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Main research projects: 1. Imaging the Black Hole Shadows in the Centers of the Milky Way and M87.
The Event Horizon Telescope
is making for the first time resolved images of
the black holes at event horizon
scales in the centers of
the Milky
Way and the M87 galaxy.
I and my group are involved in all these efforts through the
Event Horizon Telescope collaboration,
where I serve as Polarimetry Working Group coordinator and where I am a member of the Science Council.
The Event Horizon Telescope has published the first ever image of the black hole shadow in M87 galaxy in April 2019 (visible in the image on the right).
My group is building realistc models of accretion flows and jets in the close vicinity of black holes.
General relativistic simulations of plasma and magnetic field dynamics and radiative transfer
are carried out to predict observational signatures of accreting black holes.
Image on the right is an example of
a theoretical prediction of apperance of the
black hole event horizon in the center of the Milky Way at mm
wavelength at which EHT operates. These models are critical to understand the EHT observations. See one of my articles in
Astronomy and Astrophysics for more details.
Click on the figure in the right to follow the evolution of realistic model of accreting black hole
as seen by observer on earth at wavelenght > 1 mm.
The movie starts when the black hole is surrounded by a ring of magnetized
plasma. Due to viscous forces caused by magnetic turbulence the plasma
looses angular momentum and falls onto the black hole event horizon. In a later stage a
relativistic jet is formed. The movie is a result of combing 3D general relativistic MHD
simulations of fluid dynamics around Kerr black hole (with HARM-3D code) with
general relativistic radiative transfer model.
We will confront this and other models of accretion with various
radio/millimeter VLBI and high energy (like in Near Infrared
and X-ray bands)
observations and estimate the properties of plasma and
spin of the Milky Way and M87 supermassive black holes.
To confront simulations of plasma with astrophysical
observations one needs a model for light transport.
I have developed and co-developed (with graduate students) a few
various state-of-the-art codes for simulating radiative transfer
through astrophysical plasma in strong gravitational field.
My latest development is ipole (see code web here) and radpol - a semianalytic, covariant
(i.e., independent of geometry of spacetime)
general relativistic codes for polarized radiative transport.
The ipole code is public and free to use, it is available
here.
The information about geometry of
magnetic fields is in polarized component of radiation
(Stokes Q, U, and V). Modeling the polarized electromagnetic
counterparts of accreting black holes is the most promissing way to
learn about magnetizm of compact
objects. This study is crucial to find out, for example, how
relativistic jets, that we do observe in many astrophysical systems, are
launched and powered. How a magnetized accretion
flow onto a black hole looks like in polarized light? The
figure above shows one of the most accurate images of that
based on ipole calculation.
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