Systematic Uncertainties from Halo Asphericity in Dark Matter Searches

Transcription

1 Systematic Uncertainties from Halo Asphericity in Dark Matter Searches Based on: Nicolas Bernal, Jaime Forero-Romero, RG & Sergio Palomares-Ruiz JCAP 1409 (2014) 004 Raghuveer Garani University of Bonn June, 12th 2015 WIN 2015

2 Outline Direct and Indirect Searches N-body simulations: Bolshoi Impact of halo Asphericity Results

3 Direct DM Searches R n m N h i n = /m LUX, Xenon,CDMS and many more

4 Indirect DM Searches N = A eff T exp Fermi-LAT, Ice-Cube, AMS and many more

5 Indirect DM Searches d dec de (E, ) = 1 m X i BR i dn i dec de J dec ( ) 4 d ann de (E, ) = h vi 2 m 2 X i BR i dn i ann de J ann ( ) 4 J ann ( ) = J dec ( ) = 1 Z 1 Z d d Z los Z los r(s, ) 2 ds r(s, ) ds What is the impact of aspherical Halos?

6 N-Body Simulations: Bolshoi Klypin et.al 11 Parameter PLANCK WMAP7 Bolshoi Description h Hubble parameter density parameter for dark energy m density parameter for matter (dark matter+baryons) b density parameter for baryonic matter n slope of the power spectrum normalization of the power spectrum le 3.1: Cosmological parameters used in Bolshoi simulation compared with the best fit values obtained fr The density distribution in Bolshoi is best fit by NFW profile. Halo parameters such as the virial mass, radius and shape parameters are extracted.

7 Simulation Results: Halo Parameters 10 5 halos

8 Bolshoi Simulation Halo shape T jk = X i x ij x ik r 2 i Define axes ratios: b/a = T b /T a c/a = T c /T a

9 Simulation Results: Shapes Parameterize shape with Triaxiality parameter (T): T = 1 (b/a)2 1 (c/a) 2 Prolate (Sausage shaped) a b c(1 >T >2/3) Triaxial a>b>c(2/3 >T >1/3) Spherical halos are in fact very rare! Oblate (Pancake shaped) a b c (1/3 >T >0)

10 Impact of Halo Asphericity (r) = N (r/r s )[1+(r/r s )] 2 r! r e = s x y + b/a 2 z. c/a Halo Type M v [10 12 M ] R v [kpc] c e b/a c/a Approx. Spherical Prolate Oblate ble 1.ParametersoftheexamplehalosusedtoillustratetheimpactofasphericityinF

11 Impact of Halo Asphericity Approx. Spherical Prolate Oblate

12 Observational Priors Gaussian priors Flat priors Central value 1 error Lower cut Upper cut Virial mass [10 12 M ] M min v =0.7 M max v =4.0 DM mass within 60 kpc [10 11 M ] M DM 60 = =0.7 Local DM surface density [M pc 2 ] DM 1.1 = 17 =6 Sun s galactocentric distance [kpc] R min =7.5 R max =9 SDSS Bovy and Rix Table 2.Limitsforthehalovirialmass( )andthesun sgalactocentricdistance( )andcentral PDF p PDF(~! ) prior (~! )=C PDF(M v ) (M v Mv min ) (Mv max M v ) Z R max apple (M DM dr exp 60 M 60 ) 2 R min Z 2 apple ( DM d exp 1.1 p 1.1 (R, )) ,

13 Results: Local density Note that the deviations are of the order of % a-b plane: a-c plane: b-c plane: +20% 5% +15% 30% +0% 30% +40% 15% +35% 40% +10% 35%

14 Results: J factors Fermi-LAT, Daylan et al. 2014

15 Results: J factors for decay Deviations from spherical average are in the range % Typically quoted value h J dec i = 43 GeV/cm 3 kpc

16 Results: J factors for annihilations Deviations from spherical average are in the range 5-10 % Typically quoted value h J ann i = 590 GeV/cm 3 2 kpc

17 Conclusions Direct and Indirect DM searches crucially depend on Milky-Way DM halo properties, such as the local density and J factors. N-body simulation favor halos that are non-spherical. Spherical halos are rare. Using data from large N-body simulation Bolshoi, systematic uncertainties due to halo asphericity in DM searches are quantified. We find: h i = J dec h J dec i = and J ann h J ann i =