Astronomy and Astrophysics – Astronomy
Scientific paper
Aug 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997apj...485l..75c&link_type=abstract
Astrophysical Journal Letters v.485, p.L75
Astronomy and Astrophysics
Astronomy
20
Galaxies: Individual Ngc Number: Ngc 4258, Galaxies: Nuclei, Infrared: General, Radiation Mechanisms: Nonthermal
Scientific paper
We present high-resolution (~0."6) near-infrared Keck observations that probe the optically obscured nucleus of NGC 4258 (M 106), which is believed to contain a 3.6 x 107 Msolar black hole. The images show a compact central source at K (2.21 mu m) and H (1.65 mu m). To determine the strength of the compact component against the stellar background, we normalized the J (1.25 mu m) surface brightness profile, which is taken to be dominated by the bulge stars, to the K and H profiles at 200 pc and subtracted it out. The normalization constant in each case agrees well with the outer colors of highly inclined spirals. The compact source has a measured K flux of 4.5 mJy and an H flux of 1.1 mJy. After making reasonable assumptions about the intrinsic energy distribution of the central source based on optical polarimetry and X-ray measurements, we derive a reddening to the source of AV ~ 17 mag. When corrected for this extinction, the IR (1.5--3.5 mu m) luminosity is ~2 x 107 Lsolar. The corresponding X-ray (2--10 keV) luminosity is ~107 Lsolar, while the central source has been estimated at ~102 Lsolar in the radio. We suggest on the basis of the polarimetric evidence that the source of the near-infrared excess is nonthermal, although the possibility of thermal emission by dust grains in the inferred torus cannot be ruled out.
Becklin Eric E.
Chary Ranga Ram
No associations
LandOfFree
NGC 4258: A Compact Central Infrared Source Revealed does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with NGC 4258: A Compact Central Infrared Source Revealed, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and NGC 4258: A Compact Central Infrared Source Revealed will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1878287