A Compendium of Research Projects from the Past Year (D. Christodoulou, 20/6/2023)
Channel: Academy of Athens
Date: 08/11/2023

D. Christodoulou
Univ. of Massachusetts Lowell

Abstract:
I plan to present synopses of the research projects I was involved with in the past year. These projects stem from collaborations with several other researchers and graduate students and, as usual, they all appear to come to fruition at the same time. Here is a list:
1) HMXB IC10 X-1, a WR+BH system. We analyzed Gemini/GMOS spectra, and we managed to extract clean profiles of the He II 4686 emission line at various binary phases. The line is visibly skewed and kyrtic. We decomposed the signal into two “dancing” Gaussian components, and they told us how to construct a precise dynamical model of the binary, the WR wind, and the outer accretion stream around the BH.
2) False-positive gravitational-lensing pulses. We searched the TESS archive for self-lensing events, hoping to find at least one BH binary. We found 4 such lensing events (3 more beyond our wildest dreams). None of them turned out to be real. Coming back to reality, we found 4 asteroids crossing in front of G, M stars when TESS was looking.
3) Kalman filter analysis of X-ray light curves. We witnessed a brand new (to astronomy) tool in action, a linear Kalman filter fitting all the available X-ray data for SXP 18.3 and returning previously inaccessible, time-dependent information about this HMXB.
4) Elementary particles. We know why the neutron is heavier than the proton by 1.3 MeV, and why this is not quite the right question to ask. (Ask about mass deficits instead.) We also know why the charged pion is heavier than the neutral pion by 4.6 MeV. We found a new versatile quantum number that characterizes exclusively the strong interaction. Our finder’s reward—we get to use it first.
5) Standard model of particle physics. We think we know how to calculate some 16 of the 19 free parameters of the model. We have derived empirically all quark masses and coupling constants using a “mass ladder.” The same empirical rule teaches us how to connect the Planck mass to the subatomic world and several other minute (but not mundane) physical details that we are going to outline during this presentation.