Super Massive Dark Stars Douglas Spolyar Fermi lab

Super Massive Dark Stars Douglas Spolyar Fermi lab and The University of Chicago Phys. Rev. Lett. 98, 010001 (2008) ar. Xiv: 0705. 0521 D. Spolyar , K. Freese, and P. Gondolo JCAP, 11, 014 F (2008) ar. Xiv: 0802. 1724 K. Freese, D. Spolyar, and A. Aguirre Ap. J 705. 1031 S (2009) ar. Xiv: 0903. 1724 D. Spolyar, P. Bodenheimer, K Freese, and P Gondolo Super Massive ar. Xiv: 1002. 2233 K. Freese, C. Ilie, D. Spolyar, M. Valluri, and P. Bodenheimer

The Team

Our Results • Dark Matter (DM) in haloes can dramatically alter the formation of the first stars leading to a new stellar phase driven by DM annihilation. – Change: Re-ionization, Early Stellar Enrichment, Formation of early Big Black Holes. – Discover DM. • Basic Properties – Very luminous up to ~ 1011 L – – Relatively cool ~ 104 K Can be very long lived ~ 108 years Super Massive up to ~ 107 M The more massive DS can be detectable with JWST

Additional Work On DS 1 -D hydro-code Ripamonti, iocco, Ferrara, Schneider, Bressen, Margio 2010

DM heating Today’s Stars • The Sun – Krauss, K. Freese, Press, & Spergel (1985) • Stellar Structure – Bouquet & Salati (1989); Salati & Silk (1989) • Compact Objects – Bertone & Fairbairn (2008) • Main Sequence Stars – Edsjo, Scott, Fairbairn [2007, 2008, 2009]; Dark Star Code • WIMP Burners (White Dwarfs near center of Galaxy) – Moskalenko & Wai (2007) – D. Hooper, D. Spolyar, A. Vallinoto, and N. Gnedin (2010) • Inelastic DM (Solution to DAMA) (New limits in the near future)

DM critical from a cosmological Prospective

Hierarchical Structure Formation Smallest objects form first (earth mass) Merge to ever larger structures Pop III stars (inside 106 M haloes) first light Merge galaxies Merge clusters

The First Stars Also The First Structure • Important for: • End of Dark Ages. – (prior to star formation) • Re-ionize the universe. • Provide enriched gas for later stellar generations. – Important for explaining present day star formation • May be precursors to black holes which power quasars • Transform the universe into the one we are presently familiar with.

Basic Picture • The First Stars – form in a DM rich environment • Gas cools and collapses to form the first stars – the cloud compresses the DM halo. • DM annihilates – rapidly as its densities increase • At a high enough DM density – the DM heating overwhelms any cooling mechanisms which stops the cloud from continuing to cool and collapse.

Basic Picture Continued • Molecular Hydrogen core forms – supported by DM annihilation • More DM and gas accretes onto the core – Creating a massive Optically thick Ionized cloud • supported by DM annihilation. • If Fusion – Star • But DM Powered – Dark Star • DM in the star comes from 2 different mechanisms – Adiabatic Contraction – DM capture.

Outline • The First Stars- standard picture • Dark Matter • Particle physics-The LSP (lightest SUSY particle) • Astrophysics- Density Profile • 3 Conditions forming Dark Stars • Properties of Dark Stars • Observational features – JWST

First Stars: Standard Picture • Formation Basics: – First luminous objects ever. – At z = 10 -50 – Form inside DM haloes of ~106 M • Set by cooling by molecular hydrogen – Baryons 15% of the Halo Mass – Formation is a gentle process Made only of hydrogen and helium from the Big Bang. Dominant cooling Mechanism is H 2 Not a very good coolant (Hollenbach and Mc. Kee ‘ 79)

Adiabatic Contraction vs. Simulations adiabatic phase Must be cool to collapse! 104 T [K] H 2 formation line cooling 　(NLTE) 103 loitering (~LTE) 102 3 -body reaction collision induced emission adiabatic contraction Heat opaque to release molecular line number density opaque to cont. and dissociation

Time increasing Density increasing ABN 2002

0. 3 Mpc Naoki Yoshida

Self-gravitating cloud Eventually exceed Jeans Mass of 1000 Msun 5 pc Yoshida

A new born proto-star with T* ~ 20, 000 K r ~ 10 R !

Scales • Halo Baryonic Mass ~ 105 M • Jeans Mass ~ 103 M • Initial Core Mass ~ 10 -3 M feedback effects Mc. Kee and Tan 2008 (Halo Mass 106 M ) Accretion With DM heating Much more massive Final stellar Mass? ? 100 M Standard Picture 103 - 107 M Dark Star

Dark Matter Good news: cosmologists don't need to "invent" new particle: • Weakly Interacting Massive Particles (WIMP)s – – • Axions – • e. g. the nuetralino (LSP) WIMP Miracle Pecci-Quinn Solution to the strong CP problem Primordial Black Holes – First order phase transitions (GUT models, Electro-Weak Phase transition)

LSP Weakly interacting DM • Sets Mass 1 Gev-10 Te. V (take 100 Ge. V) • Sets annihilation cross section (WIMPS): – Relic Density • Later we also consider scattering (use cross sections consitent with experiments)

Three Conditions for Dark Stars (Spolyar, Freese, Gondolo 2007 aka Paper 1) • I) Sufficiently High Dark Matter Density ? • 2) Annihilation Products get stuck in star ? • 3) DM Heating beats H 2 Cooling ? New Phase

Adiabatic Contraction Further Boost DM densities • Adiabatic contraction (Blumenthal prescription): – As baryons fall into core, DM particles on circular orbits conserves angular momentum Baryons of course do not! • we likefind that the Profile steepens and roughly scales (From Blumenthal, Faber, Flores, and Primack ‘ 86)

Three Conditions for Dark Stars (Paper 1) • I) OK! High Dark Matter Density • 2) Annihilation Products get stuck in star? in star • 3) DM Heating beats H 2 Cooling? Leads to New Phase

Dark Matter Heating rate: Fraction of annihilation energy deposited in the gas: Previous work noted that at annihilation products simply escape (Ripamonti, Mapelli, Ferrara 07) 1/3 electrons 1/3 photons 1/3 neutrinos Depending upon the densities.

Crucial Transition • • At sufficiently high densities, most of the annihilation energy is trapped inside the core and heats it up When:

Three Conditions for Dark Stars (Paper 1) • 1) OK! Sufficiently High Dark Matter Density • 2) OK! Annihilation Products get stuck in star beats. H 2 Cooling? • 3) DM DM Heating beats New Phase

New proto-Stellar Phase: fueled by dark matter One zone Model Freese et al ‘ 08 • Yoshida etal. 2007 With N. Yoshida

Following DS Evolution • Gas Accretes onto molecular hydrogen Core, the system eventually forms a star. • We then solve for stellar Structure by: – Self consistently solve for the DM density and Stellar structure – (Overly Conservative) DM moves only on circular orbits. We later relax this condition

Low Temperature > 104 K Gravity turns on 779 M DM runs out (716 M ) High Temperature ~ 105 K

DS Basic Picture (Circular Orbits Only and No Capture) • We find that DS are: – Only weakly dependant upon DM mass – – Massive ~1000 M Large-a few a. u. Luminous between ~107 M Cool: 10, 000 K vs. 100, 000 K plus • Will not re-ionize the universe. • Also allows the star to grow bigger than a Pop III star – Long lived: ~106 years. – With Capture or non-circular orbits, could be very different.

Capture: More DM • n (number density of DM) cm-3 • n (number density of H) cm-3 • V(r) escape velocity at a point r Press, Spergel 85 & Gould 88 • velocity of the DM • c scattering cross section First Stars Freese etal 2009, Iocco 2009

Minimal Capture Case Capture turns on once the DS goes onto the MS 50 % DM heating 50 % Nuclear

Super Massive Dark Star • In general one power source will dominate – Previously artificially matched DM heating with fusion • If DM heating Dominates: – DM densities sufficiently high or scattering cross sections sufficiently large then: • Star cool (50, 000 K) (Assuming Sufficient DM) • Very massive (105 M ) • Very Luminous (109 L ) – Similar result as with • Umeda, Yoshida, Nomoto, Tsuruta, Sasaki, and Ohkubo (2009) • Consider Only capture – GR Instability (not likely DM helps stabilize star) – Avoids fusion and re-ionization? • Until DM reservoir depleted or disrupted • Maximum time Scale (10 -100 Myrs) due to mergers

How Much? • The DM reservoir can be significantly enhanced from a few to 104 more over a spherically symmetric halo – depending upon the global structure of the halo axisymmetric vs triaxial – (Magorrian & Tremaine 1999, Merritt & Poon 2004) • Potentially this could be even larger due to additional orbits becoming chaotic as found in the Valluri et al. 2010 – This effect will be further studied by (Freese and Valluri 2010) • Hence DM is not annihilated away. • Dark Stars can become Super Massive

JWST Extended AC JWST limits As one example

Tentative Hints • Eventually DS runs out of DM or Displaced from DM reservoir (star goes onto the main sequence and eventually collapses to a BHs – Progenitors of super massive black holes • Get the metallicity right for low metallicity stars, IGM, ICM and M 82 – Depending upon spin of star Ohkubo, Umeda, Maeda, Nomoto, Tsuruta, Rees (2006)

Conclusion • Dark stars can be dramatically different than typical first stars • 3 conditions formation – High enough, thick enough, and heating beating colling • They can be progenitors for SMBHs • Possibly detectable w/ JWST

Time increasing Density increasing ABN 2002

DM profile and Gas Profile Envelope Gas densities: Black: 1016 cm-3 Red: 1013 cm-3 Green: 1010 cm-3 Blue: Original NFW Profile Z=20 Cvir=2 M=7 x 105 M ABN 2002