SUPERNOVA REMNANTS IN THE VERY-HIGH-ENERGY SKY: PROSPECTS FOR CTA - - PowerPoint PPT Presentation

SUPERNOVA REMNANTS IN THE VERY-HIGH-ENERGY SKY: PROSPECTS FOR CTA

ICRC 2017

Pierre Cristofari* for the CTA consortium

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* pc2781@columbia.edu

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SNRs in the TeV sky

Scott Wakely & Deirdre Horan tevcat2.uchicago.edu

Gamma rays from SNRs

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RXJ 1713 - HESS

Aharonian et al. (2006) Aharonian et al. (2009)

Tycho – VERITAS

Acciari et al. (2011)

π0 → γ + γ p + p → p + p + π0

CR ISM Hadronic interactions : Pion decay i f Leptonic interactions : Inverse Compton scattering

Situation unclear for many SNRs: instead of individual study, study of the entire population

RCW 86 - HESS

Cherenkov Telescope Array (CTA)

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≈ 1 mCrab ≈ 0.05° |l|<60° ; |b|<2°

F(>1 TeV)

H.E.S.S. CTA

≈ 15 mCrab ≈ 0.1° |l|<40° ; |b|<3° ≈ 3 mCrab ≈ 0.05° All-sky survey

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What we need:

Gas density distribution in the Galaxy

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Time and Spatial distribution of SNRs

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Model for acceleration of cosmic rays in

• ne SNR

Gamma emission of one SNR Number of detectable SNRs by a given telescope

A Monte Carlo approach

Time and spatial distribution of SNRs

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Time distribution: SN rate: 3/century Spatial distribution:

Lorimer et al. (2004) Faucher-giguère, Kaspi (2006)

SN progenitor types

Thermonuclear Core-collapse

Ptuskin et al. (2010)

Weaver (1977) Wind with R-2 density profile Hot and tenuous bubble

Evolution of SNRs : type Ia

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Chevalier (1982) Truelove& Mckee (1999) Ptuskin (2005) Rsh = 5.3 ✓ E2

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n0Mej, ◆1/7 t4/7

kyr pc

ush = 3.0 × 103 ✓ E2

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n0Mej, ◆1/7 t3/7

kyr

km/s

Free expansion Sedov phase

Rsh = 4.3 ✓E2

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n0 ◆1/5 t2/5

kyr

1 − 0.06M 5/6

ej,

E1/2

51 n1/3

tkyr !2/5 pc

ush = 1.7 × 103 ✓E2

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n0 ◆1/5 t3/5

kyr

1 − 0.06M 5/6

ej,

E1/2

51 n1/3

tkyr !3/5 km/s

t 260 ✓Mej, 1.4 ◆1/5 E1/2

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n1/3 yr ISM

Type II

Ostriker & Mckee (1988)

Momentum conservation

d dt(Mush) = 4πR2

shPin

Energy conservation

E = 4π 3(γ + 1)PinR3

sh + 1

2Mu2

Thin Shell approximation

Gas distribution

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HI H2

Nakanishi&Sofue (2003) Nakanishi&Sofue (2006)

We are here We extrapolate using fits from Shibata et al. (2010)

Particle acceleration

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• 1. Efficiency :

P 0

CR = ξCR ρupu2 sh acceleration efficiency at the shock

ξCR = ηCR ≈ 0.1

• 2. Slope of accelerated particles: free parameter

NCR ∝ p−α

α = 4.1...4.4

INSTANTANEOUS TIME INTEGRATED

Supported by theoretical work Caprioli (2010), Ptuskin & Zirakashvili (2008)

• 3. Maximum energy of accelerated protons

diffusion length

D(Emax) ush ≈ 0.05...0.1 Rsh

Loss-limited X-ray filaments : fraction of kinetic energy into magnetic field

Bdown = σB0 p (ush/vd)2 + 1

Particle acceleration: electrons

Np

Ee

break

Ee

max

Ne Kep

Kep = 10−5...10−2

electron-to-proton ratio

Vannoni et al. 2009

acc rate= synch loss rate

Longair (1990)

tsynch=tage

Ee

break

Ee

max ≈ 7.3

✓ ush 1000km/s ◆ ✓ Bdown 100µG ◆−1/2 TeV

∝ E−α ∝ E−α

∝ E−α−1

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Number of detections by CTA

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≈ 400 SNRs ≈30 SNRs Above the most

• ptimistic scenario

with H.E.S.S

Cristofari et al. 2017

Number of detections by CTA

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≈ 500 SNRs ≈ 350 SNRs ≈ 180 SNRs

α=4.1 Kep=10-2

Cristofari et al. (2017)

Number of detections by CTA

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Cristofari et al. 2017

F(>1 TeV) F(>10 TeV)

Conclusions and future perspectives

• A new test for the SNR hypothesis
• Constraining parameters governing particle acceleration
• Estimation on the SNR population accessible by CTA:

– Improvement compared to H.E.S.S – Caracterization of the population

• Detection ≈ 22 - 120 SNRs
• Size ≈ 0.2°
• Distance ≈ 7-10 kpc
• Ages ≈ 4-6 kyr
• Results of our approach confronted with other instruments (HAWC,

HiSCORE)

• Detections of neutrinos from SNRs, search of PeVatrons

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