Observational Signatures of Relativistic and Newtonian Shock Breakouts

Observational Signatures of Relativistic and Newtonian Shock Breakouts Ehud Nakar Tel Aviv University § Re’em Sari (Hebrew Univ. ) § Gilad Svirsky (Tel Aviv Univ. ) § Tomer Goldfriend (Hebrew Univ. ) Death of Massive Stars Nikko, Mar 16, 2012

Studies of shock breakouts (partial list) Newtonian: • Shock breakout Colgate 74; Falk 78; Imshennik and Nadyozhin 88; Matzner & Mc. Kee 99; Katz et. al. 10; Nakar & Sari 10; Ofek et al 11, Balberg & Leob 11, Chevalier & Irwin 11 & 12, Svirsky, EN & Sari 12… • Planar expansion Piro et. al. 10, EN & Sari 10, Sapir et. al. 11, Katz et. al. 11, … • Spherical expansion Chevalier 76, 92; Waxman et. al. 07; Chevalier & Fransson 08; Piro et. al. 10, Rabinak & Waxman 10; EN & Sari 10, … • Numerical simulations Klein & Chevalier 78; Ensman & Burrows 92; Blinnikov et. al. 98, 03; Utrobin 07; Tominga et. al. 09, 11; Suzuki & Shigeyama 10; Dessart & Hillier 11; Couch et al 11; Moriya et al 11, Blinnikov & Tolstov 11, … Relativistic: Colgate 1968; Tan et al. , 2001, Waxman et al. , 2007, Katz et al. , 2010, EN & Sari 2011

Outline and Conclusions Relativistic breakout (EN & Sari 11) • g-ray flare followed by X-ray extended emission • Must take place in: long GRBs, low-luminosity GRBs, Ia SNe, Highly compact & energetic core collapse SNe • Plausible explanation for the entire emission (including grays) of ALL low-luminosity GRBs Breakout through a dense wind (Svirski, EN & Sari 12) Delayed (~10 -50 SN rise time), bright (~1041 -1043) x-ray to soft g-ray emission (See poster P-60) WR and BSG core-collapse SNe (EN & Sari 10) • T>>Tblackbody (~1 -10 ke. V) throughout the planar phase – minutes (WR) to ~20 min (BSG)

Relativistic Shock Breakouts (GRBs, Super-energetic SNe, Type Ia SNe) EN & Sari 2011

Relativistic shock breakout Main physical differences from Newtonian breakout: • Constant post shock rest frame temperature ~100 -200 ke. V Katz et. al. , 10 Budnik et. al. , 10 pairs TBB • Temperature dependent (pair) opacity • Significant post breakout acceleration

A flash of g-rays from shock breakout A quasi-spherical, windless relativistic breakout gbo – Breakout Lorentz factor Rbo – Breakout radius

Relativistic breakout relation Quasi-spherical, windless relativistic breakouts: Three observables: Tbo , tbo , Ebo Depend on two physical parameters: Rbo and gbo A test that each quasi-spherical, windless relativistic breakout must pass!

Extremely energetic supernovae (e. g. , SNe 2002 ap, 2007 bi; Mazzali et al 2002, Gal-Yam et al 2009) Detectable by Swift and Fermi out to 3 -30 Mpc • Events such as SN 2002 ap (@ ~7 Mpc) may be detectable. Events such as 2007 bi are too rare to detect.

White dwarf explosions Type Ia and. Ia SNe and AIC Detectable within the Milky way

Low luminosity GRBs Some unique properties (very different than LGRBs): • Smooth light curve • Eg that is a small fraction of the total explosion energy • Mildly relativistic ejecta with energy comparable to Eg • Delayed X-ray emission, with energy comparable to Eg • Cannot be produced by successful jets (Bromberg, EN, Piran & Sari 11) All properties naturally explained by shock breakout Previously suggested by Colgate 1968, Kulkarni et al. , 1998, Tan et al. , 2001, Campana et al. , 2006, Waxman et al. , 2007, Wang et al. , 2007, Katz et al. , 2010

Low luminosity GRBs GRB Ebo (erg) Tbo (ke. V) tbo (s) Relation tbo (s) Rbo (cm) gbbo 980425 1048 150 30 10 6 1012 3 031203 5 1049 >200 30 <35 2 1013 >4 060218 5 1049 40 2100 1500 5 1013 1 100316 D 5 1049 40 1300 1500 5 1013 1 Relativistic breakout relation

BUT: the inferred Rbo>1013 cm Much larger than WR radii ! However: Rbo is where t~1 (e. g. , mbo~10 -5 Mo) possible explanations • extended very low mass envelope • mass ejection just prior to explosion • effects of asphericity and/or a wind (needed to be calculated)

Newtonian Breakout through a Thick Wind Svirski, EN & Sari 2011 (see also Chevalier & Irwin 12) See more details in poster P-60

Unshocked wind Plasma heated by Collisionless shock (Katz et al. 11) Hard component (X and g rays) free-free of ~60 ke. V electrons. Degraded by collisions with the unshocked wind and IC cooling Soft component (opt-UV) free-free of heated unshocked wind. Main cooling source (via IC) of the hot shocked plasma

Late breakout (typically 70 d < tbo) Early breakout (typically 1 d < tbo < 20 d) Ø Brightest emission Ø X-rays suppressed Ø May explain SN 2006 gy Ø Excellent for X-ray searches Ø May explain PTF 09 uj

Early Temperature evolution of Regular corecollapse SNe from compact progenitors EN & Sari 10

Shock temperature T is set by the ability to produce enough photons RSG BSG er -th No n WR m al (Weaver 76; Katz et. al. , 10) TBB al Thermal equilibrium: vsh < 15, 000 km/s Gas that is not in thermal equilibrium at the shock crossing will not gain it at later phases (EN & Sari 10)

Observed Luminosity [erg/s] (Spherical breakout from stellar surface) Breakout Planar 1045 t-4/3 Spherical t -0. 17 - t -0. 35 Breakout layer Time EN & Sari 10 Wolf-Rayet Blue Supergiant Red Supergiant R/c 10 s 2 min 20 min R/vbo 1 min 20 min 10 hr Deeper layers

Temperature (Spherical breakout from stellar surface) Breakout Planar no thermal equilibrium t -1/3 - t -2/3 1000 T [e. V] BSG-WR Spherical 10 -100 t -1/3 RSG-BSG t-0. 6 Time EN & Sari 10

Optical-UV light curves Spherical Breakout Planar RSG BSG RSG WR WR EN & Sari 10 Optical Far UV

X-ray light curve WR BSG RSG EN & Sari 10

Conclusions Relativistic breakout (EN & Sari 11) • g-ray flare followed by X-ray extended emission • Must take place in: long GRBs, low-luminosity GRBs, Ia SNe, Highly compact & energetic core collapse SNe • Plausible explanation for the entire emission (including grays) of ALL low-luminosity GRBs Breakout through a dense wind (Svirski, EN & Sari 12) Delayed (~10 -50 SN rise time), bright (~1041 -1043) x-ray to soft g-ray emission (See poster P-60) WR and BSG core-collapse SNe (EN & Sari 10) • T>>Tblackbody (~1 -10 ke. V) throughout the planar phase – minutes (WR) to ~20 min (BSG)

Some topics for future study • Newtonian breakout through a wind (Moriya et al 11, Ofek et al 11, Balberg & Leob 11, Chevalier & Irwin 11) • A-spherical breakout (Suzuki & Shigeyama 10, Couch et al. , 11) • Effects of metallicity on the color temperature • Transition to collisionless shock (Katz et al 11) • Relativistic breakouts

Wind shock breakout (… Moriya et al 11, Ofek et al 11, Balberg & Leob 11, Chevalier & Irwin 11, Katz et al 11) When? tw >10 -30 Main observables: Larger breakout radius Brighter longer and colder Shock transition from radiation to collisionless High energy emission + Fast optical decay (Katz et al 11)

Which explosions are expected to have relativistic breakouts? EN & Sari 11

Comparison with numerical results Red supergiant R*=800 Rsun ; M*=18 Msun ; L/1. 4 E=1. 2× 1051 erg

Blue supergiant R*=45 Rsun ; M*=16 Msun ; E= 1051 and 2. 3 × 1051 erg Thermal eq. enforced

Typical properties of shock breakout Breakout duration ~ R/c Breakout luminosity (all progenitors) ~ 1045 erg/s

Breakout temperature

Time = Mass (during the spherical phase) Time [sec] 102 103 104 105 106 10 -8 10 -6 10 -4 0. 01 1 Mass probed [M ] breakout + planar recombination WR breakout + planar recombination BSG breakout + planar RSG recombination