fermi 衛星による最新成果と今後の展望

Fermi_HEAPA_2013-03.ppt

T. Mizuno et al. /33

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Fermi衛星による最新成果と今後の展望

Mar. 04, 2013@金沢(高宇連研究会 )

T. Mizuno(広島大学　宇宙科学センター )

On behalf of the Fermi-LAT collaboration



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Recent Results by Fermi-LAT and Future

ProspectsMar. 04, 2013@Kanazawa

(Annual meeting of HEAPA)T. Mizuno

(Hiroshima Astrophysical Science Center)

On behalf of the Fermi-LAT collaboration



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Fermi Gamma-ray Space Telescope

• Fermi = LAT + GBM• LAT = GeV Gamma-ray Space Telescope

(20 MeV ~ >300 GeV; All-Sky Survey )

3c454.3

2008.06 launch2008.08 Sci. Operation

1873 sourcesNolan+ 2012, ApJS 199, 31

Cape Canaveral, Florida



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Fermi-LAT Performance

• New Dataset and Response (Pass7, 2011.08-)– Improved Aeff in low Energy (E<200 MeV)– In-orbit calibration of PSF

Effective Area (P7) PSF

http://www.slac.stanford.edu/exp/glast/groups/canda/lat_Performance.htm

good enough for MW analysis of X-ray sourcesAckermann+12, ApJS 203, 70

(CA: Baldini, Charles, Rando)



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Fermi-LAT Performance

• New Dataset and Response (Pass7, 2011.08-)– Improved Aeff in low Energy (E<200 MeV)– In-orbit calibration of PSF

http://www.slac.stanford.edu/exp/glast/groups/canda/lat_Performance.htm

If you want to analyze data by yourself, please visit Fermi Science Support Centerhttp://fermi.gsfc.nasa.gov/ssc/

Big improvement over the old P6 response in E<200 MeV

Old Aeff (P6)



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Fermi-LAT Publications

• Publications by Fermi-LAT members(Cat I+II+III, as of Dec. 2012)

2008 2009 2010 2011

http://www-glast.stanford.edu/cgi-bin/pubpub

~300 papers already published

6-7 papers/month

2FGL catalog paper is the most cited paper in 2012 (in astrophysics)

2012



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Introduction: Gamma-Ray Astrophysics

A powerful probe to study CRs and ISM in distant locations

g-rays = CRs x ISM (or ISRF)

• known ISM distribution => CRs• those “measured” CRs => ISM

Fermi-LAT (2008-present)2.4p sr, 20 MeV-300 GeV

Cosmic-rays

Interstellar Medium



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Origin and Propagation of Galactic CRs

sun

To test this SNR paradigm of CRs, we need to observe• CR distribution outside of the solar system• CRs accelerated at SNRs

• uCR~1 eV/cm3 at the solar system• Vgal=1067-68 cm3, tesc~107 yr

• ESN~1051 erg, FSN~1/30 yr• If h~0.1

PCR~1041 erg/s

Pinj~1041 erg/s

g-ray



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Origin and Propagation of Galactic CRs

sun

This talk will cover Fermi-LAT obs. of• diffuse gama-rays• SNRs

This talk will also cover• local group galaxies, star-forming galaxies• extragalactic gamma-ray background• (+ISM)

• uCR~1 eV/cm3 at the solar system• Vgal=1067-68 cm3, tesc~107 yr

• ESN~1051 erg, FSN~1/30 yr• If h~0.1

PCR~1041 erg/s

Pinj~1041 erg/s

g-ray



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ISM Component not Visible by Standard Tracers

• ISM has been mapped by radio surveys (HI by 21 cm, H2 by 2.6 mm CO)

• Fermi revealed a component of ISM not measurable by those standard tracers

Ackermann+12, ApJ 755, 22(CA: Hayashi, TM)

Residual g-rays when fitted by N(HI)+COChamaeleon Molecular Cloud

g-rays w/ CO contour



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ISM Component not Visible by Standard Tracers

• ISM has been mapped by radio surveys (HI by 21 cm, H2 by 2.6 mm CO)

• Fermi revealed a component of ISM not measurable by those standard tracers, confirming an earlier claim based on EGRET study (Grenier+05)Residual gas inferred by dust

See also Abdo+10 (ApJ 710, 133), Ackermann+11 (ApJ 726, 81)and Ackermann+12 (ApJ 756, 4)

Residual g-rays when fitted by N(HI)+CO



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CRs outside the Solar System (1)

Mid-high lat. region in 3rd quadrant• small contamination of IC and

molecular gas• correlate g-ray intensity with N(HI)

electron-bremsstrahlung

nucleon-nucleon

LAT datamodel from the LIS

Abdo+09, ApJ 703, 1249(CA: TM)

• Local CR spectra ~ those directly measured at the Earth (uCR~1 eV/cm3)



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CRs outside the Solar System (2)

Casandjian+ in prep.

Data Model

• on average, local CR spectra ~ those measured at the Earth (uCR~1 eV/cm3)



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CRs on Galactic Scale

Ackermann+12, ApJ 750, 3(CA: Johannesson, Porter, Strong)

No single model to reproduce the all-sky data, but overall agreement is good

1GeV 10 100

pi0

ICe- brems.

Diffuse model (total)

Outer Galaxy

Inner Galaxy

Local



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CR Luminosity inferred from a model

• PCR=(6-8)x1040 erg/s and Lg=(7-10)x1038 erg/s are inferred by (particular) set of models• MW is electron calorimeter if IC is included

Halo size: 2kpc 4 10 2kpc 4 10

Diffusive Reacceleration, zh=4kpc

CR e-

CR p

CR a

CR e+g-rayRadio

Models by numerical calculation, Strong+10 (ApJ 722, L58)

Luminosity of MW



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SNRs seen by Fermi-LAT

• ten 2FGL sources are now identified as, or associated with SNR (# of possible association ~60)

• Hadronic scenario is usually favored



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SNRs seen by Fermi-LAT

• ten 2FGL sources are now identified as, or associated with SNR (# of possible association ~60)

• Hadronic scenario is usually favored



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IC443 Image and Spectrum

5-10 GeV g-ray image w/ radio contour

2-10 GeV

Hadronic scenario gives Wp=1x1049 erg (ECR>500 MeV)

Abdo+10, ApJ 712, 459(CA: Giordan, Kamae, Rodriguez, Torres)

2-10 GeV

PSF

g-ray spectrum w/ pi0-decay dominated model

EGRETFermiMAGICVERITASPSF



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W44 Image and Spectrum

Deconvolved g-ray image w/ Spitzer 4.5um contour (tracer of shocked H2)

2-10 GeV

Wp=6x1049 erg, We=1x1048 erg(ECR>100 MeV)

Abdo+10, Science 327, 1103(CA: Tajima, Tanaka, Uchiyama)

g-ray spectrum w/ pi0-decay dominated model



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Pion-Decay Bump in LowE Spectrum• Spectrum below 200 MeV clearly deviates from

bremsstrahlung and agrees well with a hadronic scenario

IC443 W44WSN 1x1051 erg 5x1051 erg

WCR 4x1049 (n/20cm-3)-1erg 4x1049 (n/100cm-3)-1ergConvincing evidence of proton acceleration, ESNh=WCR~1050 ergAckermann+13, Science 339, 807

(CA: Funk, Tanaka, Uchiyama)



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Local Group/Starburst Galaxies

• Study CR/ISM interaction in wide range of samples• Contribution to EGB

M82

N253M31

SMC

LMC



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Energy Spectrum

• Starburst -- Hard spectrum by Fermi+IACT (G~2)• Local Group -- Softer spectrum (G>2.5)

– Escape limited in MW. Short diffusion length in LMC

G=2.2

Abdo+10, ApJL709, 152(CA: Bechtol, Dermer, Reimer, Rodriguez, Torres)

G=2.7

M82 MW(+) & LMC(+)

Abdo+10, A&A 512, A7(CA: Jean, Knodlseder, Porter)



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SFR-Lg Relation

Ackermann+12, ApJ 755, 164(CA: Bechtol, Cillis, Funk, Torres)

• A sample of 69 is examined: quasi-linear relation between star-formation rate and Lg (Lg∝LIR

1.0-1.2)• SFR-Lg relation and hard spectrum implies hadron calorimetry

MWLMCSMC

M31

N1068

N4945 M82N253



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SFR-Lg Relation

• A sample of 69 is examined: quasi-linear relation between star-star-formation rate and Lg (Lg∝LIR

1.0-1.2) • SFR-Lg relation and hard spectrum implies hadron calorimetry

– NB MW is escape limited

MWLMCSMC

M31

N1068

N4945 M82N253

Ackermann+12, ApJ 755, 164(CA: Bechtol, Cillis, Funk, Torres)



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Extragalactic g-ray Background

• GeV gamma-ray sky= Point sources + Gal. Diffuse gs + ExtraGal. Diffuse gs

Fermi-LAT 1 year all-sky map

3c454.3

Vela

Crab

Geminga



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Extragalactic g-ray Background (EGB)



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Why is EGB Important?

• The EGB may encrypt the signature of the most powerful processes in astrophysics

Blazars contribute 20-100% of the EGB

Star forming galaxies, etc.

Particles accelerated in Intergalactic shocks

4% A

tom

s

Annihilation of Cosmological Dark Matter

Markevitch+05

Point sources

or diffuse



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EGB of EGRET Era

• “Cosmic” Extragalactic Gamma-ray Background (EGB)– known since 1970s (SAS-2)

GeV background(EGRET)

CXB(resolved into AGNs)

Sreekumar+98

E2 x F

lux

keV MeV GeV

G ~ 2.1



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The Fermi EGB

• Fermi data + improved diffuse model– new EGB spectrum in 0.2-100 GeV

Abdo+10, PRL 104, 101101

+

+

=

LAT sky

gal. diffuse

point sources

Instrumenta

l BG

+”EGB”0.1 1 GeV 10 100

G ~ 2.4

Featureless PLsofter than EGRET result

(CA: Ackermann, Porter, Sellerholm)



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Contribution of Blazars

• >70% of resolved high-lat. sources are blazars• Unresolved Blazars account for 23+/-5(stat)+/-

12(sys)% of the EGBlogN-logS:Most of un-associated sources are likely to be blazars

0.1 1 GeV 10 100

Fermi EGB vs. source contribution

Abdo+10, ApJ 720, 435(CA: Ajello, Tramacere)



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Contribution of Star-forming Galaxies

• Use Lg-LIR scaling to estimate contribution• Star-forming galaxies account for 4-23% of the EGB

(~60% at the maximum if we add Blazars and SFGs)

• Radio galaxies can account for ~25% (e.g., Inoue+11). Still some room for other source type or truly diffuse emission.

Ackermann+12, ApJ 755, 164

(CA: Bechtol, Cillis, Funk, Torres)



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Future Prospects

• Detailed modeling of Galactic CRs– CR density gradient, CR density variation (e.g., Ackermann+11, ApJ

726, 81; Ackermann+12, ApJ 755, 22)• Injection of CRs to the interstellar space

– Detailed observation of SNRs and other accelerators, Cygnus Cocoon and other star-forming regions (e.g., Ackermann+11, Science 334, 1103)

• New event classification (Pass8)– Further improvement of acceptance

Cygnus Cocoon(g-ray excess)

Pass 8(new IRF)



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Summary

• Fermi 衛星により宇宙線の探査が大きく進んできた ( 広がったガンマ線放射 , 宇宙線源候補 , 星生成銀河 )– 太陽系は「特別」ではない– SNR 起源説で概ね説明可能– 星生成銀河は CR p Calorimeter ( 天の川銀河は escape limited)– 系外ガンマ線放射に対する点源の寄与を定量評価

• 宇宙線の注入 , 伝播 , 分布を調べることが重要– 宇宙線分布の詳細観測– SNR ほか加速源の詳細観測 ( 花畑講演も参照 )

• 触れられなかった話題： AGN, GRB, PSR/PWN, DM 探査などThank you for your Attention

fermi 衛星による 最新成果と今後の展望

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fermi 衛星による最新成果と今後の展望