Black Holes in Binary Black Holes in Binary Systems and Galaxy Systems and Galaxy

NucleiNucleiA.M CherepashchukA.M Cherepashchuk

Lomonosov Moscow State Lomonosov Moscow State University,University,

Sternberg Astronomical Sternberg Astronomical InstituteInstitute

Overview:Overview:1.1. Introduction: 40 years of BHs Introduction: 40 years of BHs

investigations.investigations.2.2. Observations of stellar mass BHs in Observations of stellar mass BHs in

X-ray binary systems.X-ray binary systems.3.3. Stellar mass BH demography.Stellar mass BH demography.4.4. Observations of supermassive BHs Observations of supermassive BHs

in galactic nuclei.in galactic nuclei.5.5. Supermassive BH demography.Supermassive BH demography.6.6. Conclusion.Conclusion.7.7. Future investigations.Future investigations.

I. Introduction.I. Introduction.

A big dream of A big dream of Ya.B.ZeldovichYa.B.Zeldovich was to discover a real black was to discover a real black holes in the Universe.holes in the Universe.

According to modern theory of According to modern theory of stellar evolution taking into account stellar evolution taking into account Einstein General Relativity, if:Einstein General Relativity, if:

M M starstar < 3M => NS or < 3M => NS or WD.WD.

corcor

ee

M M starstar > 3M => > 3M => BHBH,,

corcor

ee

BH event horizon rBH event horizon rhh::

for non-rotating (Schwarzschild) for non-rotating (Schwarzschild) BH,BH,

for rotating BH.for rotating BH.

rrgg = 9 mm for the Earth, r = 9 mm for the Earth, rgg = 3 km for the Sun, = 3 km for the Sun,

rrgg = 40 AU for M = 40 AU for MBHBH = 2·10 = 2·1099 M M

2gh c

GM2rr

gh rr

40 years ago40 years ago first first Black Hole candidate Black Hole candidate (Cyg X-1) has been (Cyg X-1) has been discovered in X-ray discovered in X-ray binary system.binary system.

X-ray binary:X-ray binary: optical optical star – donor of matter star – donor of matter and accreting and accreting relativistic object – relativistic object – neutron star (NS) or neutron star (NS) or black hole (BH).black hole (BH).

R. Giacconi – Nobel Prize (2002)

II. Observations of stellar II. Observations of stellar mass BHs in X-ray binaries.mass BHs in X-ray binaries.Theoretical prediction of X-ray from Theoretical prediction of X-ray from accreting BH:accreting BH:

Zeldovich (1964) and Salpeter (1964)Zeldovich (1964) and Salpeter (1964) – – strong energy release from non-spherical strong energy release from non-spherical accretion onto BH.accretion onto BH.

Pringle and Rees (1972) Pringle and Rees (1972) Shakura and Sunyaev (1973)Shakura and Sunyaev (1973) – theory – theory

of disk of disk accretion accretion Novikov and Thorne (1973)Novikov and Thorne (1973) onto onto

BH.BH.

First X-ray observations of First X-ray observations of accreting BHs in X-ray accreting BHs in X-ray

binary systems:binary systems:

Giacconi et al. (1972)Giacconi et al. (1972) – UHURU – UHURU epoch.epoch.

~100 compact X-ray sources, most ~100 compact X-ray sources, most of which are X-ray binaries.of which are X-ray binaries.

First X-ray binaries:First X-ray binaries: Cyg X-1, Her X- Cyg X-1, Her X-1, Cen X-3, Vela X-1, SMC X-1, etc.1, Cen X-3, Vela X-1, SMC X-1, etc.

First optical identifications of First optical identifications of X-ray binaries: ellipticity and X-ray binaries: ellipticity and

reflection effects.reflection effects.Cherepashchuk, Efremov, Kurochkin, Cherepashchuk, Efremov, Kurochkin, Shakura, Sunyaev, 1972,Shakura, Sunyaev, 1972,

J. Bahcall, N. Bahcall, 1972,J. Bahcall, N. Bahcall, 1972,

Lyutyi, Sunyanev, Cherepashchuk, 1973Lyutyi, Sunyanev, Cherepashchuk, 1973

Cyg X-1

Up to now from the borders of many Up to now from the borders of many special X-ray space observatories special X-ray space observatories (Einstein, Rosat, XMM Newton, Integral (Einstein, Rosat, XMM Newton, Integral etc.) etc.) several thousandsseveral thousands of X-ray binaries of X-ray binaries have been discovered.have been discovered.

Optical investigations made by many Optical investigations made by many scientific groups (USA, England, scientific groups (USA, England, Germany, Russia etc.) Germany, Russia etc.) allowed to allowed to estimate the masses of 26 stellar mass estimate the masses of 26 stellar mass BHsBHs in X-ray binary systems. in X-ray binary systems.

Up to now masses of Up to now masses of ~50 NS in binary ~50 NS in binary systems have been determinedsystems have been determined..

Determination of BH Determination of BH masses in X-ray binariesmasses in X-ray binaries

Recently new methods of Recently new methods of interpretation of the light interpretation of the light curves, line profiles and curves, line profiles and radial velocity curves radial velocity curves have been developed in have been developed in our group. In these our group. In these methods tidal and methods tidal and rotational deformations rotational deformations of the optical star are of the optical star are taken into account. X-ray taken into account. X-ray heating effect as well as heating effect as well as the eclipsing effects are the eclipsing effects are taken into account too taken into account too ((Antokhina, Antokhina, Cherepashchuk, Cherepashchuk, Shimansky, 2003, 2005Shimansky, 2003, 2005).).

Masses, dimensions and spins Masses, dimensions and spins of BHs in X-ray binary systems.of BHs in X-ray binary systems.

Up to now Up to now masses of 26 masses of 26 stellar mass BH stellar mass BH and ~50 NS have and ~50 NS have been estimated in been estimated in binary systems. binary systems. M MBHBH = 4 – 25 M = 4 – 25 M ..

Masses of 50 NS Masses of 50 NS lie in the range (1 lie in the range (1 – 2) M . Mean – 2) M . Mean mass of the NS is mass of the NS is ~1.4 M . ~1.4 M .

Radii of BH candidates are Radii of BH candidates are estimated using rapid X-ray estimated using rapid X-ray variability: variability:

t ≈ 10t ≈ 10-3-3 s, s,

r ≤ cr ≤ ct ≈ 300 km = 10 rt ≈ 300 km = 10 rgg..

BH spins are measured basically BH spins are measured basically by X-ray continuum-fitting by X-ray continuum-fitting method (McClintock et al., method (McClintock et al., 2011), using relativistic thin-disk 2011), using relativistic thin-disk model of Novikov and Thorne model of Novikov and Thorne (1973).(1973).

NS with measured masses are X-ray NS with measured masses are X-ray pulsars, radiopulsars or X-ray bursters pulsars, radiopulsars or X-ray bursters of the first kind. All these properties of the first kind. All these properties are the evidences of the observed are the evidences of the observed surface of NS.surface of NS.

Therefore, in all 50 cases when the Therefore, in all 50 cases when the relativistic object shows evidences of relativistic object shows evidences of the observed surface its mass does not the observed surface its mass does not exceed the value 3 M – absolute exceed the value 3 M – absolute upper limit of the mass of NS predicted upper limit of the mass of NS predicted by the Einstein General Relativity (!).by the Einstein General Relativity (!).

Masses of 26 BH lie in the range (4 - Masses of 26 BH lie in the range (4 - 25) M . Mean mass of the BH is ~9 M 25) M . Mean mass of the BH is ~9 M . None of this 26 BH candidates is X-ray . None of this 26 BH candidates is X-ray pulsar, radiopulsar or X-ray burster of pulsar, radiopulsar or X-ray burster of the first kind. Therefore the first kind. Therefore none of these none of these massive (massive (mmxx > 3 M ) compact objects > 3 M ) compact objects shows the evidence of observed surfaceshows the evidence of observed surface in agreement with the predictions of in agreement with the predictions of the Einstein General Relativity (!).the Einstein General Relativity (!).

So, basic conclusion based on the So, basic conclusion based on the 40 40 yearsyears of investigations of the of investigations of the relativistic objects in binary systems relativistic objects in binary systems can be formulated as follows: NS can be formulated as follows: NS and BH are different from each and BH are different from each other other not only by the masses, but not only by the masses, but also by the observational also by the observational appearancesappearances in full agreement with in full agreement with the Einstein General Relativitythe Einstein General Relativity..

It should be stressed however, that It should be stressed however, that some some NS can not show direct evidences of the NS can not show direct evidences of the observed surfacesobserved surfaces. In particular, if . In particular, if rotational axes of the NS coincides with rotational axes of the NS coincides with the axes of magnetic dipole, the the axes of magnetic dipole, the phenomenon of the X-ray pulsar or phenomenon of the X-ray pulsar or radiopulsar can not be observed for NS. radiopulsar can not be observed for NS. Therefore all observational evidences for Therefore all observational evidences for the BH described above the BH described above are only are only necessary but not sufficientnecessary but not sufficient. .

However, big number of BH However, big number of BH candidates (26) allows us to believe in candidates (26) allows us to believe in real existence of stellar mass BH in real existence of stellar mass BH in the Universe.the Universe.

High value of spin parameter aHigh value of spin parameter a** for for some BH candidates in X-ray binaries some BH candidates in X-ray binaries (e.g., GRS 1915+105, a(e.g., GRS 1915+105, a** = 0.98) may = 0.98) may be considered as strong evidence for be considered as strong evidence for real existence of BHs.real existence of BHs.

Recently, due to operation of new Recently, due to operation of new generation optical 8 – 10 meter generation optical 8 – 10 meter telescopes, the optical investigations telescopes, the optical investigations of X-ray binary systems in some other of X-ray binary systems in some other galaxies have been realized (e.g., galaxies have been realized (e.g., Orosz et al., 2007). Due to these Orosz et al., 2007). Due to these investigations the many new mass investigations the many new mass determinations for stellar mass BH in determinations for stellar mass BH in X-ray binaries will be obtained.X-ray binaries will be obtained.

Up to now the spins of BHs in 9 X-ray Up to now the spins of BHs in 9 X-ray binaries have been measured. 5 BHs are binaries have been measured. 5 BHs are in X-ray Novae: A 0620-00, XTE J1550-in X-ray Novae: A 0620-00, XTE J1550-564, GRO J1655-40, GRS 1915+105, 4U 564, GRO J1655-40, GRS 1915+105, 4U 1543-47 (1543-47 (Remillard and McClintock, Remillard and McClintock, 20062006), and 4 BHs are in persistent X-ray ), and 4 BHs are in persistent X-ray binaries: LMC X-3 (binaries: LMC X-3 (Davis et al., 2006Davis et al., 2006), ), M33 X-7 (M33 X-7 (Lin et al., 2008, 2010Lin et al., 2008, 2010), LMC ), LMC X-1 (X-1 (Gou et al., 2009Gou et al., 2009), Cyg X-1 (), Cyg X-1 (Gou et Gou et al., 2011al., 2011). Dimensionless spin ). Dimensionless spin parameter aparameter a** = cJ/GM = cJ/GM22. a. a** ≈ ≈ 0.980.98 (GRS 1915+105) ÷ (GRS 1915+105) ÷ 0.120.12 (A 0620-00). (A 0620-00).

III. Stellar mass BH III. Stellar mass BH demography.demography.

There is no There is no correlation correlation between between masses of masses of relativistic relativistic objects and objects and those of those of companion companion stars in binary stars in binary systems.systems.

Number of BHs does Number of BHs does not increase with not increase with decreasing of their decreasing of their masses.masses.

It seems to be It seems to be strange because the strange because the number of stars in number of stars in The Galaxy – The Galaxy – progenitors of BHs progenitors of BHs ((MM > 30 M ) is > 30 M ) is strongly increasing strongly increasing with decreasing of with decreasing of their masses: their masses: N ~ MN ~ M--

55..

It can be shown (e.g., It can be shown (e.g., Cherepashchuk, 2003) that this Cherepashchuk, 2003) that this peculiarity in the mass distribution peculiarity in the mass distribution for BH for BH is not due to observational is not due to observational selection effectsselection effects (disruption of (disruption of binary system after supernova binary system after supernova explosion, strong mass loss by the explosion, strong mass loss by the star due to stellar wind etc).star due to stellar wind etc).

The gap in the range (2 – 4) M The gap in the range (2 – 4) M in the in the mass distribution of NS and BH can be mass distribution of NS and BH can be suggested (Bailyn et al., 1998; suggested (Bailyn et al., 1998; Cherepashchuk, 1998). In this range (2 Cherepashchuk, 1998). In this range (2 – 4) M the number of NS and BH – 4) M the number of NS and BH discovered in binary systems up to now discovered in binary systems up to now is close to zero. is close to zero.

It can be shown that this gap It can be shown that this gap is not due is not due to observational selection effectsto observational selection effects (Cherepashchuk, 2001, 2003; Özel at (Cherepashchuk, 2001, 2003; Özel at al., 2010; Farr et al., 2011).al., 2010; Farr et al., 2011).

Therefore, there are grounds to suggest Therefore, there are grounds to suggest that stellar mass BH formation is that stellar mass BH formation is determined determined not only by the mass of the not only by the mass of the progenitor star, but also by other progenitor star, but also by other parametersparameters: rotation, magnetic field, : rotation, magnetic field, instabilities during the collapse of the instabilities during the collapse of the stellar core etc. (e.g. Fryer and stellar core etc. (e.g. Fryer and Kalogera, 2001; Postnov and Prokhorov, Kalogera, 2001; Postnov and Prokhorov, 2001; Cherepashchuk, 2001; Belczynski 2001; Cherepashchuk, 2001; Belczynski et al., 2011).et al., 2011).

Some new possibility to explain Some new possibility to explain peculiarities in the mass distribution of peculiarities in the mass distribution of BHs has been considered by Postnov and BHs has been considered by Postnov and Cherepashchuk (2003). Deficit of low-Cherepashchuk (2003). Deficit of low-mass BH and the gap in the range (2 – 4) mass BH and the gap in the range (2 – 4) M may be due to M may be due to enhanced quantum enhanced quantum evaporation of BHevaporation of BH which have been which have been suggested in some multidimensional suggested in some multidimensional models of gravity (e.g. Randall and models of gravity (e.g. Randall and Sundrom, 1999). In these models of Sundrom, 1999). In these models of gravity the characteristic time of gravity the characteristic time of quantum evaporation of BH quantum evaporation of BH is much lessis much less than that in the Hawking (1974) than that in the Hawking (1974) mechanism.mechanism.

Normalized jet power Normalized jet power as estimated from the as estimated from the maximum radio flux of maximum radio flux of ballistic jets is in good ballistic jets is in good correlation with correlation with measured spin measured spin parameter aparameter a** of the BH of the BH ((Narayan and Narayan and McClintock, 2012McClintock, 2012): ): PPjetjet ~ a ~ a**

22. It is in . It is in agreement with the agreement with the idea that jets may be idea that jets may be powered by BH spin powered by BH spin energy (energy (Blanford and Blanford and Znajek, 1977; Znajek, 1977; Tchekhovskoy et al., Tchekhovskoy et al., 20102010).). Narayan and

McClintock, 2012

IV. Observations of IV. Observations of supermassive BHs in supermassive BHs in

galactic nuclei.galactic nuclei.

Two basic direct methods of Two basic direct methods of the supermassive BH mass the supermassive BH mass

determination.determination.1.1. Resolved Resolved

kinematics kinematics methodmethod. . Direct observations Direct observations of the motion of the of the motion of the “probe bodies” in “probe bodies” in the gravitational the gravitational field of BH (stars, field of BH (stars, gaseous disks etc.).gaseous disks etc.).

Gillessen et al., 2009

2.2. Reverberation Reverberation mapping mapping method.method.Observations of Observations of time delay time delay tt between variability between variability of emission lines of emission lines and continuum in and continuum in galactic nucleus galactic nucleus (Cherepashchuk (Cherepashchuk and Lyutyi, 1973).and Lyutyi, 1973).r ≈ c· r ≈ c· t.t.

v – from the width of emission line profile

31,G

rM

2

BH

There are several non-direct There are several non-direct methods of BH mass methods of BH mass determinations in the galactic determinations in the galactic nuclei. They are calibrated using nuclei. They are calibrated using the results of the most reliable BH the results of the most reliable BH mass determinations, obtained by mass determinations, obtained by resoled kinematics and resoled kinematics and reverberation mapping methods.reverberation mapping methods.

Up to now masses of several hundreds Up to now masses of several hundreds supermassive BHs have been measured:supermassive BHs have been measured:

MMBHBH=10=106610101010M M

(e.d. Kormendy and Ho, 2013).(e.d. Kormendy and Ho, 2013).Also the values of the spins for several Also the values of the spins for several dozens of supermassive BHs have been dozens of supermassive BHs have been estimated:estimated:

aa**=0.998-0.40 (e.d. Gnedin et al., 2012).=0.998-0.40 (e.d. Gnedin et al., 2012).

V. Supermassive BH V. Supermassive BH demography.demography.

Up to now more than dozen of bright Up to now more than dozen of bright quasars (Mquasars (MBHBH ≈ 10 ≈ 1088 – 10 – 1099 M ) with M ) with high redshiftshigh redshifts

z = 6 – 8 z = 6 – 8

have been discovered. have been discovered.

Therefore the characteristic growing Therefore the characteristic growing time for the mass of supermassive time for the mass of supermassive BHs is BHs is less then 10less then 1099 years years..

There is correlation between MThere is correlation between MBHBH and and MMbuldgebuldge, M, MBHBH and and σσbuldgebuldge (velocity (velocity dispersion of stars in the buldge):dispersion of stars in the buldge):

MMBHBH ~ M ~ M buldgebuldge (M (MBHBH = 0.001 = 0.001 MMbuldgebuldge))

0.95±0.00.95±0.0

55MMBHBH ~ ~ σσ buldgebuldge ( (αα ≈ 4 – 5) ≈ 4 – 5)αα

Some correlation between MSome correlation between MBHBH and and asymptotic rotational velocity of galaxy Vasymptotic rotational velocity of galaxy VFARFAR has been suspected (Ferrarese, 2002; Baes has been suspected (Ferrarese, 2002; Baes et al., 2003).et al., 2003).

Full massFull mass of the galaxy is determined by of the galaxy is determined by VVFARFAR: baryonic matter (~10%) and dark : baryonic matter (~10%) and dark matter (~90%).matter (~90%).

Fundamental dependence Fundamental dependence MMBHBH(V(VFARFAR)) may be expected from the may be expected from the theoretical grounds (theoretical grounds (Silk and Rees, Silk and Rees, 1998; Gurevich et al., 20031998; Gurevich et al., 2003).).

Deep cusps are formed in the Deep cusps are formed in the protogalactic clouds (consisting protogalactic clouds (consisting basically of dark matter) during their basically of dark matter) during their evolution due to gravitational evolution due to gravitational instability. instability.

Observations of rotational Observations of rotational velocities of the galaxies with velocities of the galaxies with

known masses of central known masses of central supermassive BHssupermassive BHs

(Cherepashchuk, (Cherepashchuk, Afanasiev, Zasov, Afanasiev, Zasov, Katkov, 2010)Katkov, 2010)

6-meter telescope 6-meter telescope

of SAO RASof SAO RAS

NGC 3245

NGC 3516

Basic sources on MBasic sources on MBHBH::

Ferrarese and Ford, 2004Ferrarese and Ford, 2004 Peterson, Ferrarese, Gilbert, 2004Peterson, Ferrarese, Gilbert, 2004 Graham, 2008Graham, 2008 Gultekin, Cackett, Miller, 2009Gultekin, Cackett, Miller, 2009

MMBHBH are determined by resolved are determined by resolved kinematics and reverberation kinematics and reverberation mapping methods.mapping methods.

45 galaxies45 galaxies

Correlation MCorrelation MBHBH ( (σσ))

- BHs, - nuclear clusters,

Correlations between MCorrelations between MBHBH and V(R): and V(R):

R=1 kpc R=RR=1 kpc R=R2525

Correlation between MCorrelation between MBHBH and asymptotic rotational and asymptotic rotational

velocity Vvelocity VFARFAR

Correlation between MCorrelation between MBHBH and full and full mass of the galaxy Mmass of the galaxy M2525 is better is better

than that between Mthan that between MBHBH and and baryonic mass.baryonic mass.

Masses of BHs and Nuclear Clusters are Masses of BHs and Nuclear Clusters are only weakly correlated with asymptotic only weakly correlated with asymptotic rotational velocity Vrotational velocity VFARFAR, but they are in , but they are in good correlation with the rotational good correlation with the rotational velocity at R ≈ 1 kpc (characteristic velocity at R ≈ 1 kpc (characteristic dimension of dynamically separated dimension of dynamically separated nuclear disk). It should be noted, that nuclear disk). It should be noted, that mean density of matter in the region mean density of matter in the region with R ≈ 1 kpc is determined by V(R = 1 with R ≈ 1 kpc is determined by V(R = 1 kpc)kpc)..

Masses of BHs and Nuclear Masses of BHs and Nuclear Clusters are in good correlation Clusters are in good correlation with integral (indicative) masses with integral (indicative) masses of the galaxies in the limit of of the galaxies in the limit of their optical radii Rtheir optical radii R2525 ( (this mass this mass includes baryonic and dark includes baryonic and dark mattermatter).).

All correlations between the All correlations between the mass of central supermassive mass of central supermassive object and parameters of the object and parameters of the host galaxy became host galaxy became more more regularregular for summary mass of for summary mass of central object (central object (supermassive BH supermassive BH + Nuclear Cluster+ Nuclear Cluster).).

Dependence of MDependence of MBHBH on V(R = 1 kpc) on V(R = 1 kpc) allows us to suggest that supervassive allows us to suggest that supervassive BH together with buldge is formed as a BH together with buldge is formed as a result of result of “monolithic” collapse“monolithic” collapse of central of central gaseous part of the forming galaxy gaseous part of the forming galaxy ((Zasov, Cherepashchuk, Katkov, 2011Zasov, Cherepashchuk, Katkov, 2011). ).

See, for example, results of See, for example, results of computer simulations: computer simulations: Xu et al., 2007Xu et al., 2007Cook et al., 2009Cook et al., 2009

VI. Conclusion.VI. Conclusion.A big progress in observations of stellar A big progress in observations of stellar

mass BHs and supermassive BHs has been mass BHs and supermassive BHs has been achieved during last 40 years. achieved during last 40 years. Hundreds of Hundreds of reliable BH candidates have been discovered up reliable BH candidates have been discovered up to nowto now..

All observational appearances of BH All observational appearances of BH candidates are in excellent agreement with candidates are in excellent agreement with Einstein General Relativity.Einstein General Relativity.

Taking into account observational selection Taking into account observational selection effects we can estimate the effects we can estimate the full number of stellar full number of stellar mass BHs in our Galaxy as ~10mass BHs in our Galaxy as ~1077. For the mean . For the mean mass Mmass MBHBH ≈ 9 – 10 M it is ~ 10 ≈ 9 – 10 M it is ~ 1088 M or M or 0.1% of 0.1% of the baryonic mass in our Galaxythe baryonic mass in our Galaxy..

VII. Future investigationsVII. Future investigations(stellar mass BHs).(stellar mass BHs).

Development of the theory of disk accretion Development of the theory of disk accretion (e.g. (e.g. Narayan et al., 1997; Bisnovatyi-Kogan Narayan et al., 1997; Bisnovatyi-Kogan and Lovelace, 1997; Blanford and Begelman, and Lovelace, 1997; Blanford and Begelman, 19991999).).

Optical observations of X-ray binaries in Optical observations of X-ray binaries in other galaxies using new generation 8 – 10 other galaxies using new generation 8 – 10 meters telescopes (e.g. meters telescopes (e.g. Orosz et al., 2007Orosz et al., 2007).).

X-ray investigations of low-frequency and X-ray investigations of low-frequency and high-frequency QPOs in X-ray binaries (e.g. high-frequency QPOs in X-ray binaries (e.g. Titarchuk and Osherovich, 2000Titarchuk and Osherovich, 2000). HFQPO are ). HFQPO are related to the physical processes in strong related to the physical processes in strong gravity near the BH event horizon (e.g. gravity near the BH event horizon (e.g. McClintock and Remillard, 2003McClintock and Remillard, 2003).).

Determination of spins of BHs (Determination of spins of BHs (Narayan and Narayan and McClintock, 2012McClintock, 2012).).

VII. Future investigationsVII. Future investigations(supermassive BHs).(supermassive BHs).

Search for binary supermassive BHs in galactic Search for binary supermassive BHs in galactic nuclei (e.g. nuclei (e.g. Sanders and Mirabel, 1996; Sanders and Mirabel, 1996; Komossa et al., 2003Komossa et al., 2003).).

Observations of X-ray and ultraviolet-optical Observations of X-ray and ultraviolet-optical flares from the tidal disruption of stars near flares from the tidal disruption of stars near supermassive BHs in galactic nuclei (supermassive BHs in galactic nuclei (Komossa Komossa et al., 1997, 2002; Gezari et al., 2012et al., 1997, 2002; Gezari et al., 2012).).

Investigations of BH shadow image and Investigations of BH shadow image and extreme gravitational lensing effects near extreme gravitational lensing effects near supermassive BHs in galactic nuclei (e.g. supermassive BHs in galactic nuclei (e.g. Doelman et al., 2008; Zakharov et al., 2005; Doelman et al., 2008; Zakharov et al., 2005; Backwith and Done, 2005Backwith and Done, 2005):):

VLBI and Space interferometers, e.g. VLBI and Space interferometers, e.g. Event Horizon Telescope, MILLIMETRON.Event Horizon Telescope, MILLIMETRON.

In the case of rapidly rotating inner disk flux In the case of rapidly rotating inner disk flux distribution around BH is asymmetric due to the distribution around BH is asymmetric due to the disk rotation (Doppler effect) and the frame-disk rotation (Doppler effect) and the frame-dragging effects. The shape of the shadow casted dragging effects. The shape of the shadow casted by the BH is asymmetric due to the frame-by the BH is asymmetric due to the frame-dragging effects around the rotating black hole dragging effects around the rotating black hole (Takahashi & Watarai 2007).(Takahashi & Watarai 2007).

MillimetronMillimetron observa- observa-

tions of Sgr A* will tions of Sgr A* will

allow to investigate allow to investigate

the vicinity of event the vicinity of event

horizon with muchhorizon with much

more details.more details.

Recent VLBI observations of Sgr A* at = Recent VLBI observations of Sgr A* at = 1.3 mm (Doeleman et al. 2008) obtained a 1.3 mm (Doeleman et al. 2008) obtained a size of microarcseconds for the intrinsic size of microarcseconds for the intrinsic diameter of Sgr A*. diameter of Sgr A*.

161037

This is less than the expected apparent This is less than the expected apparent size of the event horizon (~ 52 size of the event horizon (~ 52 microarcseconds) of the presumed BH. microarcseconds) of the presumed BH. It can be suggested that the bulk of It can be suggested that the bulk of Sgr A* emission may not be centered Sgr A* emission may not be centered on the BH, but arises in the on the BH, but arises in the surrounding accretion flow or surrounding accretion flow or outflowing jet. outflowing jet.

MillimetronMillimetron observations will observations will open a new window onto open a new window onto fundamental black hole physics.fundamental black hole physics.

M87, M87, λλ = 1.3 mm = 1.3 mm