Detalles de publicación
PP 013070
INTERLOCKING RESONANCE PATTERNS IN GALAXY DISKS.
1. Instituto de Astrofísica de Canarias,jfont@iac.es, jeb@iac.es, serroz@iac.es.
2. Departamento de Astrofísica. Universidad de La Laguna, Tenerife, Spain.
3. Consejo Superior de Investigaciones Científicas, Spain.
4 Max-Plack.Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany:
querejeta@mppia.de
5. Laboratoire d’Astrophysique de Marseille, Université d’Aix-Marseille & CNRS, UMR7326, 38 rue
F. Juliot-Curie, 13388 Marseille Cedex 13, France: benoit.epinat@oamp.fr.
6 Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton
Wharf, Birkenhead, CH41 ILD, UK: paj@astro.livjm.ac.uk
7 Department of Astronomy, University of Stockholm, AlbaNova, 10691, Stockholm, Sweden
8 Instituto de Astrofísica de Andalucia, CSIC, Apdo. 3004, 18080 Granada, Spain: blasco@iaa.es
9 Departamento de Física Teórica y del Cosmos, Universidad de Granada, Spain: isa@ugr.es
We have developed a method for finding dynamical resonances in disk galaxies
using the change in sense of the radial component of the in-plane velocity at a resonance radius. Using simulations we show that we would expect to find these changes at corotation radii, with a weaker effect at the ILR and a small effect at the OLR. The method works well with observations at high spectral and angular resolutions, and is suited to the analysis of 2D velocity fields in Hα from Fabry-Perot spectroscopy, (though it is also applicable to fields in 21cm emission from HI, or to CO emission lines). The observations are mainly from the GHASP spectrometer data base, taken on the 1.93m telescope at Haute Provence, plus some data from the GHαFaS spectrometer on the 4.2m WHT at La Palma. We find clear indications of resonance effects in the disk velocity fields of virtually all of the 104 galaxies. The number of resonance radii detected ranges
from one to seven, with a median of four. We have derived the resonance curves:
Ω, Ω±κ/2, Ω±κ/4 against radius for all the galaxies, and used them to derive the ILR, theOLR, and the two 4:1 resonances for each corotation in each galaxy. This led us to discover a pattern in over 70% of the sample: given two pattern speeds, say Ω1 and Ω2,the OLR of Ω1 coincides with the corotation of Ω2, and the inner 4:1 resonance of Ω2 coincides with the corotation of Ω1. Although the second coincidence has been predicted, a prediction of this double coincidence is not found in the literature. This pattern is found once in 42 of the galaxies, twice in a further 26, three times in five, and even four times in
one galaxy. We also compute the ratio of corotation radius to bar length where we have good enough image quality, finding a mean value of 1.3, and a shallow increase towards later type galaxies.
Subject headings: galaxies: spirals - galaxies: fundamental parameters - galaxies: kinematics
using the change in sense of the radial component of the in-plane velocity at a resonance radius. Using simulations we show that we would expect to find these changes at corotation radii, with a weaker effect at the ILR and a small effect at the OLR. The method works well with observations at high spectral and angular resolutions, and is suited to the analysis of 2D velocity fields in Hα from Fabry-Perot spectroscopy, (though it is also applicable to fields in 21cm emission from HI, or to CO emission lines). The observations are mainly from the GHASP spectrometer data base, taken on the 1.93m telescope at Haute Provence, plus some data from the GHαFaS spectrometer on the 4.2m WHT at La Palma. We find clear indications of resonance effects in the disk velocity fields of virtually all of the 104 galaxies. The number of resonance radii detected ranges
from one to seven, with a median of four. We have derived the resonance curves:
Ω, Ω±κ/2, Ω±κ/4 against radius for all the galaxies, and used them to derive the ILR, theOLR, and the two 4:1 resonances for each corotation in each galaxy. This led us to discover a pattern in over 70% of the sample: given two pattern speeds, say Ω1 and Ω2,the OLR of Ω1 coincides with the corotation of Ω2, and the inner 4:1 resonance of Ω2 coincides with the corotation of Ω1. Although the second coincidence has been predicted, a prediction of this double coincidence is not found in the literature. This pattern is found once in 42 of the galaxies, twice in a further 26, three times in five, and even four times in
one galaxy. We also compute the ratio of corotation radius to bar length where we have good enough image quality, finding a mean value of 1.3, and a shallow increase towards later type galaxies.
Subject headings: galaxies: spirals - galaxies: fundamental parameters - galaxies: kinematics