Finding The First Cosmic Explosions

1. Finding The First Cosmic Explosions Daniel Whalen McWilliams Fellow in Cosmology Carnegie Mellon University

2. 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)

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

4. The Universe at Redshift 20 128 kpc comoving

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

6. ENZO AMR Cosmology Code • 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

7. protostar density 0.6 pc 0.06 pc 1200 AU disk temperature

8. Properties of the First Stars • 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 • H2 cooling during formation • Tsurface ~ 100,000 K • extremely luminous sources of ionizing and LW photons • (> 1050 photons s-1) • 2 - 3 Myr lifetimes

9. Transformation of the Halo Whalen, Abel & Norman 2004, ApJ, 610, 14

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

11. Final Fates of the First Stars Heger & Woosley 2002, ApJ 567, 532

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

13. Mixing in 150 – 250 Msol Pop III PI SNe Joggerst & Whalen 2011, ApJ, 728, 129

14. 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

15. No PISN? • 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

16. Elemental Yield Comparison to HMP Stars

17. IMF-Averaged Yields and the EMP Stars

18. Recipe for an Accurate Primordial Supernova Remnant • 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

19. 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

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

21. Explosions in Neutral Halos: Containment Late Radiative Phase Fallback

22. SN Remnant Luminosity Profile in an H II Region

23. SN Remnant Luminosity Profile in a Neutral Halo

24. Conclusions • if a primordial star dies in a supernova, it will destroy • any cosmological halo < 107 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

25. LANL Pop III Supernova Light Curve Effort Whalen et al. ApJ 2010a,b,c in prep • begin with 1D Pop III 15 – 40 Msol CC SN and 150 – 250 Msol • PI SN blast profiles • 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

26. 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

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

28. Our Grid of Pop III SN Light Curve Models • 150, 175, 200, 225, and 250 Msol PI SN explosions, • blue and red progenitors, in modest winds and in • diffuse relic H II regions (18 models) • 15, 25, and 40 Msol 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

29. u150 u175 u200 u225

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

31. Spectra at Breakout The spectra evolve rapidly as the front cools

32. 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

33. 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

34. Conclusions • 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)