Primordial Supernovae and the Assembly of the First Galaxies Daniel Whalen Bob Van Veelen X-2, LANL Utrecht Michael Norman Brian O’Shea UCSD T-6, LANL arXiv:

Current Paradigms for the Formation of the First Galaxies assemble a few stars at a time as individual small dark matter halos, each hosting a solitary star, consolidate by mergers form stars consecutively, each in the relic H II region of its progenitor (O’Shea, Abel, Whalen & Norman 2005, Yoshida, et al 2007) in some cases, form stars in both the metals and H II regions of their predecessors (Greif, et al 2007, Wise & Abel 2007)

2 nd Star Formation in Relic H II Regions fossil H II regions of the first stars cool out of equilibrium, and their temperatures fall faster than they recombine H 2 and HD rapidly form in such circumstances, causing primordial gas to condense and fragment into new stars If HD cooling dominates, gas temperatures fall to the CMB, causing it to fragment on smaller mass scales than the parent star this process results in at most a few new stars forming in the halo of the progenitor on timescales less than merger times ( Myr at z ~ 20)

Yoshida, Oh, Kitayama & Hernquist 2007

Greif, et al 2007 Wise & Abel 2008 primordial 1 st generation stars explode in their H II regions in these numerical scenarios, metals are preferentially expelled into voids of low density in which star formation cannot occur protogalaxies are again built up a few stars at a time and are contaminated gradually as inflow and mergers carry metals back into halos, typically on timescales of Myr metallicities greater than solar can result in a direct rollover to a low mass 2 nd generation

Current numerical models fail to properly resolve primordial H II region and supernova dynamics, both of which may lead to a prompt second generation of stars Consequently, the first galaxies may have formed with far greater numbers of stars and different metallicities than now supposed

~ 200 pc Cosmological Halo z ~ 20

Properties of the First Stars thought to be very massive ( solar masses) due to inefficient H 2 cooling form in isolation (one per halo) T surface ~ 100,000 K extremely luminous sources of ionizing and LW photons (> photons s -1 ) Myr lifetimes new results extend Pop III lower mass range down to 15 solar masses (O’Shea & Norman 2007, ApJ, 654, 66)

Transformation of the Halo ZAMSEnd of Main Sequence

Primordial Ionization Front Instabilities

Final Fates of the First Stars Heger & Woosley 2002

Primordial Supernova in Cosmological Simulations: Neutral Halos temperatures skyrocket to 10 9 K at the center of the halo the hot, ionized, dense center emits intense bremsstrahlung x-rays the core radiates away the energy of the blast before it can sweep up its own mass in the halo They Fizzle! Yoshida & Kitayama 2005, ApJ, 630, 675

Recipe for an Accurate Primordial Supernova initialize blast with kinetic rather than thermal energy couple primordial chemistry to hydrodynamics with adaptive hierarchical timesteps implement metals and metal-line cooling use moving Eulerian grid to resolve flows from pc to 1 kpc include the dark matter potential of the halo Truelove & McKee 1999, ApJ, 120, 299

ZEUS-MP 1D Primordial Supernova: 9 Models Halos: 6.9 x 10 5, 2.1 x 10 6, and 1.2 x 10 7 solar masses Stars: 25, 40, and 200 solar masses (Type II, hypernova, and pair-instability supernovae) Stage 1: illuminate each halo for the lifetime of its star Stage 2: set off the blast and evolve the remnant for 7 Myr

4 SN Remnant Stages in H II Regions t < 10 yr: free-expansion shock 30 yr < t < 2400 yr: reverse shock 19.8 kyr < t < 420 kyr: collision with shell / radiative phase t > 2 Myr: dispersal of the halo

Reverse ShockCollision with the Shell

4 SN Remnant Stages in Neutral Halos t < 1 yr: free-expansion shock t < 20 yr: early radiative phase 100 yr < t < 5000 yr: late radiative phase t > 1 Myr: fallback

Late Radiative PhaseFallback

Enormous, Episodic Infall Rates During Fallback

Observational Signatures of Primordial Supernovae

Halo Destruction Efficiency

Conclusions if a primordial star dies in a supernova, it will destroy any cosmological halo < 10 7 solar masses supernovae in neutral halos do not fizzle--they seriously damage but do not destroy the halo primordial SN in H II regions may trigger a second, prompt generation of low-mass stars that are unbound from the halo blasts in neutral halos result in violent fallback, potentially fueling the growth of SMBH seeds and forming a cluster of low-mass stars

2D Metal Mixing Due to Radiative Cooling

Thanks!

Primordial Supernova in Cosmological Simulations: H II Regions the remnant collides with the dense H II region shell and later grows to half the radius of the H II region metals preferentially permeate voids neither metals nor gas return to the halo in less than a merger time (~ Myr) Star Formation is Postponed! Bromm, Yoshida & Hernquist 2003, ApJ, 596, 195L Grief, Johnson & Bromm 2007, ApJ, 670, 1