Hirotaka Ito RIKEN

Collaborators

Jin Matsumoto (RIKEN)

Shigehiro Nagataki (RIKEN)

Don Warren (RIKEN)

Maxim Barkov (Perdue Univ.)

Daisuke Yonetoku (Kanazawa Univ.)

Photospheric Emission from Collapsar Jets in

3D Relativistic Hydrodynamics

＠ FOE２０１７, Corvallis, OR 2017/6/6

Model for Emission Mechanism

Internal Shock Model

Photospheric Emission Model

photosphere Internal shock

External shock

γ γ

・Low efficiency for gamma-ray production

・Clustering of peak energy ~ 1MeV

(e.g., Rees & Meszaros 2005, Pe’er et al.2005, Thompson 2007)

flaw

Natural consequence of fireball model

・High radiation efficiency

・Difficult to model hard spectrum in low energy band

Photospheric Emission in GRB jet

Pe’er +2005,2006,2011; Giannios 2008; Beloborodov

2010,2011; Vurm+2011,2016; Lundman+2013,2014,

Ito+2013,2014

Radiation transfer calculation based on

3D hydrodynamical simulation

Previous Studies

approximated treatment for radiation

Dynamics of Jet and

Radiation transfer must be solved

Ioka+2011

Dynamics of Jet have significant effect on the radiation signature

See also Lazzati 2016 and Tyler’s talk

steady outflow model

Lazzati+2009,2011,2013; Mizuta+2011;Nagakura+2011;

Lopez-Camara+2014

Ito+2015, Ito+2017 in prep.

This Study

Lj = 1050 erg/s

qj = 5°

Gj = 5

Gｈ = 500

Calculation of relativistic jet breaking out of massive progenitor star

Progenitor star

16TI （Woosley & Heger 2006）

M* ~14Msun

R* ~ 4×1010 cm@presupernova phase

Jet parameter

Propagation of photons are calculated until they reach optically thin region

Radiative transfer calculation

g

g

tinj >> 1

g

g

t= 1

t=4s

t=300s

Ｒinj = 1010 cm

Model 1: steady injection

Model 2: precession

3D relativisitic hydrodymaical simulation

log GModel 1 steady injection

Photons are bulk Comptonized

at the shock

However

β＝-2.5

４°

α＝-1

log G

Numerical diffusion smears out the sharp shock

structure

Efficiency of Comptonization is artificially

suppressed

Model 1 steady injection

log G

Model 2 Precession (tpre=2s θpre = 3°)

α＝-1β＝-2.5

log G

Model 2 Precession (tpre=2s θpre = 3°)

Precession activity can

be directly observed in

the lightcurve

On-going Project

Lj = 1049 erg/s Lj = 1050 erg/s Lj = 1051 erg/s

t=40s

Toward systematic studies Ito + 2017 in prep.

Light curves

20%

10%

0%

5%

15%

DOP（％）＝(I

+-I -

) / (I

++

I-)

polarization

High polarization (>10%) at off-axis regions

Summary

Jet structure developed during propagation causes notable

time variability-

- High polarization at large viewing angle

Effect is prominent when the jet power is weaker

multi-color effect, bulk Comptonization

- Central engine activity can be directly observed in the light curve

engine activity is not smeared out during the propagation

- Structure of jet broadens the thermal spectrum