High Energy Gamma-Rays in Magnetar Powered Supernovae: Heating Efficiency and Observational Signatures

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1 High Energy Gamma-Rays in Magnetar Powered Supernovae: Heating Efficiency and Observational Signatures Dmitry A. Badjin 1,2 with Maxim V. Barkov and Sergei I. Blinnikov 1 N.L. Dukhov Research Institute of Automatics (VNIIA), Moscow, Russia 2 Institute for Theoretical and Experimental Physics, Moscow, Russia 18th Workshop on Nuclear Astrophysics Ringberg Castle March 14 19, 2016

2 2 Magnetar Powered Supernova Sources of additional power: Rotation energy potentially available: E rot = 1 2 IΩ erg ( ) Spin-down losses: L rot = L t α, τ 45 erg L 0 10 s, τ 105 s, α 2 Inner Shock heating HEGR heating! Simple deposition of L rot at the shell base seems promising for fitting observed SLSN light curves D. Kasen, L. Bildsten, ApJ, 2010, 717, p.245 C. Inserra et al. ApJ, 2013, 770:128 M. Nicholl et al. Nature, 2013, 502, p.346

3 3 Magnetar Powered Supernova Magnetar Driven Shock: 1D-simulations D.Kasen, B.Metzger, L.Bildsten, arxiv: , accepted to ApJ

4 4 Magnetar Powered Supernova Questions: Whether the magnetar powering is pronounced against the initial (strong) SLSN explosion and Ni-Co-Fe decays?? t: L M (t) L burst (t), L Ni (t) It seems better: the magnetar to be strong (but this means a short time-scale of losses) or the explosion weak (but how could it provide a strong M?) or t long (but heating power is also weak) HEGRs may be locked inside the wind cavern by high opacity for pair-production on the thermal background of ejecta, until the latter cools enough. Tests are required.

5 Tested Scenario MRI-driven Hypernova with Magnetar Powering Eburst = 1 10 foe, LM = erg, s Ni-free but with HEGRs according to Barkov M.V. & Komissarov S.S., Mon.Not.Roy.Astron.Soc., 2011, 415, pp

6 6 Magnetar Cavern Initial burst a Thermal Bomb SN ejecta (IV) expands into ISM (V) Forward Shock (FS) Magnetar e ± -wind (I) (γ e = !) is terminated by IV 3 discontinuities: Termination shock (TS), leptons-plasma Contact (CD), Inner shock (IS) 2 regions: shocked wind (II), shocked plasma (III). Plasma is hot ( K) thermal emission (TE) inwards ( free escape) and outwards (diffusion free escape) Relativistic e ± + B and TE HEGRs: synchrotron (10 MeV 10 GeV) and IC (up to 100 TeV) HEGRs + plasma (direct Compton) and TE (pair production) heating and pressure.

7 7 Methods of Testing Radiative Hydrodynamics with STELLA (Blinnikov et al., 1998) for TE: Spherical symmetric lagrangean hydrodynamics Coupled (unsplit) + multigroup time dependent radiation transport of energy and flux (0th and 1st moments of the Boltzmann equation, variable Eddington factor closure, O(v/c) in moving media) High order accurate implicit solver (2-nd in space, up to 6-th in time) Scattering and expansion opacity Artificial mixing acceleration Improvements for high-energy effects: + Source of HEGR accounts for spin-down luminosity (e ± injection), coupling of wind and plasma via pressure and energy balance. + Spectral transport of HEGRs. Energy deposition. Outcoming emission ectimation. + Optimization of moment equations closure HEGRStella (Badjin)

8 8 Wind-Plasma Coupling Scheme at TS: p e + p B = E + B2 3V 8π = Lw 4πcR 2 TS E e = L e + (η 1)L γ p e V E B = L B p B V L γ = L Syn (B, T TE ) + L IC (J(ν), B) at CD: p e + p B nkt everywhere above TS: γ + e γ + heat γ + hν e ± heat heat = E e or 3 2 nkt

9 9 HEGR Source Calculation Input: B, L e (t), dn0 e (t,γ e) dγ e STELLA Quasi-stationary fast e-cooling: dn e(γ e,t) dt = N 0(t) γ α e L e (t)γe 2, T rad or J ν (ν) from native Ne(γe,t) γ e,max t cool (T rad,b,γ + N e(γ e,t) e) t cool (T rad,b,γ e γe)dγ e = 0 dne(γe,t) dγ e dnγ(ε,t) dε Syn, dnγ(ε,t) dε IC L γ (t) HEGR spectral density over 100 MeV 100 TeV logarithmic grid special thanks to Dmitry V. Khangulyan γ e

10 10 HEGRs & Compton Scattering HEGRs are emitted by ultrarelativistic leptons strong radial collimation sharp angular dependence, low-order moment approximations do not work. Direct CS (off cold e ): HEGRs either are weakly deflected, or (otherwise) lose most of energy Strongly downscattered photons do not contribute photon density at final energy significantly Simplification: HEGRs are discretized into a set of expanding spherical shells of photons collimated within θ c < 1 3 : small-angle scattering gradual softening, large-angle scattering photon destruction, immediate energy thermalization.

11 11 HEGR Transport Equation Superposition of direct and scattered (only within θ c ) emission on every elementary path r 0 r 1 = r 0 + c t. Transfer equation formal solution: N ε(r 1, ε) = N ε(r 0, ε)e τ(ε) σtsc(ε) S C(ε) = ε max ε 1 N ε(r 0, ε 0)F(ε, ε 0) ε 0 τ(ε) = r 1 r 0 r 1 r 0 n e(r )e r r 0 χ(ε, r, t (r ))dr χ(ε 0 )dr r1 χ(ε)dr r dr d ln ε 0

12 12 Kinetics and Opacity Downscattering rate ε 0 ε (if allowed by the angular selection rule): F(ε, ε 0) = (1 + (1 + 1 ε 0 1 ε )2 + εε 0( 1 ε 0 1 ε )2 ) ε 0 ε max(ε, θ) opacity χ accounts for CS: ( 3 σ T χ KN(ε) = n e 8 ε (ε 2 2 ε ) ln(1 + 2ε) + 2ε2 (1 + ε) (1 + 2ε) 2 and pair production of photons of local effective temperature T eff : χ pp(ε, ν) = 2r2 0Θ 3 1 ν 2 sσ(s) ln(1 e νs ) ds, πλ 3 e ν(ε, T eff ) = m 2 c 4 /(εkt eff ), Θ = kt eff /m ec 2, Λ e = /m ec (derived from Gould & Schreder, 1967) ),

13 13 Calculation Setup RSG Mass: 15 25M 15 Scale factor for CE: MRI-SN burst energy erg, duration s 3, 30 L w = 3 ( ) t 2.1 erg 10 5 s s, B Magnetization parameter σ = : σl B + L e = (σ + 1)L w Lepton spectrum: γ 2 e, γ e = Output: light curves and spectra of outcoming HEGRs and observable TE during the first several years

14 14 Conditions in the Cavern R, cm t, days R src R cdb T rad B, kgs; T rad, 10 5 K

15 15 HEGR Outcome Source Outcome log L γ, erg s Bol GeV 1-10 GeV GeV TeV Strong absorption in the shell the signal is rather weak and late

16 16 HEGR Blocking Key effect: Plasma is hot a lot of thermal hν, to kill the most of HEGRs before they pass the CD HEGRs (almost) do not enter the plasma no re-heating of the shell Cold shell does not intercept HEGRs no re-heating, weak TE. Negative feedback hν γ. Magnetar energy turns into work.

17 17 Magnetar Driven Shock The MDS is radiative Dense Shell. HEGRStella Optically and geometrically thin dense shell Extremely hard for numerical differential transfer Long-characteristic integral scheme for TE Blondin, Chevalier & Frierson, ApJ, 2001, 563, p.806

18 17 Magnetar Driven Shock The MDS is radiative Dense Shell. But! It is known to be RT-unstable (Bernstein & Book 1978) HEGRStella Optically and geometrically thin dense shell Extremely hard for numerical differential transfer Long-characteristic integral scheme for TE Credit: S. Glazyrin Time to smear Artificial RT-viscosity boost

19 18 Thermal Emission: Bolometric The work is actually in progress NoHEGR NoNi 3 foe + HEGR 1.2 foe + HEGR NoHEGR M Ni log L TE,bol, erg s t, days

20 19 STELLA: 15M, 1-3 foe: Conclusions... Magnetars seem not so almighty. At least in extended envelopes. SLSN -? Distinctive magnetar tail only at the latest stages (t > T Ni Co Fe 10 2 d.) Unless the shell is too cold, its thermal background blocks the HEGRs within the cavern, otherwise it is transparent. HEGRs heat not the ejecta but the shocked wind

21 19 STELLA: 15M, 1-3 foe: Conclusions... Magnetars seem not so almighty. At least in extended envelopes. SLSN -? Distinctive magnetar tail only at the latest stages (t > T Ni Co Fe 10 2 d.) Unless the shell is too cold, its thermal background blocks the HEGRs within the cavern, otherwise it is transparent. HEGRs heat not the ejecta but the shocked wind... and new questions. Why the MDS does not shine brightly? Non-Eq emission into the central cavity or an artifact of mixing? If there are other ways of the shocked wind energy dissipation and heat conduction? The radiative thin dense shell around CD requires special TE transfer methods or properly enhanced mixing (based on multi-d analysis).

22 Thank you! 20