A Multi-telescope Campaign on FRB 121102: Implications for the FRB Population

We present results of the coordinated observing campaign that made the first subarcsecond localization of a fast radio burst, FRB 121102. During this campaign, we made the first simultaneous detection of an FRB burst using multiple telescopes: the VLA at 3 GHz and the Arecibo Observatory at 1.4 GHz. Of the nine bursts detected by the Very Large Array at 3 GHz, four had simultaneous observing coverage at other observatories at frequencies from 70 MHz to 15 GHz. The one multi-observatory detection and three non-detections of bursts seen at 3 GHz confirm earlier results showing that burst spectra are not well modeled by a power law. We find that burst spectra are characterized by a ∼500 MHz envelope and apparent radio energy as high as 10⁴⁰ erg. We measure significant changes in the apparent dispersion between bursts that can be attributed to frequency-dependent profiles or some other intrinsic burst structure that adds a systematic error to the estimate of dispersion measure by up to 1%. We use FRB 121102 as a prototype of the FRB class to estimate a volumetric birth rate of FRB sources {R}_{FRB}≈ 5× {10}^-5/{N}_r Mpc^-3 yr^-1, where N _r is the number of bursts per source over its lifetime. This rate is broadly consistent with models of FRBs from young pulsars or magnetars born in superluminous supernovae or long gamma-ray bursts if the typical FRB repeats on the order of thousands of times during its lifetime.