A Polar-Nulceus Dark Lane in the Barred Spiral M83: Three-Dimensional Accretion in the Nucleus

The central region of the barred spiral galaxy M83 reveals a polar-nucleus dust lane, wh ich extends from the NE molecular bar and crosses the central bulge. Its SW counterpart is not visible, being hidden behind the bulge. This asymmetry, in spite of the galaxy's face-on orientation and the symmetric bar struct ure in the CO-line emission, indicates that the dark lane is an off-plane structure. Such a ``polar-nucleus'' structure can be formed by a non-coplanar, three-dimensional acc retion in a warped disk.Comment: (to appear in AJ), 5 pages, plainTeX, U-Tokyo Astro. No.93-2

CO Observations of Luminous IR Galaxies at Intermediate Redshift

We present new measurement of $^{12}$CO($J=1-0$) emission from 16 luminous infrared galaxies (LIGs) at intermediate redshift ($cz \sim 10,000 - 50,000 {\rm km s^{-1}}$). These new data were selected by isolated and normal morphology. The CO observations were performed using the NRO 45-m telescope. Comparison of the CO and dust properties of the new result with those from other CO measurements revealed characteristics of this sample: (1) It is the deepest CO observations of IRAS galaxies at intermediate redshift without strong interaction features. (2) It has typical properties of normal IRAS galaxies in terms of star-formation efficiency, color-color diagrams and galactic nuclear activity. (3) It has smaller gas-to-dust ratio than normal IRAS galaxies. This can be explained by two-component dust model, and our sample consists of most of warm dust.Comment: To appear in PASJ, text 9 pages, 5 tables, and 12 figure

The Large-scale Bipolar Wind in the Galactic Center

During a 9-month campaign (1996--1997), the Midcourse Space Experiment (MSX) satellite mapped the Galactic Plane at mid-infrared wavelengths (4.3--21.3um). Here we report evidence for a spectacular limb- brightened, bipolar structure at the Galactic Center extending more than a degree (170 pc at 8.0 kpc) on either side of the plane. The 8.3um emission shows a tight correlation with the 3, 6 and 11 cm continuum structure over the same scales. Dense gas and dust are being entrained in a large-scale bipolar wind powered by a central starburst. The inferred energy injection at the source is ~10^54/kappa erg for which \kappa is the covering fraction of the dusty shell (kappa <= 0.1). There is observational evidence for a galactic wind on much larger scales, presumably from the same central source which produced the bipolar shell seen by MSX. Sofue has argued that the North Polar Spur -- a thermal x-ray/radio loop which extends from the Galactic Plane to b = +80 deg -- was powered by a nuclear explosion (1-30 x 10^55 erg) roughly 15 Myr ago. We demonstrate that an open-ended bipolar wind (~10^55 erg), when viewed in near-field projection, provides the most natural explanation for the observed loop structure. The ROSAT 1.5 keV diffuse x-ray map over the inner 45 deg provides compelling evidence for this interpretation. Since the faint bipolar emission would be very difficult to detect beyond the Galaxy, the phenomenon of large-scale galactic winds may be far more common than has been observed to date.Comment: 24 pages, 6 figures, aastex. High resolution figures are available at ftp://www.aao.gov.au/pub/local/jbh/astro-ph/GC/. Astrophysical Journal, accepte

Optical and CO Radio Observations of Poor Cluster Zwicky 1615.8+3505

The cluster Zwicky 1615.8+3505 is considered to be a dynamically young poor cluster. To investigate the morphology and star-formation activity of galaxies under the environment of a dynamically young poor cluster, we have performed V, R, and I surface photometry, optical low-resolution spectroscopy, and 12CO (J=1-0) line observations for member galaxies. Our data show that more than 90% of the observed galaxies show regular morphologies and no star-formation activities, indicating that the environment does not affect these galaxy properties. Among sixteen galaxies observed, only NGC 6104 shows a significant star-formation activity, and shows a distorted morphology, indicating a tidal interaction. This galaxy contains double knots, and only one knot possesses Seyfert activity, though the sizes and luminosities are similar to each other; we also discuss this feature.Comment: LaTeX manuscript (text.tex, use PASJ style files), four PS figures (fig[a-d].ps), and three PASJ style files. text.tex, figb.ps, and figd.ps are up-dated. To be appeared in The Publications of the Astronomical Society of Japan, Vol. 51, No. 3 (1999 June issue

Distance Measurement of Galaxies to Redshift of 0.1 using the CO-Line Tully-Fisher Relation

We report on the first results of a long-term project to derive distances of galaxies at cosmological distances by applying the CO-line width-luminosity relation. We have obtained deep CO-line observations of galaxies at redshifts up to 29,000 km/s using the Nobeyama 45-m mm-wave Telescope, and some supplementary data were obtained by using the IRAM 30-m telescope. We have detected the CO line emission for several galaxies, and used their CO line widths to estimate the absolute luminosities using the line-width-luminosity relation. In order to obtain photometric data and inclination correction, we also performed optical imaging observations of the CO-detected galaxies using the CFHT 3.6-m telescope at high resolution. The radio and optical data have been combined to derive the distance moduli and distances of the galaxies, and Hubble ratios were estimated for these galaxies. We propose that the CO line width-luminosity relation can be a powerful method to derive distances of galaxies to redfhift of z = 0.1 and to derive the Hubble ratio in a significant volume of the universe. Key words: Cosmology - Galaxies: general - Distance scale - CO lineComment: To appear in PASJ, Plain Tex, 3 figures (in 10 ps files

First Detection of 12CO (1--0) Emission from Two Narrow-Line Seyfert 1 Galaxies

In order to investigate how the growth of galactic bulges progresses with the growth of central black holes (BHs), we observed molecular gas (fuel for the coming star formation) in possibly young active galaxies, narrow-line Seyfert 1 galaxies (NLS1s). We present the results of radio observations of 12CO(1--0) using the Nobeyama Millimeter Array (with 2--4 kpc spatial resolution) for two FIR-bright NLS1s, yielding the first detection of their CO emission. Corresponding molecular--gas masses M(H2) of (1-3) X 109 Msun are the 2nd and 4th largest ones among NLS1s. By estimating dynamical masses and bulge masses M(bulge) for these two NLS1s using CO channel map and CO line widths, we found M(H2) amount to 0.13--0.35 of these masses. Taking account the star formation efficiency (~ 0.1), the increase in M(bulge) in those NLS1s in the near future (~< 10^{7.5} yr) is expected not to be a huge fraction (1--5% of the preexisting stars). Bulge growth may have finished before BH growth, or bulge--BH coevolution may proceed with many, occasional discrete events, where one coevolution event produces only a small amount of mass growth of BHs and of bulges. We also discuss the ratios of star-formation rate--to--gas accretion rate onto BHs, finding that two NLS1s have very small ratios (~ 1) compared with the M(bulge)/M(BH) ratios found in active and inactive galaxies (~ 700). This huge difference suggests either the non-overlapped coevolution, long star formation duration or temporarily high accretion rate during NLS1 phase.Comment: 29 pages, 8 figures, Accepted for publication in The Astrophysical Journa