Yoshiaki Sofue

We present a unified rotation curve of the Galaxy re-constructed from existing data by re-calculating the distances and velocities for a set of Galactic constants, $R_0$$=$ 8 kpc and $V_0$$=$ 200 km s$^{-1}$. We decomposed it into a bulge with de Vaucouleurs-law profile of half-mass scale radius 0.5 kpc and mass 1.8 $\times$ 10$^{10}M_\odot$, an exponential disk of scale radius 3.5 kpc and 6.5 $\times$ 10$^{10}M_\odot$, and an isothermal dark halo of terminal velocity 200 km s$^{-1}$. A $r^{1/4}

We present high-resolution central-to-outer rotation curves for Sb, SBb, Sc, and SBc galaxies. We discuss their general characteristics, particularly their central behavior, as well as dependencies on morphological types, activity, and peculiarity. The rotation curves generally show a steep nuclear rise, and high-velocity central rotation, followed by a broad maximum in the disk and then by a flat rotation due to the massive halo. Since the central high velocity and steep rise are common to all

In the 1960s, novel and increasingly powerful observational techniques opened up the field of high-energy astrophysics. Cosmology started to become an empirical science, and there was a resurgence in the study of general relativity. Martin Rees became a ...Read More

A grand rotation curve of the Milky Way Galaxy was constructed, which covers a wide range of radius from the Galactic Center to $ \sim$ 1 Mpc, and was deconvolved into bulge, disk, and halo components by least-squares fittings. We determined the masses and scale radii of the bulge and disk to be $ {M_{\rm b}}$$ =$ (1.652 $ \pm$ 0.083) $ \times$ 10$ ^{10}{\ M_\odot}$ , $ {a_{\rm b}}$$ =$ 0.522 $ \pm$ 0.037 kpc, $ {M_{\rm d}}$$ =$ (3.41 $ \pm$ 0.41) $ \times$ 10$ ^{10}{\ M_\odot}$ , and $ {a_{\rm

We review the current status of the study of rotation curve (RC) of the Milky Way, and present a unified RC from the Galactic Center to the galacto-centric distance of about 100 kpc. The RC is used to directly calculate the distribution of the surface mass density (SMD). We then propose a method to derive the distribution of dark matter (DM) density in the in the Milky Way using the SMD distribution. The best-fit dark halo profile yielded a local DM density of ρ ⊙ = 0.36 ± 0.02 GeV cm − 3 . We a

Using the all-sky ROSAT soft X-ray and 408-MHz radio continuum data, we show that the North Polar Spur and its western and southern counter-spurs draw a giant dumbbell-shape necked at the galactic plane. We interpret these features as due to a shock front originating from a starburst 15 million years ago with a total energy of the order of $\sim 10^{56}$ ergs or $10^5$ type II supernovae. We simulate all-sky distributions of radio continuum and soft X-ray intensities based on the bipolar-hyper-s

An analysis is made of Faraday rotation measures (RMs) of extragalactic radio sources. It is shown that a large-scale magnetic field in our Galaxy is oriented along the spiral arms. The field lines change their direction from one arm to the next across the neutral line in the interarm region. The loci of maximum field strength trace the spiral arms defined by H II regions. Characteristic features of the RM distribution on the sky are well reproduced by a model in which the magnetic field is in a

We have derived rotation curves of nearby galaxies, which are almost completely sampled from the inner to outer regions. We used high-resolution position–velocity diagrams in the CO line along the major axes for the inner regions, and HI-line data for the outer regions. We combined the CO and HI data to obtain total rotation curves from the nuclear to outer regions. The rotation curves show a steep nuclear rise within a radius smaller than the resolutions of the CO-line observations, indicating

We simulate the propagation of a shock front through the galactic halo induced by an explosion and/or a starburst at the galactic center. A huge dumbbell ($\Omega$)-shaped shock front produced by an explosion of energy $3\times 10^{56}$ ergs about fifteen million years ago can mimic the radio and X-ray North Polar Spur as well the southern large X-ray spur. The post-shock high-temperature gas in the corona will explain the observed X-ray bulge around the galactic center. Key workds Galaxy: cente

Abstract Based on a high-resolution CO survey of Virgo spirals with the Nobeyama Millimeter-wave Array, we determined the dynamical centers using velocity fields, and derived position–velocity diagrams (PVDs) along the major axes of the galaxies across their dynamical centers. We applied a new iteration method to derive rotation curves (RCs), which reproduce the observed PVDs. The obtained high-accuracy RCs generally show a steep rise in the central $\sim 100$ to 200 pc regions, followed by flat

Abstract We present the results of the Virgo high-resolution CO survey (ViCS) obtained with the Nobeyama Millimeter-wave Array (NMA). This survey was made during the course of a long-term project at Nobeyama from 1999 December through 2002 April. The objects were selected from Virgo cluster members, while considering the CO richness from the single-dish flux, mild inclination, and a lack of strong tidal perturbations. The central ${1{}^{\mathrm {\prime }}}$ regions ($\sim 4.7 \,\mathrm{kpc}$) of

Abstract Rotation curves of more than 100 spiral galaxies were compiled from the literature, and deconvolved into bulge, disk, and dark halo components using χ2 fitting in order to determine their scale radii and masses. Correlation analyses were obtained of the fitting parameters for galaxies that satisfied selection and accuracy criteria. Size–mass relations indicate that the sizes and masses are positively correlated among different components in such a way that the larger or more massive the