The Nuclear Spectrum of M87

Details The Nuclear Spectrum of M87 The Nuclear Spectrum of M87

1998-01-06

arxiv.org/abs/astro-ph/9801037v1

Astronomy and Astrophysics

Astrophysics

5 pages, 3 postscript figures, to appear in the Proceeding of the M87 Workshop (Lecture Notes in Physics: Springer Verlag), 19

Scientific paper

10.1007/BFb0106442

The nuclear spectrum of M87 covering the Ly_a-H_a wavelength range was obtained with the HST Faint Object Spectrograph (FOS) trough a 0.21 arcsec aperture. Contrary to some previous claims, a single power law (F(nu)~nu^(-a)) can not reproduce the observed continuum shape and at least a broken power law is require for a good fit (a = 1.75 and 1.41 shortward and longward of the break at ~4500 A). We detect a set of broad (FWHM ~ 400 km/s) absorption lines arising in the gas associated with M87. These are only lines from neutral and very low ionization species blueshifted by ~150 km/s relative to the M87 systemic velocity, indicating a net gas outflow and turbulence. The excitation sensitive emission line ratios suggest that shocks may be the dominant energy supplier. The nuclear source in M87 is significantly variable. From the FOS target acquisition data, we have established that the flux from the optical nucleus varies by a factor ~2 on time scales of ~2.5 months and by as much as 25% over 3 weeks, and remains unchanged (<2.5%) on time scales of ~1 day. These timescales limit the physical size of the emitting region to a few hundred gravitational radii. The variability, combined with other observed spectral properties, strongly suggest that M87 is intrinsically of BL Lac type but is viewed at an angle too large to reveal the classical BL Lac properties.

Affiliated with

Also associated with

No associations

Rating

The Nuclear Spectrum of M87 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 The Nuclear Spectrum of M87, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Nuclear Spectrum of M87 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-613631