Probing galaxy formation with high energy gamma-rays

We discuss how measurements of the absorption of $\gamma$-rays from GeV to TeV energies via pair production on the extragalactic background light (EBL) can probe important issues in galaxy formation. We use semi-analytic models (SAMs) of galaxy formation, set within the hierarchical structure forma...

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Main Authors: Primack, J, Somerville, R, Bullock, J, Devriendt, J
Format: Journal article
Published: AIP Publishing 2001
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author Primack, J
Somerville, R
Bullock, J
Devriendt, J
author_facet Primack, J
Somerville, R
Bullock, J
Devriendt, J
author_sort Primack, J
collection OXFORD
description We discuss how measurements of the absorption of $\gamma$-rays from GeV to TeV energies via pair production on the extragalactic background light (EBL) can probe important issues in galaxy formation. We use semi-analytic models (SAMs) of galaxy formation, set within the hierarchical structure formation scenario, to obtain predictions of the EBL for 0.1-1000$\mu$m. SAMs incorporate simplified physical treatments of the key processes of galaxy formation --- including gravitational collapse and merging of dark matter halos, gas cooling and dissipation, star formation, supernova feedback and metal production --- and have been shown to reproduce key observations at low and high redshift. Here we also introduce improved modelling of the spectral energy distributions in the mid-to-far-IR arising from emission by dust grains. Assuming a flat \lcdm cosmology with $\Omega_m=0.3$ and Hubble parameter $h=0.65$, we investigate the consequences of variations in input assumptions such as the stellar initial mass function (IMF) and the efficiency of converting cold gas into stars. We conclude that observational studies of the absorption of $\gamma$-rays with energies from 10s of Gev to 10s of TeV will help to determine the EBL, and also help to explain its origin by constraining some of the most uncertain features of galaxy formation theory, including the IMF, the history of star formation, and the reprocessing of light by dust.
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spelling oxford-uuid:6b200c4c-bd10-42e6-9ef1-39ab33b3f7892022-03-26T19:01:45ZProbing galaxy formation with high energy gamma-raysJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:6b200c4c-bd10-42e6-9ef1-39ab33b3f789Symplectic Elements at OxfordAIP Publishing2001Primack, JSomerville, RBullock, JDevriendt, J We discuss how measurements of the absorption of $\gamma$-rays from GeV to TeV energies via pair production on the extragalactic background light (EBL) can probe important issues in galaxy formation. We use semi-analytic models (SAMs) of galaxy formation, set within the hierarchical structure formation scenario, to obtain predictions of the EBL for 0.1-1000$\mu$m. SAMs incorporate simplified physical treatments of the key processes of galaxy formation --- including gravitational collapse and merging of dark matter halos, gas cooling and dissipation, star formation, supernova feedback and metal production --- and have been shown to reproduce key observations at low and high redshift. Here we also introduce improved modelling of the spectral energy distributions in the mid-to-far-IR arising from emission by dust grains. Assuming a flat \lcdm cosmology with $\Omega_m=0.3$ and Hubble parameter $h=0.65$, we investigate the consequences of variations in input assumptions such as the stellar initial mass function (IMF) and the efficiency of converting cold gas into stars. We conclude that observational studies of the absorption of $\gamma$-rays with energies from 10s of Gev to 10s of TeV will help to determine the EBL, and also help to explain its origin by constraining some of the most uncertain features of galaxy formation theory, including the IMF, the history of star formation, and the reprocessing of light by dust.
spellingShingle Primack, J
Somerville, R
Bullock, J
Devriendt, J
Probing galaxy formation with high energy gamma-rays
title Probing galaxy formation with high energy gamma-rays
title_full Probing galaxy formation with high energy gamma-rays
title_fullStr Probing galaxy formation with high energy gamma-rays
title_full_unstemmed Probing galaxy formation with high energy gamma-rays
title_short Probing galaxy formation with high energy gamma-rays
title_sort probing galaxy formation with high energy gamma rays
work_keys_str_mv AT primackj probinggalaxyformationwithhighenergygammarays
AT somerviller probinggalaxyformationwithhighenergygammarays
AT bullockj probinggalaxyformationwithhighenergygammarays
AT devriendtj probinggalaxyformationwithhighenergygammarays