### Lev Grigory Titarchuk

##### FIAN, ASC, AN Russia

**Spectral Index-Mass Accretion Rate Correlation and Evaluation of Black Hole Masses in AGNs 3C 454.3 and M87***Elena Seifina, Alexandre Chekhtman,Indira Ocampo*

We present a discovery of the correlations between the photonl index, Gamma and Mdot observed in AGNs. 3C~454.3 and M87. We analyze spectral transition observed in these AGNs using Chandra, Swift, Suzaku, BeppoSAX, ASCA and RXTE data. We apply a scaling technique for a BH mass evaluation which uses a correlation between the Gamma and normalization of the seed component proportional Mdot. We develop an analytical model that shows the Gamma of the X-ray spectrum undergoes an evolution from lower to higher values depending on a Mdot. To estimate a BH mass in 3C~454.3 we consider SMBHs, NGC~4051 and NGC~7469 as well as BHs Cyg X-1 and GRO J1550 as reference sources for which distances, inclination angles and the BH masses have been already evaluated. While for M87, we provide the BH mass scaling using IMBHs: ESO~243--49 HLX--1 and M~101 ULX--1 and Galactic BHs: XTE J1550, 4U 1630, GRS 1915 and H 1743) as reference sources. Application of the scaling technique for the Gamma vs. Mdot correlation provides estimates of the BH masses in 3C~454 and M87 to be about 3.4 x 10^9 and 5.6 x 10^7 M_{\odot}, respectively. We also compared our scaling BH masses with a recent BH mass estimate, M_{87}=6.5 x 10^9 M_{\odot} using {Event Horizon Telescope, EHT} which gives an image at 1.3 mm and based on the angular size of ``BH event horizon''. Thus our result for a BH mass estimate in M87 gives a much lower BH mass, at least of two orders of magnitude less than that made by the EHT team.