from Dark Matter Annihilation into e - -e + Pairs Maneenate - PowerPoint PPT Presentation

Multi-Messenger Constraints and Pressure from Dark Matter Annihilation into e - -e + Pairs Maneenate Wechakama Kasetsart University, Thailand M. Wechakama 1

Outline • Introduction to Dark Matter (DM) • The e - and e + excess in the solar neighbourhood • Propagation of e - and e + from DM annihilation • Pressure from DM annihilation • Multi-messenger constraints on DM annihilation • Outlook M. Wechakama 2

Outline • Introduction to Dark Matter (DM) • The e - and e + excess in the solar neighbourhood • Propagation of e - and e + from DM annihilation • Pressure from DM annihilation • Multi-messenger constraints on DM annihilation • Outlook M. Wechakama 3

Cosmological Evidences for DM Image credit: http://cdms.phy.queensu.ca/Public_Docs/DM_Intro.html Image credit: Hubble Space Telescope Image credit: S. Gottlöber, G. Yepes, A. Klypin, A. Khalatyan Rotation curves of galaxies Gravitational lensing Large scale structure Total amount of DM Image credit: http://www.nasa.gov/mission_pages/planck/ Planck Collaboration et al. 2013 M. Wechakama, AIP 4

How to detect dark matter? Image credit: http://cdms.berkeley.edu/Education/DMpages/science/directDetection.shtml Image credit: Sky & Telescope / Gregg Dinderman Indirect detection Direct detection M. Wechakama, AIP 5

Outline • Introduction to Dark Matter (DM) • The e - and e + excess in the solar neighbourhood • Propagation of e - and e + from DM annihilation • Pressure from DM annihilation • Multi-messenger constraints on DM annihilation • Outlook M. Wechakama, AIP 6

e - and e + Excess in the Solar Neighbourhood Anti-proton flux Positron fraction e + /(e + + e - ) e + + e - flux Figures from Cirelli 2012 Indirect detection experiments in the solar neighborhood show • an e - and e + excess with respect to the astrophysical background. • no excess in the anti-proton flux. • need an unknown source which produce only e - and e + but not anti-proton!! M. Wechakama, AIP 7

e - and e + Excess in the Solar Neighbourhood Anti-proton flux Positron fraction e + /(e + + e - ) e + + e - flux Figures from Cirelli 2012 • These results can be interpreted in term of DM annihilations. • Red curve: 3 TeV DM particles annihilating into  +  - (Meade et al. 2009) • It might be that the e - and e + in the solar neighbourhood are created by DM annihilation. M. Wechakama, AIP 8

Signatures of DM from e - and e + Wechakama & Ascasibar 2012 • If the e - and e + in the solar neighbourhood originate from DM annihilation, then e - and e + should be created everywhere in the Galactic DM halo. • We can look for astrophysical signatures of DM through e ± . M. Wechakama, AIP 9

Purpose of the Research • Look for signatures of DM annihilation in the Galaxy • local e - and e + spectrum • photons from the Galactic centre • pressure of e - and e + from DM annihilation • Constrain the DM properties • mass • annihilation cross-section • DM density profile M. Wechakama 10

Outline • Introduction to Dark Matter (DM) • The e - and e + excess in the solar neighbourhood • Propagation of e - and e + from DM annihilation • Pressure from DM annihilation • Multi-messenger constraints on DM annihilation • Outlook M. Wechakama 11

- Electron H + - - + H - ɣ + H - H + - + + - H Positron e  lose energy by ISRF, Dark Matter ISM and magnetic fields Dark Matter Halo Dark Matter Halo M. Wechakama 12

Electron and Positron Propagation Diffusion-loss equation       n n n d d d                ( , x ) K x ( , ) ( , x ) b x ( , ) ( , x ) Q x ( , )           t d d d e  Spectrum Diffusion Energy Loss Source is number density of e - and e + n    2 is Lorentz factor ( E m c ) e is the space coordinate x M. Wechakama 13

Diffusion       d n d n d n                ( , x ) K x ( , ) ( , x ) b x ( , ) ( , x ) Q x ( , )           t d d d We use a constant diffusion coefficient from Donato et al. 2004 & Delahaye et al. 2008     K K ( ) 0      25 2 1 K 1.67 10 cm s , 0.7 0 M. Wechakama, AIP 14

Energy Loss       d n d n d n                ( , x ) K x ( , ) ( , x ) b x ( , ) ( , x ) Q x ( , )           t d d d e  - photon • Inverse Compton • Synchrotron e  - thermal electron • Coulomb collisions • Bremsstrahlung e  - hydrogen atom • Ionization M. Wechakama 15

Source       d n d n d n                ( , x ) K x ( , ) ( , x ) b x ( , ) ( , x ) Q x ( , )           t d d d The electrons and positrons are produced from DM annihilation 2    r ( )    dm  Q 0 ( ) r v  e   m dm DM Density DM Annihilation Profile Cross-Section M. Wechakama 16

Dark Matter Density Profile NFW Profile:  =1 Characteristic Density of the DM Halo    s ( ) r    dm 3     r r      1  r   r  s s Inner Logarithmic Characteristic Radius Slope of the DM Halo Navarro, Frenk &White 1997 M. Wechakama 17

Model of e  propagation Assuming steady-state + spherical symmetry      n n d d               0 K (r, ) (r, ) b (r, ) (r, ) Q (r, )         d d d ( , ) n r  The solution of e  spectrum,  d depends on  Diffusion Tell us about the  Energy losses distribution of electrons  Source and positrons from DM annihilation in a DM halo M. Wechakama 18

Model Parameters Galactic properties (energy losses) Canonical Model  g • • Gas density: 1 cm -3 (ref 1.) • Ionization fraction: X ion • 0 (ref 1.) • 6  G Magnetic fields: B • (ref 2.) DM properties (Source term) • Dark matter density profile:  dm • NFW (ref 3.) • Cross-section: <  v > • Constrained by Integral, • Fermi and HESS DM Mass : E 0 = m dm c 2 1. Dehnen & Binney 1998, Ferrière 2001, Robin et al. 2003 2. Ferrière 2001, Beck 2001, Ascasibar & Díaz 2010 3. Dehnen & Binney 1998, Klypin et al. 2002 M. Wechakama 19

Outline • Introduction to Dark Matter (DM) • The e - and e + excess in the solar neighbourhood • Propagation of e - and e + from DM annihilation • Pressure from DM annihilation • Multi-messenger constraints on DM annihilation • Outlook M. Wechakama 20

Dark Matter Pressure Gravity + - - + - + - + e - , e + gas pressure Dark Matter Halo M. Wechakama 21

Dark Matter Pressure      2 2 m c d ( , ) n r 1     e   P ( ) r d   dm   3 d 1 Dark Matter Pressure  e  spectrum M. Wechakama 22

Results: Dark Matter Pressure as a function of • DM particles ( m d m , Q 0 ) • Magnetic fields • Gas density • Ionization fraction • DM density profile Wechakama & Ascasibar MNRAS 2011 M. Wechakama 23

Results: Dark Matter Pressure as a function of • DM particles ( m d m , Q 0 ) • Magnetic fields • Gas density • Ionization fraction • DM density profile Wechakama & Ascasibar MNRAS 2011 M. Wechakama 24

Results: Dark Matter Pressure as a function of • DM particles ( m d m ) • Magnetic fields • Gas density • Ionization fraction • DM density profile Wechakama & Ascasibar MNRAS 2011 M. Wechakama 25

Results: Dark Matter Pressure as a function of • DM particles ( m d m ) • Magnetic fields • Gas density • Ionization fraction • DM density profile Wechakama & Ascasibar MNRAS 2011 M. Wechakama 26

Effect on Rotation Curves of Galaxies Image credit: NOAO, AURA, NSF, T.A.Rector P r r d ( )     dm v ( ) r rg r ( ) rg ( ) r rg ( r )   rot gas d m ( ) r d r g Circular velocity + DM pressure gradient M. Wechakama 27

Effect on the Milky Way Model without DM pressure with DM pressure Wechakama & Ascasibar MNRAS 2011 M. Wechakama 28

Effect on Different DM Profile without DM pressure Wechakama & Ascasibar MNRAS 2011 with DM pressure M. Wechakama 29

Effect on Observed Rotation Curves 14 Low Surface Brightness Galaxies (de Blok & Bosma 2002) M. Wechakama 30

Effect on Observed Rotation Curves Observed Rotation Curve from de Blok&Bosma 2002 M. Wechakama, AIP 31

Effect on Observed Rotation Curves Star & Gas Data from de Blok&Bosma 2002 star gas M. Wechakama, AIP 32

Effect on Observed Rotation Curves Rotation Curve Without DM pressure from de Blok&Bosma 2002 star gas M. Wechakama, AIP 33