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[email protected] Introduction to GRB: Classifications and Progenitors. Chang-Hwan Lee @. GRB. Introduction to GRB. Short Hard GRB. NS-NS, NS-BH Mergers. Hee-Suk Cho & Soomin Jeong’s Talk. Long Soft GRB. Supernova Association. Another class ?. Some Recent Issues. GRB. Gamma-ray Bursts.

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[email protected]

Introduction to GRB:

Classifications and Progenitors

Chang-Hwan Lee @


GRB

Introduction to GRB

Short Hard GRB

NS-NS, NS-BH Mergers

Hee-Suk Cho & Soomin Jeong’s Talk.

Long Soft GRB

Supernova Association

Another class ?

Some Recent Issues


GRB

Gamma-ray Bursts


GRB

Gamma-Ray Burst

Duration: milli sec - min

1970s : Vela Satellite

1990s: CGRO, Beppo-SAX

2000s: HETE-II, Swift



GRB

Galactic ?



GRB

Two groups of GRBs

  • Short Hard Gamma-ray Bursts:Duration time < 2 secNS-NS, NS-LMBH mergers

  • Long-duration Gamma-ray Bursts:from spinning HMBH

HMBH (High-mass black hole)

5-10 solar mass


SHB

Short-Hard Gamma-ray Bursts

Talks by

Hee-Suk Cho

Soomin Jeong


Short hard grbs
Short-hard GRBs

SHB

hard

BATSE

Sample

  • No optical counterpart (?)

  • Origin

    • Neutron star merger?

    • Magnetar flare?

    • Supernova?

short

long

soft

0.01

1000

1


SHB

NS (radio pulsar) which coalesce within Hubble time

(2003)(2004)

(1990)

(2004)

(1975)

(1990)(2000)

Not important

Globular Cluster : no binary evolution

White Dwarf companion


Introduction

  • All masses are < 1.5 M⊙

  • 1534, 2127: masses are within 1%

  • J0737, J1756: DM = 0.1 - 0.2 M⊙


SHB

Short-Hard Gamma-ray Burst : Colliding NS binaries

Very Important for Gravitational Waves, too

Science 308 (2005) 939


SHB

Laser Interferometer Gravitational Wave Observatory

LIGO I : in operation (since 2004)

LIGO II: in progress (2010 ?)


Introduction

Network of Interferometers

LIGO

Virgo

GEO

TAMA

LIGO Louisiana 4km

AIGO


L-GRB

Long-duration Gamma-ray Bursts


L-GRB

Long-duration GRBs: Afterglow

Host Galaxy Association

= Distance Estimation


L-GRB

GRB/Supernova Association

Afterglow

GRB980425 SN1998bw


L-GRB

  • Gamma-Ray Bursts are the brightest events in the Universe.

  • During their peak, they emit more energy than all the stars and galaxies in the Universe combined !


L-GRB

What caused GRB/Supernova ?

Most-likely Black Holes

Callapsar: Asymmetric Explosion of a Massive Star Most-likely Rapid-Rotation


L-GRB

How to form rapidly spinning black holes?

Most likely in BH binaries (Soft X-ray Transients)

Companion star can keep BH progenitor rotating

Formation of rapidly rotating stellar mass BHs


at birth

Tidal interaction

Fe

rapidlyspinning BH


L-GRB

Q) How to generate chaotic(?) light curves ?Q) Is there a model that explains all the light curves ?


L-GRB

A Generic GRB Fireball

UV/opt/IR/radio

gamma-ray

X-ray

UV/optical

IR

mm

radio

gamma-ray

central photosphere internal external shocks

engine shocks (reverse & forward)



Fraction of fainter or equal pixels

SN

GRBs are concentrated in the more bright regions of galaxy

GRBs

GRBs from low metallicity galaxies



Fruchter et al.

  • L-GRBs are far more conentrated in the very brightest regions of their host galaxies than core-collapse SN

  • Host galaxies of L-GRBs are significantly fainter and more irregular than the hosts of core-collapse SN.

  • L-GRB are associated with the most extremely massive stars and may be restricted to galaxies of limited chemical evolution (lower metallicity).


GRB 060614

  • Duration : 102 sec (Long-GRB ?)

  • Long-lag : Short-GRB ?(usually, short-lag : Long-GRBs)

  • Some pulses of GRB 060614 show no lag : consistent with Long-GRBs

The existence of new class:still open questions


Key Issues

Classifications:Is there third or sub-classes ?

Progenitors:S-GRB: NS-NS, NS-BH, …L-GRB: with SN, w/o SN, ….

Properties of host galaxies & afterglow!


Korean GRB

Theory:

-- Progenitors

-- Central Engine -- Statistical Approaches

Observations & Experiment

-- afterglow observations (SHBs & L-GRBs)

-- gamma-ray & X-ray telescope



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