Abel Lawrence Peirson

I am a Ph.D student in Physics at Stanford University, where I research theoretical astrophysics and applications of artifical intelligence as a NASA FINESST fellow. I am also interested in theoretical neuroscience, geophysical fluid dynamics, accelerator physics and plasma physics.

I received my bachelors and masters (MPhys) in Physics from the University of Oxford, Christ Church, where I specialised in theoretical and particle physics.

I have spent time at CERN working on beam parameter measurement software for the CLIC test facility's electron-positron collider and at the University of Science and Technology of China working on plasma confinement in the KMAX axisymmetric tandem mirror machine. At Stanford I have recently worked on visual unsupervised learning in the NeuroAILab and on developing a 2D path integration model in the fly brain with the Druckmann Lab. I currently focus on astrophysics, characterising the polarization behaviour of astrophysical jets and improving X-ray polarization sensitivty using machine learning for the IXPE collaboration.

Outside of Physics, I designed an AI that generates memes: Dank Learning. What started as a fun class project ended up being featured on Techcrunch and AINews. Inspired, I worked together with Dylan Freedman to create the free iOS app Dank Learning so anyone can use the AI to generate memes. I discuss the work in the NVIDIA AI podcast and its implications for the future of jewellery (yes this is real) at the Pratt Institute. A current fun side project I am excited about is making exoplanet inspired art.

Besides my research, I enjoy engaging in scientfic outreach. I have recently become a Wonderfest Science Envoy; I look forward to improving my public speaking and communicating science to public audiences through the program. I am a science pen pal, an undergraduate student mentor and a leading member of the Stanford Astronomical Society. I also enjoy competing for the Stanford Judo Club and the Stanford Triathlon Club.

                 

Research

I'm currently interested in how the geometry of relativistic jets affects their polarized emission, the role of fluid mechanics in jet evolution and how gravitational lensing might affect the observed polarization. Furthermore, I am trying to incorporate AI in searches for rare blazar lensing events, improve IXPE's polarization sensitivity, and take Dank Learning to the next stage.

Deep Ensemble Analysis for X-ray Polarimetry
A.L.Peirson, R.W.Romani, H.L.Marshall, J.F.Steiner, L.Baldini
Nuclear Instruments and Methods in Physics Research A , 2020

Using Deep ensembles to improve IXPE's sensitivity.

In order to measure polarization using a GPD, a distribution of photoelectron angles must be extracted from noisy images of their individual tracks on a hexagonal grid. We use a convolutional neural network architecture to predict the initial photoelectron angle and its uncertainty for each track image, as well as the absorption point and energy. By combining predictions from an ensemble of networks in a weighted maximum likelihood analysis we estimate the polarization fraction and EVPA of the X-ray source.

The Polarization Behavior of Relativistic Synchrotron Self-Compton Jets
A.L.Peirson, R.W.Romani
The Astrophysical Journal, 2019

Exploring the expected synchrotron self-Compton polarization from blazar jets. A continuation of our multizone jet model.

For low-synchrotron peaked blazars, the X-ray emission will be dominated by synchrotron self-Compton. Understanding what polarization levels IXPE is likely to see in this case is important for distinguishing between hadronic and leptonic blazar emission models. We find that our multizone model recovers simple predictions for SSC polarization, but describes new dependencies on jet viewing geometry. Importantly we find that a rise in synchrotron polarization fraction at high energies is guaranteed by basic relativity considerations.

Prospects for Detecting X-Ray Polarization in Blazar Jets
I.Liodakis, A.L.Peirson, R.W.Romani
The Astrophysical Journal, 2019

A study in the detectability of X-ray polarization in blazars for IXPE.

Using the models developed in the adjacent relativistic jet papers and optical polarization observations by RoboPol, we are able to make predictions of the average expected X-ray polarization fraction. This work will help the IXPE team choose appropriate first year observing targets.

The X-ray Polarization Probe Mission Concept
K.Jahoda, H.Krawczynski, F.Kislat, H.L.Marshall, T.Okajima ... L.Peirson ...
Decadal Survey on Astronomy and Astrophysics , 2020

A white paper for the upcoming Decadal survey introducing XPP, a second generation X-ray polarimeter that will cover 0.2 - 60keV!

Hopefully we will demonstrate the potential of imaging X-ray polarimeters with IXPE.

The Polarization Behavior of Relativistic Synchrotron Jets
A.L.Peirson, R.W.Romani
The Astrophysical Journal, 2018

Using simple helical geometry and relativistic aberration effects to explain blazar polarization angle rotations.

Follow up paper for the synchrotron self-Compton emission coming soon.

Dank Learning: Generating Memes Using Deep Neural Networks
A.L.Peirson V, E.M.Tolunay
Accepted to Advances in Intelligent Systems and Computing, 2018
code

An image captioning system that can take any image and turn it into a first generation meme.

Uses pre trained Inception CNN followed by an LSTM with temperature selection for language generation. Trained on a dataset of over 300,000 image caption pairs.

Transverse Beam Phase-Space Measurement Experience at CTF3
D.Gamba, B.Constance, R.Corsini, S.Dobert, L.Malina, L.Martin, A.Peirson Serratosa, T.Persson, J.Roberts, A.Rollings, Piotr SkowroĊ„ski, Frank Tecker
8th International Particle Accelerator Conference, 2017   ,

Characterising the transverse phase space of the CTF3 beam before and after beam recombination with the Delay Loop.

Side Projects

I'm indebted to Dylan Freedman for introducing me to the very American concept of a side project -- as such many of my projects are collaborations with him. For fun and more...

Planet Plotter

Making and displaying unique exoplanet inspired art.

We bought a 1982 HP7470a plotter printer and we make it plot starfields around exoplanets. Check out our gallery of all the exoplanets we know of! (We can plot other astronomical objects too... The image on the left is M51: the whirlpool galaxy).

Curve2d
code

We made a lightweight implementation in javascript of one of our favourite games: Achtung, die Kurve!. I have to admit, this one was mainly D (I still smash him at the game though); one of my main contributions was including a poisson distribution for generating threadable gaps in the curves. We have also made a 3d version in Unity: Achtung, 3die Kurve!, not available online yet.


Teaching

Physics 100: Introduction to Observational Astrophysics

Cloned from