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UTC+3

10:00	0:40	Prof. Zhijie Qu Prof. Zhijie Qu Tsinghua University	Multi-Wavelength View of the Milky Way Circumgalactic Medium
The circumgalactic medium (CGM) plays a critical role in regulating galaxy evolution, yet the physical properties of the multiphase structures remain poorly constrained. This talk presents our recent studies of multiphase gas in and around the Milky Way (MW). In particular, the warm gas is measured using the UV QSO absorption spectroscopy, showing significant gas flows around the MW. For the hot gas, I will introduce the X-LEAP program, a survey of OVII, OVIII, and FeL emission lines in the XMM-Newton archive. We noted that the SWCX is a temporally and spatially varied foreground contamination, which must be removed for a clean MW hot gas emission. After correcting the SWCX, we characterized the temperature structures in the MW. Finally, we explored the connection between the warm and hot phases.
10:00	0:40	Prof. Zhijie Qu Prof. Zhijie Qu Tsinghua University
Multi-Wavelength View of the Milky Way Circumgalactic Medium

10:40	0:30	Valentin Nezabudkin Valentin Nezabudkin IKI, MIPT	X-ray emission of the Nuclear Stellar Disk as seen by SRG/ART-XC
The Nuclear Stellar Disk (NSD), together with the Nuclear Stellar Cluster and the supermassive black hole Sgr A, forms the central region of the Milky Way. Galactic X-ray background emission is known to be associated with the old stellar population, predominantly produced by accreting white dwarfs. In this work we characterize the X-ray emission of the Galactic Center (GC) region using wide-field observations with the ART-XC telescope on board the SRG observatory in the 4-12 keV energy band. Our analysis demonstrates that the X-ray emission of the GC at a spatial scale of a few hundred parsecs is dominated by the regularly shaped NSD aligned in the Galactic plane, and characterized by latitudinal and longitudinal scale heights of approximately 20 pc and approximately 100 pc, respectively. The measured flux, 6.8 (+0.1, -0.3) x 10^-10 erg/s/cm^2 in the 4-12 keV band, corresponds to a luminosity of 5.9 (+0.1, -0.3) x 10^36 erg/s, assuming the GC distance of 8.178 kpc. The average mass-normalized X-ray emissivity of the NSD, 5.6 (+0.5, -0.7) x 10^27 erg/s/M_sun, exceeds the corresponding value of the Galactic ridge by a factor of 3.3 (+0.4, -0.5), confirming other studies. We also perform a deprojection of the observed NSD surface brightness distribution in order to construct a three-dimensional X-ray luminosity density model, which can be directly compared to the existing three-dimensional stellar mass models. The emissivity of the NSD as a function of distance to Sgr A reveals a centrally concentrated maximum, indicating an enhanced radiative output per unit stellar mass in the inner NSD region. Finally, we conclude that the observed spatial properties of the NSD are fully consistent with the stellar mass density distribution, leaving only a small room for a possible diffuse component.
10:40	0:30	Valentin Nezabudkin Valentin Nezabudkin IKI, MIPT
X-ray emission of the Nuclear Stellar Disk as seen by SRG/ART-XC

11:10	0:30	Coffee Break

11:40	0:30	Dr. Irek Khamitov Dr. Irek Khamitov Kazan Federal University	850 SRG/eROSITA X-ray sources associated with Pleiades stars
Using data from the SRG/eROSITA all-sky X-ray survey and the GAIA-based catalog of 2,209 members of the Pleiades open star cluster, we found 850 X-ray sources associated with the cluster stars. Over 650 of them were detected in X-rays for the first time. At the distance of the Pleiades, the nominal sensitivity of eROSITA corresponds to a luminosity of $L_X \sim 1.6 \cdot 10^{28}$ erg/s in the 0.3--2.3 keV band. The eROSITA sources associated with Pleiades stars have a total luminosity of $L_{X,tot} \sim 1.3 \cdot 10^{32}$ erg/s , a million times greater than the X-ray luminosity of the quiet Sun. Strong X-ray variability, more than 10 times, was recorded for 27 sources. Most of them are known as eruptive optical variables of the dM class. The value of $R_X=log(L_X/L_{bol})$ increases with decreasing effective temperature of the star from $R_X\approx -5$ to $R_X\approx -2$. The distribution of stars over $R_X$ is bimodal, with the left peak at $R_X\sim-4.3$ being formed by stars of FGK classes, and the right peak at $R_X\sim-3.1$ being mainly populated by M--stars. The relation between $R_X$ and the Rossby number $Ro$ depends on the spectral class. For K- and M- stars, at low Rossby numbers $R_X\sim -3$ and depends weakly on $Ro$. At $Ro \gt 0.25$, a rapid drop in $R_X$ is observed for K stars, while in our sample there are no M stars with large Rossby number. Most of F- and G- stars appear to have smaller $R_X\sim -4.5$, however, our sample size is insufficient for a more detailed characterization of their $R_X-Ro$ dependence.
11:40	0:30	Dr. Irek Khamitov Dr. Irek Khamitov Kazan Federal University
850 SRG/eROSITA X-ray sources associated with Pleiades stars

12:10	0:40	Prof. Yongquan Xue Prof. Yongquan Xue University of Science and Technology of China	Defying TDE Paradigms: An IMBH TDE Revealed by Multi-wavelength Observations and the Faintest Yet Extremely Variable X-ray TDE
In this talk we present two unique tidal disruption events (TDEs) that might defy TDE paradigms. First, we present our late-time observations and comprehensive multi-wavelength analyses of an extraordinary TDE at the center of a dwarf galaxy, whose characteristics are consistent with the scenario of a TDE caused by an intermediate-mass black hole with a mass of ∼10^5 solar masses, but are difficult to comprehend completely. Second, we report an unusual X-ray transient discovered in the 7 Ms Chandra Deep Field-South, and find that a supermassive black hole binary TDE model is in acceptable accordance with its light curves, but fails to match its short-timescale fluctuations exactly. Therefore, these two TDEs provide a key benchmark for improving our understanding of TDEs.
12:10	0:40	Prof. Yongquan Xue Prof. Yongquan Xue University of Science and Technology of China
Defying TDE Paradigms: An IMBH TDE Revealed by Multi-wavelength Observations and the Faintest Yet Extremely Variable X-ray TDE

12:50	0:20	Dr. Georgii Khorunzhev Dr. Georgii Khorunzhev IKI	Distinguishing TDEs and AGNs among the eROSITA X-ray variable sources using by ground-base spectroscopic data
A classification of tidal disruption events (TDEs) among other extragalactic X-ray variable sources which nearly always appear to be an active galactic nuclei (AGNs) is a complex problem. The observed variation in the X-ray flux more than an order of magnitude is indicative of a substantial release of energy. These flux variation is a common for the TDEs. Unfortunatelly, a significant number of AGNs demonstrate the same extreme variability on a half-year scale, thus contaminating the TDE candidates sample. However optical spectroscopy can provide significant information about the distance, type and bolometric luminosity of the X-ray source's optical counterpart. To improve selection efficiency we have proposed a method for distinguishing TDEs from AGNs based on optical and X-ray properties. This method been applied to the samples of the eROSITA variable sources selected by X-ray flux variations more than 10 times. The method have revealed tens of a new TDE candidates. In addition to using well-known relation between nebular emission lines fluxes we have proposed a relationship between the soft X-ray peak luminosity measured by eROSITA and the O[III] (5007A) emission line luminosity obtained from the optical spectrum. It takes several advantages, because it allows to classify TDE using moderate optical spectrum (with a low signal-to-noise ratio or for a distant object). The line O[III] is the one of the brightest emission lines in an AGN's spectrum and tightly correlated with the AGN bolometric luminosity. The line flux remains constant over thousands years. The most of AGNs except LINERS conform to the empirical correlation between the X-ray and O[III] fluxes, even with extreme X-ray flux variations. Only TDE candidates exhibit a relationship between these luminosities greater than ~1000. This criterion is very helpful to separate low-luminosity TDEs from AGNs. Even if a TDE occurs in a quiescent galaxy, the upper limit for AGN bolometric luminosity can be determined.
12:50	0:20	Dr. Georgii Khorunzhev Dr. Georgii Khorunzhev IKI
Distinguishing TDEs and AGNs among the eROSITA X-ray variable sources using by ground-base spectroscopic data

13:10	0:10	Concluding Remarks

13:20	1:10	Lunch

14:30	4:00	Boat Trip on the Moskva River (16:00 – 18:30)