Isolated sector production from primordial BHs Hannah Tillim Oxford - PowerPoint PPT Presentation

Isolated sector production from primordial BHs Hannah Tillim Oxford University (supervisors J. March-Russell & S. M. West) YTF Durham, December 2018

Dark Matter from Primordial Black Holes O. Lennon, J. March-Russell, R. Petrossian-Byrne, H. Tillim, Black Hole Genesis of Dark Matter , JCAP 1804 (2018), arXiv:1712.07664 Hannah Tillim Isolated sectors from primordial black holes December 19, 2018 1 / 13

Isolated sector DM • The WIMP paradigm - requires couplings “Isolated” Interactions between sectors - much of the parameter space with SM purely now explored gravitational • Important to explore alternatives • Production mechanisms (freeze-out, freeze-in) not applicable to isolated sectors • Coupling to gravity → Hawking radiation Hannah Tillim Isolated sectors from primordial black holes December 19, 2018 2 / 13

Hawking radiation Hawking temperature: M 2 Pl T BH = 8 πM BH Hawking radiation rate: � d N s,i � (2 ℓ + 1) Γ i,s,ℓ,h ( ω ) � d = exp( ω/T ( t )) + ( − 1) (2 s +1) d ω d t 2 π ℓ,h S. Hawking, Commun.Math.Phys. 43 (1975) 199-220 D. Page, Phys. Rev. D13 (1976) 198206 Hannah Tillim Isolated sectors from primordial black holes December 19, 2018 3 / 13

Hawking radiation � M 0 � 2 � → N s,i ≃ f s,i g s,i 1 ( T 0 > m i /d s ) d 2 s T 2 0 /m 2 2 e T M Pl ( T 0 < m i /d s ) i � e T = g i,s e i,s i,s Hannah Tillim Isolated sectors from primordial black holes December 19, 2018 4 / 13

Setup • Model: • Population of micro pBHs with near-uniform initial density n 0 • Any other initial energy density is SM radiation (no DM) • DM is single species, long-lived, sub-Planckian massive particles, spin ≤ 2 • Simplifying assumptions: • All Schwarzschild • All masses = M 0 • T 0 > v W Hannah Tillim Isolated sectors from primordial black holes December 19, 2018 5 / 13

Setup M 4 d ρ BH Pl + 3 Hρ BH = − e T M 2 n d t M 4 d ρ rad Pl + 4 Hρ rad = + e T M 2 n d t H ( t ) 2 = 8 π ( ρ BH + ρ rad ) / 3 M 2 Pl d t = − M 4 M 4 d M Pl � Pl e s,i g s,i ≡ − e T M 2 M 2 s,i • Fast vs. slow evaporation • Light vs. heavy DM • Yield Y i ≡ n i /s tot Hannah Tillim Isolated sectors from primordial black holes December 19, 2018 6 / 13

Light DM results � 1 � M Pl ≃ 1 f s,i g s,i 2 Y slow i 1 1 2 M 0 g ∗ e 4 2 T � n 0 4 � M 0 � 1 � 5 ≃ 1 f s,i g s,i 4 Y fast i 1 M 3 2 M Pl g ∗ e T 4 Pl • Y × m DM = 0 . 43 eV Hannah Tillim Isolated sectors from primordial black holes December 19, 2018 7 / 13

Light DM constraints Constraints for single real s = 0 dof before free-streaming constraint is imposed. • red line: B 0 = 1 • blue line: one pBH per initial Hubble patch • blue shaded regions: T RH < 3 MeV • pink, dotted line: T RH = 200 GeV. • upper purple region: ρ BH (0) > M 4 Pl . Free streaming : excludes most of light region (for s < 3 / 2) Hannah Tillim Isolated sectors from primordial black holes December 19, 2018 8 / 13

Thermalisation Ongoing work with J. March-Russell, S. M. West Hannah Tillim Isolated sectors from primordial black holes December 19, 2018 9 / 13

Thermalisation • Emitted with non-thermal spectrum and very high energy tail • Underpopulated compared to equilibrium density • Require redistribution of energy (2 → 2) and particle creation (2 → 3 ...) Kinetic f ( p ) = 1 / (exp[ − ( E − µ ) /T ] ± 1) T i = T Thermal � µ in i = � µ fin Chemical j • Other studies in this direction: S. Davidson & S. Sarkar arXiv:0009.078v3; M. Garny et. al. arXiv:1810.01428, S. Heeba; F. Kahlhoefer & P. St¨ ocker arXiv:1809.04849, .... Hannah Tillim Isolated sectors from primordial black holes December 19, 2018 10 / 13

Thermalisation • Kinetic, thermal and ‘partial chemical’ → evolution to full chemical • Boltzmann equation governs evolution - depends on a collision term n + 3 Hn = g � d 3 p C [ f ] ˙ π 2 Hannah Tillim Isolated sectors from primordial black holes December 19, 2018 11 / 13

Thermalisation: interim results Hannah Tillim Isolated sectors from primordial black holes December 19, 2018 12 / 13

What’s next • Robust model-independent framework for estimating thermalisation timescales • Concrete pheno of permanently underpopulated sectors • Application to pBH production model to reopen light DM case Thank you! Hannah Tillim Isolated sectors from primordial black holes December 19, 2018 13 / 13