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 StarsNikko, Mar 16, 2012

Studies of shock breakouts (partial list)Newtonian:• Shock breakoutColgate 74; Falk 78; Imshennik and Nadyozhin 88; Matzner & McKee 99; Katz et. al. 10; Nakar & Sari 10; Ofek et al 11, Balberg & Leob 11, Chevalier & Irwin 11 & 12, Svirsky, EN & Sari 12…

• Planar expansionPiro et. al. 10, EN & Sari 10, Sapir et. al. 11, Katz et. al. 11, …

• Spherical expansionChevalier 76, 92; Waxman et. al. 07; Chevalier & Fransson 08; Piro et. al. 10, Rabinak & Waxman 10; EN & Sari 10, …

• Numerical simulationsKlein & 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)• -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 -rays) 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 -ray emission (See poster P-60)

WR and BSG core-collapse SNe (EN & Sari 10)

•T>>Tblackbody (~1-10 keV) 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 keV

• Temperature dependent (pair) opacity

• Significant post breakout acceleration 31 initialfinal

104

105

10-2

10-1

100

101

102

V (km/s)

T (

ke

V)

TBB

pairs

Katz et. al., 10Budnik et. al., 10

s22

sunbo

bobo R

Rt

keV 50 boboT

A flash of -rays from shock breakout

erg 102

35.144

sun

bobobo R

RE

A quasi-spherical, windless relativistic breakout

bo – Breakout Lorentz factorRbo – Breakout radius

Quasi-spherical, windless relativistic breakouts:Three observables: Tbo , tbo , Ebo

Depend on two physical parameters: Rbo and bo

Relativistic breakout relation

7.22/1

46 keV 50erg 10s 20

bobobo TEt

A test that each quasi-spherical, windless relativistic breakout must pass!

Extremely energetic supernovae (e.g., SNe 2002ap, 2007bi; Mazzali et al 2002, Gal-Yam et al 2009)

Detectable by Swift and Fermi out to 3-30 Mpc• Events such as SN 2002ap (@ ~7 Mpc) may be detectable. Events such as 2007bi are too rare to detect.

erg 1010~ 4644 boE

s 303~ bot

keV 100~boT

White dwarf explosions Type Ia and .Ia SNe and AIC

Detectable within the Milky way

erg 1010~ 4240 boE

ms 301~ bot

MeV ~boT

Some unique properties (very different than LGRBs):

• Smooth light curve

• E that is a small fraction of the total explosion energy

• Mildly relativistic ejecta with energy comparable to E

• Delayed X-ray emission, with energy comparable to E

• 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

Low luminosity GRBs

GRB Ebo

(erg)Tbo

(keV)tbo

(s)Relation

tbo (s)Rbo

(cm)bo

980425 1048 150 30 10 61012 3

031203 5104

9

>200 30 <35 21013 >4

060218 5104

9

40 2100 1500 51013 1

100316D 5104

9

40 1300 1500 51013 1

Relativistic breakout relation

7.22/1

46 keV 50erg 10s 20

bobobo TEt

BUT: the inferred Rbo>1013 cm

Much larger than WR radii !

However: Rbo is where ~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 WindSvirski, EN & Sari 2011 (see also Chevalier & Irwin 12)

See more details in poster P-60

Soft component (opt-UV)free-free of heated unshocked wind.Main cooling source (via IC) of the hot shocked plasma

Hard component (X and rays)free-free of ~60 keV electrons. Degraded by collisions with the unshocked wind and IC cooling

Plasma heated by Collisionlessshock (Katz et al. 11)

Unshocked wind

Excellent for X-ray searches May explain PTF 09uj

Early breakout (typically 1 d < tbo < 20 d)

Late breakout (typically 70 d < tbo)

Brightest emission X-rays suppressed May explain SN 2006gy

Early Temperature evolution of Regular core-collapse SNe from compact progenitors

EN & Sari 10

Shock temperatureT is set by the ability to produce enough photons(Weaver 76; Katz et. al., 10)

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)

104

105

10-2

10-1

100

101

102

V (km/s)

T (

ke

V)

TBB

Thermal

Non-th

erm

al

RSGBSG

WR

Breakout

Planar

Spherical

1045

Lum

ino

sity

[erg

/s]

TimecR* bovR*

t-4/3

t -0.17 - t -0.35

Wolf-Rayet Blue Supergiant Red Supergiant

R/c 10 s 2 min 20 min

R/vbo1 min 20 min 10 hr

Observed Luminosity(Spherical breakout from stellar surface)

EN & Sari 10

Breakoutlayer

Deeperlayers

Temperature(Spherical breakout from stellar surface)

Breakout Planar

Spherical

1000

T [e

V]

TimecR* bovR*

t-0.6

t -1/3 - t -2/3

t -1/3

t-0.6

10 -100RSG-BSG

BSG-WR

no thermal equilibrium

EN & Sari 10

Optical-UV light curves

Optical Far UV

cR*

bovR*

Breakout Planar

Spherical

RSG

WR

RSG

WR

BSG

EN & Sari 10

X-ray light curve

RSGWR BSG

EN & Sari 10

Conclusions

Relativistic breakout (EN & Sari 11)• -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 -rays) 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 -ray emission (See poster P-60)

WR and BSG core-collapse SNe (EN & Sari 10)

•T>>Tblackbody (~1-10 keV) 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? w >10-30

Main observables:

Larger breakout radius

Brighter longer and colder

Shock transition from radiation to collisionless(Katz et al 11)

High energy emission+Fast optical decay

Which explosions are expected to have relativistic breakouts?

EN & Sari 11

95.0

*

2.1

sun

7.1

53

exp

5M5erg 10 14

sun

ejectalosionbo R

RME

1042

1044

L [

erg

/s]

104

105

106

104

time [s]

T [

k]

Tominaga et al 2009Nakar & Sari 2010

Comparison with numerical results

L/1.4

Red supergiantR*=800 Rsun ; M*=18Msun ; E=1.2×1051 erg

1042

1044

L [

erg

/s]

102

103

104

104

105

106

time [s]

T [

k]Ensman & Burrows 1992Nakar & Sari 2010

E51

=2.3

E51

=1 (L/4)

E51

=2.3

E51

=1 (T/4)

Thermal eq.enforced

Blue supergiantR*=45 Rsun ; M*=16Msun ; E= 1051 and 2.3 ×1051 erg

Typical properties of shock breakout

Breakout luminosity (all progenitors) ~ 1045 erg/s

Rayet- Wolf km/s 000,40

Supergiant Blue km/s 000,20

Supergiant Red km/s 000,7

shv

WR M 103

BSG M 103

RSG M 01

sun8

sun6

sun-3

m

WR erg 01

BSG erg 103

RSG erg 01

45

46

48

E

Breakout duration ~ R/c

Breakout temperature

WR km/s 000,40

BSG km/s 000,20

RSG km/s 000,7

v

Time = Mass(during the spherical phase)

102 103 104 105 106

10-8 10-6 10-4 0.01 1

WR

BSG

RSG

Time [sec]

Mass probed [M ]

breakout + planar recombination

recombination

recombination

breakout + planar

breakout + planar