Hypothesis for the Supernova Origin of Cosmic Rays

1
Hypothesis for the Supernova Origin of Cosmic Rays

• Local energy density of CR
• uCR ? 1 eV cm-3 ? 10-12 ergs cm-3
• Cosmic ray power requirements
• LCR ? uCRVgal/tesc ? 5?1040 ergs s-1
• Galactic volume
• Vgal ? ?(15 kpc)2?200 pc ? 4?1066 cm3
• Cosmic ray escape time from galaxy
• tesc ? L/rc ? 10 gm-cm-2 / (mp 1 cm-3 c) ?
  6?106 yr
• (information from 10Be used to determine mean
  density ? smaller r and larger Vgal)
• Galactic SN luminosity 1 SN/ 30 yrs ? 1051 ergs
  in injection energy ?
• LSN ? 1042 ergs/s

2
No Observational Evidence for Hadronic CR
Component

• Unidentified EGRET sources are not firmly
  associated with SNRs and do not display p0
  features pp ? p0 ? 2g (70 MeV)
• TeV g rays not detected at expected levels
• Spectrum of diffuse galactic g-ray background
  harder than expected from locally observed CRs
• Origin, composition, and spectrum of CRs at and
  above the knee of the CR spectrum unexplained

3
Where have all the Hadrons Gone?

• It is a matter of some disappointment for the
  many cosmic-ray physicists who entered the field
  of high energy g-ray astronomy that none of the
  sources detected can be positively identified
  with hadron progenitors. In the early days it was
  widely believed that g-ray astronomy would
  finally solve the mystery of the cosmic
  radiationIn no source is the much heralded
  bump in the energy spectrum near 70 MeV seen.
• while we have learned some interesting
  astrophysics we have come no closer to a
  definitive model of cosmic-ray origin.

T. Weekes, in GeV-TeV Gamma Ray Astrophysics
Workshop, ed. B. L. Dingus, M. L. Salamon, and D.
Kieda (2000)
4
Ultra-High Energy Cosmic Rays from GRBs?

• GRBs are extragalactic

• BATSE (Meegan et al. 1992) no evidence for
  anisotropy in directions to different GRBs
• Peak count size distribution deviates from -3/2
  size distribution

• N ? fp-3/2

Implied geometry We are at the center of a
spherical, bounded distribution. Most natural
geometry is entire universe, with reduction of
faint GRBs due to cosmological effects
GRB Peak Count Rate Distribution
5
Waxman-Vietri Coincidence
Waxman (1995) Vietri (1995)

• Typical fluence and rate of BATSE GRBs
• Fg ? 10-6 ergs cm-2 NGRB ? 1/day
• If weakest GRBs at z 1, then d ? 1028 cm
• Eg ? 4pd2 Fg ? 1051 ergs EGRB ? 1052 ergs
• UHECRs lose energy due to photomeson processes
  with CMB
• p g ? p p0 , n p
• GZK Radius x1/2 (1020 eV) ? 140 Mpc
• Energy density within GZK Radius
• uUHECR ? z eGRB (x1/2 /c) ?
• z EGRB (140 Mpc/c) ?
  z 5?10-22 ergs/cm3

.
Stanev et al. (2000)
____________________
day?(4p/3)(1028cm)3
6
GRB Power into the Milky Way

• Average GRB emissivity
• Density of L galaxies
• If Milky Way is an L galaxy, then GRB power into
  the Milky Way is
• LGRB ? 2?1038 ergs s-1
• This value is lt 1 of required CR power. Is it
  impossible for GRB progenitors to make the cosmic
  rays?
• Require better statistical treatment of GRBs

• eGRB ? 3?10-38 ergs/(cm3-s) ? 3?1052
  ergs/(Gpc3-yr)

• 1 L/(200 Mpc3)

• Proton Larmor radius

rL ? 2 pc /BmG at E 2 ?1015 eV
(knee) rL ? 10 kpc /BmG at E 1019
eV (UHECRs)
7
Gamma Ray Bursts and the Origin of Cosmic Rays
C. Dermer (Naval Research Laboratory)

• Gamma Ray Bursts
• Produced by collapse of massive stars
• GRB/Supernova connection
• New statistical treatment of GRBs within the
  External Shock Model (M. Böttcher
  CD 2000)
• Waxman/Vietri coincidence remains
• If GRB/UHECR hypothesis is valid
• Predictions for neutrino production
• Predictions of radiation halos around GRB-active
  galaxies
• Cosmic Rays from GRBs Can GRBs make all Cosmic
  Rays?
• If GRBs are Birth Event of Black Holes
• GRB statistics ? Number of Black Holes in the
  Galaxy
• Unidentified EGRET g-Ray Sources Isolated
  Accreting Black Holes

8
Redshift Distribution
Costa et al. (1999)
GRB 970228

• 12 GRBs with Measured Redshifts

Beppo-Sax X-ray afterglow discovery allowing
counterpart identification
Redshift Distribution
9
Connection of GRBs to Star Forming Regions and
Supernovae

• Blue excesses in GRB host galaxies
• GRB optical counterparts coincident with center
  or spiral arms of galaxy hosts
• X-ray afterglows with no optical counterparts
  (due to extinction)

• Weak evidence for Fe Ka line in X-ray afterglow
  spectra
• Spatial and temporal coincidence of GRB 980425
  with SN 1998bw (Type Ic)
• Reddened supernova emission in late time optical
  afterglow spectra

Reichart (1999)
10
GRBs Duration and Peak Energy Distributions
Sample of Different GRB Light Curves

• Light Curves and Durations

GRB Duration Distribution
Kouveliotou et al. (1993)
t (s)
0 2 4 6 8
Peak Energy Distribution
Epk Peak energy of nFn Distribution
Spectra
?
?
Mallozzi et al. (1997)
Epk
Epk
Schaefer et al. (1998)
11
Fireball/Blast Wave Model for GRBs
Observation large energy releases and
powers Explanation Deposit energy in small
region to form pair fireball. Fireball
adiabatically expands and reaches coasting
velocity determined by baryon loading.

• Initial Lorentz factor G0 E/Mbc2
• To avoid gg transparency,
• G0 gt 100
• Charged particles captured by blast wave receive
  energy G in comoving frame
• Protons carry bulk of energy due to their larger
  mass

External Shock Model Single explosive event
12
Numerical SimulationStandard Model
8
1

• Two peaks in nFn distribution
• Generic rise in intensity until tdec, followed by
  constant or decreasing flux except in
  self-absorbed regime
• Dominant SSC component for this parameter set

opt
1
rad
3 keV
100 keV
GeV
TeV
8
Chiang and Dermer (1999)
13
External Shock Model Reproduces Smooth Profiles

• Reproduces generic temporal behavior of so-called
  FRED (fast rise/exponential decay-type) light
  curves and GRB phenomenology
• Synchrotron-shock model reproduces time-averaged
  gamma-ray spectra of GRBs (Tavani 1996 Cohen et
  al. 1997)

14
Variability in GRB Light Curves

• Interaction of blast wave with clouds or
  progenitor wind produces pulses with mean
  duration determined by special relativistic time
  delays
• Peak flux reached depends strongly on angle with
  respect to line-of-sight

• Monte Carlo Simulation

• Require cloud radii ltlt R/G

• Clouds with thick columns
• (gt 4x1018 cm-2)
• Total cloud mass small (ltlt10-4 Mo)

Dermer and Mitman (ApJ, 1999, 513, L5)
15
Statistics of GRBs MonoParametric Results

• Assume that distribution of GRB progenitors
  follows star formation history of universe (Madau
  et al. 1998)
• Trigger on 1024 ms timescale using BATSE trigger
  efficiencies (Fishman et al. 1994)
• E54 0.5 G0 240
  n2 1 q 5x10-4
• Vary radiative regimes g

Data Meegan et al. 1996
Data Mallozzi et al. 1997
Data Kouveliotou et al. 1993
Radiative regime g 1.6 (solid), 1.8 (dashed),
2.1 (dot-dashed), and 2.8 (long-dashed)
16
Statistics of GRBs Fits to Data

• Broad distributions of baryon-loading G0 and
  directional energy releases are required. Assume
  power laws for these quantities.
• 10-6 lt E54lt 1 N(E54) ? E54-1.52 G0 lt 260
  N(G0) ? G0 -0.25

• Equally good fits if n0G0 8 is constant
• ? Fireball event rate of 440 GRBs yr-1 Gpc-3 or
  92 Galactic events per Myr or ? 1 Fireball
  Transient (FT) every 5000 years
• Events with G0 ltlt 100 not detected as GRBs (dirty
  fireballs)
• Only nearby weak events detected
• (Does not explain short population of GRBs )

Böttcher Dermer (ApJ, 2000, 529, 635)
17
Fireball Transients Rates and Emissivities
.

• nFT(E52,G0z) FTs/(Gpc3 -yr - G0 - E52 )
  dNFT/dVdt E52 dG0 0.022 S(z) E52 -1.52 G0
  -0.25 10-4 lt E52lt 100 1 lt G0 lt 260

S(z)
.

• FT Rate nFT(z 0) 440 Gpc-3 yr-1 Earlier
  estimate 1 GRB/day ? 2 Gpc-3 yr-1
  4p/3(1028 cm)3
• ? Many weak undetected FTs, similar to GRB
  980425 FT emissivity eGRB (z 0) ?
  3.6?1053 ergs/(Gpc3-yr)
• Waxman-Vietri coincidence remains valid
• Represents 5 of power needed to supply galactic
  CRs
• Average energy of FT 8?1050 ergs
• One-half of FT emissivity comes from FTs with E ?
  2?1053 ergs (very rare)

______________
.
18
Fireball Transients and Supernovae

• FT rate ? 0.006 SNu, where SN unit SNu is of
  events/(1010 Lo,B-102 yr)
• If FTs are related to SNe of a given type,
• Type II SNe - Type Ib/c SNe

MFTgt MSNgtSnu(SN) 1/aIMF
________
Scalo and Wheeler (2000)
Snu(FT)
MFTgt/M0 ?115(?60), aIMF1.3
MFTgt/M0 ?400(?200)
140(?70)
60(?30), aIMF1.8

• aCapellaro et al. (1999) Panagia (2000) aFT
  rate assumed to be equally divided between two
  groups

19
Neutral Particle Production in GRB Blast Waves

• Assume UHECR/GRB hypothesis valid. ? protons
  with g ?1010 in GRBs
• Photomeson production with synchrotron photons in
  comoving frame
  p g ? n
  p ? ? ? m nm ? ?? p
  e- ne
• Competing processes
• Proton synchrotron radiation
• Secondary pion production

_
t1/2103 s
?? e ne nm
_
20
Standard Parameter Sets
a b_

• Total Energy E0 (ergs) 2?1053 2?1053
• Initial Lorentz factor G0 300 300
• Electron energy transfer ee 0.5 0.1
• Magnetic field parameter eB 10-4 10-1
• Density n0(cm-3) 100 100
• Particle injection index p 2.2 2.2
• Nonthermal proton fraction x 0.5 0.5

21
Neutron and Neutrino Production Spectra

• Instantaneous and Time-Integrated Production
  Spectra of Neutrons and Neutrinos from a Single
  GRB

• Most of the energy carried by a few, very high
  energy particles

22
Production Efficiencies for Neutrons and Neutrinos

• Calculate fraction of total explosion energy that
  emerges in the form of high-energy neutrinos and
  neutrons
• For E0 gt 2?1053 ergs,
• Neutron production efficiency gt 1
• Neutrino production efficiency gt 0.1
• ? 1 GRB explosion with E0 gt 2?1053 ergs every 5
  million years in an L galaxy

23
Production Time Profiles

• Most energy in neutral particles released in
  afterglow phase

24
Diffuse Neutrino Background from GRBs and FTs

• Parameter sets A (solid) and B (dotted) for
  diffuse neutrino background produced by fireball
  transients and GRBs.

25
Neutrino Event Rate in km2 Detector

• Calculations of expected event rate of neutrinos
  from GRBs for a 1 km2 detector for parameter sets
  A (solid) and B (dotted).

26
Radiation Halos from Neutrons Produced by FTs
_

• Neutron b-decay n? p e- ne If the bulk
  of the energy is carried by neutrons with gn
  1010 g10, neutron travels a distance rn ? 100
  g10 kpc.
• Three types of neutron-decay halos
• Type b-halos due to neutron-decay b- electron
  radiation
• Type p-halos due to neutron-decay proton
  radiation
• Type n-halos due to neutron-decay neutrinos
• Maximum luminosity of b-halos and p-halos
• Halos from a single GRB persist for gt 1000 gn s ?
  3x105 g10 yrs ? gt 8 g10 of L galaxies have
  neutron-decay halos

Lhalomax ? 1035 (m/me)(E54 /g10) ergs s-1
27
Synchrotron and Compton b Halos

• Inject nonthermal electrons with g ? g n
• Produce nonthermal synchrotron radiation,
  depending on strength of halo magnetic field
• Produce nonthermal g rays from Compton scattering
  of CMB
• g rays materialize through gg? ee-
• form extended pair and gamma-ray halo
• Relative strengths of synchrotron and Compton
  Halos give strength of halo magnetic field
• Potentially much brighter signal from p-Halos

28
Spatially Integrated Synchrotron and Thomson
b-Halos
gn,max 109

• B 1 mG 2.7 K CMB

29
Spatially Integrated Synchrotron and Thomson
b-Halos
gn,max 1011

• B 1 mG 2.7 K CMB

30
Prospects for Detecting Neutron-Decay Halos

• Maximum source distance of b-halo due to limiting
  sensitivity S(ergs cm-2 s-1 ) of detector
• X-ray/soft g-ray detection SOSSE 10-11 ergs
  cm-2 s-1 (not feasible for b-halo or p halo).
  SChandra 10-15 ergs cm-2 s-1 (best sensitivity
  for point sources)
• Optical detection halo is 6-9 orders of
  magnitude (15-22 magnitudes weaker) than stellar
  luminosity. At 100 Mpc, halo ? 3g10 arcmin
• Radio detection SVLA 10-18 ergs cm-2 s-1.
  However, synchrotron b-halo is not bright in
  radio unless magnetic field is small, and then
  most power is in Compton component. However, all
  L galaxies will have radio halos
• High energy g-ray detection SGLAST 10-13 ergs
  cm-2 s-1 (only feasible for p halo).

dlim (Lhalo/4pS)1/2 ? (E54/g10S-15)1/2 Mpc S
10-15S-15 ergs cm-2 s-1

• Detection would provide compelling evidence for
  UHECR/GRB hypothesis.

31
Black Holes from Fireball Transients

• If GRBs and FTs signal birth event of a black
  hole then gt 2?106
  black holes with masses gt 10-30 Mo are formed
  during the age of the Galaxy
• Gravitational deflection will increase their
  scale heights
• Isolated accreting black holes that accrete from
  ISM could be cause of unidentified EGRET g-ray
  sources (Dermer 1997, 2000 Armitage and Natarjan
  1999)

Low and mid-latitude unidentified g-ray sources
acrrete from molecular clouds and dilute ISM,
respectively.
No new population of mid-latitude g-ray sources
(Gehrels et al. 2000) is required
Credit R. C. Hartman and EGRET team
32
Gamma-Ray Bursts Sources of Hadronic Cosmic Rays?

• Galaxy-averaged emissivity represents 5 of power
  needed for galactic cosmic radiation. However
  estimate neglects
• Potential contribution from undetected clean and
  dirty fireballs
• Temporal stochastic variations
• Enhancements due to preferential location

33
Hypothesis that Cosmic Rays Originate from
GRBs(astro-ph/0005440)

• Cosmic rays come from an extreme and rare type of
  SN
• Stellar progenitors of FTs and GRBs have masses
  gt60 Mo
• Sources of GRBs spin-stabilized core of 2-50 Mo
  Fe core that collapses to a nuclear fluid and
  then to a black hole.

• Require enhanced FT emissivity in neighborhood of
  Solar system for hypothesis to be plausible
• Gould belt enhancement
• Evidence from sedimentation layers in deep sea
• Strong biological effects of GRBs
• Episodic dosages of high-energy radiation
  stimulate species variation
• Anthropic favoritism improves chances for
  sentient creatures to evolve

34
Observable Phenomena from GRBs

• Statistical study implies 1 GRB (4p/DW)/(104
  yr) with a mean energy of 8x1050 (DW/4p) ergs per
  GRB.
• Energy input into MW Galaxy gt 8x1050 ergs/104
  yr 3 x 1039 ergs/s (factor of 20 greater than
  previous studies)

• hypernova remnants in nearby galaxies or Milky
  Way (e.g. luminous X-ray sources in M101 Wang
  1999)
• remnant ages lt 106 yrs
• total energies gt 1052-1053 ergs
• HI shells, stellar arcs (Efremov et al. 1998
  Loeb and Perna 1999)

35
GRBs Near Massive Stars

• Massive star h Carinae most likely progenitor of
  GRB. Thomson-thick clouds lt 1016 cm from central
  star flash-heated by GRB
• Photon front photoionizes and Compton-scatters
  ambient electron. Back-scattered photons
  pair-produce with successive waves of photons
• Make pair plasma which expands and cools. Pair
  efficiency of 0.1 of 2.6 x 1039 ergs/s can
  produce 4x1042 annihilation photons per second
  observed in Galaxy

Dermer and Böttcher (2000)