Probing the Highz Universe with GRB Multiwavelength Emission

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Probing the High-z Universe withGRB
Multiwavelength Emission
Susumu Inoue
?? ?
1. radio dispersion and cosmic reionization
history Inoue, MNRAS, in press
(astro-ph/0309364)
2. mm to IR emission and atomic/molecular
absorption Inoue Ciardi, in prep.
3. GeV gamma-ray absorption and high-z UV
background Inoue Miniati, in prep.
From radio, submm, IR to GeV gamma-rays
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From the dark ages to enlightenment what went on
at z30-z5?

• 1st generation star/quasar formation by H2/HD
  cooling
• feedback on 2nd generation
• H2 dissociation (UV) or catalysis (X-ray,
  cosmic ray)?
• SN heating/compression
• IGM reionization When? How? What?
• suppression of small galaxies
• metal enrichment ? transition to Pop II

quasar absorption troughsHI at z6
CMB polarization anisotropiesHII at z17
cooling of metal free gas
HHe
H2
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GRBs emission properties

• luminosity Lg1052-1054 f? erg/s
• (collimation f?????0????0?)

afterglow emission
prompt emission
fireball shock model
?
Meszaros 01,02
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GRBs as probes of the high-z universe
vs
quasars
GRBs

• bright, broadband
• steady
• more signal, but masks host
• less luminous, much rarer at higher z
• more massive, (spheroidal) host
• hazardous to environment

• broadband, brighter at peak
• transient
• less signal, but leaves host alone
• unique variability/delay signatures
• similarly (more?) luminous and
• abundant at higher z
• less massive, star forming hosts
• safer to environment

mass function of collapsed objects ?BHs, galaxies
e.g. Lamb Reichart 00, Ciardi Loeb
00 Barkana Loeb 03, Furlanetto Loeb 03
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radio dispersion and ionized IGM
dispersion measure pc cm-3
Inoue 03 MNRAS in press (astro-ph/0309364)
see also Ioka 03 Haddock Sciama 65, Weinberg
72 Ginzburg 73, Palmer 93
GRB
mean effect assuming homogeneous IGM
delay time hour
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discriminating reionization histories
delay time hour
gradual
Ciardi, Ferrara White 03
?obs30 MHz
two-epoch
Cen 03
at z10, Dt10 hour differences in Dt few hours
caveat low-z warm-hot IGMmay cause large
fluctuationsif l.o.s. covering fraction large
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dispersion in radio afterglows?
time-dependent spectra
strongly self-absorbed at low n?

• very low flux ltmJy
• rising light curve
• ? suppression of early flux

further complications scintillation by Galactic
ISM contamination by host galaxy emission source
confusion
light curve
extremely challenging to detect perhaps
marginally possible for rare, bright afterglows
with SKA
flux-redshift
reverse shock (radio flare) unimportant below
few GHz
extremely challenging, even with SKA
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coherent radio emission?
Sagiv Waxman 02
synchrotron maser in external shock not observed
yet need dense ambient media n104 cm-3 and low
magnetic fields eB/eelt10-6

• high flux Jy at z1
• duration 1 min, fast decay
• ?rest0.1-0.3 GHz

perfect for probing the reionization epoch!
LOFAR

• LOFAR can
• confirm emission at low z
• probe reionization history to z10 or higher!

stronger for denser ambient media and lower
ambient magnetic fields leads UV emission ?
unaffected by local ff absorption
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reverse shock emission
optical flash
Akerlof et al. 99 Sari Piran 99
1Jy at 100 s
afterglow
GRB 990123
radio flare
Kulkarni et al. 99
0.1 mJy at 1 day

• energy comparable with forward shock
• dissipated on shorter timescale
• DTGRB10-100s
• lower peak frequency nrnf /G2
• much brighter flux!

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mm to infrared emission and atomic/molecular
absorption
Inoue Ciardi, in prep.
c.f. Gou et al. 03

• GRBs at tfew hr are brightest in mm-IR
• peak flux 0.1-1 mJy, nearly constant for z5-30
  (redshifttime dilation)

• window of opportunity for studying reverse shock
• ? GRB physics (initial G, ejecta B)
• radio-IR atomic/molecular absorption lines?

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absorption lines
column densities
early galaxiesTvlt104K truncated isothermal
sphereTvgt104K exponential disk
primordial molecules?rotational lines (ground
state) assume NH1024 cm-2, Dv1 km s-1H2 (28
mm10.7 THz) t3.010-3 (xH210-3)HD
(112 mm2.68 THz) t2.510-3 (xHD10-8)LiH
(675 mm444 GHz) t1.410-3 (xLiH10-12)
Haiman et al. 00, Oh Haiman 02
very weak, but maybe not hopeless ALMA? EVLA,
SKA? SAFIR
H2 electronic lines of vib. excited states pumped
by GRB UV photons? (rltpc) c.f. Draine 00,
Draine Hao 02
Subaru/IRCS? JWST, SPICA?
BUT GRBs occur after massive star evolution Are
molecules still there?
lt-gt X-rays, cosmic rays
primordial atoms? assume NH1024 cm-2, Dv10 km
s-1Li I (6708A) t4.5102 (xLi10-9)but
very easily ionized
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absorption lines
column densities
heavy moleculesCO (0.26 cm115 GHz)
NCO(t??)1015 cm-2
EVLA, SKA
metals e.g. O I (1302A), Fe II (2383A), C I
(1334A)tgtgt1 (Z10-2.5Zsol)
Subaru/IRCS, JWST, SPICA
probe transition to Pop II
worthy of more study!
early galaxiesTvlt104K truncated isothermal
sphereTvgt104K exponential disk
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cosmology with GRBs summary
1. radio dispersion (especially coherent
emission, if it exists) probe of ionized IGM
-gt cosmic reionization history maybe
also low-z warm-hot IGM (combined with e.g. X-ray
abs. line) 2. mm to IR emission including
reverse shock at tfew hr, brightest in
mm-IR, peak flux mJy for z5-30 probe of
atoms/molecules at early epochs? 1st
generation probably difficult, but Pop II
transition promising 3. GeV gamma-ray
absorption potential probe of high-z UV
background (Pop III?)

• Brightest objects by far in the early universe-
  why not use them?
• Basic emission properties can be described by
• simple and robust models
• (or at least were ignorant of complicating
  details at this moment)
• The entire electromagnetic spectrum is the
  limit!
• SWIFT will be up soon-
• nows the time to think and have fun!

GRB
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GeV gamma rays and high z UV background
Inoue Miniati, in prep.
thick (thin) for UV target above (below) Ly
edge Eg?gt(lt)18 GeV -gt limited z range for pair
production zsource-zthin
crucial, unique probe of high-z UVB (longward of
Ly)
S. Peng Oh 01
g-ray attenuation
UV background spectrum
feasible with bright blazars?

• very rare above z10
• spectral extention to gt100 GeV?

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GRB high energy emission
GRB941017
Gonzalez et al. 03
GRB940217
Hurley et al. 94
not very well constrained, but often distinct
spectral and/or temporal difference sometimes
energetically dominant
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forward shock SSC emission
E531, n1, ee0.1, eB0.01, p2.2 typical
afterglow
Aharonian et al. 01
KN effects included source gg absorption
important gtTeV
5_at_5 g-ray Cerenkov detector 5 GeV threshold at
5000 km altitude
detectable to zlt10
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forward shock SSC emission
E5310, n1, ee0.5, eB0.001, p2.2 bright
afterglow
5_at_5 g-ray Cerenkov detector 5 GeV threshold at
5000 km altitude
detectable to z30!
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warm-hot IGM?
Dave et al. 01
105ltTlt107 K, overdensity dWH10-30
line of sight covering fraction fWH? c.f. volume
fraction0.1
DMWH?ltfWHdWHgt
important contribution to dispersion?
Cen Ostriker 99
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contribution from warm-hot IGM
numerical simulations by F. Miniati
cool phase (Tlt105K, d0) dominant but warm hot
phase non-negligible or comparable
combination with e.g. X-ray absorption lines -gt
probe of WHIGM?
----- z0 ----- z0.1 ----- z0.3 -----
z0.5 ----- z1.0
dash Tlt105 solid 105ltTlt107 dot 107ltT
column density
column density