One Approach to the Star-Formation History Inferred from the GRB Lag--Luminosity Relation
Abstract
The distances of about thirty gamma-ray bursts (GRBs) are known. The most remote one is at ∼ 4.5, and the remaining more dimmer GRBs are supposed to be more remote. If we can estimate the distances for the dimmer GRBs, their distances should be much beyond ∼ 4.5. Two independent studies to estimate their distances were previously conducted. One was based on the variability-luminosity relation, and the other was based on the lag-luminosity relation. However, these relations can apply only for a very limited range of luminosity. In this paper, we introduce the viewing angles and use a new lag-luminosity relation by Ioka and Nakamura (2001, ApJ, 554, L163), which is capable of explaining the luminosity of the nearest GRBs. By applying the new relation, we infer the star-formation history out to ∼ 4. Our result shows an increasing trend of star-formation out to ∼ 4. However, the lag-luminosity relation itself is still a matter of debate, and thus this w ork is a tentative approach. For example, we have used only eight known GRB distances. Our result should be checked and calibrated by future data with Swift, observing more distant GRBs.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- October 2003
- DOI:
- 10.1093/pasj/55.5.L65
- Bibcode:
- 2003PASJ...55L..65M
- Keywords:
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- cosmology: early universe;
- gamma-rays: bursts;
- stars: formation