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BLACK HOLES IN THE UNIVERSE

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.

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BLACK HOLES IN THE UNIVERSE

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  1. 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 T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009

  2. BLACK HOLES IN THE UNIVERSE GALACTIC CENTERS:Supermassive BHs M ~ 1038 – 1043 g rs ~ 10 -3 - 103 AU INTERMEDIATE MASS BLACK HOLES?: M ~ 1037 grs ~ 103 km STELLAR COLLAPSE: M ~ 1034 – 1035 g rs ~ 10 - 102 km PRIMORDIAL BLACK HOLES?: M ~ 10 -5 – 1043g rs ~ 10 -33 cm - 103 AU T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009

  3. PRIMORDIAL BLACK HOLESFORMATION 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 T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009

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

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

  8. HAWKING RADIATION Sources: Page, Elster, Simkins

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

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

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

  12. 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 TBH ~ ΛQCD T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009

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

  14. Astrophysical Spectra from Uniformly Distributed PBHs with dn/dMi αMi-2.5 Source: MacGibbon and Carr (1991)

  15. 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 T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009

  16. ANTIPROTONS Barrau et al (2002)

  17. 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? T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009

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

  19. 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 Aeff requires X photons over time t to register burst, need i.e. BH must be closer than T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009

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

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

  22. Comparison of Detectors To detect, BH must be closer than: Scanned volume where ωA 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 Aeff but small ωA , largeΩ, background-limited Fermi: smaller Aeff ~ 0.8 m2 but large ωA , smallΩ ~ 1°, good time resolution, lower energy threshold, background-free T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009

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

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

  25. 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 (TBHincreases with time as BH loses mass and ) T.N. Ukwatta et al "Fermi Sensitivity to PBH Bursts" MG12 Paris July 12 - 18 2009

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