Compatibility of the CO and HI Linewidths Considering the Gas Distribution and Rotation Curves

We have examined the trend between CO and HI linewidths by compiling the linewidths of 219 nearby galaxies. The trend is that the CO linewidths of fast rotating galaxies tend to be larger than the HI linewidths, and that the HI linewidths of slow rotating galaxies tend to be larger than the CO linewidths, whereas the intermediately rotating galaxies have almost equal values. We have explained the trend using the synthetic rotation curve model, which provides the linewidth - absolute magnitude relations at any radii, and concluded that the trend has been occurred by the different distributions of CO and HI in a galaxy and the gradient of the rotation curves. The exact linewidth should be corrected for the effects of the gradient of the rotation curve and the gas distribution.Comment: To appear in A&A, LaTeX manuscript(paper.tex, use A&A style file l-aa.sty) and five PS figures, 5 page

Nuclear Rotation Curves of Galaxies in the CO Line Emission

We have obtained high-resolution position-velocity (PV) diagrams along the major axes of the central regions of nearby galaxies in the CO-line emission using the Nobeyama 45-m telescope and the Millimeter Array. Nuclear rotation curves for 14 galaxies have been derived based on the PV diagrams using the envelope-tracing method. The nuclear rotation curves for most of the galaxies show a steep rise within a few hundred pc, which indicates a high-density concentration of mass. Keywords: Galaxies: general - Galaxies: structure - ISM: molecular lineComment: To appear in AJ, Plain TeX, Figures on reques

Nuclear-to-Disk Rotation Curves of Galaxies in the H_alpha and [NII] Emission Lines

We have obtained optical CCD spectroscopy along the major axes of 22 nearby spiral galaxies of Sb and Sc types in order to analyze their rotation curves. By subtracting the stellar continuum emission, we have obtained position velocity (PV) diagrams of the H alpha and [NII] lines. We point out that the H alphaline is often superposed by a broad stellar absorption feature (Balmer wind) in the nuclear regions, and, therefore, the [NII] line is a better tracer of kinematics in the central a few hundred pc regions. By applying the envelope-tracing technique to the H alpha and [NII] PV diagrams, we have derived nucleus-to-disk rotation curves of the observed galaxies. The rotation curves rise steeply within the central a few hundred parsecs, indicating rapidly rotating nuclear disk and mass concentration near the nucleus. [For more rotation curves : http://www.ioa.s.u-tokyo.ac.jp/]Comment: 10 pages Latex, 8 fig. directories, each 22 galaxies ps figures. PASJ Vol. 50, No.5, in pres

High resolution imaging of molecular line emission from high redshift QSOs

We present moderate (1'') and high resolution (0.2'') observations of the CO(2-1) emission at 43 GHz, and radio continuum emission at 1.47 GHz, from the z=4.7 QSO BRI 1202-0725 and the z=4.4 QSO BRI 1335--0417 using the Very Large Array. The moderate resolution observations show that in both cases the CO emission is spatially resolved into two components separated by 1'' for 1335-0417 and 4'' for 1202-0725. The high resolution observations show that each component has sub-structure on scales of 0.2'' to 0.5'', with intrinsic brightness temperatures > 20K. The CO ladder from (2-1) up to (7-6) suggests a high kinetic temperature for the gas (70 K), and a high column density (10^{24} cm^{-2}). In both sources the continuum-to-line ratio: L_{FIR}/L'_{CO(1-0)} = 335. All these characteristics (brightness temperature, excitation temperature, column density, and continuum-to-line ratio) are comparable to conditions found in low redshift, ultra-luminous nuclear starburst galaxies. We find that the CO emitting regions in 1202-0725 and 1335-0417 must be close to face-on in order to avoid having the gas mass exceed the gravitational mass, implying perhaps unreasonably large rotational velocities. While this problem is mitigated by lowering the CO luminosity-to-H_2 mass conversion factor (X), the required X values become comparable to, or lower than, the minimum values dictated by optically thin CO emission. We considered the possibility of magnification by gravitational lensing in order to reduce the molecular gas masses.Comment: aastex 12 postscript figures. to appear in the Astronomical Journa