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Session 11 - AGN.
Display session, Monday, January 13
Metropolitan Ballroom,

[11.04] NGC 4258: A Compact Central Infrared Source Revealed

R. Chary, E. E. Becklin (UCLA)

We present high resolution (\sim0.6\arcsec) near infrared Keck observations which probe the optically obscured nucleus of NGC 4258 (M 106) which is believed to contain a massive black hole. The images show a compact central source at H (1.65\micron) and K (2.23\micron) after the J (1.23\micron) component, which was taken to be dominated by the bulge stars, was subtracted out. The compact source has a measured K flux of \sim3 mJy and might be marginally resolved. When corrected for A_V\sim20 mag of extinction the IR luminosity (1.5\micron - 3.0\micron) is \sim3\times10^7 L_\sun. The corresponding X-ray (2-10 keV) luminosity is \sim10^7 L_\sun while the central source has been estimated at \sim10^2 L_\sun in the radio. We argue that our near infrared source is a spherical dust shell around the center which is reprocessing the radiation emitted by the black hole inferred to be at the center.

Program listing for Monday