Daniel Whalen
McWilliams Fellow in Cosmology
Carnegie Mellon University

My Collaborators
• Chris Fryer (CCS-2 LANL)
• Daniel Holz (University of Chicago)
• Massimo Stiavelli (JWST / STSci)
• Candace Joggerst (T-2 LANL)
• Lucy Frey (XTD-6 LANL)
• Catherine Lovekin (T-2 LANL)
• Alexander Heger (University of Minnesota)
• Wes Even (XTD-6 LANL)

The WMAP Cosmic Microwave
Sky: a Baby Picture of the Universe ( t ~ 400,000 yr)

The Universe at Redshift 20
128 kpc comoving

Sites of First Star
Formation
~ 200 pc 100 pc
Filamentary Inflow
Into a Virialized Halo z ~ 20

• Enzo is now a public community research code applied by many research groups to a variety of astrophysical fluid dynamics problems
• PM dark matter / PPM hydro code
• includes cosmological expansion
• multispecies primordial chemistry and atomic/molecular cooling processes
• uniform ionizing and dissociating radiation backgrounds
• self-gravity
• Compton cooling due to CMB
• now has radiative transfer and magnetic fields

density 0.6 pc 0.06 pc protostar
1200 AU disk temperature

• believed to mostly form in isolation (one per halo), but
Pop III binaries have been found to form 20% of the time in recent simulations
• very massive (25 - 500 solar masses) due to inefficient
H
2 cooling during formation
• T surface
~ 100,000 K
• extremely luminous sources of ionizing and LW photons
(> 10 50 photons s -1 )
• 2 - 3 Myr lifetimes

Whalen, Abel & Norman 2004, ApJ, 610, 14

Primordial Ionization Front Instabilities
Whalen & Norman 2008, ApJ, 675, 644

Heger & Woosley 2002, ApJ 567, 532

Mixing & Fallback in
15 – 40 M sol
Pop III SNe
Joggerst, .., Whalen, et al 2010
ApJ 709, 11

Mixing in 150 –
250 M sol
PI SNe
Pop III
Joggerst & Whalen 2011,
ApJ, 728, 129

Stellar Archaeology: EMP and HMP Stars
• Hyper Metal-Poor (HMP) Stars:
-5 < [Fe/H] < -4  thought to be enriched by one or a few SNe
• Extremely Metal-Poor (EMP) Stars:
-4 < [Fe/H] <-3  thought to be enriched by an entire population of SNe because of the small scatter in their chemical abundances

• original non-rotating stellar evolution models predict a strong ‘odd-even’ nucleosynthetic signature in PISN element production
• to date, this effect has not been found in any of the EMP/HMP surveys
• intriguing, but not conclusive, evidence that Pop III stars had lower initial masses than suggested by simulation
• this has directed explosion models towards lower-mass stars
Heger & Woosley 2002

Elemental Yield Comparison to HMP Stars

IMF-Averaged Yields and the EMP Stars

• 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 0.0005 pc to 1 kpc
• include the dark matter potential of the halo
Whalen, et al 2008, ApJ, 682, 49

• 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

Primordial SNe in Relic H II Regions: Enrichment of the Dense Shell
Reverse Shock Collision with the Shell:
Fragmentation?

Explosions in Neutral Halos: Containment
Late Radiative Phase Fallback

SN Remnant Luminosity Profile in an H II Region

SN Remnant Luminosity Profile in a
Neutral Halo

• 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

LANL Pop III Supernova Light Curve Effort
Whalen et al. ApJ 2010a,b,c in prep
• begin with 1D Pop III 15 – 40 M sol
PI SN blast profiles
CC SN and 150 – 250 M sol
• evolve these explosions through breakout from the surface of the star out to 6 mo (CC SNe) or 3 yr (PI SNe) in the LANL radiation hydro code RAGE (Radiation Adaptive Grid Eulerian)
• post-process RAGE profiles with the LANL SPECTRUM code to compute LCs and spectra
• perform MC Monte Carlo models of strong GL of z ~ 20 SNe to calculate flux boosts
• convolve boosted spectra with models for absorption by the Lyman alpha forest and JWST instrument response to determine detection thresholds in redshift

RAGE
• LANL ASC code RAGE (Radiation Adaptive Grid Eulerian)
• 1D RTP AMR radiation hydrodynamics with grey/multigroup
FLD and Implicit Monte Carlo transport
• 2T models (radiation and matter not assumed to be at the same temperature)
• LANL OPLIB equilibrium atomic opacity database
• post process rad hydro profiles to obtain spectra and light curves

Post Processing Includes Detailed LANL Opacities but the atomic levels are assumed to be in equilibrium, a clear approximation

Our Grid of Pop III SN Light
Curve Models
• 150, 175, 200, 225, and 250 M sol
PI SN explosions, blue and red progenitors, in modest winds and in diffuse relic H II regions (18 models)
• 15, 25, and 40 M sol
CC SN explosions, red and blue progenitors, three explosion energies in relic H II regions only
• red and blue progenitors span the range of expected stellar structures for Pop III stars
• core-collapse KEPLER blast profiles are evolved in 2D in the CASTRO AMR code first up to shock breakout to capture internal mixing —these profiles are then spherically averaged and evolved in RAGE to compute LCs

u150 u200 u175 u225

PISN Shock Breakout
• 150 – 1200 eV fireball temperature
• transient (a few hours in the local frame)

Spectra at
Breakout
The spectra evolve rapidly as the front cools

Long-Term
Light-Curve
Evolution even the lowest energy PISN at z ~ 10 produces a large signal in the JWST NIR camera over the first 50 days

Late Time Spectra spectral features after breakout may enable us to distinguish between
PISN and CC SNe larger parameter study with well-resolved photospheres is now in progress

Conclusion s
• PISN will be visible to JWST out to z ~ 10 ; strong lensing may enable their detection out to z ~ 15 (Holz, Whalen & Fryer 2010
ApJ in prep)
• dedicated ground-based followup with 30-meter class telescopes for primordial SNe spectroscopy
• discrimination between Pop III PISN and Pop III CC SNe will be challenging but offers the first direct constraints on the Pop III IMF
• complementary detection of Pop III PISN remnants by the SZ effect may be possible (Whalen, Bhattacharya & Holz 2010, ApJ in prep)