Search for the event horizon evidences by means of optical observations with high temporal resolution G.Beskin, V.Debur, S.Karpov, V.Plokhotnichenko Special Astrophysical Observatory of Russian Academy of Sciences, Russia XXVI General Assembly of International Astronomical Union, Prague, 2006 Search for Isolated Black Holes: Why, What, Where and How Final stages of stellar evolution Isolated BH special case of stellar evolution Laboratory of strong gravitational fields Its existence itself is a test for various theories Search for Isolated Black Holes: Why, What, Where and How Necessary features (for any theory): Compactness large mass for small size (M>3M 0 for stellar mass BH) High energy density Fast variability ~ r g /c Sufficient feature the presence of event horizon it is what separates the BH from all other classes of compact massive objects, which may present in alternative gravity theories. Search for Isolated Black Holes: Why, What, Where and How The presence of event horizon manifest itself in the emission of accreted matter in its vicinity. Redshift and radiation damping Periodic components of emission Variable polarization etc, etc, etc... It is necessary to study the complete set of parameters of photons generated near the BH horizon with maximal possible time resolution (r g /c ~ s) It is the accreting gas that makes it possible to see the event horizon (the BH itself), but there should not be plenty of it, to keep the horizon visible. Search for Isolated Black Holes: Why, What, Where and How Standard laboratories Accreting black holes (M > 3M 0 ) in X-ray binaries accretion rate ~ M 0 /year Accreting supermassive BHs(M>10 6 M 0 ) in active galactic nuclei accretion rate ~ M 0 /year Problem: the event horizon is screened due to high accretion rate Isolated stellar-mass black hole (ISMBH) is the best object to detect and study the event horizon Low accretion rate, ~ M 0 /year Low optical depth, < the event horizon is open ~30 % of radiation comes from inside 2r g Search for Isolated Black Holes: Why, What, Where and How Observable Manifestations of ISMBH (Shvartsman 1971, Bisnovatyi-Kogan & Ruzmaikin1975, Ipser&Price 1982,...) Spherical accretion (for ~ 90% of Galaxy volume) Importance of magnetic field (ties the particles together) Equipartition of energies (gravitational, magnetic, kinetic, thermal) Mostly optical (synchrotron) emission with flat featureless spectrum Fast variability due to MHD instabilities New results (Beskin & Karpov 2005) Magnetic field energy conversion (due to equipartition) by reconnections of magnetic field lines in current sheets Acceleration of electrons in current sheets up to ~ 10 5 Nonthermal (hard) variable tail of emission spectrum Flares due to clouds of accelerated electrons Search for Isolated Black Holes: Why, What, Where and How Complete set of ISMBH manifestations: Number ~ 10 7 in the Galaxy (~1000 inside 300 pc) Brightness: m ~ 16 m 25 m Featureless spectra from radio to gamma-rays Mass > 3M 0 (if it is possible to estimate) Variability on wide time scale range 10 7 s Critical feature the shortest flares with ~ s with particular spectral behaviour and possible polarization Optical range is the best to detect and study such set of critical properties maximum information about each detected photon Search for Isolated Black Holes: Why, What, Where and How In order to search for it one need The list of candidate objects (matching all or some of predicted properties) Special hardware to get complete information on each photon with time resolution of s Special software to analyze parameters of each photon Special people ready to play flute in front of tulips like Erasm Darwin Such activity had been started by Shvartsman in 1970s as a MANIA experiment We are MANIACS!!! MANIA - Multichannel Analysis of Nanosecond Intensity Alterations Objects-candidates Objects with Continuous Optical Spectra -...OCOSes radio - ROCOSes gamma - GOCOSes radio + x-ray - XROCOSes DC-dwarfs ~ 200 WDs without lines, 13 m 20 m, I/I < 5% ROCOSes and XROCOSes ~ 40, 15 m 22 m, with limits on spectral features I/I < 1-5% (for example, Tsarevsky et al 2005, Marti et al 2004) GOCOSes unidentified point-like gamma-ray (100 Mev) sources EGRET ( ) - ~200 with square deg boxes example: J 0.5 deg box ~150 x-ray sources, 75 optical identifications up to 22 m, ~20% could be featureless (La Palombara et al 2004). MANIA - Multichannel Analysis of Nanosecond Intensity Alterations Objects-candidates Candidates with estimation of masses Long microlensing events - MACHOs ( > 1 year) N = 3 with T = 490 1120 days, V t ~ 31 79 km/s OGLE III detects ~10 3 events / year, with expected ~3 long due to massive objects (BHs?) MANIA - Multichannel Analysis of Nanosecond Intensity Alterations Objects-candidates Candidates with estimation of masses Self-lensing in binaries (Beskin & Tuntsov 2003) BH + WD 10 6 10 7 binaries in Galaxy ~10 3 till 23 m Optimal orientation probability ~ 3 10 -3 For SDSS facilities - ~3 such binary systems per year LAMOST - ~5 VISTA - ~5 MANIA - Multichannel Analysis of Nanosecond Intensity Alterations Software processing of photon time of arrivals to study the variability of emission Historical y2-functions (Shvartsman 1977) statistical analysis of time intervals between photons Contemporary Fourier power spectra Light curve analysis intensity statistics, normalized residuals and flares Periodograms MANIA - Multichannel Analysis of Nanosecond Intensity Alterations Hardware Russian 6-m BTA telescope Old maniacal epoch (before 1997) Standard multicolor photometer with diaphragm using PMTs U, B, V, R filters 4 10 arcsec diaphragm 10% quantum efficiency 1 us time resolution Real limit ~ 17 m - 18 m MANIA - Multichannel Analysis of Nanosecond Intensity Alterations Hardware Russian 6-m BTA telescope New maniacal epoch (since 1998) Development of position-sensitive detectors (PSDs) with high time resolution based on multichannel plates (MCPs) electron multiplication The coordinates are measured by means of comparison of electron charges on a different parts of a multi-segment cathode Now we may work with objects ~ mag fainter Position-Sensitive Detector Photocathode S20 (3700 7500 ) MCP stack gain Collector configuration cross-like (4 electrodes) Spatial resolution 70 m (0.21'') Time resolution 700 ns Number of pixels 710 4 Work diameter 22 mm Detector noise counts/s Position-Sensitive Detector Acquisition system Quantochron 4-48 - special time-code convertor Designed as a PCI-slot device based on SPARTAN FPGA chip Max data flow 10 6 counts/s Time resolution 30 ns Multichannel Panoramic Spectropolarimeter Modes of operation One-color (U, B, V, R) photometry and polarimetry Panoramic, FOV ~ 1' Four-color photometry and polarimetry Object + comparison star, FOV ~15'' Spectropolarimetry 1''-5'' slit simultaneous measurement of 3 Stokes parameters Limits (good weather conditions) 20 m 21 m for T=1 h exposure Spectroscopic Spectrololarimetric Multicolor photopolarimetric Panoramic photopolarimetry Photon counting Results of old MANIA program DC-dwarfs 20 most interesting objects studied Long-time variability Unusual colors Upper limits derived S var < 50% - 2% for 40 s ROCOSes 20 most interesting objects studied Radio compactness Long-time variability Upper limits S var < 20% - 1% for 40 s New Results: MACHO-99-BLG-22 First direct single black hole candidate Microlensing event with T=112090 days Projected velocity 758 km/s Baseline magnitude I=19.2 m Model of lens position (Bennett et al 2002) D=0.5 kpc M=130M 0 Vt=70 km/s D=2 kpc M=30M 0 Vt=56 km/s D=6 kpc M=3.5M 0 Vt=19 km/s New Results: MACHO-99-BLG-22 Optical limits: Hubble ACS (Feb 27, 2005) I < 20 m BTA MANIA (Jun 28, 2006) Variable component: B < 21.2 m on 1 s time scale X-ray limits: RXTE PCA Scans (Revnivtsev, Sunyaev 2002) < // 2 ROSAT All Sky Survey < // 2 XMM-Newton (Vestrand, unpublished) < // 2 5'' x 5'' New Results: MACHO-99-BLG-22 Distance > 2kpc 3.5M 0 < Mass < 30M 0 Observations to be continued... New Results: ROCOSes (2006) 8C Highly variable radio + optical object with featureless spectrum B=15.5 Studied on BTA in multicolor mode Fractional RMS < 5% on 1 s J (thanks to G.Tsarevsky) XROCOS with R=16.1 Studied on BTA in polarimetric mode Fractional RMS < 10% on 1 s Perspectives... New position-sensitive detector GaAr photocathode QE ~ 50% over 4000 8500 16-electrode collector spatial resolution ~ 10 20 m - like CCD Number of pixels ~ like CCD Observations in Dec 2006 Our testbed - Crab pulsar (2006) Hearthbeat of a pulsar spectrum Phased light curve with 5 s resolution We most likely already see several hundreds of isolated black holes All we need is to prove it Maniacs hope for the best