* Astronomy

Title: UBVRI Hubble Diagrams of Gamma-ray Burst Supernovae
Author: Zach Cano, Pall Jakobsson

In this paper we demonstrate, in principle, how gamma-ray burst supernovae (GRB-SNe) can be used to measure the Hubble constant, H_0. Using two statistical data-fitting procedures, a linear-least squares (LLS) method and a Monte-Carlo (MC) method, we first present a statistically significant luminosity--decline relationship of GRB-SNe in filters UBVRI, and then provide constraints on H_0. Using SN 1998bw, and a fiducial distance to its host galaxy of 37 Mpc, we constrain H_0 to the range 61--69 km/s/Mpc. In our analysis, we adopt conservative errors of 20% in the SN magnitudes. The subsequent errors in H_0 derived from the MC method are of order 2--4 km/s/Mpc, and roughly ten times larger using the LLS method. Interestingly, the weakest luminosity--decline relation is seen in the B-band; however the B-band (and V-band) data provide one of the tightest constraints on H_0 of all the filters. Finally, as GRB-SNe arise from massive star progenitors, whose lifetimes are of order several million years, they are likely to occur at earlier times in the universe than SNe Ia, as the latter require at least one white-dwarf star in a binary system, which forms only after a few billion years. This suggests that with suitable instrumentation and facilities, GRB-SNe can be found at larger redshifts/earlier times in the universe than SNe Ia, and eventually providing useful constraints on the fundamental cosmological parameters in the early universe.

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