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Gamma-Ray Burst Host Galaxies Have "Normal" Luminosities
The Astrophysical Journal
|March 23, 2000
Summary
Gamma-ray burst host galaxies are not subluminous. New data reveals these galaxies have typical luminosities, challenging previous assumptions about their environments and progenitor systems.
Area of Science:
- Astronomy and Astrophysics
- Cosmic Gamma-Ray Bursts
- Galaxy Evolution
Background:
- Previous studies suggested gamma-ray burst (GRB) host galaxies were subluminous, implying specific progenitor systems.
- Two early arguments indicated that GRB host galaxies were significantly dimmer than typical galaxies.
Purpose of the Study:
- To re-evaluate the luminosity of gamma-ray burst host galaxies using new data and analysis.
- To resolve the apparent discrepancy between bright and faint GRB luminosities and their host galaxy environments.
Main Methods:
- Analysis of 16 known GRB host galaxies, including 10 with redshift data.
- Comparison of absolute magnitudes with a Schechter luminosity function.
- Investigating the relationship between GRB brightness, redshift, and host galaxy detection limits.
Main Results:
- The first two known host galaxies were subluminous, but subsequent discoveries showed typical luminosities.
- Analysis of 16 hosts aligns with a Schechter luminosity function (R*=-21.8+/-1.0), consistent with normal galaxies.
- A varying burst number density tied to star formation rates explains luminosity differences between bright and faint GRBs without violating host galaxy limits.
Conclusions:
- All current evidence indicates that gamma-ray burst host galaxies possess normal luminosities.
- The galactic environment of GRBs is consistent with normal galaxy populations.
- This finding refines our understanding of GRB progenitor systems and their cosmic evolution.