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

Dutta, Jayanta (2015) DOES THE CHEMOTHERMAL INSTABILITY HAVE ANY ROLE IN THE FRAGMENTATION OF PRIMORDIAL GAS. In: ASTROPHYSICAL JOURNAL, 811 (2).

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Abstract

The collapse of the primordial gas in the density regime similar to 10(8)-10(10) cm(-3) is controlled by the three-body H-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-2 cooling, the heating due to H-2 formation and compressional heating together set a density and temperature structure in the disk that favors fragmentation, not the chemothermal instability.

Item Type:	Journal Article
Publication:	ASTROPHYSICAL JOURNAL
Publisher:	IOP PUBLISHING LTD
Additional Information:	Copy right for this article belongs to the IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND
Keywords:	hydrodynamics; instabilities; stars: early-type; stars: formation; stars: Population III
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	24 Nov 2015 06:02
Last Modified:	24 Nov 2015 06:02
URI:	http://eprints.iisc.ac.in/id/eprint/52820

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