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G.Beskin, V.Debur, S.Karpov, V.Plokhotnichenko

G.Beskin, V.Debur, S.Karpov, V.Plokhotnichenko Special Astrophysical Observatory of Russian Academy of Sciences, Russia. Search for the event horizon evidences by means of optical observations with high temporal resolution. XXVI General Assembly of International Astronomical Union, Prague, 2006.

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G.Beskin, V.Debur, S.Karpov, V.Plokhotnichenko

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  1. G.Beskin, V.Debur, S.Karpov, V.Plokhotnichenko Special Astrophysical Observatory of Russian Academy of Sciences, Russia Search for the event horizon evidences by means of optical observations with high temporal resolution XXVI General Assembly of International Astronomical Union, Prague, 2006

  2. 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

  3. Search for Isolated Black Holes:Why, What, Where and How • Necessary features (for any theory): • Compactness – large mass for small size (M>3M0 for stellar mass BH)r ~ 1024 M0-2 ... • High energy density • Fast variability ~ rg/c • Sufficient feature • the presence of event horizonit is what separates the BH from all other classes of compact massive objects, which may present in alternative gravity theories.

  4. Search for Isolated Black Holes:Why, What, Where and How • The presence of event horizonmanifest 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 generatednear the BH horizonwith maximal possible time resolution (rg/c ~ 10-5 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.

  5. Search for Isolated Black Holes:Why, What, Where and How • «Standard laboratories» • Accreting black holes (M > 3M0) in X-ray binariesaccretion rate ~ 10-11 – 10-8 M0/year • Accreting supermassive BHs(M>106 M0) in active galactic nucleiaccretion rate ~ M0/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, ~10-18 – 10-14 M0/year • Low optical depth, < 10-5 – the event horizon is open • ~30 % of radiation comes from inside 2rg

  6. 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 g ~ 105 • Nonthermal (hard) variable tail of emission spectrum • Flares due to clouds of accelerated electrons

  7. Search for Isolated Black Holes:Why, What, Where and How

  8. Search for Isolated Black Holes:Why, What, Where and How • Complete set of ISMBH manifestations: • Number ~ 107 in the Galaxy (~1000 inside 300 pc) • Brightness: m ~ 16m – 25m • Featureless spectra from radio to gamma-rays • Mass > 3M0 (if it is possible to estimate) • Variability on wide time scale range 10-7 – 107 s • Critical feature – the shortest flares with t ~ 10-7 – 10-5 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

  9. 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 10-7 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!!!

  10. MANIA - Multichannel Analysis of Nanosecond Intensity Alterations • Objects-candidates • Objects with Continuous Optical Spectra - ...OCOSesradio - ROCOSes gamma - GOCOSes radio + x-ray - XROCOSes • DC-dwarfs ~ 200 WDs without lines, 13m – 20m, dI/I < 5% • ROCOSes and XROCOSes~ 40, 15m – 22m , with limits on spectral features dI/I < 1-5%(for example, Tsarevsky et al 2005, Marti et al 2004) • GOCOSes – unidentified point-like gamma-ray (100 Mev) sourcesEGRET (1991-1995) - ~200 with square deg boxesexample:J0616-33 – 0.5 deg box ~150 x-ray sources, 75 optical identifications up to 22m ,~20% could be featureless (La Palombara et al 2004).

  11. 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, Vt ~ 31 – 79 km/sOGLE III detects ~103 events / year, with expected ~3 long due to massive objects (BHs?)

  12. MANIA - Multichannel Analysis of Nanosecond Intensity Alterations • Objects-candidates • Candidates with estimation of masses • Self-lensing in binaries (Beskin & Tuntsov 2003)BH + WD – 106 – 107 binaries in Galaxy~103 till 23mOptimal orientation probability ~ 3 ·10-3 For SDSS facilities - ~3 such binary systems per yearLAMOST - ~5 VISTA - ~5

  13. MANIA - Multichannel Analysis of Nanosecond Intensity Alterations • Softwareprocessing 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

  14. 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 ~ 17m - 18m

  15. MANIA - Multichannel Analysis of Nanosecond Intensity Alterations • Hardware • Russian 6-m BTA telescope • «New maniacal epoch» (since 1998) • Development of position-sensitivedetectors (PSDs) with high timeresolution based on multichannelplates (MCPs) electron multiplicationThe coordinates are measured by meansof comparison of electron charges on a different parts of a multi-segment cathode • Now we may work with objects~ 2 - 3 mag fainter

  16. Position-Sensitive Detector • Photocathode – S20 (3700 – 7500 ll) • MCP stack gain – 106. • Collector configuration – cross-like (4 electrodes) • Spatial resolution – 70 mm (0.21'') • Time resolution – 700 ns • Number of pixels – 7·104 • Work diameter – 22 mm • Detector noise – 200-500 counts/s

  17. 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 – 106 counts/s • Time resolution – 30 ns

  18. 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) • 20m – 21m for T=1h exposure

  19. Photon counting Panoramic photopolarimetry Spectroscopic Multicolor photopolarimetric Spectrololarimetric

  20. Results of old MANIA program • DC-dwarfs • 20 most interesting objects studied • Long-time variability • Unusual colors • Upper limits derived • Svar < 50% - 2% for 10-6 – 40 s • ROCOSes • 20 most interesting objects studied • Radio compactness • Long-time variability • Upper limits • Svar < 20% - 1% for 10-6 – 40 s

  21. NewResults: MACHO-99-BLG-22 • First direct single black hole candidate • Microlensing event with T=1120±90 days • Projected velocity – 75±8 km/s • Baseline magnitude – I=19.2m • Model of lens position (Bennett et al 2002) • D=0.5 kpc M=130M0 Vt=70 km/s • D=2 kpc M=30M0 Vt=56 km/s • D=6 kpc M=3.5M0 Vt=19 km/s

  22. New Results: MACHO-99-BLG-22 • Optical limits: • Hubble ACS (Feb 27, 2005) • I < 20m • BTA MANIA(Jun 28, 2006) • Variable component: B < 21.2mon 10-5 – 1 s time scale • X-ray limits: • RXTE PCA Scans (Revnivtsev, Sunyaev 2002)< 10-11 эрг/с/см2 • ROSAT All Sky Survey< 10-13 эрг/с/см2 • XMM-Newton (Vestrand, unpublished)< 10-14 эрг/с/см2 5'' x 5''

  23. New Results: MACHO-99-BLG-22 Distance > 2kpc 3.5M0 < Mass < 30M0 Observations to be continued...

  24. NewResults: ROCOSes (2006) • 8C 0716+714 • Highly variable radio + optical object with featureless spectrum • B=15.5 • Studied on BTA in multicolor mode • Fractional RMS < 5% on 10-5 – 1 s • J1942+10 (thanks to G.Tsarevsky) • XROCOS with R=16.1 • Studied on BTA in polarimetric mode • Fractional RMS < 10% on 10-5 – 1 s

  25. Perspectives... • New position-sensitive detector • GaAr photocathodeQE ~ 50% over 4000 – 8500 ll • 16-electrode collectorspatial resolution ~ 10 – 20 mm - like CCD • Number of pixels ~ 106 - like CCD • Observations in Dec 2006

  26. Our testbed - Crab pulsar (2006) Hearthbeat of a pulsar spectrum Phased light curve with 5ms resolution

  27. We most likely already see several hundreds of isolated black holes All we need is to prove it

  28. Maniacs hope for the best

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