Accelera'on of cosmic rays and gamma ray emission from supernova remnants in the Galaxy

Transcription

1 Accelera'on of cosmic rays and gamma ray emission from supernova remnants in the Galaxy P. Cristofari h9p:// arxiv.org/pdf/ v1.pdf S. Gabici, R. Terrier, S. Casanova, E. Parizot

2 The local cosmic ray spectrum S. Swordy (1990) 2

3 The local cosmic ray spectrum Bulk of CRs energy density : 1 ev cm- 3 Slope : E «knee» ~ 4 PeV S. Swordy (1990) 3

4 The local cosmic ray spectrum Bulk of CRs energy density : 1 ev cm Which sources can provide that? Slope : E «knee» ~ 4 PeV S. Swordy (1990) 4

5 The local cosmic ray spectrum Bulk of CRs energy density : 1 ev cm Which sources can provide that? Slope : E Which acceleraxon mechanism? «knee» ~ 4 PeV S. Swordy (1990) 5

6 The local cosmic ray spectrum Bulk of CRs energy density : 1 ev cm Which sources can provide that? Slope : E Which acceleraxon mechanism? «knee» 3. Can the sources be PeVatrons? ~ 4 PeV S. Swordy (1990) 6

7 The local cosmic ray spectrum Bulk of CRs energy density : 1 ev cm Which sources can provide that? (Baade&Zwicky 1934) Supernovae can provide the required energy if the acceleraxon efficiency ~% Slope : E Which acceleraxon mechanism? «knee» 3. Can the sources be PeVatrons? ~ 4 PeV S. Swordy (1990) 7

8 The local cosmic ray spectrum Bulk of CRs energy density : 1 ev cm- 3 Slope : E «knee» 1. Which sources can provide that? (Baade&Zwicky 1934) Supernovae can provide the required energy if the acceleraxon efficiency ~% 2. Which acceleraxon mechanism? (Bell et al. 1978) Diffusive shock acceleraxon can provide an injecxon spectrum roughly E Can the sources be PeVatrons? ~ 4 PeV S. Swordy (1990) 8

9 The local cosmic ray spectrum Bulk of CRs energy density : 1 ev cm- 3 Slope : E «knee» 1. Which sources can provide that? (Baade&Zwicky 1934) Supernovae can provide the required energy if the acceleraxon efficiency ~% 2. Which acceleraxon mechanism? (Bell et al. 1978) Diffusive shock acceleraxon can provide an injecxon spectrum roughly E Can the sources be PeVatrons? ~ 4 PeV B field amplificaxon - > DSA can do it S. Swordy (1990) 9

10 SNRs seen in TeV gamma rays Tycho VERITAS Acciari et al. (2011) Hadronic interac'ons : Pion decay W 28 - HESS RXJ HESS Aharonian et al. (2006) Aharonian et al. (2006) CR ISM p + p p + p + π 0 π 0 γ + γ

11 SNRs seen in TeV gamma rays Tycho VERITAS Acciari et al. (2011) Hadronic interac'ons : Pion decay W 28 - HESS RXJ HESS Aharonian et al. (2006) Aharonian et al. (2006) CR ISM p + p p + p + π 0 π 0 γ + γ Leptonic interac'ons : Inverse Compton scaoering i f 11

12 SNRs seen in TeV gamma rays Tycho VERITAS Acciari et al. (2011) Hadronic interac'ons : Pion decay W 28 - HESS RXJ HESS Aharonian et al. (2006) Aharonian et al. (2006) CR ISM p + p p + p + π 0 π 0 γ + γ Leptonic interac'ons : Inverse Compton scaoering i f 12

13 SNRs detected at 1 TeV by HESS Several HESS sources (extended survey) were iden'fied as SNRs : - RXJ J RCW86 - W41 - W49B - + about several uniden'fied sources PopulaXon study of SNRs that one should expect to detect in the HESS survey of the galacxc plane. 13

14 How many SNRs should we see at TeV energy? What we need : Time and SpaXal distrisbuxon of SNRs 14

15 How many SNRs should we see at TeV energy? What we need : Time and SpaXal distrisbuxon of SNRs Gas density distribuxon in the galaxy

16 How many SNRs should we see at TeV energy? What we need : Time and SpaXal distrisbuxon of SNRs Gas density distribuxon in the galaxy + + Model for acceleraxon of cosmic rays in one SNR 16

17 How many SNRs should we see at TeV energy? What we need : Time and SpaXal distrisbuxon of SNRs Gas density distribuxon in the galaxy + + Model for acceleraxon of cosmic rays in one SNR Gamma emission of one SNR Number of detectable SNRs for a given telescope 17

18 SNR distribu'on What we need : Time and SpaXal distrisbuxon of SNRs Time distribuxon : SN rate : 3/century SpaXal distribuxon : Lorimer et al. (2004) Faucher- giguère, Kaspi (2006) 18

19 SNR distribu'on What we need : Time and SpaXal distrisbuxon of SNRs Thermonuclear Core- collapse Evolu'on of SNRs - - > Chevalier 1982Truelove& Mckee (1999) 19

20 Gas distribu'on What we need : Time and SpaXal distrisbuxon of SNRs + Gas density distribuxon in the galaxy 20

21 Gas distribu'on What we need : Gas density distribuxon in the galaxy HI H 2 Nakanishi&Sofue (2003) Nakanishi&Sofue (2006) 21

22 Gas distribu'on What we need : Time and SpaXal distrisbuxon of SNRs + Gas density distribuxon in the galaxy 22

23 What we need : Time and SpaXal distrisbuxon of SNRs Gas distribu'on Gas density distribuxon in the galaxy + + Model for acceleraxon of cosmic rays in one SNR 23

24 What we need : Time and SpaXal distrisbuxon of SNRs Par'cle accelera'on Gas density distribuxon in the galaxy + + Model for acceleraxon of cosmic rays in one SNR We follow the approach by Ptuskin&Zirakashvili (2005) 1. Efficiency : P 0 CR = ξ CR ρ up u 2 sh acceleraxon efficiency at the shock A fracxon of the ram pressure is converted into CRs 24

25 What we need : Time and SpaXal distrisbuxon of SNRs Par'cle accelera'on Gas density distribuxon in the galaxy + + Model for acceleraxon of cosmic rays in one SNR We follow the approach by Ptuskin&Zirakashvili (2005) 1. Efficiency : P 0 CR = ξ CR ρ up u 2 sh acceleraxon efficiency at the shock Assump'on : ξ CR = η CR 0.1 = ESN CR E SN Supported by theorexcal work by Ptuskin,Zirakashvili, Caprioli.. 25

26 What we need : Time and SpaXal distrisbuxon of SNRs Par'cle accelera'on Gas density distribuxon in the galaxy + + Model for acceleraxon of cosmic rays in one SNR We follow the approach by Ptuskin&Zirakashvili (2005) 1. Efficiency : P 0 CR = ξ CR ρ up u 2 sh 2. Spectrum : acceleraxon efficiency at the shock Assump'on : ξ CR = η CR 0.1 = ESN CR E SN Supported by theorexcal work by Ptuskin,Zirakashvili, Caprioli.. N CR p α where α = Blasi (2011) 26

27 Par'cle accelera'on maximum energy What we need : Time and SpaXal distrisbuxon of SNRs Gas density distribuxon in the galaxy + + Model for acceleraxon of cosmic rays in one SNR 3. Maximum energy : diffusion length D(E max ) u sh R sh Ptuskin&Zirakashvili

28 Par'cle accelera'on maximum energy What we need : Time and SpaXal distrisbuxon of SNRs Gas density distribuxon in the galaxy + + Model for acceleraxon of cosmic rays in one SNR 3. Maximum energy : diffusion length D(E max ) u sh R sh Ptuskin&Zirakashvili 2008 X- ray filament measurements Volk et al

29 Par'cle accelera'on maximum energy What we need : Time and SpaXal distrisbuxon of SNRs Gas density distribuxon in the galaxy + + Model for acceleraxon of cosmic rays in one SNR 3. Maximum energy : diffusion length D(E max ) u sh R sh Ptuskin&Zirakashvili 2008 X- ray filament measurements ~3.5% of shock kinexc energy into magnexc field Volk et al

30 Par'cle accelera'on maximum energy What we need : Time and SpaXal distrisbuxon of SNRs Gas density distribuxon in the galaxy + + Model for acceleraxon of cosmic rays in one SNR 3. Maximum energy : B down = B 0 σ u 2 sh v 2 d +1 diffusion length D(E max ) u sh X- ray filament measurements ~3.5% of shock kinexc energy into magnexc field R sh Ptuskin&Zirakashvili 2008 E max 280 E 3/5 51 n 1/ 0 t 4/5 kyr Type Ia, sedov phase TeV Volk et al

31 How many SNRs should we see at TeV energy? What we need : 3. Maximum energy (protons) : OTHER SCENARIOS No field amplifica'on B down σb 0 E max 34 E51 n 0 Model for acceleraxon of cosmic rays in one SNR 2/5 t 1/5 kyr TeV well blow the knee

32 How many SNRs should we see at TeV energy? What we need : 3. Maximum energy (protons) : OTHER SCENARIOS No field amplifica'on B down σb 0 E max 34 Two zone model Atoyan, Dermer (20) amplified field here E51 n 0 Model for acceleraxon of cosmic rays in one SNR 2/5 t 1/5 kyr TeV well blow the knee weak field here (damping?) Enhanced Inverse Compton Sca9ering

33 How many SNRs should we see at TeV energy? What we need : ELECTRONS electron- to- proton raxon K ep = Model for acceleraxon of cosmic rays in one SNR N e N p K ep Following Longair (1990) Ebreak e Emax e acc rate= synch loss rate Emax e 7.3 u sh 00km/s 1/2 Bdown 0µG TeV Vannoni et al t synch =t age E e break

34 Does this work? RXJ 1713 Tycho E 2 L [TeV cm -2 s -1 ] HESS FERMI pion decay (*0) IC E 2 L [TeV cm -2 s -1 ] VERITAS FERMI pion decay years pion decay years pion decay years IC years E [TeV] Type II age =1630 yr slope 4.3 d= 1 kpc B 2 =5 μg K ep = - 2 ξ= E [TeV] Type Ia age =441 yr slope 4.25 d= 3.5 kpc B 2 =5 μg K ep = - 4 ξ=0.18 n 0 =0.24 cm

35 Log N Log S of SNRs 1. No B field amplifica'on Number of SNRs 0 1 =4.4 No field amplification Kep= -5 Kep= -2 Cristofari et al. (2013) F(>1 TeV) [cm -2 s -1 ] 35

36 Log N Log S of SNRs ~same # of hadronic and leptonic 0 1 Number of SNRs 1. No B field amplifica'on =4.4 No field amplification Kep= -5 Kep= -2 Cristofari et al. (2013) 1% Crab F(>1 TeV) [cm -2 s -1 ] 36

37 Log N Log S of SNRs 2. B- field amplifica'on 0 Kep= -5 Kep= -2 Number of SNRs 1 =4.4 B amplified Cristofari et al. (2013) F(>1 TeV) [cm -2 s -1 ] 37

38 Log N Log S of SNRs about the same - > all hadronic 0 2. B- field amplifica'on Kep= -5 Kep= -2 Number of SNRs 1 =4.4 B amplified Cristofari et al. (2013) 1% Crab F(>1 TeV) [cm -2 s -1 ] 38

39 Log N Log S of SNRs 3. Two- zone model 00 =4.1 =4.4 Number of SNRs 0 1 Amplified B ; Kep= -2 Two zones model ; B 2 =30µG Cristofari et al. (2013) F(>1 TeV) [cm -2 s -1 ] 39

40 Log N Log S of SNRs too many! Two- zone model =4.1 =4.4 Number of SNRs Cristofari et al. (2013) 0 1 Amplified B ; Kep= -2 Two zones model ; B 2 =30µG 1% Crab F(>1 TeV) [cm -2 s -1 ] 40

41 Comparison with the HESS scan Gast et al <b<3-1.5 % CRAB 40 <l<40 - RXJ HESS CTB 37B - sensixvity scales as source extension - PSF: SNRs/MC (CTB 37A, W28 ) / 17 uniden'fied sources 41

42 Number of detections Distance [kpc] Comparison with the HESS scan Median, resolved SNRs Median, all SNRs Maximum, all SNRs K ep = -2 K ep = -5 K ep = -2 Size [degree] Age [kyear] Cristofari et al. (2013) 25 K ep = Fraction 1.2 K ep =

43 Too many! Number of detections Distance [kpc] Comparison with the HESS scan Median, resolved SNRs Median, all SNRs Maximum, all SNRs K ep = -2 K ep = -5 K ep = -2 3 shells+ all undid. sources 3 shells only Size [degree] Age [kyear] Cristofari et al. (2013) 25 K ep = Fraction 1.2 K ep =

44 Too many! Resolved SNRs are closer than point- like sources Number of detections Distance [kpc] Comparison with the HESS scan Median, resolved SNRs Median, all SNRs Maximum, all SNRs K ep = -2 K ep = -5 K ep = -2 3 shells+ all undid. sources 3 shells only Horizon smaller for weaker sources Size [degree] Age [kyear] Cristofari et al. (2013) 25 K ep = Fraction 1.2 K ep =

45 Too many! Resolved SNRs are closer than point- like sources Number of detections Distance [kpc] Comparison with the HESS scan Median, resolved SNRs Median, all SNRs Maximum, all SNRs K ep = -2 K ep = -5 K ep = -2 3 shells+ all undid. sources 3 shells only Horizon smaller for weaker sources Young sources detected first Size [degree] Age [kyear] Cristofari et al. (2013) 25 K ep = Trend in the oldest sources Fraction 1.2 K ep =

46 Too many! Resolved SNRs are closer than point- like sources Number of detections Distance [kpc] Comparison with the HESS scan Median, resolved SNRs Median, all SNRs Maximum, all SNRs K ep = -2 K ep = -5 K ep = -2 3 shells+ all undid. sources 3 shells only Horizon smaller for weaker sources Young sources detected first Size [degree] Age [kyear] Cristofari et al. (2013) 25 K ep = Fraction 1.2 K ep = Trend in the oldest sources About 50%- 50% extended and point- like sources

47 Too many! Resolved SNRs are closer than point- like sources Young sources detected first Number of detections Distance [kpc] Size [degree] Comparison with the HESS scan Age [kyear] Median, resolved SNRs Median, all SNRs 25 K ep = Fraction 1.2 K ep = Maximum, all SNRs K ep = -2 K ep = -5 K ep = -2 3 shells+ all undid. sources 3 shells only Horizon smaller for weaker sources Substan'al agreement between data and expecta'ons (no complete catalogue of SNR available at TeV energies) Cristofari et al. (2013) Trend in the oldest sources About 50%- 50% extended and point- like sources

48 Comparison with the HESS scan Substan'al agreement between data and expecta'ons (no complete catalogue of SNR available at TeV energies)

49 Comparison with the HESS scan Substan'al agreement between data and expecta'ons (no complete catalogue of SNR available at TeV energies) - L CR MW up by a factor of f : each SNR factor of f brighter - - > visible up to a distance f 1/2 further - - > visible within volume f larger - - > f more sources!