Open AccessIntergalactic medium heating by dark matter
Author(s) -
Ripamonti E.,
Mapelli M.,
Ferrara A.
Publication year - 2007
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.11222.x
Subject(s) - physics , dark matter , neutrino , redshift , astrophysics , sterile neutrino , warm dark matter , reionization , hot dark matter , particle physics , mass fraction , galaxy , dark energy , cosmology , neutrino oscillation , thermodynamics
We derive the evolution of the energy deposition in the intergalactic medium (IGM) by dark matter (DM) decays/annihilations for both sterile neutrinos and light dark matter (LDM) particles. At z > 200 sterile neutrinos transfer a fraction f abs ∼ 0.5 of their rest mass energy into the IGM; at lower redshifts this fraction becomes ≲0.3 depending on the particle mass. The LDM particles can decay or annihilate. In both the cases f abs ∼ 0.4–0.9 at high (>300) redshift, dropping to ≈0.1 below z = 100 . These results indicate that the impact of DM decays/annihilations on the IGM thermal and ionization history is less important than previously thought. We find that sterile neutrinos (LDM) decays are able to increase the IGM temperature by z = 5 at most up to 4 K (100 K), about 50–200 times less than predicted by estimates based on the assumption of complete energy transfer to the gas.