PhD Defenses

PHYSICS DISSERTATION DEFENSE: Abel Lawrence Peirson V

Date
Wed March 1st 2023, 3:00 - 4:00pm
Location
Allen 101X

When built, the MAGIS-100 atom interferometer will be the largest in the world. But it's still missing a key component: a detailed camera. Stanford University

Ph.D. Candidate:  Abel Lawrence Peirson V

Research Advisor: 
Roger W. Romani

Date:
03/01/23
Time:
3:00 pm PT

Location: Allen 101X


Zoom Link: 
https://stanford.zoom.us/j/94678615030

Zoom Password: email nickswan [at] stanford.edu (nickswan[at]stanford[dot]edu) for password.

Title: 
Relativistic Jets in the Era of X-ray Polarimetry

Abstract: 
Measuring X-ray polarization has been a major goal in astrophysics for the last 40 years. With the launch of NASA's Imaging X-ray Polarimetry Explorer (IXPE) in December 2021, soft X-ray polarimetry (1-10 keV) is now possible. In this talk, I introduce an optimal signal extraction method for X-ray polarimeters based on gas pixel detectors. Using IXPE's thus improved sensitivity, I make progress towards identifying the high-energy emission processes and magnetic field geometries responsible for radiation in blazar jets. First, I develop a simulation-based inference framework for measuring X-ray polarization as a function of time, energy, and position in gas pixel detectors, proving that for a fixed model budget the framework is optimal. Second, I propose a simple geometrical jet model to study the polarization properties of leptonic blazar jets, including their observed EVPA rotations and their detection prospects with IXPE. Finally, I interpret IXPE's measurements of BL Lacertae across the synchro-Compton transition region to suggest leptonic-dominated emission processes in blazars, and of Mrk 421 to provide evidence for helical magnetic fields as the source of EVPA rotations.