Astrophysics Brown Bag Lunch Talk 2/28/2022: Speakers: Amruta Jaodand (Caltech) And Navin Sridhar (Columbia University )

Monday February 28, 2022 12:00 pm
via Zoom

12:05 pm Astro Brown Bag Lunch Talk
First Speaker: Amruta Jaodand, Caltech
Title: The strange case of transitional millisecond pulsars:  pulsating in optical and UV wavebands
Abstract: Transitional millisecond pulsars (tMSPs) switch between a low-mass X-ray binary (LMXB) and a radio millisecond pulsar (RMSP) state, establishing a firm evolutionary link between the two source classes. tMSPs provide a great avenue to study the low-level accretion processes that spin-up pulsars to millisecond periods. Systematic, multi-wavelength observational campaigns over the last decade have resulted in surprising finds such as: i) persistent, multi-year-long, low-level (Lx <10^34 ergs/s) accretion state with coherent pulsations; ii) radio outflows, and iii) uninterrupted pulsar spin down in the X-rays. In this unique state, we have now found the first known UV millisecond pulsar with a dedicated multi-wavelength campaign involving the Hubble space telescope. I will highlight this exciting discovery which challenges our understanding of pulsar emission.



12:30 pm Astro Brown Bag Lunch Talk
Second Speaker:  Navin Sridhar, Columbia
Title: Periodic Fast Radio Bursts from Luminous X-ray Binaries
Abstract:  The discovery of periodicity in the arrival times of the fast radio bursts (FRBs), and some of them being localized to old globular clusters pose a challenge to the oft-studied magnetar scenarios. The models that postulate that FRBs arise from magnetized shocks or magnetic reconnection in a relativistic outflow are not specific to magnetar engines; instead, they require only the impulsive injection of relativistic energy into a dense magnetized medium. Motivated thus, I will outline a new scenario in which periodic FRBs are powered by short-lived relativistic outflows from accreting compact objects, which propagate into the cavity of the pre-existing (“quiescent”) jet.



Event Contact

Josh Borrow