## Summary

In the upcoming years, the field of cosmology will see a wealth of new and high quality data from the current Stage-3 (and the forthcoming Stage-4) surveys of cosmic microwave background (CMB) and large-scale structure (LSS). Simultaneously, low-frequency gravitational wave background (GWB) observations with pulsar-timing arrays (PTAs) and surveys of the 21cm hydrogen-line will achieve sufficient accuracy for cosmological inference. These provide unique and exciting opportunities to study the fundamental constituents of the Universe.

As an observationally-motivated theorist, the focus of my research is to effectively probe fundamental physics using cosmological observations. These observables include primordial density fluctuations, scale-dependent features and non-Gaussianity in the maps of the CMB and LSS, as well as the statistical anisotropy of the low-frequency GWB.

I am also a member of the Simons Observatory and contribute to the development of various analysis pipelines in order to facilitate the measurement of the CMB sky to finest precision to date in the next years.

There are three key themes to my work: identifying new observables[2] to extract unique cosmological information from data; developing (different) methods[1,3] to improve the detection significance of upcoming experiments to various cosmological observables; building cosmological models[4] and calculating their observational predictions.

My current research is on large-scale cosmological observables. The focus of my research is to effectively probe fundamental physics using cosmological observations. In particular, I study the secondary effects on the cosmological radiation observed by our telescopes. In the next few years, measurements of secondaries (such as weak gravitational lensing, kinetic and thermal Sunyaev Zel'dovic effects) will become observationally significant for the first time as CMB and LSS surveys will achieve the necessary precision. The statistics of these secondaries and their cross-correlations with the LSS carry information about cosmological fluctuations on large scales and at late times.

The relevant scientific program is focused on various inter-connected tasks, including the mitigation of these effects on the primary CMB, and reconstruction of large-scale cosmological density and velocity fields. The large-scale cosmological fluctuations locally re-distribute the small-scale power in density fluctuations and induce small-scale statistical anisotropies. Observation of these small-scale statistical anisotropies from secondaries allow cosmologists to infer details about the largest scales in the Universe at an unprecedented accuracy. These large-scale cosmological observables are in turn extremely valuable for cosmological inference, as they are often protected from non-linear effects. The benefit of the large scale observables are further elevated by velocity fluctuations which provide significantly higher signal-to-noise when constraining density fluctuations. The velocity-induced secondary effects include the kinetic SZ (kSZ) and the moving lens effect.

See also my research page for some of the recent work I have been doing.

Additionally, I work on theoretical models of the early universe, with a focus on the phenomenological outcomes of having different theories explain the early universe epochs, such as inflation and reheating. More recently, I have been focused on the connections between cosmology and beyond the standard model (BSM) particle physics through studying phenomenological models that have both cosmological and particle physics implications.

At Imperial, I was advised by Prof. Andrew Jaffe, and was an IC President's Scholar.

I was a Balzan Fellow (a visiting JRF by Oxford and Johns Hopkins University) in 2019. I also held a Visiting Graduate Fellowship from Perimeter Institute for Theoretical Physics in Canada.

In 2021 I joined Johns Hopkins University as a Horizon postdoctoral fellow.

## TALKS & VISITS

- November 2019 - Invited talks at Perimeter Institute, Columbia University and UC Berkeley (LBNL) link
- (1/2) 16 September 2019 -
**CMB-S4 meeting**, Parallel seminar on 'The moving lens effect', UCSD - (2/2) 17 September 2019 -
**CMB-S4 meeting**, Parallel seminar on 'Delensing the CMB for N_eff', UCSD - (1/2) 5 September 2019 - Parallel
**Seminar**, 'A new window into the largest scales: Transverse velocities with the moving lens effect',**COSMO 19**, Aachen, Germany - (2/2) 5 September 2019 - Parallel
**Seminar**, 'The search for statistical anisotropy in the gravitational-wave background with pulsar-timing arrays and astrometry',**COSMO 19**, Aachen, Germany - 16 August 2019 -
**Seminar**,*'From the moving lens effect to the largest scales: potential applications of reconstructing of velocity fields',***CITA**, Toronto, Canada - 15 August 2019 -
**Seminar**, 'From the moving lens effect to the largest scales: potential applications of reconstructing of velocity fields',**Perimeter Institute**, Canada - August 2019 -
**Visitor**, Perimeter Institute, Canada - 30 July 2019 - Seminar, '
*Applications of the CMB secondaries and t**he moving lens effect*',**UCSD**, La Jolla, San Diego, USA - July 2019 -
**Visitor**, UCSD, San Diego, USA - 2 July 2019 -
**Fireslide**, '*Detecting the moving lens effect with Simons Observatory*', Simons Observatory meeting, UC**Berkeley**, USA - 21 June 2019 -
**Seminar**, '*The moving lens effect and potential applications*',**NYU**, New York, USA - June 2019 -
**Visitor**, NYU, USA - 6 June 2019 -
**Seminar**, ''*Late-time effects (secondaries) on the CMB and the moving lens effect*',**Carnegie Mellon**, Pittsburgh, USA - 5 June 2019 -
**Seminar**, '*The moving lens effect and potential applications*',**UPitt**, Pittsburgh, USA - June 2019 -
**Visitor**, University of Pittsburgh (UPitt), Pittsburgh, USA - 18 April 2019 -
**Talk**, '*The search for anisotropy in the gravitational wave background with pulsar timing arrays*', NanoGrav telecon - 3 April 2019 -
**Seminar**, '*Late-time effects (secondaries) on the CMB and the moving lens effect*',**UCL**, London, UK - 15 March 2019 -
**Seminar**,*'The moving lens effect'*, DAMTP, Cambridge, UK. - 27 February 2019 -
**Seminar**, '*CMB secondaries in high definition: Constraints on cosmological parameters and new observables'*.**Johns Hopkins University**, Baltimore MD. - February 2019 -
**Visitor**, Johns Hopkins University, Baltimore MD. - 14 December 2018 -
**Seminar**, CMB in high definition workshop, Centre for Computational Astrophysics,**Flatiron Institute**, NYC. - June 2018 -
**Visitor**, Flatiron Institute - June 2018 -
**Visitor**, CITA - 5 December 2017 -
**Seminar**, Imperial College London, '*Inflation on random potentials'*(blackboard talk). - 26 October 2017 -
**Seminar**, London Cosmology Discussion Meeting (LCDM), '*Phenomenology of many-field inflation'*. - 11 October 2017 -
**Seminar**, - 10 October 2017 -
**Seminar**, CITA, '*Reheating the Universe with many scalar fields'*. - October 2017 -
**Visitor**, CITA - 18 September 2017 -
**Seminar**, UK Cosmo, Imperial College London.

## PUBLICATIONS

- Selim C. Hotinli, Matthew C. Johnson, Joel Meyers,
*Optimal filters for the moving lens effect 4 Jun 2020,*arXiv:2006.03060 - Selim C. Hotinli, James B. Mertens, Matthew C. Johnson, Marc Kamionkowski, Probing correlated compensated isocurvature perturbations using scale-dependent galaxy bias, 23 Aug 2019, arXiv:1908.08953
- Selim C. Hotinli, Marc Kamionkowski, Andrew H. Jaffe,
*The search for anisotropy in the gravitational-wave background with pulsar-timing arrays and astrometry,*Apr 10, 2019. 9 pp.

e-Print: arXiv:1904.05348 [astro-ph.CO] - Selim C. Hotinli, Joel Meyers, Neal Dalal, Andrew H. Jaffe, Matthew C. Johnson, James B. Mertens, Moritz Münchmeyer, Kendrick M. Smith, Alexander van Engelen,
*Transverse Velocities with the Moving Lens Effect*, (2018) arXiv:1812.03167, published in PRL. - Selim C. Hotinli, Jonathan Frazer, Andrew H. Jaffe, Joel Meyers, Layne C. Price, Ewan R.M. Tarrant,
*Effects of reheating on predictions following multiple field-inflation*, (2017) (PRD) PhysRevD.97.023511