Very-High-Energy (TeV) Observations of Pulsar Wind Nebulae and Supernova Remnants

Nukri Komin

University of the Witwatersrand Johannesburg, South Africa

Nukri Komin 9th International Fermi Symposium (2021) 1 PWNe and SNRs in a Nutshell possible binary systems black holes supernova explosion isolated neutron stars of massive star

rotating neutron star core contraction → pulsar rotation driven 28 38 e surrounded by electron wind Ė 10 ...10 erg/s xp (C) A Hitchhikers Gui an → pulsar wind nebula de to Space and Pla si sma Physics on o f o ut er composites la ye rs kinetic SN energy warf explosion supernova type Ia white d supernova remnant ~1051 erg

Nukri Komin 9th International Fermi Symposium (2021) 2 TeV Instruments ➲ ground based observations of atmospheric showers ➲ Imaging Air Cherenkov Telescopes → Cherenkov light in air → small field of view, low-duty cycle → detailed studies of individual sources → H.E.S.S., MAGIC, VERITAS ➲ Extensive Air Shower Arrays → direct detection of shower particles → large field of view, large duty cycle → population studies, large sources → Cherenkov light in water tanks (HAWC) → scintillation counters (Tibet Air Shower Array)

Nukri Komin 9th International Fermi Symposium (2021) 3 Hubble (NASA/ESA) Crab Nebula: TeV Observation Timeline

➲ 1989, Whipple [Weekes et al. 1989 ApJ v.342, p.379] → 9σ detection, >0.7 TeV ➲ 1996, HEGRA [HEGRA Collaboration 1996 APh v. 4-3, p. 199-215] H.E.S.S. 2006 → 10σ detection, 1-3 TeV, power law spectrum ➲ 2003, Milagro [Atkins et al. ApJ v. 595, Issue 2, pp. 803-811]

→ 3 6.4σ, 4 TeV median energy 186 MAGIC >25 GeV ➲ 2006, H.E.S.S. [H.E.S.S. Collaboration, A&A, v. 457-3, pp.899-915] 185 → ~100σ, 440 GeV – 40 TeV, spectral cut-off 184 ➲ 2008, MAGIC [MAGIC Collaboration, ApJ v. 674-2, p. 1037-1055] 183

-1 -0.5 0.501 → 60 GeV – 9 TeV, curved power law Phase ➲ pulsed emission → 2008, MAGIC [MAGIC Collaboration, Science, Volume 322, Issue 5905, pp. 1221] → 2011, VERITAS [VERITAS Collaboration, Science 334: 69] ➲ > 100 TeV photons → 2019, Tibet [Amenomori et al. PhysRevL, v. 123, Issue 5, id.051101] → 2019, HAWC [HAWC Collaboration ApJ, Volume 881, Issue 2, article id. 134] ➲ 2020, H.E.S.S. [H.E.S.S. Collaboration, NatAs Volume 4, p. 167-173] → extension ➲ many other publications and instruments (CTA prototypes, ...) [MAGIC, JHEAp, Volume 5, p. 30-38.]

Nukri Komin 9th International Fermi Symposium (2021) 4 Crab Nebula ➲ PSR B0531+21 → P = 33.4 ms, Ṗ =4.2×10-13, Ė = 4.5×1038 erg/s, age ~1000 years → d = 2 kpc [MAGIC, JHEAp, Volume 5, p. 30-38.] ➲ gamma-ray luminosity → 50 GeV – 30 TeV → 1035 erg/s (0.02% Ė) ➲ Why is it so bright in TeV? → 2nd most luminous pulsar → point-like source ● X-ray extension 50’’ (0.5 pc) → strong synchrotron emission → SSC

Nukri Komin 9th International Fermi Symposium (2021) 5 Crab Nebula with H.E.S.S. ➲ [HESS 2020, Nat. Astron,, v, 4, p. 167-173] ➲ increase angular resolution → simulate detector response on run-by-run basis → account for detector problems, night-sky-background, ... → 0.05° (68% containment) X C M h

➲ a 1.0 - 3.0 TeV Electrons Crab extension 52’’ (1σ of Gaussian) a M n d U 3.0 - 10.0 TeV Electrons r a −7 V 10 W 10.0 - 30.0 TeV Electrons H 1 . → E

smaller than in UV . S . S ) −8 . 1 10 −

→ significantly larger than in X-rays s 2

− −9

m 10 c

➲ g

H.E.S.S. probes electron energies r

e −10 ( 10 ν

that are not well observed in F synchrotron emission ν 10−11 10−12

10−7 10−4 10−1 102 105 108 1011 1014 Energy (eV)

Nukri Komin 9th International Fermi Symposium (2021) 6 HESS J1825–137 ➲ [HESS 2019, A&A 621, A116] ➲ PSR B1823–13 → Ė = 2.8×1036 erg/s, age 21 kyrs → d ~ 4 kpc ➲ PWN at TeV → ~0.8° (~56 pc) ● larger than X-ray nebula (15’) [Uchiyama et al., PASJ 2009, v.61, pp.S189] ● larger than 1-100GeV nebula (0.56°) [Grondin et al 2011 ApJ 738 42] → L = 3.1×1035 erg/s = 11% Ė

Nukri Komin 9th International Fermi Symposium (2021) 7 HESS J1825–137 ➲ energy dependent morphology → highest energy electrons do not travel too far away from pulsar → >16 TeV photons come only from X-ray nebula

Table 3. Extent measurements as a function of energy for analyses A and B, with statistical and systematic errors.

Energy range Extent (A) Extent (B) <125 GeV – 0.37◦ ±0.15◦ ±0.3◦ 125−250 GeV – 0.63◦ ±0.07◦ ±0.07◦ <250 GeV 0.66◦ ±0.04◦ ±0.3◦ – 250−500 GeV 0.76◦ ±0.03◦ ±0.2◦ 0.71◦ ±0.09◦ ±0.01◦ 500 GeV−1 TeV 0.72◦ ±0.02◦ ±0.05◦ 0.72◦ ±0.05◦ ±0.2◦ 1−2 TeV 0.64◦ ±0.02◦ ±0.11◦ 0.62◦ ±0.07◦ ±0.4◦ 2−4 TeV 0.47◦ ±0.04◦ ±0.08◦ 0.51◦ ±0.05◦ ±0.1◦ 4−8 TeV 0.38◦ ±0.04◦ ±0.13◦ 0.33◦ ±0.07◦ ±0.04◦ 8−16 TeV 0.27◦ ±0.07◦ ±0.06◦ 0.30◦ ±0.12◦ ±0.3◦ >16 TeV – 0.22◦ ±0.12◦ ±0.2◦ 16−32 TeV 0.19◦ ±0.08◦ ±0.14◦ – X-ray nebula >32 TeV 0.14◦ ±0.1◦ ±0.05◦ –

Nukri Komin 9th International Fermi Symposium (2021) 8 Particle Transport in HESS J1825–137 ) o

➲ energy dependent diffusion (

t n e → size would increase with energy t 1 x E

l a

➲ diffusion and cooling i d a

→ maximum extend at energy where cooling R time meets age

● Ee = 4 TeV, B ≈12 μG (BX-rays ≈5 μG) → nebula becomes smaller with energy

➲ advection South A South B → nebula confined by ISM δ 10-1 EDGE =0 → nebula even smaller than for diffusion EDGE δ=1 Fit Analysis A ➲ energy-dependent morphology allows Fit Analysis B Diffusion the study of the particle transport Advection → more prominent at larger distance from 10-1 1 10 pulsar Energy TeV

Nukri Komin 9th International Fermi Symposium (2021) 9 TeV J2032+4130 VERITAS

➲ first unidentified and extended TeV source

→ HEGRA [A&A, v.431, p.197-202 (2005)] → Whipple [A&A, v.423, p.415-419 (2004)] → MAGIC [ApJL, Volume 675, Issue 1, pp. L25 (2008)] → VERITAS [ApJ, Volume 783, Issue 1, article id. 16, 9 pp. (2014)] ➲ PSR J2032+4127 → Ė = 1.5×1035 erg/s, age 2×105 years, distance 1.3 kpc ➲ nebula → TeV extension 9.5’ × 4.0’ (3.6 pc × 1.5 pc), L ~ 0.3% Ė → X-ray extension 12’ → good PWN candidate ➲ binary system on 50-years orbit → detected at periastron by VERITAS and MAGIC ● [ApJL, Volume 867, Issue 1, article id. L19, 8 pp. (2018)] → orbit < 200 AU MAGIC → binary system inside a PWN (?)

Nukri Komin 9th International Fermi Symposium (2021) 10 TeV PWN Population

20 PSRs > 1034 erg/s/kpc 2 Randomised PSRs > 1034 erg/s/kpc 2

15

N 10

5 ➲ PWN in the H.E.S.S. Galactic Plane Survey 0 0.0 0.5 1.0 1.5 2.0 → [A&A, Volume 612, id.A2, 25] Squared Angular Distance PSR-TeV [deg 2]

28 34 2 → 140 PSRs 10 - 10 erg/s/kpc correlation between pulsar and TeV emission Randomised PSRs 1028 - 1034 erg/s/kpc 2 for Ė/d2 > 1034 erg/s/kpc2 120 100

80 → 14 firmly identified PWN N 60 → 18 PWN candidates 40 20

0 0.0 0.5 1.0 1.5 2.0 Squared Angular Distance PSR-TeV [deg 2]

Nukri Komin 9th International Fermi Symposium (2021) 11 TeV PWN Population

r yr ky ➲ -11 1 k 0 young, high-Ė pulsars 10 Kes 75 1

MSH 15-52 yr ➲ exception -12 0 k 10 10 Crab Nebula CTA 1 → PSR B1742−30 3C 58 r ] Vela X ky 1 -13 00 − 10 J1825-137 10

33 s N157B ● Ė = 8.5×10 erg/s s [

● 5 e τ = 5.5×10 years t -14 s a 10 / g

R r

e ● 9 d = 200 pc n 3 0

w 1

o -15

→ d 10 2 candidate TeV sources - n i ● p very small: 0.2°, 0.06° S -16 /s 10 g r ● e unlikely PWN candidates 7 3 Firm identifications 0 1 -17 Candidate PWNe 10 /s /s g g PWNe outside HGPS r r e e 5 3 3 3 ATNF pulsars 0 0 10 -18 1 1 10 -2 10 -1 10 0 10 1 Period [s]

Nukri Komin 9th International Fermi Symposium (2021) 12 TeV PWN Population 10 2 ➲ efficiency: Firm identifications 10 1 Candidate PWNe PWNe outside HGPS Lim its → 0 Ė of pulsar at present time 10 Varied Model ˙ E /

V Baseline Model → e L1-10TeV from electrons injected over T -1 0

1 10

− J1825-137

life time of pulsar 1 L

y -2 c 10 ➲ efficiency grows with age n

e MSH 15-52 i c

i N157B CTA 1 f

f -3 Kes 75 e 10

V e T -4 Vela X 10 Crab Nebula

10 -5 3C 58

10 -6 10 0 10 1 10 2

Characteristic age τc [kyr]

Nukri Komin 9th International Fermi Symposium (2021) 13 TeV PWN Population

➲ offset of pulsar from TeV 10 2

emission centroid J1825-137 ➲ increases with age N157B 10 1 ]

→ proper motion of pulsar c MSH 15-52 CTA 1 p [

t Kes 75 3C 58 Vela X → e inhomogeneous medium leads to s f f

o 0 asymmetric (“crushed”) PWN 10 r Crab Nebula a s l u P Firm identifications Candidate PWNe -1 10 PWNe outside HGPS Min. offset (0.0056 deg) at 5.1 kpc Max. offset (0.5 deg) at 5.1 kpc 500 km /s 10 -2 10 0 10 1 10 2

Characteristic age τc [kyr]

Nukri Komin 9th International Fermi Symposium (2021) 14 TeV PWN Population

Firm identifications 10 3 ➲ extension of nebula Candidate PWNe PWNe outside HGPS increases with age Varied Model Baseline Model ] c

p 2 N157B [ 10 N W P

R J1825-137 n o i s n

e MSH 15-52

t 1

x 10

e CTA 1

V 3C 58

e Crab Nebula

T Kes 75 Vela X on teracti hock in n rse s o reve si n a 0 p 10 x e e e fr

10 0 10 1 10 2

Characteristic age τc [kyr]

Nukri Komin 9th International Fermi Symposium (2021) 15 Composite Supernova Remnants ➲ radio/X-rays: PWN and SNR shell visible ➲ HESS J1554–550 → pulsar not identified Chandra X-rays → TeV emission smaller then shall [Temim et al., ApJ 2015, 808, 100] → most likely PWN emission ➲ HESS J1119–614 → PSR J1119−6127, Ė = 2.3×1036 erg/s → d = 8.4 ± 0.4 kpc → emission from PWN or shell?

Nukri Komin 9th International Fermi Symposium (2021) 16 Supernova Remnants and Cosmic Rays up to 1015 eV ➲ Are SNRs the sources of Galactic CRs (protons) up to 1015 eV? → is the emission hadronic? → what is the cut-off of the spectrum? AB IC 443 W44 10-10 10-10 ) ) 1 1 - - s s 2 2 - - m m c c

g g r -11 r -111 e 10 e 10 ( (

E E d d / / N N d Best-fit broken power law d 2 2 Best-fit broken power law Fermi-LAT E VERITAS ( ) E Fermi-LAT -12 MAGIC ( ) -12 AGILE ( ) 10 AGILE ( ) 10 π0-decay π0-decay Bremsstrahlung Bremsstrahlung Bremsstrahlung with Break Bremsstrahlung with Break

108 109 1010 1011 1012 108 109 1010 1011 1012 Energy (eV) [Fermi/LAT, Science 2013, 339, 807A] Energy (eV)

Nukri Komin 9th International Fermi Symposium (2021) 17 TeV SNR shells ➲ shell-like morphology → [HESS 2018, A&A, 612, 6] → [HESS 2018, A&A 612, 7] → [HESS 2010, A&A, 516, 62] → [HESS 2018, 612, 8] RX J1713.7–3964 (Ø 1.2°) Vela Junior (Ø 2°) → [HESS 2011, A&A, 531, A81] SN 1006 (Ø 0.5°)

HESS J1534-571 (Ø 0.4°) HESS J1614-518 (Ø 0.42°) HESS J1912+101 (Ø 0.49°) HESS J1731–347 (Ø 0.5°)

Nukri Komin 9th International Fermi Symposium (2021) 18 Are TeV Shells Proton Accelerators? ➲ example: Vela Junior → leptonic or hadronic scenario -9 ] 1

- 10 0

s π decay 2

- ■ Fermi/LAT [Tanaka et al. 2011, ApJ, 740, 51]

→ hadronic (or mixed) scenarios need m inverse Compton c ● H.E.S.S. g r e

higher magnetic field (~100μG) [ -10 E 10 d / N d 2 E

10-11

10-12

➲ TeV gamma-ray observations do 10-13 10-4 10-3 10-2 10-1 1 10 102 not constrain particle type E [TeV]

Nukri Komin 9th International Fermi Symposium (2021) 19 Highest Energies ➲ clear detection of cut-offs (spectral indices 1.6 … 1.8) → RX J1713.7–3964: 12.9 ± 1.1 TeV [HESS 2018, A&A, 612, 6] → Vela Junior: 6.7 ± 1.2 TeV [HESS 2018, A&A 612, 7] → RCW 86: 3.5 ± 1.2 TeV [HESS A&A 612 (2018) A4] ➲ only up to Ep ~ 100 TeV, Where are the PeVatrons? ) 2 - −10

m 10 H.E.S.S. (2016) RXJ1713.7-3946 c 1 - s

g r e

(

E d / N d 2 E 10−11 H.E.S.S. Data (this work) Systematic uncertainty Best-fit model 2016 Best-fit model 2007 Vela Junior RCW 86 10−12

t −1 i 103 1 10 F

/

Energy ( TeV ) a t

a 2 D

o i t 1 a R

10−1 1 10 Energy ( TeV )

Nukri Komin 9th International Fermi Symposium (2021) 20 TeV SNR Population ➲ search for TeV emission in the HGPS survey from known SNRs → [HESS 2018, A&A 612, 3]

Nukri Komin 9th International Fermi Symposium (2021) 21 Summary

➲ Pulsar Wind Nebulae → largest galactic TeV source population → driven by rotational energy loss of pulsar → electron/positron acceleration → increasing size (tens of parsecs) with increasing age (up to 100 kyr) ➲ Supernova Remnants → rather small population → driven by kinetic energy of SN explosion (1051 erg) → electron/positron and proton acceleration → resolved shells → gamma-ray cut-off around 10 TeV (corresponding to 100 TeV protons) ➲ laboratories to study particle acceleration and propagation ➲ Future: Cherenkov Telescope Array → higher sensitivity probes larger distances and higher energies

Nukri Komin 9th International Fermi Symposium (2021) 22