CDROM/AJ/V111/P0696     Seyfert Galaxies With Companions (Keel 1996)
================================================================================
Seyfert Galaxies With Companions: Orbital and Kinematic Clues to AGN Triggering
      William C. Keel
      <1996, AJ, 111, 696>
      =1996AJ....111..696K
================================================================================

Abstract:
  This paper presents imaging and optical spectroscopy of paired Seyfert
  galaxies and their companions.  The aim is to seek common properties of
  Seyfert galaxies in interacting systems, which might provide evidence
  of AGN triggering in a way independent of the usual two-sample
  statistics which have proven ambiguous on this issue.  Three kinds of
  comparison have been made -- the kinds of interactions involving
  Seyfert galaxies, the relative luminosities of the Seyferts and their
  companions, and the level of kinematic disturbance as measured from
  rotation curves.  (1) Dynamics and tidal features have been used to
  determine (or at least limit) the sense of orbital motion (direct/
  retrograde/polar with respect to the Seyfert galaxy's disk) for many of
  these pairs.  There is no obviously preferred kind of interaction --
  direct, polar, and retrograde encounters are all well represented,
  despite the gross differences in dynamical response of a disk to these
  various kinds of encounter.  To the extent that triggering of Seyfert
  nuclei occurs due to tidal encounters, the existence of a perturbation
  seems more important than its exact duration or detailed effects on the
  disk.  However, the ratio of merging to paired Seyferts is higher than
  for disk galaxies in general, consistent with more effective triggering
  of AGN in this specific phase; the implied time scale for enhanced
  occurrence during mergers is the same as the timescape for merger
  remnants to appear as such, a few disk-edge crossing times (typically
  several times 10^8 yr).  (2) Seyfert nuclei occur preferentially in the
  brighter members of galaxy pairs, by a median of 0.93 mag after making
  the maximal correction for contaminating nonstellar light in the
  nuclei.  Only about 1/3 of this effect can be accounted for by the
  known tendency of Seyfert nuclei to occur in more luminous galaxies.
  Enhancement of AGN by interactions is evidently more effective for more
  luminous galaxies (though this will also be the case if both star
  formation and AGN occurrence are enhanced in the same galaxies).
  (3) The rotation curves of the paired Seyferts show systematically
  small regions of rising or solid-body rotation compared to the disk
  radius, as a group comparable to Sa but very different from Sb or Sc
  galaxies (even for Seyfert galaxies with Hubble type later than Sa).
  There is weak evidence that this difference is also present with
  respect to more isolated Seyfert galaxies.  Despite the obvious utility
  of a dynamically disturbed disk for transport of angular momentum and
  "feeding the monster," Seyfert galaxies in pairs actually have smaller
  kinematic disturbances (measured by the maximum departure from a
  symmetric rotation curve, normalized to the full rotation amplitude)
  than found in a complete sample of non-Seyfert spirals in pairs.


File Summary:
--------------------------------------------------------------------------------
File Name    Lrecl    Records   Explanations
--------------------------------------------------------------------------------
table2.dat      64       1317   Rotation curve data
--------------------------------------------------------------------------------

Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
   Bytes Format  Units   Label      Explanations
--------------------------------------------------------------------------------
   1-10   A10    ---     Name      *Object name
  11-15   F5.1   deg     PA         []? Position angle
  16-21   F6.1   km/s    Corr       []? Correction to heliocentric velocity
  22-28   F7.1   pix     Peak       []? Pixel number of continuum peak
  29-32   I4     pix     Pixel     *Pixel number along the slit
  33-40   F8.1   km/s    RVobs     *Mean radial velocity
  41-47   F7.1   km/s    e_RVobs    2-sigma error derived from photon statistics
  48-55   F8.1   ---     Int_Ha    *Total H-alpha intensity (instrumental units)
  56-62   F7.1   ---     Int_Cont   Continuum intensity
  63-64   I2     ---     N          No. of emission lines measured at each point
--------------------------------------------------------------------------------

Notes for file: table4.dat
--------------------------------------------------------------------------------
Name:
  If this field is blank the data in fields Pixel, RVobs, e_RVobs,
  Int_Ha, Int_Cont, and N are continuations of the previous record.

Pixel:
  Pixel number along the slit, at a scale of 0.78 arcsec/pix.

RVobs:
  Mean radial velocity, in the observed frame and the so-called
  relativistic convention.

Int_Ha:
  Total H-alpha intensity in instrumental units (neglecting the
  broad-line component where it can be distinguished).
--------------------------------------------------------------------------------

================================================================================
(End)                                             Lee Brotzman [ADS] 08-Mar-1996