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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. Recent Results by Fermi -LAT and Future Prospects. Mar. 04, 2013@Kanazawa (Annual meeting of HEAPA) T. Mizuno (Hiroshima Astrophysical Science Center) - PowerPoint PPT Presentation
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Fermi_HEAPA_2013-03.ppt
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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