with Illustris, no additional clumping is necessary to explain the extents, luminosities, and surface brightness profiles of the “giant Ly α nebulae” observed. Furthermore, the maximal extents of the objects show a wide spread for a given luminosity and do not correlate significantly with any halo properties. We also show how the detected size depends strongly on the employed surface brightness cutoff, and predict that further examples of such objects will be found in themore » near future.« less

Authors:
 [1];  [2]
  1. Institute of Theoretical Astrophysics, University of Oslo, Postboks 1029 Blindern, NO-0315 Oslo (Norway)
  2. Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218 (United States)
Publication Date:
OSTI Identifier:
22663887
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 835; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ALPHA SPECTRA; BRIGHTNESS; COMPARATIVE EVALUATIONS; EMISSION; GALAXIES; IONIZATION; LUMINOSITY; LYMAN LINES; NEBULAE; QUASARS; RADIANT HEAT TRANSFER; RED SHIFT; RESOLUTION; SCATTERING; SIMULATION; STARS; SURFACES

Citation Formats

Gronke, Max, and Bird, Simeon, E-mail: maxbg@astro.uio.no. Giant Ly α Nebulae in the Illustris Simulation. United States: N. p., 2017. Web. doi:10.3847/1538-4357/835/2/207.
Gronke, Max, & Bird, Simeon, E-mail: maxbg@astro.uio.no. Giant Ly α Nebulae in the Illustris Simulation. United States. doi:10.3847/1538-4357/835/2/207.
Gronke, Max, and Bird, Simeon, E-mail: maxbg@astro.uio.no. Wed . "Giant Ly α Nebulae in the Illustris Simulation". United States. doi:10.3847/1538-4357/835/2/207.
@article{osti_22663887,
title = {Giant Ly α Nebulae in the Illustris Simulation},
author = {Gronke, Max and Bird, Simeon, E-mail: maxbg@astro.uio.no},
abstractNote = {Several “giant” Ly α nebulae with an extent ≳300 kpc and observed Ly α luminosity of ≳10{sup 44} erg s{sup −1} cm{sup −2} arcsec{sup −2} have recently been detected, and it has been speculated that their presence hints at a substantial cold gas reservoir in small cool clumps not resolved in modern hydrodynamical simulations. We use the Illustris simulation to predict the Ly α emission emerging from large halos ( M > 10{sup 11.5} M {sub ⊙}) at z ∼ 2 and thus test this model. We consider both active galactic nucleus (AGN) and star driven ionization, and compare the simulated surface brightness maps, profiles, and Ly α spectra to a model where most gas is clumped below the simulation resolution scale. We find that with Illustris, no additional clumping is necessary to explain the extents, luminosities, and surface brightness profiles of the “giant Ly α nebulae” observed. Furthermore, the maximal extents of the objects show a wide spread for a given luminosity and do not correlate significantly with any halo properties. We also show how the detected size depends strongly on the employed surface brightness cutoff, and predict that further examples of such objects will be found in the near future.},
doi = {10.3847/1538-4357/835/2/207},
journal = {Astrophysical Journal},
number = 2,
volume = 835,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}