Dark Matter Ultracompact Minihalos the Early Universe Hamish

Dark Matter Ultracompact Minihalos & the Early Universe Hamish Clark University of Sydney Hamish Clark 1

Outline Based on three recent papers: ➔ Clark, Lewis & Scott 2015 a (ar. Xiv: 1509. 02938, MNRAS accepted) ➔ Clark, Lewis & Scott 2015 b (ar. Xiv: 1509. 02941, MNRAS accepted) ➔ Adams, Aslanyan, Bringmann, Clark, Easter, Lewis, Price & Scott (will appear on the ar. Xiv today!) ● The primordial Universe ● ‘Ultracompact’ dark matter halos ● Constraining abundance of rare objects ● Implications on the properties of the early Universe Hamish Clark 2

Primordial Fluctuations Small fluctuations in the density of the early Universe seeded structure formation. Hamish Clark 3

Primordial Fluctuations Small fluctuations in the density of the early Universe seeded structure formation. Hamish Clark 4

Primordial Fluctuations Small fluctuations in the density of the early Universe seeded structure formation. Hamish Clark 5

Primordial Fluctuations Small fluctuations in the density of the early Universe seeded structure formation. Hamish Clark The initial perturbations appear to have: - Gaussian-distributed amplitudes: 6

Primordial Fluctuations Small fluctuations in the density of the early Universe seeded structure formation. The initial perturbations appear to have: - Gaussian-distributed amplitudes: - about the same power on all scales, characterised by a spectral index: ns ≈ 1 Hamish Clark 7

Primordial Fluctuations Bringmann, Scott, Akrami (2012) Hamish Clark 8

Primordial Fluctuations Bringmann, Scott, Akrami (2012) Hamish Clark 9

Primordial Fluctuations Bringmann, Scott, Akrami (2012) Hamish Clark 10

Primordial Fluctuations ? Bringmann, Scott, Akrami (2012) Hamish Clark 11

Primordial Fluctuations X Bringmann, Scott, Akrami (2012) Hamish Clark 12

Primordial Fluctuations ✓ Bringmann, Scott, Akrami (2012) Hamish Clark 13

Ultracompact Minihalos Requirements formation - A fluctuation of amplitude 10 -3 < �� < 0. 3 - Isolated formation (seeded well before matter-radiation equality) - providing purely radial infall Hamish Clark 14

Ultracompact Minihalos Requirements formation - A fluctuation of amplitude 10 -3 < �� < 0. 3 - Isolated formation (seeded well before matter-radiation equality) - providing purely radial infall Properties - Extremely dense dark matter halo: an Ultracompact Minihalo (UCMH) - �� ∝ r -2. 25 compared to standard �� ∝ r -1 Hamish Clark 15

Ultracompact Minihalos Requirements formation UCMHs are very useful - A fluctuation of amplitude 10 -3 < �� < 0. 3 - Persist through to present day - Isolated formation (seeded well before matter-radiation equality) - providing purely radial infall - Mass maps to scale. Abundance maps to primordial power. - Much more likely to form than PBHs Properties - Very good indirect DM detection targets - Extremely dense dark matter halo: an Ultracompact Minihalo (UCMH) - �� ∝ r -2. 25 compared to standard �� ∝ r -1 Hamish Clark 16

Constraining UCMHs Gamma-ray Sources Hamish Clark 17

Implied Constraints on the Early Universe Bringmann, Scott, Akrami (2012) Hamish Clark 18

Implied Constraints on the Early Universe Bringmann, Scott, Akrami (2012) Hamish Clark 19

Implied Constraints on the Early Universe Assuming that dark matter annihilates! Bringmann, Scott, Akrami (2012) Hamish Clark 20

Gravitational Lensing ● Least ‘sensitive’: Strong Lensing Hamish Clark 21

Gravitational Lensing ● Least ‘sensitive’: Strong Lensing ● Microlensing: Magnification & Position Hamish Clark 22

Gravitational Lensing ● Least ‘sensitive’: Strong Lensing ● Microlensing: Magnification & Position Hamish Clark 23

Gravitational Lensing ● Least ‘sensitive’: Strong Lensing ● Microlensing: Magnification & Position ● Negligible deflection: Time-delay microlensing Light travel time Hamish Clark 24

Gravitational Lensing ● Least ‘sensitive’: Strong Lensing ● Microlensing: Magnification & Position ● Negligible deflection: Time-delay microlensing Light travel time Integral over path C parameterised by s Hamish Clark 25

Gravitational Lensing ● Least ‘sensitive’: Strong Lensing ● Microlensing: Magnification & Position ● Negligible deflection: Time-delay microlensing Light travel time Integral over path C parameterised by s Hamish Clark Newtonian gravitational potential 26

Pulsar Timing Single lensing event Clark et al. (2015), ar. Xiv: 1509. 02938 Hamish Clark 27

Pulsar Timing Single lensing event Population of lenses Clark et al. (2015), ar. Xiv: 1509. 02938 Hamish Clark 28

Pulsar Timing Single lensing event Population of lenses Clark et al. (2015), ar. Xiv: 1509. 02938 Hamish Clark 29

Pulsar Timing Clark et al. (2015), ar. Xiv: 1509. 02938 Hamish Clark 30

Pulsar Timing Clark et al. (2015), ar. Xiv: 1509. 02938 Hamish Clark 31

Implied Constraints on the Early Universe Assuming that dark matter annihilates! Bringmann, Scott, Akrami (2012) Hamish Clark 32

Implied Constraints on the Early Universe Assuming that dark matter annihilates! Bringmann, Scott, Akrami (2012) Hamish Clark 33

Implied Constraints on the Early Universe Assuming that dark matter annihilates! Assuming that UCMHs can form up until z = 200. . . Bringmann, Scott, Akrami (2012) Hamish Clark 34

Implied constraints (95% CL) dns/dlnk - Primordial power spectral index, and higher order running d 2 ns/dlnk 2 Aslanyan et al. (In prep) Hamish Clark 35

Implied constraints (95% CL) - Primordial power spectral index, and higher order running - Inflation (slow roll parameters) Aslanyan et al. (In prep) Hamish Clark 36

Implied constraints (95% CL) - Primordial power spectral index, and higher order running - Inflation (slow roll parameters) Aslanyan et al. (In prep) Hamish Clark 37

Implied constraints (95% CL) - Primordial power spectral index, and higher order running - Inflation (slow roll parameters) Step Size - Stepped primordial power Step scale, ks (Mpc-1) Clark et al. (2015), ar. Xiv: 1509. 02941 Hamish Clark 38

Implied constraints (95% CL) - Primordial power spectral index, and higher order running - Inflation (slow roll parameters) - Stepped primordial power - Non-Gaussianity: f. NL< 8. 2 (CMB) f. NL< O(10) (PBHs) f. NL< O(100) (UCMHs) Hamish Clark 39

Implied constraints (95% CL) - Primordial power spectral index, and higher order running - Inflation (slow roll parameters) - Stepped primordial power - Non-Gaussianity: f. NL< 8. 2 (CMB) f. NL< O(10) (PBHs) f. NL< O(100) (UCMHs) - Cosmic string loop tension: Gμ < 1. 7 x 10 -7 (CMB) -8 Gμ < 6. 5 x 10 (K < 1000) -6 Gμ < 1. 5 x 10 (K < 100) Hamish Clark et al. (2015), ar. Xiv: 1509. 02941 40

Summary ● Should significant additional primordial power be available on small scales, dark matter ‘Ultracompact Minihalos’ would be expected to form. ● UCMHs are fantastic dark matter structures for both indirect detection & lensing. ● These rare objects provide a new avenue of investigation into the early Universe. ● This is all new! More work is needed, and will significantly improve existing results (N-body simulation, improving UCMH & PBH abundance limits, cosmic string loop K-factor). Hamish Clark 41