TY - JOUR

T1 - Critical assessment of CMB limits on dark matter-baryon scattering

T2 - New treatment of the relative bulk velocity

AU - Boddy, Kimberly K.

AU - Gluscevic, Vera

AU - Poulin, Vivian

AU - Kovetz, Ely D.

AU - Kamionkowski, Marc

AU - Barkana, Rennan

N1 - Publisher Copyright:
© 2018 American Physical Society.

PY - 2018/12/15

Y1 - 2018/12/15

N2 - We perform an improved cosmic microwave background (CMB) analysis to search for dark matter-proton scattering with a momentum-transfer cross section of the form σ0vn for n=-2 and n=-4. In particular, we present a new and robust prescription for incorporating the relative bulk velocity between the dark matter and baryon fluids into the standard linear Boltzmann calculation. Using an iterative procedure, we self-consistently include the effects of the bulk velocities in a cosmology in which dark matter interacts with baryons. With this prescription, we derive CMB bounds on the cross section, excluding σ0>2.3×10-33 cm2 for n=-2 and σ0>1.7×10-41 cm2 for n=-4 at 95% confidence, for dark matter masses below 10 MeV. Furthermore, we investigate how these constraints change when only a subcomponent of dark matter is interacting. We show that Planck limits vanish if 0.4% of dark matter is tightly coupled to baryons. We discuss the implications of our results for present and future cosmological observations.

AB - We perform an improved cosmic microwave background (CMB) analysis to search for dark matter-proton scattering with a momentum-transfer cross section of the form σ0vn for n=-2 and n=-4. In particular, we present a new and robust prescription for incorporating the relative bulk velocity between the dark matter and baryon fluids into the standard linear Boltzmann calculation. Using an iterative procedure, we self-consistently include the effects of the bulk velocities in a cosmology in which dark matter interacts with baryons. With this prescription, we derive CMB bounds on the cross section, excluding σ0>2.3×10-33 cm2 for n=-2 and σ0>1.7×10-41 cm2 for n=-4 at 95% confidence, for dark matter masses below 10 MeV. Furthermore, we investigate how these constraints change when only a subcomponent of dark matter is interacting. We show that Planck limits vanish if 0.4% of dark matter is tightly coupled to baryons. We discuss the implications of our results for present and future cosmological observations.

UR - http://www.scopus.com/inward/record.url?scp=85059369932&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.98.123506

DO - 10.1103/PhysRevD.98.123506

M3 - Article

AN - SCOPUS:85059369932

VL - 98

JO - Physical Review D - Particles, Fields, Gravitation and Cosmology

JF - Physical Review D - Particles, Fields, Gravitation and Cosmology

SN - 1550-7998

IS - 12

M1 - 123506

ER -