Maximilian Abitbol

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Maximilian Abitbol

Beecroft Fellow in Theoretical Cosmology

I started as a Beecroft Fellow in October 2018 after receiving my Ph.D. from Columbia University. My dissertation spanned several topics related to cosmic microwave background (CMB) research with projects in theory, data analysis, and instrumentation. In particular I studied systematic errors that effect CMB experiments, forecasted capabilities for future experiments, performed data analysis for a balloon-borne experiment called EBEX, and worked on readout technology for a new photon detector called kinetic inductance detectors. Currently my research is focused on using CMB data to reveal information about the beginning of the Universe.

The goal of many modern CMB experiments is to detect evidence for inflation; a process believed to occur during the first fraction of a second that produced a rapid expansion of space. Inflation provides a mechanism to seed initial density fluctuations throughout the Universe, which would then grow into all the observable structure that we see today. The inflationary process not only creates density fluctuations but also predicts a background of gravitational waves. These primordial gravitational waves leave an imprint that is observable as a parity-violating signature in the polarization of the CMB, called B-modes. A detection of primordial B-modes would provide strong evidence that the Universe began with an inflationary epoch, revolutionizing our understanding of cosmology.

My publications can be found here:
arXiv

and my github here:
https://github.com/mabitbol

Tutor at Queen's College, Oxford

  • F2018-S2019: Electricity, Magnetism and Optics.

Teaching Assistant at Columbia. I was the preceptor (lead TA) for Columbia Physics from 2014-2015.

  • F2016-S2018: Advanced Physics Lab
  • S2016-S2017: Electromagnetic Waves and Optics
  • S2015-F2016: General Physics
  • F2015: Classical and Quantum Waves
  • F2013-S2015: General Physics Lab

Teaching Assistant in Math at Johns Hopkins University.

  • S2014: Differential Equations
  • F2012: Linear Algebra
  • S2012: Vector Calculus (III)
  • F2011: Calculus (II)

My research focus is in data analysis methods for cosmic microwave background experiments. In particular I am working on foreground subtraction to enable B-mode science with the Simons Observatory.

In order to detect the B-mode signal, precise measurements must be made that require the use of specialized telescopes in space or regions with low atmospheric emission. The primary challenge in identifying B-modes comes from the fact that our observations necessarily include contamination from our Galaxy. Thermally emitting dust particles in the Milky Way and cosmic rays spiraling in the Galactic magnetic field produce microwave radiation in the same frequency range as the CMB. These signals must be constrained and subtracted before a detection of B-modes can be claimed. This analysis requires applying physical and statistical considerations to combine our understanding of astrophysics with our knowledge of the telescope to produce a robust method for measuring B-modes. This analysis stage is one of the most critical components of the whole experiment.

One of the leading experiments in the field is the Simons Observatory, a set of telescopes being built in the Atacama Desert in Chile for the purpose of measuring the B-mode inflationary signal. David Alonso and I are members of this collaboration and are leading the B-mode analysis effort. We are also members of the Atacama Cosmology Telescope, which has been making observations of the CMB since 2007.

Another way to study the early Universe is to track the thermal evolution of the CMB. The thermal history of the Universe is tightly coupled to the CMB during early times and produces a faint but observable signal in the CMB. These signals are called CMB spectral distortions, as they are distortions from the blackbody spectrum that is produced when radiation and matter are in thermal equilibrium. Spectral distortions can be created by a variety of non-equilibrium processes, including for example the difference in the cooling rates of matter and radiation from the expansion of the Universe. We could also detect several non-standard cosmological scenarios such the existence of primordial blackholes using spectral distortions. To this end I am studying how one could design an experiment to measure CMB spectral distortions and have forecasted the capabilities for several missions proposed to NASA and the ESA.

Please see my arXiv page here:
arXiv