Warped molecular gas disk in NGC 3718

¹ Universität zu Köln, I. Physikalisches Institut, Zülpicherstrasse 77, 50937 Köln, Germany
² Instituto de Astrofísica de Andalucía (IAA), c/ Camino Bajo de Huétor 24, 18008 Granada, Spain
³ Institut de Radio-Astronomie Millimétrique (IRAM), 300 rue de la Piscine, Domaine Universitaire, 38406 Saint Martin d'Hères, France

Corresponding author: J.-U. Pott, pott@ph1.uni-koeln.de

Received: 22 April 2003
Accepted: 1 October 2003

Abstract

We present the first observations of the CO(1–0), CO(2–1) and HCN(1–0) rotational line emission of NGC 3718, conducted with the IRAM 30 m telescope. The results of the data analysis show a thin strongly warped molecular gas disk harboring the active galactic nucleus (AGN). The ratio of the total molecular gas mass ( ) to the dynamical mass, enclosed within the same region, is found to be rather low (~), but still typical for spiral galaxies. The found molecular gas disk is well associated with the dust lane, visible at optical wavelengths. We traced the warped CO structure down to the central . In its outer region the molecular disk is well correlated with the HI distribution. The CO data is used to improve the kinematic modelling in the inner part of the galaxy () employing a tilted ring-model. Furthermore the properties of NGC 3718 are compared with those of its northern sky “twin” NGC 5128 (Centaurus A).