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Merger of dark matter axion clumps and resonant photon emission (2020)

Hertzberg, Mark P.; Li, Yao; Schiappacasse, Enrico D. (2020). Merger of dark matter axion clumps and resonant photon emission. Journal of Cosmology and Astroparticle Physics, 2020 (7), 067. DOI: 10.1088/1475-7516/2020/07/067

JYU-tekijät tai -toimittajat

Julkaisun tiedot

Julkaisun kaikki tekijät tai toimittajat: Hertzberg, Mark P.; Li, Yao; Schiappacasse, Enrico D.

Lehti tai sarja: Journal of Cosmology and Astroparticle Physics

eISSN: 1475-7516

Julkaisuvuosi: 2020

Volyymi: 2020

Lehden numero: 7

Artikkelinumero: 067

Kustantaja: Institute of Physics

Julkaisumaa: Britannia

Julkaisun kieli: englanti

DOI: http://doi.org/10.1088/1475-7516/2020/07/067

Avoin saatavuus: Julkaisukanava ei ole avoin

Julkaisu on rinnakkaistallennettu (JYX): https://jyx.jyu.fi/handle/123456789/71776

Julkaisu on rinnakkaistallennettu: https://arxiv.org/abs/2005.02405


A portion of light scalar dark matter, especially axions, may organize into gravitationally bound clumps (stars) and be present in large number in the galaxy today. It is therefore of utmost interest to determine if there are novel observational signatures of this scenario. Work has shown that for moderately large axion-photon couplings, such clumps can undergo parametric resonance into photons, for clumps above a critical mass Mਮc determined precisely by some of us in ref. [1]. In order to obtain a clump above the critical mass in the galaxy today would require mergers. In this work we perform full 3-dimensional simulations of pairs of axion clumps and determine the conditions under which mergers take place through the emission of scalar waves, including analyzing head-on and non-head-on collisions, phase dependence, and relative velocities. Consistent with other work in the literature, we find that the final mass from the merger Mਮfinal≈ 0.7(Mਮ1+Mਮ2) is larger than each of the original clump masses (for Mਮ1∼ Mਮ2). Hence, it is possible for sub-critical mass clumps to merge and become super-critical and therefore undergo parametric resonance into photons. We find that mergers are expected to be kinematically allowed in the galaxy today for high Peccei-Quinn scales, which is strongly suggested by unification ideas, although the collision rate is small. While mergers can happen for axions with lower Peccei-Quinn scales due to statistical fluctuations in relative velocities, as they have a high collision rate. We estimate the collision and merger rates within the Milky Way galaxy today. We find that a merger leads to a flux of energy on earth that can be appreciable and we mention observational search strategies.

YSO-asiasanat: astrofysiikka; kosmologia; pimeä aine; alkeishiukkaset; fotonit

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Viimeisin päivitys 2020-16-09 klo 07:33