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K-GRB2@hanyang. 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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K-GRB2@hanyang

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


GRB

Galactic ?


GRB


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

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)


Recent Issues


Fraction of fainter or equal pixels

SN

GRBs are concentrated in the more bright regions of galaxy

GRBs

GRBs from low metallicity galaxies


GRB hosts (blue color) are fainter & smaller


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


Thank you


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