Imaging Compact Imaging Compact Supermassive Supermassive Binary Black Binary Black

Holes with VLBIHoles with VLBIG. B. Taylor (UNM), C. G. B. Taylor (UNM), C.

Rodriguez (UNM), R. T. Zavala Rodriguez (UNM), R. T. Zavala (USNO) A. B. Peck (CfA), L. K. (USNO) A. B. Peck (CfA), L. K. Pollack (UCSC), H.L. Maness Pollack (UCSC), H.L. Maness

(UCB), and R. W. Romani (UCB), and R. W. Romani (Stanford)(Stanford)

Black Holes: From Stars to Galaxies

IAU General Assembly Prague, Aug 24,

2006

IntroductionIntroduction

3C 3C 7575

NGC 6240NGC 6240 7 kpc separation7 kpc separation 1.4 1.4 kpc separationkpc separation

VLA image of 3C 75 at 6 cm VLA image of 3C 75 at 6 cm (Owen (Owen et alet al. 1985) . 1985)

Chandra image of NGC 6240 Chandra image of NGC 6240 (Komossa (Komossa et alet al. 2003) . 2003)

Hydra A

10 kpc

1946+708

10 pc

C1C2

0402+379 at 5 GHz (Pollack 0402+379 at 5 GHz (Pollack et alet al. . 2004)2004)

Discovery of 0402+379 Discovery of 0402+379 by Pollack by Pollack et alet al. . (2004).(2004).

Possible explanations Possible explanations for its properties:for its properties:Background SourceBackground Source

Gravitational LensingGravitational Lensing

Jet ComponentJet Component

Binary Supermassive Binary Supermassive Black Hole SystemBlack Hole System

11. .

22. .

33. .

44. .

20 pc

VLBA observations were made in 2005 at 0.3, 5, 8, 15, VLBA observations were made in 2005 at 0.3, 5, 8, 15, 22, and 43 GHz. 22, and 43 GHz.

We also obtained fully-calibrated 5 GHz VLBI data We also obtained fully-calibrated 5 GHz VLBI data taken in 1990 (Xu taken in 1990 (Xu et alet al. 1995), in 1996 (VCS; Beasley . 1995), in 1996 (VCS; Beasley et alet al. 2002), in three epochs (1994, 1996, and 1999) . 2002), in three epochs (1994, 1996, and 1999) of the CJ Proper Motion Survey (Britzen of the CJ Proper Motion Survey (Britzen et alet al. 2003) . 2003) and in 2003 (Maness and in 2003 (Maness et alet al. 2004).. 2004).

The Very Long Baseline Array The Very Long Baseline Array (VLBA). (VLBA).

ResultsResultsRadio Continuum Rodriguez et al. astro-Radio Continuum Rodriguez et al. astro-ph/0604042ph/0604042

Naturally weighted 2005 VLBA imagesNaturally weighted 2005 VLBA imagesof 0402+379 at 0.3, 5, 8, 15, 22, and 43 of 0402+379 at 0.3, 5, 8, 15, 22, and 43

GHz. GHz.

C1: 0.183 ± C1: 0.183 ± 0.048 pc 0.048 pc

C2: 0.124 ± C2: 0.124 ± 0.035 pc 0.035 pc Projected Projected separation separation between C1 and between C1 and C2 equal to 7.3 C2 equal to 7.3 pcpc

Evidence against Evidence against background background sourcesource

Component MotionsComponent Motions

Components model for theComponents model for theVLBA observations of 0402+379VLBA observations of 0402+379

Northern jet is moving Northern jet is moving away from the two away from the two central components to central components to the northeast,the northeast, N1: (0.185 ± N1: (0.185 ± 0.008)c0.008)c N2: (0.114 ± N2: (0.114 ± 0.019)c 0.019)c

Southern jet is moving Southern jet is moving away to the southwest, away to the southwest, though more slowly,though more slowly, S2: (0.0251 ± S2: (0.0251 ± 0.0085)c0.0085)c S3: (0.056 ± S3: (0.056 ± 0.010)c0.010)c

The results obtained The results obtained for C2 show no for C2 show no significant motion. A significant motion. A limit of less than limit of less than 0.088c was obtained.0.088c was obtained.

Evidence against jet Evidence against jet componentcomponent

Component VariabilityComponent Variability

Light curves of the differentLight curves of the differentcomponents of 0402+379 at 5 GHz. components of 0402+379 at 5 GHz.

Component C1 Component C1 substantially substantially increases in flux increases in flux density over the 15 y density over the 15 y baseline. baseline.

Component C2 is also Component C2 is also variable. variable.

For the southern and For the southern and northern components, northern components, there is no there is no substantial variation substantial variation in the flux densities in the flux densities over the 15 y over the 15 y baseline.baseline.Evidence against lensingEvidence against lensing

In both hotspots of In both hotspots of the source, N2 and the source, N2 and S2, a steep spectrum S2, a steep spectrum was found.was found.

For both central For both central components, C1 and components, C1 and C2, the spectrum C2, the spectrum peaks at ~10 GHz. peaks at ~10 GHz.

Spectral index distribution between 8 Spectral index distribution between 8 andand

22 GHz from the 2005 VLBA observations. 22 GHz from the 2005 VLBA observations.

Radio Continuum SpectraRadio Continuum Spectra

Evidence against lensingEvidence against lensing

Evidence against jet Evidence against jet componentcomponent

HET SpectroscopyHET Spectroscopy

The optical spectrum at 5.6 ÅThe optical spectrum at 5.6 Åspectral resolution taken by the HETspectral resolution taken by the HET

Hobby-Eberly TelescopeHobby-Eberly Telescope

Red shoulder found Red shoulder found suggesting two suggesting two components with components with velocity separation of velocity separation of 300 km s300 km s−1−1..

Spectrum of the core of 0402+379 obtained on 2004 Spectrum of the core of 0402+379 obtained on 2004 December 11 with the 9.2m Hobby-Eberly telescope December 11 with the 9.2m Hobby-Eberly telescope (HET).(HET).

0402+379 neutral hydrogen in absorption

Maness et al 2004

Evidence for Multiple velocitysystems

Consistent with a merger

Binary Supermassive Black Binary Supermassive Black Hole SystemHole System

Most likely explanation:Most likely explanation:

Constraints on the Mass of the Constraints on the Mass of the Black HolesBlack Holes

Supermassive Binary Black Hole Orbital Supermassive Binary Black Hole Orbital ParametersParameters

Combining HET and VLBA observations a system mass of Combining HET and VLBA observations a system mass of 1.5 × 101.5 × 1088 M MSun Sun was obtained.was obtained.

According to Kepler’s Laws the period of rotation for According to Kepler’s Laws the period of rotation for such a binary system should be ~ 1.5 × 10such a binary system should be ~ 1.5 × 1055 y, implying y, implying a a projected velocity between both components of ~ 0.001c.projected velocity between both components of ~ 0.001c.

Gravitational Wave SignalGravitational Wave Signal Natural gravitational wave frequency (Hughes 2003) is Natural gravitational wave frequency (Hughes 2003) is approximately 2 × 10approximately 2 × 10−13−13 Hz. Hz.

A binary black hole on a circular orbitA binary black hole on a circular orbit in the final in the final stage of evolution will merge within the time (Peters stage of evolution will merge within the time (Peters 1964):1964):

Merger time equal to ~10Merger time equal to ~101818 y. Some other loss of y. Some other loss of angular momentum will be necessary if this system is angular momentum will be necessary if this system is to merge in less than a Hubble time.to merge in less than a Hubble time.

VLBI Imaging of Active Galactic Nuclei

VLBA Imaging Polarimetry Survey (VIPS)• 1127 sources: S > 85 mJy, 65 > dec > 20, |b|>10 at 5 GHz in SDSS northern cap• First epoch observations on the VLBA in 2006 • Identifications and redshifts from SLOAN, HET, Palomar, …• Goals: - Characterize GLAST sources - Study Evolution of Radio Sources - Study AGN environments

- Find more supermassive binary black holes

http://www.phys.unm.edu/~gbtaylor/VIPS/

Some Candidate SBBH Systems from VIPS

ConclusionsConclusions

• C1 and C2: two active nuclei of a single galaxy. C1 and C2: two active nuclei of a single galaxy.

• Closest binary black hole system yet discovered. Closest binary black hole system yet discovered. Projected separation of 7.3 pc. Projected separation of 7.3 pc.

• Total mass of the system: 1.5 × 10Total mass of the system: 1.5 × 1088 M MSunSun. .

• Gravitational radiation frequency: 2 × 10Gravitational radiation frequency: 2 × 10−13−13 Hz. Hz.

• Searching for more binary black hole systems. The Searching for more binary black hole systems. The VLBA Imaging and Polarization Survey (VIPS, Taylor VLBA Imaging and Polarization Survey (VIPS, Taylor et et alal. 2005) has imaged 1127 sources.. 2005) has imaged 1127 sources.