A5082368062- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Spectroscopy and Laser Applications
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Calibration and Measurement Techniques
- Astrophysics and Cosmic Phenomena
- CCD and CMOS Imaging Sensors
- Atmospheric Ozone and Climate
- Phase Equilibria and Thermodynamics
- Cosmology and Gravitation Theories
- Plant Water Relations and Carbon Dynamics
- Infrared Target Detection Methodologies
- Agricultural risk and resilience
- Advanced Sensor Technologies Research
- SAS software applications and methods
- Superconducting and THz Device Technology
- Spacecraft Design and Technology
- Advanced Surface Polishing Techniques
- Pulsars and Gravitational Waves Research
- Molecular Spectroscopy and Structure
The University of Tokyo
2006-2024
Institute of Astronomy
2004-2023
National Astronomical Observatory of Japan
2009-2023
Japan Aerospace Exploration Agency
2010-2018
Institute of Space and Astronautical Science
2010-2018
California Institute of Technology
2009-2013
Tokyo Gakugei University
2009
Infrared Processing and Analysis Center
2009
Japan Society for the Promotion of Science
2008
Abstract The dependence of the star formation efficiency (SFE) on galactic structures—especially whether SFE in bar region is lower than those other regions—has recently been debated. We report SFEs 18 nearby gas-rich massive star-forming barred galaxies with large apparent major axes (≧75″). statistically measure by distinguishing center, end, and regions for first time. molecular gas surface density derived from archival CO(1–0) and/or CO(2–1) data assuming a constant CO-to-H 2 conversion...
Abstract While cloud–cloud collisions (CCCs) have been proposed as a mechanism for triggering massive star formation, it is suggested that higher collision velocities ( v col ) and lower giant molecular cloud (GMC) mass M GMC and/or density (Σ tend to suppress formation. In this study, we choose the nearby barred galaxy NGC 3627 examine formation rate efficiency (SFE) of colliding <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow>...
We present a revised method for simultaneous determination of the pattern speed and star formation timescale spiral galaxies, its application, results CO Ha images nearby galaxies. Out 13 we were able to derive 2 parameters 5 categorize them as "C" find (1) The corotation radius is close edge data, about half optical 3 (2) roughly consistent with free-fall time typical molecular clouds, which indicates that gravitational instability dominant mechanism triggering in arms. (3) found be almost...
We report the CO(J = 1–0) observations of Whirlpool Galaxy M51 using both Combined Array for Research in Millimeter Astronomy (CARMA) and Nobeyama 45 m telescope (NRO45). describe a procedure combination interferometer single-dish data. In particular, we discuss (1) joint imaging deconvolution heterogeneous data, (2) weighting scheme based on root-mean-square (rms) noise maps, (3) sensitivity uv coverage requirements, (4) flux recovery combined map. generate visibilities from map calculate...
We report systematic variations in the emission line ratio of CO J = 2–1 and 1–0 transitions (R2–1/1–0) grand-design spiral galaxy M51. The R2–1/1–0 shows clear evidence for evolution molecular gas from upstream interarm regions into arms back downstream regions. In regions, is typically <0.7 (and often 0.4–0.6); this similar to ratios observed Galactic giant clouds (GMCs) with low far-infrared luminosities. However, rises >0.7 (often 0.8–1.0) arms, particularly at leading (downstream) edge...
We resolve 182 individual giant molecular clouds (GMCs) larger than 2.5 $\times$ 10$^{5}$ \Msun in the inner disks of five large nearby spiral galaxies (NGC 2403, NGC 3031, 4736, 4826, and 6946) to create largest such sample extragalactic GMCs within analogous Milky Way. Using a conservatively chosen most likely adhere virial assumption, we measure cloud sizes, velocity dispersions, $^{12}$CO (J=1-0) luminosities calculate masses. The average conversion factor from CO flux H$_{2}$ mass (or...
We present the results of a Nobeyama 45 m H2O maser and NH3 survey all 94 northern GLIMPSE extended green objects (EGOs), sample massive young stellar (MYSOs) identified based on their 4.5 μm emission. observed NH3(1,1), (2,2), (3,3) inversion lines, detected emission toward 97%, 63%, 46% our sample, respectively (median rms ∼ 50 mK). The detection rate is 68% 0.11 Jy). derived clump-scale gas properties are consistent with identification EGOs as MYSOs. To explore degree variation among...
SIGNALS, the Star formation, Ionized Gas, and Nebular Abundances Legacy Survey, is a large observing program designed to investigate massive star formation HII regions in sample of local extended galaxies. The will use imaging Fourier transform spectrograph SITELLE at Canada-France-Hawaii Telescope. Over 355 hours (54.7 nights) have been allocated beginning fall 2018 for eight consecutive semesters. Once completed, SIGNALS provide statistically reliable laboratory including over 50 000...
Abstract We present Atacama Large Millimeter/submillimeter Array (ALMA) imaging of molecular gas across the full star-forming disk barred spiral galaxy M83 in CO( J = 1–0). jointly deconvolve data from ALMA’s 12 m, 7 and Total Power arrays using MIRIAD package. The have a mass sensitivity resolution 10 4 M ⊙ (3 σ ) 40 pc—sufficient to detect resolve typical cloud Milky Way with diameter × 5 pc, respectively. coverage shows that characteristics change radially center outer disk, locally...
Abstract We analyze the CO-to-H 2 conversion factor ( α CO ) in nearby barred spiral galaxy M83. present new H i observations from VLA and single-dish GBT disk of galaxy, combine them with maps CO(1-0) integrated intensity dust surface density literature. gas-to-dust ratio δ GDR are simultaneously derived annuli kpc width R = 1–7 kpc. find that both increase radially, by a ∼2–3 center to outskirts disk. The luminosity-weighted averages over 3.14 (2.06, 4.96) <mml:math...
We report a super-linear correlation for the star formation law based on new CO(J = 1–0) data from CARMA and NOBEYAMA Nearby-galaxies (CANON) CO survey. The sample includes 10 nearby spiral galaxies, in which structures at sub-kpc scales are spatially resolved. Combined with rate surface density traced by Hα 24 μm images, provide slope of N 1.3. becomes even steeper (N 1.8) when diffuse stellar dust background emission is subtracted images. In contrast to recent results 2–1) that found...
We present the results of wide-field $^{12}$CO (1--0) observations nearby barred galaxy M83 carried out with Nobeyama Millimeter Array (NMA). The interferometric data are combined obtained 45-m telescope to recover total-flux. target fields cover molecular bar and part spiral arms, a spatial resolution ~110 pc x 260 pc. By exploiting sensitivity extended CO emission, impact galactic structures on gas content is investigated in terms kinematics star formation. inspecting kinematics, pattern...
Abstract We present results of the 12CO (1–0) mosaic observations nearby barred-spiral galaxy M 83 obtained with Atacama Large Millimeter/submillimeter Array (ALMA). The total flux is recovered by combining ALMA data single-dish using Nobeyama 45 m telescope. combined map covers a ∼13 kpc2 field that includes galactic center, eastern bar, and spiral arm resolution 2${^{\prime\prime}_{.}}$03 × 1${^{\prime\prime}_{.}}$15 (∼45 pc ∼25 pc). With comparable to typical sizes giant molecular clouds...
We present spatial variations of the CO J=2-1/1-0 line ratio in M83 using Total Power array data from ALMA. While intensities these two lines correlate tightly, varies over disk, with a disk average 0.69, and shows galactic center two-arm spiral pattern. It is high (>0.7) regions molecular gas surface density, but ranges low to ratios density. The correlates well distributions FUV IR emissions, being best correlated. also better (70/350mic), proxy for dust temperature, than intensities....
We conduct a $^{12}$C$^{16}$O($J$=1-0) (hereafter CO) mapping survey of 64 galaxies in the Fornax cluster using ALMA Morita array cycle 5. CO emission is detected from 23 out galaxies. Our sample includes dwarf, spiral and elliptical with stellar masses $M_{\rm star}\sim10^{6.3-11.6}$~M$_\odot$. The achieved beam size sensitivity are $15''\times8''$ $\sim12$~mJy~beam$^{-1}$ at velocity resolution $\sim10$~km~s$^{-1}$, respectively. study cold-gas (molecular- atomic-gas) properties 38...
We present the largest sample to date of giant molecular clouds (GMCs) in a substantial spiral galaxy other than Milky Way. map distribution gas with high resolution and image fidelity within central 5 kpc NGC 6946 12CO (J=1-0) transition. By combining observations from Nobeyama Radio Observatory 45-meter single dish telescope Combined Array for Research Millimeter Astronomy (CARMA) interferometer, we are able obtain accurate measurements LCO compared previous purely interferometric studies....
Using star-forming galaxies sample in the nearby Universe (0.02<z<0.10) selected from SDSS (DR7) and GALEX all-sky survey (GR5), we present a new empirical calibration for predicting dust extinction of H-alpha-to-FUV flux ratio. We find that H-alpha (A(Ha)) derived with H-alpha/H-beta ratio (Balmer decrement) increases increasing H-alpha/UV as expected, but there remains considerable scatter around relation, which is largely dependent on stellar mass and/or equivalent width (EW(Ha)). At...
There are two theories of stellar spiral arms in isolated disc galaxies that model with different longevities: quasi-stationary density wave theory, which characterizes spirals as rigidly rotating, long-lived patterns (i.e. steady spirals), and dynamic differentially transient, recurrent spirals). In order to discriminate between these models observationally, we investigated the differences gas velocity predicted by hydrodynamic simulations. We found azimuthal phases relative peaks gaseous...
Abstract High-resolution observations of ionized and molecular gas in the nuclear regions galaxies are indispensable for delineating interplay star formation, gaseous inflows, stellar radiation, feedback processes. Combining our new Atacama Large Millimeter/submillimeter Array band 3 mapping archival Very Telescope/MUSE data, we present a spatially resolved analysis central 5.4 kpc region NGC 1365. We find formation rate/efficiency (SFR/SFE) inner circumnuclear ring is about 0.4/1.1 dex...
Abstract We present 12 CO( J = 1 – 0) mapping observations over ∼1/2 of the optical disk nearby galaxies from Fundamental CO 1–0 Transition Survey (FACTS), using ALMA Total Power array. Variations in 2 − 1)/ line ratio r 21 are investigated. The luminosity-weighted 11 sample ranges 0.52 to 0.69 with an average 0.61. use position–velocity diagrams along major axis and tilted ring models separate normal rotating galactic kinematic outliers that deviate pure circular rotation. find is...
While cloud-cloud collisions (CCCs) have been proposed as a mechanism for triggering massive star formation, it is suggested that higher collision velocities ($v_{\rm col}$) and lower GMC mass ($M_{\rm GMC}$) or/and density ($\Sigma_{\rm tend to suppress formation. In this study, we choose the nearby barred galaxy NGC 3627 examine SFR SFE of colliding ($m^\star_{\rm CCC}$ $\epsilon_{\rm CCC}$) explore connections between $m^\star_{\rm CCC}$, $M_{\rm GMC}$($\Sigma_{\rm $v_{\rm col}$, galactic...
Abstract We show the variations of CO J = 2–1/1–0 line ratio ( R 21/10 ) across barred spiral galaxy M83, using 46 pc resolution data from Atacama Large Millimeter/submillimeter Array. The map clearly evidences systematic large-scale as a function galactic structures. Azimuthally, it starts low ≲ 0.7 in interarm regions and becomes high ≳0.7 bar arms, suggesting that density and/or kinetic temperature molecular gas increase by about factor 2–3. This evolution is seen even parts arms without...
We examined offsets between HII regions and molecular clouds belonging to spiral arms of a late type galaxy NGC 4254 (M99). used high resolution CO(1-0) image obtained by Nobeyama Millimeter Array (NMA) an H-alpha image. derived angular (theta) in the galactic disk, found that these show linear dependence on rotation velocity gas (Omega_G). This relation can be expressed equation: theta =(Omega_G - Omega_P) * t_{H-alpha}, where Omega_P t_{H-alpha} are constant. Here, corresponds pattern...
We have combined Halpha and recent high resolution CO(J=1-0) data to consider the quantitative relation between gas mass star formation rate, or so-called Schmidt law in nearby spiral galaxies at regions of molecular density. The quantity rate has not been previously studied for density regions, but using CO obtained NMA(Nobeyama Millimeter Array), we found that is valid densities as $10^3 \mathrm{M_\odot} \mathrm{pc}^{-2}$ sample galaxies, which an order magnitude denser than what known be...
We present sensitive and high angular resolution CO(1-0) data obtained by the Combined Array for Research in Millimeter-wave Astronomy (CARMA) observations toward nearby grand-design spiral galaxy M 51. The of 0.7" corresponds to 30 pc, which is similar typical size Giant Molecular Clouds (GMCs), sensitivity also enough detect GMCs. Within 1' field view centered on a arm, number GMC-scale structures are detected as clumps. However, only few clumps found be associated with each Association...