This award will support a project to obtain and analyze time-series data at infrared wavelengths. There are many advantages that infrared observations have over studies at visible wavelengths. These include better data on cool stars, such as red extragalactic transients and young stars, and amelioration of the effects of interstellar dust. The goals of this project are several: characterization of variability using large existing and proposed datasets; a targeted campaign on extragalactic cluster environments; a study of roughly 100 pulsating variables (RR Lyrae, Cepheids, and Miras); a systematic study and analysis of Type Ia and Type II-P supernovae in the infrared; and rapid observations of several gamma-ray bursts.
The researchers will create a web portal to rapidly disseminate the results of this study to the astronomical community and to the general public. In addition, the team will make almost seven years of historical infrared time-domain data public with the archive and web portal. Finally, Dr. Bloom will be actively engaged in mentorship of the undergraduate students, graduate students and postdoctoral scholars involved in the project.
While the visible-light portion of the night's sky has been well studied at a variety of depths and timescales, the infrared regime has been relatively poorly characterized and understood. Infrared light is particularly important for the study of dust enshrouded sources, high-redshift gamma-ray bursts (GRBs), and cool-temperature events. With this grant we observed, discovered, and began to understand a number of time-variabable phenomena, lifting the veil on this exciting part of the electromagnetic spectrum. In particular, we found: 1. The first luminosity-period relation for pulsational-variable RRLyrae at mid-infrared wavebands using the WISE satellelite. We showed that absolute distances could be obtained for RRLyrae to 2% accuracy. This is critically important as a stepping stone to getting precision distances to Type Ia supernovae and, ultimately, measuring the amount and nature of dark energy in the universe. 2. Dust in the early universe appears to be enriched by supernovae, rather than Asymptotic Giant Branch (AGB) stars. Dust all around us in the universe is largely created by AGB stars but there were only few AGB stars in the early universe (they take ~billion years to reach that stage in their lifecycle) so it was a natural expectation that if we found a distant GRB that it would be extinguished by a different sort of dust. Only one study previously (using distant quasars) had inferred the supernova-synthesized dust profile. 3. FU Ori outbursts are connected with classical T Tauri stars. These are two different types of activity from young stars and we found what appears to be the "rosetta stone" connecting them. 4. GRBs may arise from galaxies as far back as z=10, based on the highest redshift photometric detection of a GRB afterglow. This is photometric evidence for a GRB that occured less than 500 Million years after the Big Bang, the earliest event in the universe found to date. 5. Temporary relativistic jets can be powered by black holes that tidally disrupt stars. This project supported the research of 6 graduate students, 2 undergraduates, and 4 postdoctoral scholars at Berkeley.
