Dark Matter in the Early Universe

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Egbert Cain
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1 Dark Matter in Early Universe : bound on low-reheating temperature [Based on work with Tomo Takahashi] Ki -Young Choi

2 Contents. Reheating temperature. Reheating and Dark matter in early Universe 3. Low bound on reheating temperature 4. Discussion

3 Expanding Universe Expanding Universe implies it was hot and dense in early times. Matters in Universe are in rmal equilibrium with given temperature.

4 Temperature Universe What is available range this temperature? What is highest temperature? What is lowest temperature?

5 Inflation before Hot Universe Beginning Universe?? Inflation Reheating Hot Universe

6 Inflation and Reheating Inflation: vacuum-dominated Oscillation : matter-dominated Decay : radiation-dominated

7 Reheating During inflation, Universe is cold. After inflation, energy inflation is converted to production light particles. Usually inflaton field oscillates around vacuum and decay to particles. The particles are rmalized and Universe is heated to some temperature. We call highest temperature when radiationdomination starts, reheating temperature.

8 now / H most H? tensor-to-sca matters. At least we understand mattp atoms. They are made charged particles, Since is fixed and V, s t 9 (k). t h R 0. The tensor-to-scalar ratio is protons M atoms. They are made charged particles, and elec may interact with light by electromagnetic int inflation pl r /4 may interact with light by electromagnetic interactions. Those are successful at least in world /4 t (k) V Those are successful at.least in world around us on ea r 0.0 system.temperature However in larger scales, such as Reheating.4 The Energy Scale Inflation (k) s system. However in larger scales, such as galaxy, clusters cosmological scales, it seems that somethin Large values tensor-to-scalar ratio, r 0.0, cosmological scales, it seems that something is missing. / Tensor fluctuations are ten normalized relative to (measured) ampli e s is fixed and H V, tensor-to-scalar ratio is a direct measure en t energies The tensor-to-scalar ratio is flation s R Tensor to scalar ratio Energy scale inflation constrain r /4 highest temperature H (3) P (Treh ) < V t /4 6 V 0 GeV. Phr(k) t', Pt P (k)6 reheating temperature The Lyth Bound 3 r P MP.k s (k) (T ) < V e values tensor-to-scalar ratio, r 0.0, correspond to inflation occuring at G Note from Eqns. (03) and (6) that tensor-toreh (T Vr gives energy scale inflatio4 reh) < The determination s s e-folds N 3 0 Since s is fixed andt inflaton / H asv a, tensor-to-scalar ratio is+ a direct m gies. function hh, h i ( ) (k k ) 0 k k H H a M inflation P (k), P P (k) h t h 3 8M d M k /4 4 r P 4H (3) /4P 6 r (T ) g T V 0 3GeV.M 0 5 The Lyth Bound ( ) (k + k nowledgments 30 pl) dn M s s 3 0 s hhk, hk0 i ratio, ( )ratio (k0.0, + k )correspond vk to Large and values r to inflati from Eqns. (03) (6) thattensor-to-scalar tensor-to-scalar relates directly ev The total field evolution between time when 4 3P 0 CM potential energy during inflation a M ( ) (k + k )Ph ( (T ) g T energies.by nflaton a function e-folds NScience end 30 inflation at Program N can refore be written and tensor-to-scalar ratio Lyth bound end.c. wasassupported Basic Research through 4H 3 0 Nati ( ) (k + k ) ( + k ) 3 Z Ncmb M k n r aa 8 d P s Foundation Korea (NRF) funded by Ministry Education, Science r Bound The Lyth ( ) + k )P Treh <r(n GeV dn During slow-roll evolution, ) doesn t evolve(kmuch and one may obtain M0 h (k) M pl pl Nend Basic Science Research Program through National Re m Grant No K.-Y.C. acknowledges Max Planck Society relation [7] relates Note from Eqns. (03) and (6) thatfluctuations tensor-to-scalar ratio d H m ' 5 total field evolution between time when CMB exited horizon at n 4 r a s / 6 3M r NRF) funded by Ministry Education, Science and Tech4 H P inflaton as a function e-folds N ea Ministry Education, Science and Technology (MEST), Gyeongsangbuk following O() integral, end inflation at Nend can refore be written as Mpl 0.0 m wledgments

9 Low-Reheating Temperature. Big Bang Nucleosynsis : at low-reheating temperature, neutrinos are not fully rmalized and light element abundances are changed, T reh & MeV reheating temperatur T reh &.5 MeV 4 MeV for hadronic decays [Kwasaki, Kohri, Sugiyama, 999, 000]. BBN+CMB+LSS : precise calculation cosmic neutrino background and CMB T reh & 4.7MeV [Salas, Lattanzi, Mangano, Miele, Pastor, Pisanti, 05]

10 T MeV (t sec) Local Thermal Equilibrium protons and neutrons Big-Bang Nucleosynsis n $ p + e + e n + e $ p + e p + e $ n + e + T MeV (t sec) Weak freeze-out n p e (m n m p )/T 6 Decay free neutrons n ' 880 sec n + p D + γ Deuterium bottleneck T 0.07 MeV (t 3 min) n/p /7 most neutrons to He4 small D, He3 Li7 ( mt n g π ) 3/ e (m µ)/t m n m p.9 MeV

11 New bound on low-reheating temperature 3. Dark matter halos : density perturbation during early matter-domination and no observation small scale DM halos. T reh & 30 MeV [KYChoi, Tomo Takahashi, in preparation]

12 Inflation and Reheating Inflation: vacuum-dominated Oscillation : matter-dominated Decay : radiation-dominated

13 Evolution Density Perturbation Super-horizon scales : it is constant Inside horizon: it can grow Radiation (rel. particles) : oscillates DM (non rel. particles with vanishing pressure) : grows Rad-domination: logarithmically grows Matter-domination: linearly grows

14 Evolution in Standard Model non-linear growth / a 0 5 / log a Radiation domination Matter domination horizon entry rad-matter equality a scale factor

15 Primordial Black Holes or UCMHs If primordial density perturbation is large: & 0. The matters and radiation collapse when y enters horizon and make black holes (primordial black hole) No observation primordial black hole rule out this large density perturbation. & 0 3 It does not make black hole, but can make small scale dm dominated halos (ultra compact mini halo, UCMH) No observation yet. The constraint depends on properties dark matter.

16 Primordial Black Holes or UCMHs non-linear growth / a 0 5 / log a Radiation domination Matter domination horizon entry rad-matter equality a scale factor

n bevinf. proved by h G Treh -ray signal. (308) Compact (33) Mini Halo Treh Ultra f f (UCMH) : Non-baryonic UCMHs in Galaxy T?

0 for kpc 0 (t) General expectation afterwards: tidal disruption primodial (for field halos and adopting a special multi-scale

survive... Berezinsky et al., PRD 03, PRD 08; Moore 05, Diemand, Kuhlen & Madau ApJ 06; Green & Goodwin, MNRAS 07, Goerdt et al.

0 MeV Treh not well understood and still under debate, (r ) d kdetails (t) k more input from simulationskneeded! (3) r.

17 n bevinf. proved by h G Treh -ray signal. (308) Compact (33) Mini Halo Treh Ultra f f (UCMH) : Non-baryonic UCMHs in Galaxy T? (309) reh Massive compact halo object N-body simulations can follow evolution until z~6 (08) (34) m 0(30) > M5X (t, x )> mg (t, x) 0 for kpc 0 (t) General expectation afterwards: tidal disruption primodial (for field halos and adopting a special multi-scale technique) Diemand, Moore & Stadel, Nature 05 (3) >N /TM) X (35) (00 TeV), m3 q TeV, Mpc ( (08) important, but compact core should survive... Berezinsky et al., PRD 03, PRD 08; Moore 05, Diemand, Kuhlen & Madau ApJ 06; Green & Goodwin, MNRAS 07, Goerdt et al., MNRAS 07;......though prospects might be much worse. Zhao et al., ApJ 07 vu (t, x), Tkd 0 MeV. 0 MeV Treh not well understood and still under debate, (r ) d kdetails (t) k more input from simulationskneeded! (3) r.5 Torsten Bringmann, University Hamburg TeV, X, N,, G, a, a (33) h c ( Survival microhalos!nsg + i (080) g s 0.75 (34) ( (083) Thermal decoupling WIMPs! (36) / (37) / g ( (

18 Observation UCMHs WIMP dark matter Annihilation or decay WIMPs in UCMHs : gamma-ray, neutrino, cosmic rays. Fermi-LAT constrains strongly [Bringmann, Scott, Akrami, 0] Non-WIMP dark matter Gravitational effects can be observed - distortion in macrolensed quasars, mcrolensing, pulsar timing,... [Clark, Lewis, Scott, 05]

19 UCMHS with Low-Reheating Temperature Before reheating, epoch matter-domination exists (early matter-domination). The perturbation which enters during early matter-domination can grow linearly and help to generate UCMHs. Non-observation UCMHs can constrain primordial power spectrum and stage early matter-domination.

20 h & 70 MeV 7030MeV (T ) 30 g T (34) (34) 6 Treh ( 4 < 0 GeV (3) (T 4 (T ) g T 6 (3) ) g T T < 0 GeV (35) reh (T ) g T UCMHs and early Matter-Domination 6 Treh Treh & 30 MeV 6 Treh & 30 < 0 GeV Treh < 0 GeV 70 MeV (35) 30 ( 6 (36) ( (33) UCMHs (33) Treh < 0 GeV(34) Treh & MeV (34) Treh & 30early70matter MeV a /a ( 0 / domination Science Research Program through National Re- (35) Treh & MeV (35) ded by Ministry Education, Science and Tech 4 (36) 0 / log a cknowledgments Y.C. acknowledges Max Planck Society (MPG), 5 (36) 3 0 / a&radiation ( 0 Matter.-Y.C. was supported by(mest), Basic Science Research Programand through Nat ce and Technology Gyeongsangbuk-Do sresearch Programdomination through domination National Rech Foundation Korea (NRF) funded by Ministry Education, Science a 4 ependent Junior Research Group 0 at AsiaPacific / a gy Grant No.Basic K.-Y.C.Program acknowledges Max Planck ReSociety Ministry Education, Science and Techorted by Science Research through National horizon reheating scale factor rad-matter Korea Ministry Education, Science and Technology (MEST), Gyeongsangbuk entry equality Korea (NRF) funded by Ministry Education, Science and Tech( knowledges TMax Planck Society (MPG), T P). reh dom ang City for support Independent Junior Research Group at As

21 Discussion. Reheating process follows early matter-domination epoch.. Dark matter density perturbation before reheating and can generate large number UCMHs. 3. Non-observation UCMHs can constrain low-reheating temperature. We can find new bound on temperature.

Probing the early Universe and inflation with indirect detection

Probing the early Universe and inflation with indirect detection Pat Scott Department of Physics, McGill University With: Yashar Akrami, Torsten Bringmann, Jenni Adams, Richard Easther Based on PS, Adams,