高エネルギー天文学宇宙物理学の進歩と展望「超熱的宇宙」“The superthermal universe”

井上 進（国立天文台）

selected topics
1. The origin of cosmic rays
Galactic CRs, SNR X/γ-rays, ultra high energy CRs

2. Gamma-ray mysteries
new & unidentified TeV sources

3. The nature of GRBs
SWIFT progress: short GRBs, L correlations, lots of confusion, …

4. High energy cosmology
high-z GRBs, blazars

5. Large-scale high energy astrophysics
HE processes in galaxies, clusters, …
role of CRs in star/galaxy/cluster formation, …

extremely rapid progress, great surprises & expectations
ever growing impact on other fields (large-scale universe)

1. The origin of cosmic rays
observed CR spectrum:

great power-law in the sky
up to knee (<1015-16 eV)
Galactic SNRs?
LGCR~1041 erg/s~0.1xESN/tSN
BUT
simple theory: Emax<1014eV?
no direct evidence for protonskneeknee-ankle (1015-16-1018 eV)
Galactic? no new source?
ankle
Gaisser 05

toeabove ankle (>1018 eV)extragalactic: AGNs?
GRBs?
???

shock acceleration- power-law spectrumdN/dE~∝E-2 for strong shock- very efficient
up to ~50% of kinetic energy

馬場、山崎 04

basic emission processes
e-+B→ e-+γ
synchrotron
e-+γ→ e-+γ
inverse Compton
p-p pi0pCR+ptarget→ π0, π+−π0→2γ
π+-→e+-3νSNRs: X-rays in high resolution
Chandrashock surfaces ~ very thin filaments→ B~ few 100 µG
CR B amplification?
Lucek Bell 00, Bell 04
acceleration up to Eknee!
Bamba+ 03

SNRs: TeV gamma-ray image!
RX J1713.7-3946

Aharonian+ 04 Nat., 05, 06(discovered by CANGAROO Enomoto+ 02)

p-p pi0e-IC

p-p pi0 likely (+some e-IC?)Emax~100 TeV< Eknee
later/other SNRs up to Eknee?
ν source?

HESSUHECRs: observations
spectrumat least up to 1020 eVAGASA

Emax~3x1020 eV~50J ~ kinetic Eof 100km/h fastball

HiRes

composition>1020 eV

globally isotropic
no ID with sources

Xmax [g cm-2]

arrival directions

light dominant
up to ~<2x1019 eV?

UHECR sources?
“Hillas plot”

Badapted from
Yoshida & Dai 98

AGN jets

GRBs
B~∝R-1GRBs

AGN jetsclusters

something else???

RE ≦ Ze B R (v/c)

cluster accretion shocksRyu+ 03

accretion(minor merger)
strong shocks

Ep, max~ 1018-1019 eV
Kang, Rachen, Biermann 97
HOWEVER
if Bs~1 µG
Fe nuclei (Z=26)
EFe, max>~1020 eVprotons

UHECRs as nuclei from clusters
spectrum

SI, Sigl, Miniati, Armengaud
PRL, submitted(astro-ph/0701167)
anisotropy

with IGB

fCR~0.01-0.6
no IGBfCR~0.004
1019 eV1020 eVcomposition
consistent with current data(including AGASA?)

clear predictions forAuger, Telescope Array, EUSO
1019 eV1020 eVUHE proton-induced hard X/γ emission from clustersp(1019eV) +γCMB→ p+ e+e- (1016eV)
e+e-+B(~µG)→keV, e+e-+γCMB→TeV

SI, Aharonian, Sugiyama 05

Coma
D=100 Mpc

Rg(1019eV) ~10 kpc (B/µG) -1 ~25”
X-ray imaging of UHE proton acceleration

SI & Aharonian
in prep.

2. Gamma-ray mysteries
GeV gamma-ray sky

Galactic: pulsars+nebulae, backgroundunidentified (SNRs? binaries?)
extragalactic: blazars, GRBs
unidentified, backgroundTeV Galactic plane survey
HESS

Aharonian+ 05 Sci., 06

2(+2?) SNRs
5(+2?) pulsarnebulae
3 X-ray binaries1 Gal. Center

8 unidentified!

TeV unID sources: dark accelerators!
SuzakuHESSpossibilities- OB stellar winds+CRs- old SNRs
- GRB remnants- photoexcitation of CR nuclei- dark matter???

protons, hard spectra→ true sources of Galactic CRs??
HESS J1616-508
Matsumoto+ 06

other TeV discoveries

mostly HESS, also MAGIC

Galactic Center A+ 04, 06
origin?
dark matter ruled out
Galactic plane A+ 06 Nat.
CR spectral variations
γ-ray binaries
A+ 05 Sci., 06(microquasars) Albert+ 06 Sci.
orbital modulation, pair absorptionBH (microblazar) or NS (wind nebulae)?
ν source?
radio galaxy A+ 06 Sci.
surprisingly fast variability→ emission site few Rs?
stellar winds A+ 07p-p pi0 or e-IC?

M87

LS5039

progress forecast for high energy astronomy“Kifune plot”?
GLAST
HESS (II)MAGIC (II)CANG. III
VERITAS20XX

UHECR?
neutrino?

+~5 years
http://www.mpi-hd.mpg.de/hfm/HESS/HESS.html?

3. The nature of gamma-ray bursts

2
E=mc

==
原子爆弾

太陽~1033g

GRB~1052erg

太陽が一生かけて出すエネルギーを数秒で放出

GRBは宇宙一明るい謎の天体
井岡氏より

GRBs: emission properties
luminous Lγ~1052-1054 fΩ erg/s (collimation fΩ~0.001-0.01?)
broadband radio-GeV γ-rays
afterglow emission
prompt emission

external shock

internal shock?
?

Meszaros 01,02

GRB global properties
high-z ~0.2-6.3
event rate (z=0)~10-7 fΩ-1 /yr/gal~0.001-0.01 xSN?
long-soft/short-hard dichotomy
otherwise very diverse

pre-SWIFT view of (long) GRBs

coincident SN,
star-forming host→ massive starcollapse

short GRBs with SWIFT
for at least some:
elliptical hostz<<1, low Lno SN
low surrounding n→ compact binary mergers
gravitational wave connection
Gehrels+ 05 Nat.
Fox+ 05 Nat.
Berger+ 05 Nat.
etc.

BUT
high-z short GRBs
long short GRBs

surprises (chaos) with SWIFT
NS-SN GRB

magnetar?

SN-less GRB
dark
hypernovae?

Mazzali+
06 Nat.

Fynbo+
06 Nat.

060614060218/2006aj

early afterglow steep-flat phaselate afterglow
chromaticbreaks

X-ray

opticalPanaitescu 06

GRBs in the SWIFT era: what is clear?
- (some) short GRBs different from long GRBs
- GRBs not as simple as once thought(high-z/long short GRBs, NS-SN GRBs, SN-less GRBs,
early steep-flat decay, chromatic breaks…)- GRBs promising as high-z probes

GRB prompt emission: unsolved mysteryenergy dissipation?
emission process?

luminosity correlations (=distance indicators)cannot be explained
easily with “standard”
internal shock sync.
also crucial
for cosmology
Amati relation
Ep~Eiso1/2

optical emission
SWIFT+RAPTOR

Vestrand+05 Nat.

need broadband observations!
GeV-TeV, IR, radio, neutrino…

t(sec)

prompt GeV-TeV: expectationsAsano & SI, in prep.
models with hadronic
processes, pair cascading
determine Γ, B
test UHECR accel.
ν production

GLASTMAGIC4. high energy cosmology (probing the universe at HE)
gamma-ray “absorption”: probe of diffuse radiation fields
γ + γ → e+ + e E εe.g. TeV + 1eV (IR)100 GeV + 10 eV (UV)
Costamante+ 03

probing local IR background with gamma-ray absorption
γ-ray absorption in blazars at z=0.165, 0.186 (highest to date)
Aharonian+ 06 Nat.

• strongly rules out NIR peak
• probably little “missing light”no strong Pop III<-> Matsumoto+Kashlinsky+

GRB050904

z=6.295!!!

SWIFT/XRT light curve

optical flash
TAROT(25cm!)

Boer+ 05

Subaruspectroscopic z

Kawai+ 05 Nat.

Watson+ 05

100x flux ofquasar at same z
new constraints on HI fraction

Totani+ 05

GRBs at very high z: expectations
observed z-distribution of SWIFT bursts

history of record redshifts

Jakobsson+ 05• mean z=2.8• fraction at z>5 7-40%
Bromm & Loeb 02, 05• model predictionsrate(z>10)~1-10/yr?

GRBs as dark energy probe?

problems with distance indicators:
1. unclear selection effects
2. no physical basis!

e.g. Schaefer astro-ph/0612285⇔ SNIaGRBs as star formation rate indicators
GRBs as signposts for high-z (low metal.) galaxies

GRBs as broadband beacons: probing the dark ages
GeV: UV background from pair absorption
SI, Salvaterra, Choudhury, Schneider,Ciardi, Ferrara, in prep.

GeV: weak intergalactic B field fromdelayed secondary emission
Ichiki, Takahashi, SI, in prep.

radio-submm: star-forming gas fromatomic/molecular absorption lines
SI, Omukai, Ciardi 06

LF radio: ionized IGM from dispersion delay
SI04, Ioka 03
others
NIR: IGM HI from Lyα damping wing
metal evolution from absorption lines
X: WHIM from absorption lines
radio: HI from 21cm absorption…

probing high-z UV background with pair absorption
SI, Salvaterra, Choudhury, Schneider, Ciardi, Ferrara, in prep.
GRB GeVbright GRBsz~<10 with GLAST
typical GRBsz>~30 with 5@5
high-z UV model
exp(-tau(E))

significant opt. depth from z~5-8 at several GeV→ important info on UV at reionization epochbut not much effect above z~8Choudhury & Ferrara 05, 06
consistent withWMAP3, xHI, HUDF NIR…

GLASTdark matter
If GLAST sees, discovery of the century!
If GLAST doesn’t see, no problem for anyone(including those who say it will).

Bertone 06

5. large-scale high energy astrophysics
large scale structure formation (SF) shocks
formation of galaxies, groups, clusters...
= hierarchical, dark matter-driven mergers and accretion→ shock formation → gas heating + particle acceleration→ nonthermal radiation
thermal emission

shock velocitiescosmological hydro simulations by Ryu+ 03

expected high energy emission from clusters• primary electron IC• LE proton p+p->π0Miniati 03>100 keV

traces shocktIC<<tshock
traces gastloss, tconf>>tH

e.g. Waxman & Loeb 00
Totani & Kitayama 00

thermal>100 MeVe.g. Völk+ 96
Berezinsky+ 97

assume p=2+ • UHE proton-induced pair syn.+ICSI, Aharonian, Sugiyama 05

gamma-rays from clusters: expectations
SI, Gabici, Aharonian, Rowell
HESS proposal

outskirts

core
different processes should dominate
at different energy, location

ongoing/future observations of clusters
TeV SI, Gabici, Aharonian, Rowell, HESS proposal
observations under way!
hard X Nakazawa+, Suzaku observations of A3667
SI, Nakazawa, Fukazawa+, Suzaku AO-2 proposal, submittedSuzaku
XX

GeV
GLAST
hard X NeXT
imagingγHESSγ

probing structure formation with gamma-rays:
warm-hot IGM (missing baryons)
SI & Nagashima, in prep.
(see also astro-ph/0502338)
WHIM
SF shocks →e-+γCMB→ e-+γ
γ source counts

DIOSGLAST

Dave+ 01

baryon condensation into stars-> shock suppression affects
γ-ray source statistics,contribution to γ backgroundimportant constraint on WHIM,
complementary to thermal lines

LiBeB archaeology: CR activity in the early Galaxy
disk galaxy formation with CDM
320 kpc
Abadi+ 03

light element production by CRs
p, α + C,N,O → 7Li, 6Li , Be, B + …
α + α → 7Li, 6Li + …
LiBeB in metal-poor halo stars= fossil record of past CR activity

SF shocks in the early Galaxy

key element: 6Li
Suzuki & SI 02

40 kpcno ejection of fresh CNO, Fe⇔ SN CRs
7Li dominated by BBN

final major merger z~2-1
SF shocks!

Subaru observations of 6Li in metal-poor halo stars
Aoki, SI+ in prep.
errorspreliminary

total 5.5 nights
very challenging!
high 6Li/Fe insome stars atvery low Fe/H!
but also
upper limits→ intrinsic
dispersion
SF CRs:need large delay
between SF andstar formation

nonstandard supernovae origin for 6Li?
energetic SNIbc
Nakamura, SI, Wanajo, Shigeyama 06

σ (α+α → 6Li)

ejecta“spectra”
σ(N+He→ 9Be)

Pop III SNe (vs SF CRs)
SI, Rollinde, Vangioni, Olive, in prep.

σ(O+He→ 9Be)

CR feedback on structure formation?
feedback during galaxy formation
SN, AGN, UV…
CR?
CRs compared to thermal gas- more compressible, more buoyant- less cooling- more diffusive
potential effects- pressure (support, displacement)- heating

Ostriker 06
effects not included incurrent simulations:- cosmic rays
- magnetic fields- dustp ∝ ρ4/3

- B amplification?
- nonthermal emission- LiBeB production

CR feedback in simulations of galaxy formation
Ensslin+ 06, Jubelgas+ 06significant suppression of star formation in small galaxies M~<1010 Msol,,at high z(slightly) flatter faint end slope of galaxy LF
solve angular momentum problem?
BUT formulation may be oversimplified(no momentum conserv. for CRs!)other potential roles of CRs
star formation near SNRs
enhanced CR ionization?
less ambipolar diffusion & core collapse?
→ more disk MRI & accretion rate?
Fatuzzo+ 06

galactic winds (starburst galaxies)
crucial for galaxy evolution (feedback, metal ejection)
but wind mechanism unknown
Socrates+ 06
thermal? radiative? ⇔ CR-driven?

cluster cool cores (“cooling flows”)
requires distributed, fine-tuned heating (by AGNs?)
CR heating?
nonequil. excitation by CRs?

まとめ：高エネルギー天文学と超熱的宇宙
長年の謎の解決
相次ぐ新しい発見と驚き
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