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Title: DOES THE CHEMOTHERMAL INSTABILITY HAVE ANY ROLE IN THE FRAGMENTATION OF PRIMORDIAL GAS

Abstract

The collapse of the primordial gas in the density regime ∼10{sup 8}−10{sup 10} cm{sup −3} is controlled by the three-body H{sub 2} formation process, in which the gas can cool faster than free-fall time—a condition proposed as the chemothermal instability. We investigate how the heating and cooling rates are affected during the rapid transformation of atomic to molecular hydrogen. With a detailed study of the heating and cooling balance in a 3D simulation of Pop III collapse, we follow the chemical and thermal evolution of the primordial gas in two dark matter minihalos. The inclusion of sink particles in modified Gadget-2 smoothed particle hydrodynamics code allows us to investigate the long-term evolution of the disk that fragments into several clumps. We find that the sum of all the cooling rates is less than the total heating rate after including the contribution from the compressional heating (pdV). The increasing cooling rate during the rapid increase of the molecular fraction is offset by the unavoidable heating due to gas contraction. We conclude that fragmentation occurs because H{sub 2} cooling, the heating due to H{sub 2} formation and compressional heating together set a density and temperature structure in the disk that favors fragmentation,more » not the chemothermal instability.« less

Authors:
 [1]
  1. Department of Physics, Indian Institute of Science, Bangalore-560012 (India)
Publication Date:
OSTI Identifier:
22525347
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 811; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPUTERIZED SIMULATION; COOLING; DENSITY; HEATING RATE; HYDRODYNAMICS; HYDROGEN; INSTABILITY; NONLUMINOUS MATTER; STARS

Citation Formats

Dutta, Jayanta, E-mail: jd.astrop@gmail.com. DOES THE CHEMOTHERMAL INSTABILITY HAVE ANY ROLE IN THE FRAGMENTATION OF PRIMORDIAL GAS. United States: N. p., 2015. Web. doi:10.1088/0004-637X/811/2/98.
Dutta, Jayanta, E-mail: jd.astrop@gmail.com. DOES THE CHEMOTHERMAL INSTABILITY HAVE ANY ROLE IN THE FRAGMENTATION OF PRIMORDIAL GAS. United States. doi:10.1088/0004-637X/811/2/98.
Dutta, Jayanta, E-mail: jd.astrop@gmail.com. Thu . "DOES THE CHEMOTHERMAL INSTABILITY HAVE ANY ROLE IN THE FRAGMENTATION OF PRIMORDIAL GAS". United States. doi:10.1088/0004-637X/811/2/98.
@article{osti_22525347,
title = {DOES THE CHEMOTHERMAL INSTABILITY HAVE ANY ROLE IN THE FRAGMENTATION OF PRIMORDIAL GAS},
author = {Dutta, Jayanta, E-mail: jd.astrop@gmail.com},
abstractNote = {The collapse of the primordial gas in the density regime ∼10{sup 8}−10{sup 10} cm{sup −3} is controlled by the three-body H{sub 2} formation process, in which the gas can cool faster than free-fall time—a condition proposed as the chemothermal instability. We investigate how the heating and cooling rates are affected during the rapid transformation of atomic to molecular hydrogen. With a detailed study of the heating and cooling balance in a 3D simulation of Pop III collapse, we follow the chemical and thermal evolution of the primordial gas in two dark matter minihalos. The inclusion of sink particles in modified Gadget-2 smoothed particle hydrodynamics code allows us to investigate the long-term evolution of the disk that fragments into several clumps. We find that the sum of all the cooling rates is less than the total heating rate after including the contribution from the compressional heating (pdV). The increasing cooling rate during the rapid increase of the molecular fraction is offset by the unavoidable heating due to gas contraction. We conclude that fragmentation occurs because H{sub 2} cooling, the heating due to H{sub 2} formation and compressional heating together set a density and temperature structure in the disk that favors fragmentation, not the chemothermal instability.},
doi = {10.1088/0004-637X/811/2/98},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 811,
place = {United States},
year = {2015},
month = {10}
}