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Astron. Astrophys. 354, 1123-1126 (2000)

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Neutrino decay and the thermochemical equilibrium of the interstellar medium

N.M. Sánchez 1,2 and N.Y. Añez 1

1 Departamento de Física, Facultad Experimental de Ciencias, Universidad del Zulia, Maracaibo, Venezuela
2 Centro de Astrofísica Teórica, Facultad de Ciencias, Universidad de los Andes, Mérida, Venezuela

Received 23 September 1999 / Accepted 22 December 1999


We calculate the thermochemical equilibrium of the diffuse interstellar medium, including ionization by a photon flux [FORMULA] from neutrino decay. The main heating mechanism considered is photoelectrons from grains and PAHs. For the studied range of [FORMULA] values, there always exists two regions of stability (a warm and a cold phase) that can coexist in equilibrium if the thermal interstellar pressure is between a maximum value ([FORMULA]) and a minimum value ([FORMULA]). High [FORMULA] values ([FORMULA] cm-2 s-1) can be consistent with observed interstellar pressures only if more efficient sources are heating the gas. It is shown that a neutrino flux increase (due, for example, to an increase in the supernova explosion rate) may stimulate the condensation of cold gas by decreasing [FORMULA] below the interstellar pressure value.

Key words: ISM: general – ISM: clouds – stars: formation – elementary particles

Send offprint requests to: N. Sánchez

Correspondence to: nestor@orion.ciens.luz.ve

© European Southern Observatory (ESO) 2000

Online publication: February 25, 2000