Monday, December 13, 2021
12:00 – 12:30pm
Mohit Bhardwaj, McGill University
Uncovering the Origins of FRBs using Local Universe Bursts
Abstract: Fast radio bursts (FRBs) are one of the newest unsolved mysteries in astronomy. Though a plethora of models has been proposed to explain FRBs, the origin of these intense millisecond-duration pulses of radio emission remains a topic of intense debate, owing to the paucity of well-localized FRBs. A promising method to test the proposed FRB theories is by associating FRBs with other astronomical phenomena. By identifying their hosts and/or multi-wavelength counterparts, we can narrow down potential progenitors of FRBs. Unfortunately, due to the limited sensitivity of telescopes, multi-wavelength follow-up is most promising for nearby FRBs (distance < 100 Mpc). The Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB project has been detecting FRBs since July 2018, and many of them have sufficiently low dispersion measure (DM) suggesting a nearby origin. Even better, the localization of low-DM FRBs to few arc-minute precision using the CHIME/FRB baseband system can result in a reliable host association for nearby FRBs. In this talk, I will report on recent CHIME/FRB discoveries of local universe FRBs, including 20200120E and 20181030A, for which we identified M81 (3.6 Mpc) and NGC 3252 (20 Mpc) as the promising hosts, respectively. Lastly, I will also discuss how these localized nearby FRBs can be useful in constraining different FRB progenitor models.
Bio: Mohit Bhardwaj is a PhD candidate at McGill University and a member of the CHIME/FRB collaboration. In his PhD work, he is using local Universe CHIME bursts to decipher the origins of FRBs. FRBs, he believes, can provide a unique view into the aftermath of some of the Universe’s most violent events. In addition to solving the FRB origin problem, he wants to use FRBs to map the cosmic web. Finally, he is always on the lookout for unexplored enigmas of the Universe. So, if you know of any, don’t hesitate to contact him.
Rohan Naidu (Harvard University CfA)
The First Glimpse of the First Galaxies with the James Webb Space Telescope
Abstract: One of the last great unknowns in our history of the Universe is when, why, and how the first galaxies emerged after the Big Bang. These galaxies transformed the cosmos — they illuminated the invisible scaffolding of dark matter that underpins the Universe, they ionized the intergalactic reservoirs of hydrogen, and they synthesized the elements that would one day seed life on Earth. Thanks to NASA’s flagship James Webb Space Telescope launching this December, the first galaxies will finally come into view. In this talk I will motivate and preview two JWST programs I am leading during its inaugural year that will: (i) help constrain when the first galaxies were born, and (ii) test whether rare, bright galaxies or numerous ultra-faint galaxies reionized the Universe.
Bio: I am a final-year PhD student at Harvard University. I work on the first galaxies — both via direct studies at the highest redshifts (cosmic reionization, cosmic dawn), and via archaeological studies of accreted galaxies dissolved in the Milky Way’s stellar halo (primordial chemistry, dark matter substructure).