Heating in Magnetar Crusts from Electron Captures

Autor: J. L. Zdunik, Lami Suleiman, Nicolas Chamel, Anthea Fantina, Pawel Haensel
Přispěvatelé: Université libre de Bruxelles (ULB), Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Copernicus Astronomical Center of the Polish Academy of Sciences (CAMK), Polish Academy of Sciences (PAN), Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), The work of N.C. was funded by Fonds de la Recherche Scientifique-FNRS (Belgium) under Grant Number IISN 4.4502.19., L.S., P.H., and J-L.Z. acknowledge the financial support from the National Science Centre (Poland) Grant Number 2018/29/B/ST9/02013., This work was also partially supported by the European Cooperation in Science and Technology Action CA16214 andthe CNRS International Research Project (IRP) 'Origine des éléments lourds dans l’univers: Astres Compacts et Nucléosynthèse (ACNu)', Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Universe, Vol 7, Iss 193, p 193 (2021)
Universe
Volume 7
Issue 6
Universe, 2021, 7 (6), pp.193. ⟨10.3390/universe7060193⟩
Universe, 7 (6
ISSN: 2218-1997
DOI: 10.3390/universe7060193⟩
Popis: The persistent thermal luminosity of magnetars and their outbursts suggest the existence of some internal heat sources located in their outer crust. The compression of matter accompanying the decay of the magnetic field may trigger exothermic electron captures and, possibly, pycnonuclear fusions of light elements that may have been accreted onto the surface from the fallback of supernova debris, from a disk or from the interstellar medium. This scenario bears some resemblance to deep crustal heating in accreting neutron stars, although the matter composition and the thermodynamic conditions are very different. The maximum possible amount of heat that can be released by each reaction and their locations are determined analytically taking into account the Landau--Rabi quantization of electron motion. Numerical results are also presented using experimental, as well as theoretical nuclear data. Whereas the heat deposited is mainly determined by atomic masses, the locations of the sources are found to be very sensitive to the magnetic field strength, thus providing a new way of probing the internal magnetic field of magnetars. Most sources are found to be concentrated at densities $10^{10}-10^{11}$ g cm$^{-3}$ with heat power $W^\infty\sim 10^{35}-10^{36}$ erg/s, as found empirically by comparing cooling simulations with observed thermal luminosity. The change of magnetic field required to trigger the reactions is shown to be consistent with the age of known magnetars. This suggests that electron captures and pycnonuclear fusion reactions may be a viable heating mechanism in magnetars. The present results provide consistent microscopic inputs for neutron star cooling simulations, based on the same model as that underlying the Brussels-Montreal unified equations of state.
Comment: 24 pages, 4 figures
Databáze: OpenAIRE
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