Photospheric Emission from Collapsar Jets in 3D ...lazzatid/FOE2017... · Photospheric Emission in...
Transcript of Photospheric Emission from Collapsar Jets in 3D ...lazzatid/FOE2017... · Photospheric Emission in...
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
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
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.
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