Baryon-Dark matter interaction in presence of magnetic fields in light of EDGES signal

Abstract

Abstract We have shown that in presence of a cosmic magnetic field the bounds on baryon dark matter cross-section ($${\hat{\sigma }}$$ σ^ ), dark-matter mass ($$m_d$$ md ) and values of the magnetic field ($$B_0$$ B0 ) can strongly influence each other. This requires to rework the bounds on $${\hat{\sigma }}\,$$ σ^ , $$m_d$$ md and $$B_0$$ B0 which can explain the observed absorption signal by EDGES collaboration. The upper limit on the magnetic field strength can modify in presence of baryon-dark matter interaction cross-section. In the presence of a strong magnetic field, a large baryon-dark matter interaction cross-section is required to balance magnetic heating of gas to explain the EDGES signal as compared to a weak magnetic field. Subsequently, the strong magnetic-fields can even erase the 21 cm signal–this gives an upper bound on the strength of magnetic-fields, dark-matter mass and baryon-dark matter cross-section. In the special case when $${\hat{\sigma }}$$ σ^ = 0, one can recover the bound on magnetic field strength calculated in [1]. In this work we find that the allowed range of the primordial magnetic field can increase by three orders of magnitude in comparison with [1]. We get upper bound on the magnetic field strength: $$3.48\times 10^{-6}$$ 3.48×10-6 G for the dark matter mass $$\lesssim 10^{-2}$$ ≲10-2 GeV.