short hard bursts

Short hard bursts

S. R. Kulkarni

References

• This is a tutorial • Primary reference: E. Berger (2013) Annual

Review• GW perspective: Kalsiwal & Nissanke (2013)

Properties

• Defined primary by duration (T<2 s) and further refined by hardness ratio

• In the BATSE sample the rate of short hard bursts (SHBs) is one quarter that of the total population (the remaining are Long Soft bursts).

• Less fluence relative to long duration GRBs

Host Galaxies

• Found in all types of environments– Clusters of galaxies – Elliptical galaxies– Field star forming galaxies

• Interesting Clue: Association with ULRGs– GRB 100206A (dusty ULIRG, z=0.407)– GRB 120804A (dusty ULIRG, z=1.3)– But only 1% of mass is in ULIRGs

Comparing to other samples

• Long duration GRBs are primarily found in low mass star-forming galaxies

• SHBs appear to trace the field population of star forming galaxies

• Just like SN of type Ia, SHBs arise infield galaxies of both old population and young star forming field galaxies– However the SN rate is higher in star-forming

galaxies