Imaging Compact Supermassive Binary Black Holes with VLBI

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Imaging Compact Supermassive Binary Black Holes
with VLBI G. B. Taylor (UNM), C. Rodriguez
(UNM), R. T. Zavala (USNO) A. B. Peck (CfA), L.
K. Pollack (UCSC), H.L. Maness (UCB), and R. W.
Romani (Stanford)
Black Holes From Stars to Galaxies IAU General
Assembly Prague, Aug 24, 2006
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Introduction
3C 75
NGC 6240
7 kpc separation 1.4
kpc separation
VLA image of 3C 75 at 6 cm (Owen et al. 1985)
Chandra image of NGC 6240 (Komossa et al. 2003)
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Hydra A
10 kpc
4
1946708
10 pc
5
20 pc
0402379 at 5 GHz (Pollack et al. 2004)
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The Very Long Baseline Array (VLBA).
VLBA observations were made in 2005 at 0.3, 5, 8,
15, 22, and 43 GHz. We also obtained
fully-calibrated 5 GHz VLBI data taken in 1990
(Xu et al. 1995), in 1996 (VCS Beasley et al.
2002), in three epochs (1994, 1996, and 1999) of
the CJ Proper Motion Survey (Britzen et al. 2003)
and in 2003 (Maness et al. 2004).
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Results
Radio Continuum Rodriguez et al.
astro-ph/0604042
Naturally weighted 2005 VLBA imagesof 0402379
at 0.3, 5, 8, 15, 22, and 43 GHz.
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Component Motions
Components model for theVLBA observations of
0402379
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Component Variability
Evidence against lensing
Light curves of the differentcomponents of
0402379 at 5 GHz.
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Radio Continuum Spectra
In both hotspots of the source, N2 and S2, a
steep spectrum was found. For both central
components, C1 and C2, the spectrum peaks at
10 GHz.
Evidence against lensing Evidence against jet
component
Spectral index distribution between 8 and22 GHz
from the 2005 VLBA observations.
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HET Spectroscopy
Spectrum of the core of 0402379 obtained on 2004
December 11 with the 9.2m Hobby-Eberly telescope
(HET).
Hobby-Eberly Telescope
Red shoulder found suggesting two components with
velocity separation of 300 km s-1.
The optical spectrum at 5.6 Åspectral resolution
taken by the HET
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0402379 neutral hydrogen in absorption
Evidence for Multiple velocity systems Consisten
t with a merger
Maness et al 2004
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(No Transcript)
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Constraints on the Mass of the Black Holes
Combining HET and VLBA observations a system mass
of 1.5 108 MSun was obtained.
Supermassive Binary Black Hole Orbital Parameters

According to Keplers Laws the period of rotation
for such a binary system should be 1.5 105 y,
implying a projected velocity between both
components of 0.001c.
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VLBI Imaging of Active Galactic Nuclei

• VLBA Imaging Polarimetry Survey (VIPS)
• 1127 sources S gt 85 mJy, 65 gt dec gt 20, bgt10
  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/
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Some Candidate SBBH Systems from VIPS
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Conclusions

• C1 and C2 two active nuclei of a single galaxy.
  
• Closest binary black hole system yet discovered.
  Projected separation of 7.3 pc.
• Total mass of the system 1.5 108 MSun.
• Gravitational radiation frequency 2 10-13 Hz.
  
• Searching for more binary black hole systems.
  The VLBA Imaging and Polarization Survey (VIPS,
  Taylor et al. 2005) has imaged 1127 sources.