WIMP dark matter stars Fabio Iocco Institut de

WIMP dark matter & stars Fabio Iocco Institut de Physique Theorique, CEA/Saclay Institut d’Astrophysique de Paris GDR Terascale, Grenoble 31/3/09

Outline WIMP DM and stars: general mechanism and effects The local Universe: Compact Objects in Globular Clusters Stars at the Galactic Center The Early Universe Proto-stellar phase and DM, which effects? How long can DM burning Pop. III survive?

Scattering and capture Halo WIMPs are captured Captured WIMPs accumulate inside the star, thermalize and “sink” to the center by scattering off the gas of the star

DM and stars: scattering and capture Capture rate C “Dark Luminosity” inside the star WIMPs thermally relaxed within the star: Distribution WIMP annihilation point-source RX<<Rc Equilibrium timescales are short At equilibrium Virtually no dependence on self-annihilation rate < v> Seminal literature by: Gould, Griest, Press, Raffelt, Salati, Seckel, Spergel

The Sun: HE s from DM Icecube Collaboration ar. Xiv: 0902. 2460 Wikstrom & Edsjo ar. Xiv: 0903. 2986

Probing the cold disk? (DM distribution in the solar system) Cold dark disk in gas+DM simulations Read et al. ar. Xiv: 0902. 009 Bruch et al. ar. Xiv: 0902. 4001

White dwarfs in Globular Clusters White dwarfs DENSE and with no intrinsic energy production WD, blackbody approx T *, L * r * C * DM profile reconstructed from baryons/stars (sample stars from the innermost field) Bertone & Fairbairn 08 (WD at the Galactic Center by Moskalenko & Wai 07)

Going cool: WIMP burning � (stars have negative specific heat) Fairbairn et al. 08 Iocco et al. 08 Taoso et al. 08

DM burning at the Galactic Center At the limit of effectiveness With current upper limits on cross section Scott, Fairbairn & Edsjo 2009

The first stars (Population III) Form in halos of Mh 106 Msun at z 20 (Tvir< 104 K) First Stars primordial chemical composition (BBN: no C, N, O -- A > 7) Weak cooling: H 2 vs CO big masses Smooth collapse, at the center of the halo No fragmentation, one star per halo Live fast, die young (30 -300 Msun go SNe) Hot: first engines for IGM Reionization (possibly) seed BH, correlated to quasars As of now, we have (very likely) not seen one yet Simulations! By courtesy of M. J. Turk

Building the DM cusp Gas (collisional) cooling and collapsing to the center (gravitationally)“pulling in” embedded DM Spolyar, Freese & Gondolo 07 (PRL 100, 2008) (modeled through adiabatic contraction) Iocco et al. 08 (also Freese+ 08)

Powering the structure (with DM) Energy production DM profile critical! + Energy deposition Gas profile critical! Energy repartition for WIMP annihilation: 1/3 electrons 1/3 photons 1/3 neutrinos (lost) Spolyar, Freese & Gondolo 07 (PRL 100, 2008) At ngas 1012 #/cm 3 structure opaque to annihilation products

Feedback effects DM annihilation induces heating : T up Central shell DM annihil. induces ionization Ionization catalizes H 2 formation H 2 is a coolant : T down T = ? ? Jeans mass unchanged E. Ripamonti, FI et al 09; ar. Xiv: 0902. 0346

Evolving “Dark Stars” Proto-stellar stages (or early pre-MS) at T 5000 K Lasting ≈ 104 years Adopted fiducial values: (m. X=200 Ge. V, shorter times)

DM burning: prolonging lifetimes DM powered stars are “frozen” frozen as long as environmental DM stays supecritical frozen evolving Taoso et al 08 Iocco et al 08 SD 0=10 -38 cm 2

Why should you care? (astrophysical signatures) z (not actual size) Halo merger DM cusp erosion (baryons + self-annihilation) Bertone & Merritt 05 Wechsler + 02

Concluding We can learn something from interactions of WIMPs with stars In the local Universe: The Sun & the Earth (neutrinos!) Compact Objects (observe them in dense environments) In the early Universe: Pop. III are very likely most affected Observables yet to be modeled