1. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 SENSITIVITY OF THE FERMI DETECTORS TO GAMMA-RAY BURSTS FROM EVAPORATING PRIMORDIAL BLACK HOLES (PBHs) T. N. Ukwatta, Jane H. MacGibbon, W. C. Parke, K. S. Dhuga, A. Eskandarian, N. Gehrels, L. Maximon, D. C. Morris and Stephen Rhodes JANE H MACGIBBON UNIVERSITY OF NORTH FLORIDA

2. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 BLACK HOLES IN THE UNIVERSE GALACTIC CENTERS: Supermassive BHs M ~ 10 38 – 10 43 g r s ~ 10 -3 - 10 3 AU INTERMEDIATE MASS BLACK HOLES?: M ~ 10 37 g r s ~ 10 3 km STELLAR COLLAPSE: M ~ 10 34 – 10 35 g r s ~ 10 - 10 2 km PRIMORDIAL BLACK HOLES?: M ~ 10 -5 – 10 43 g r s ~ 10 -33 cm - 10 3 AU

3. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 PRIMORDIAL BLACK HOLES FORMATION MECHANISMS Collapse of Overdense Regions - Primordial Density Inhomogeneities - Inflation, Soft Equation of State, Cosmological Phase Transitions Colliding Bubbles of Broken Symmetry Oscillating Cosmic Strings Collapse of Domain Walls

4. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 PBH FORMATION BH mass up to ~ cosmic horizon mass at formation If form from Scale-Invariant Density Perturbations

5. PBH LIMITS Constraints on β = fraction of regions of mass M which collapse Graph: Carr (2005)

6. PBH LIMITS Constraints on ε = fractional overdensity of formation regions Graph: Carr (2005)

7. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 BLACK HOLE THERMODYNAMICS HAWKING TEMPERATURE: Solar Mass BH T BH ~ 10 -7 K M BH ~ 10 25 g T BH ~ 3 K CMB HAWKING RADIATION FLUX:

8. HAWKING RADIATION Sources: Page, Elster, Simkins

9. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 TOTAL BLACK HOLE EMISSION MASS LOSS RATE: BLACK HOLE LIFETIME: Mass of PBH whose lifetime equals age of Universe (MacGibbon, Carr & Page 2008):

10. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 STANDARD PICTURE BH should directly evaporate those particles which appear non-composite compared to wavelength of the radiated energy (or equivalently BH size) at given T BH As T BH increases: BH directly emits photons + gravitons  + neutrinoes  + electrons  + muons  + pions Once T BH >>Λ QCD : BH directly emits quarks and gluons (not direct pions) which shower and hadronize into astrophysically stable γ, ν, p, pbar, e -, e +

11. BH EMISSION SPECTRA Source: MacGibbon and Webber (1990)

12. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 BH EMISSION SPECTRA Photosphere/Chromosphere Models (due to interactions between emitted particles) eg Heckler, Cline and Hong, Kapusta and Daghigh, Belyanin et al, Bugaev et al MacGibbon, Carr and Page 2008: None of the photosphere/chromosphere models work because they neglect the requirement that the emitted particles must be in causal contact to interact and neglect LPM effects in any multiple scatterings; Also no quark-gluon plasma when T BH ~ Λ QCD

13. BH EMISSION SPECTRA Source: MacGibbon and Webber (1990)

14. Astrophysical Spectra from Uniformly Distributed PBHs with dn/dM i α M i -2.5 Source: MacGibbon and Carr (1991)

15. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 ASTROPHYSICAL SPECTRA GAMMA RAY EXTRAGALACTIC BACKGROUND (Carr & MacGibbon 1998): IF PBHS CLUSTER IN GALACTIC HALO: Local density enhancement Galactic Halo Gamma Ray Background (Wright 1996) Antiprotons, Positrons Antimatter interactions, Microlensing

16. ANTIPROTONS Barrau et al (2002)

17. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 ASTROPHYSICAL SPECTRA CAN BURSTS FROM INDIVIDUAL BLACK HOLES AT THE END OF THEIR LIFE BE DETECTED? Greater detection probability if number density of PBHs is locally enhanced WHAT WOULD PBH BURST SIGNAL LOOK LIKE?

18. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 PBH Bursts PBHs Expiring Today: (independent of formation spectrum) Number Expiring: Remaining lifetime for given T BH :

19. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 PBH as Seen by Ideal Detector Photon Flux from BH: Photon flux per unit area reaching Earth from BH at distance d: If detector of effective area A eff requires X photons over time t to register burst, need i.e. BH must be closer than

20. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 PBH as Seen by Ideal Detector What T BH maximizes chance of detection? Take maximum t to be remaining BH lifetime τ evap. Then BH will be detected by ideal detector if it is closer than distance d:  Detectability is maximized for lowest T BH BH visible above background and/or by using longest detector exposure time

21. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 PBH as Seen by Ideal Detector For detector of angular resolution Ω to resolve BH above background F γ : Take EGRET background: Then BH will be resolved above background by ideal detector if it is closer than distance d:

22. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 Comparison of Detectors To detect, BH must be closer than: Scanned volume where ω A is detector acceptance angle (field of view). To resolve above background, BH must be closer than: Number that may be Expiring Today: Air Shower Detectors: large A eff but small ω A, large Ω, background-limited Fermi: smaller A eff ~ 0.8 m 2 but large ω A, small Ω ~ 1 °, good time resolution, lower energy threshold, background-free

23. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 FERMI Gamma-Ray Space Telescope launched June 2008 detectors: Gamma-ray Burst Monitor (GBM) Large Area Telescope (LAT)

24. PBH Bursts Source: MacGibbon and Webber (1990) Fermi LAT Energy Range: 20 MeV – 300 GeV

25. T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009 Detecting BH Bursts with LAT Spectral Lag Method: Compare light curve in two energy bands Does not need many counts because not reconstructing full spectrum BH burst will show positive to negative evolution with increasing energy (T BH increases with time as BH loses mass and )