Ilya S. Khrykin
astrophysicist, Ph.D

I am Ilya Khrykin, currently a Postdoctoral Researcher at Institute of Physics, Pontificia Universidad Católica de Valparaíso (PUCV, Chile) working with Prof. Nicolas Tejos. My research is focused on combining the multi-wavelength observations and numerical simulations to unravel the evolution of matter in the Intergalactic (IGM) and Circumgalactic (CGM) media across cosmic time. At low redshift (z < 1), I utilize the Fast Radio Bursts (FRB) to study the distribution of cosmic baryons, properties of galactic halos, magnetic fields, and galactic feedback mechanisms. At high redshifts (2 < z < 5), I study how quasar radiation changes the ionization and thermal state of the IGM during and after He II Reionization.

I was born in Rostov-on-Don, USSR (now Russia) and got my Bachelor and Master's degrees in Physics from the Southern Federal University (Rostov-on-Don, Russia). I did my PhD at the Max Planck Institute for Astronomy (Heidelberg, Germany) with Joe Hennawi (UC Santa Barabra). Before moving to Chile, I was a short term researcher at the Research Institute for Physics (Southern Federal University, Rostov-on-Don, Russia) and later did a postdoc at Kavli IPMU (Japan) in the group of Khee-Gan Lee.

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Curriculum vitae

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My current research

• Fast Radio Bursts: search for the missing baryons

Fast Radio Bursts (FRBs) are transient radio sources of an extragalactic origin. While the radio signal from FRBs is traveling towards Earth through the intergalactic medium (it also intersects the circumgalactic media of the galaxies along the line-of-sight), it experiences dispersion by free electrons along the line-of-sight. This dispersion is quantified by the so-called Dispersion Measure (DM) - one of the main properties of the FRBs. It is also possible to distinguish the contributions of different traversed regions into the measured DM. The largest contribution is expected from the underling large-scale gas in the IGM, parametrized by the fraction of baryons that reside in it. The holy grail will be the measurement of this baryon fraction as it might shed light on the old standing cosmological problem of the missing baryons. However, the cosmic variance introduces significant uncertanty into any estimates of the IGM contrubution. Ideally, one would need to map the large-scale density field that is traversed by the FRB signal in order to significantly reduce the uncertainty.

I am the member of the FLIMFLAM spectroscopic survey (PI: K.G. Lee; Lee, Ata, Khrykin et al. 2022) collecting samples of foreground galaxies used in density reconstruction. We have developed a novel method to reconstruct the large scale matter distribution in the foreground of localized FRBs (via bayesian algorithm ARGO; Ata et al. 2015), given the spacial position of the galaxies in the observed volume. This allows us to estimate the contribution of baryons in IGM or CGM of galaxies near the FRB sightline to the observed dispersion measure of the FRB signal, and precisely determine the whereabouts of cosmic baryons. Recently, in Khrykin et al. (2024b) we have published the first FLIMFLAM data release and the first ever constraints on the distribution of cosmic baryons using FRBs!

• Quasar proximity zones: inferring properties of the SMBH and IGM

Analogous to how O-stars transform their nearby interstellar medium, the enhanced radiation field in the so-called proximity zones of luminous quasars, dramatically alters the ionization state of the surrounding intergalactic medium (IGM), resulting in enhanced Lyα transmission near the quasar itself. By studing the quasar proximity zones we can infer several important properties of both quasars and the IGM.

One of the key quantities necessary to distinguish between various models of formation and growth of the supermassive black holes, the evolution of quasars, and the feedback effects on the surrounding gas is the duration of individual accretion episodes, i.e., the quasar lifetime. By measuring the extent of observed quasar He II proximity zones at z~3-4 (analogous to HI Lya proximity zones at z~6, but sensetive to the lifetime timescales 3 orders of magnitude longer) and comparing them to the results of the hydrodynamical and radiative transfer simulations, we are able to measure the quasar lifetime to the unprecedented accuracy.

Recently, we have developed a fully Bayesian algorithm to infer lifetimes of individual quasars, and sucsessfully applied it to all existing He II Lya transparent quasars. Our analyses has revealed a surprisingly broad distribution of individual lifetimes, both very young (<1 Myr) and old (>30Myr). Please check out these cool results presented in Khrykin et al. (2019) and Worseck, Khrykin et al. (2021)

In addition, quasars not only ionize gas in their proximity zones, but also dramatically increase the temperature of the surrounding IGM. In Khrykin et al. (2017) we showed that his effect, also known as thermal proximity effect can be measured in spectra of z~3-5 quasars and can yield the measurement of HeII fraction to ~0.04 absolute precision. This opens up the possibility to directly constrain the extent and timing of the He II reionization!

• Magnetic fields in galactic environments probed by FRBs

Coming soon..

• Temperature-Density relation in the IGM at z~2.5

Coming soon..

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Selected Publications

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Public Outreach

I have presented public lectures about astrophysics, supermassive black holes and cosmology on several Science Festivals across Russia (2017-2019). I have also organized monthly public outreach event in Rostov-on-Don called "Science Burger" (a version of Astronomy on Tap), where young scientists could present there research to public in a lively and friendly environment.

From Spring 2021, I am co-host of a weekly podcast on Clubhouse social media platform, dedicated to explaining astronomical and astrophysical discoveres to the general public.

I strongly believe that communication with public is one of the key responsibilities of scientists, therefore, I frequently participate in public outreach events live, online and on the radio.

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Contact Details

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