ORCID Profile
0000-0002-7616-7427
Current Organisation
福井工業大学/Fukui University of Technology
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Publisher: Oxford University Press (OUP)
Date: 07-2021
DOI: 10.1093/PASJ/PSAB060
Abstract: The barred spiral galaxy NGC 613 has a star-forming ring in the center, and near-infrared observations have previously shown that the star formation activity on the eastern and western sides of the ring is asymmetric. We examined the dynamics and physical state of the molecular gas in the ring using high-resolution (∼15 pc) 12CO(1–0), 12CO(3–2), and 13CO(1–0) observations with ALMA. Using a dendrogram, we identified 111 molecular clouds in the bar and ring, and found that the virial parameter (αvir) gradually decreases (αvir & 2) toward the confluence of the northern bar and eastern ring, while the virial parameter is large (αvir & 2) around the corresponding confluence in the western side of the ring. A non-LTE analysis using RADEX showed that the temperature and density of the molecular gas increase downstream of the eastern point of confluence, whereas they change irregularly on the western side. The star formation efficiency is (1.7 ± 0.2) × 10−8 yr−1 in the eastern side of the ring, which is substantially higher than the (0.9 ± 0.3) × 10−8 yr−1 for the western side of the ring. Position–velocity diagrams show that the relative velocity of the gas between the bar and the ring is ∼70 km s−1 in the east, while it reaches ∼170 km s−1 in the west. We suggest that the star formation activity in the central region of NGC 613 depends strongly on the relative velocity of the gas between the bar and the ring.
Publisher: EDP Sciences
Date: 09-2018
DOI: 10.1051/0004-6361/201832873
Abstract: Aims. We discuss the results of the relationships between the K -band and stellar mass, FIR luminosities, star formation rate, and the masses of the dust and gas of nearby galaxies computing the bivariate K -band-luminosity function (BLF) and bivariate K -band-mass function (BMF) of the Herschel Reference Survey (HRS), a volume-limited s le with full wavelength coverage. Methods. We derive the BLFs and BMFs from the K -band and stellar mass, FIR luminosities, star formation rate, dust and gas masses cumulative distributions using a copula method, which is outlined in detail. The use of the computed bivariate taking into account the upper limits allows us to derive a more solid statistical ground for the relationship between the observed physical quantities. Results. The analysis shows that the behaviour of the morphological (optically selected) subs les is quite different. A statistically meaningful result can be obtained over the whole HRS s le only from the relationship between the K -band and the stellar mass, while for the remaining physical quantities (dust and gas masses, far-infrared luminosity, and star formation rate), the analysis is distinct for late-type (LT) and early-type galaxies (ETG). However, the number of ETGs is small to perform a robust statistical analysis, and in most of the case results are discussed only for the LTG subs le. The luminosity and mass functions (LFs, MFs) of LTGs are generally dependent on the K -band and the various dependencies are discussed in detail. We are able to derive the corresponding LFs and MFs and compare them with those computed with other s les. Our statistical analysis allows us to characterise the HRS which, although non-homogeneously selected and partially biased towards low IR luminosities, may be considered as representative of the local LT galaxy population.
Publisher: IOP Publishing
Date: 03-2023
Abstract: Modern interferometers routinely provide radio-astronomical images down to subarcsecond resolution. However, interferometers filter out spatial scales larger than those s led by the shortest baselines, which affects the measurement of both spatial and spectral features. Complementary single-dish data are vital for recovering the true flux distribution of spatially resolved astronomical sources with such extended emission. In this work, we provide an overview of the prominent available methods to combine single-dish and interferometric observations. We test each of these methods in the framework of the CASA data analysis software package on both synthetic continuum and observed spectral data sets. We develop a set of new assessment tools that are generally applicable to all radio-astronomical cases of data combination. Applying these new assessment diagnostics, we evaluate the methods’ performance and demonstrate the significant improvement of the combined results in comparison to purely interferometric reductions. We provide combination and assessment scripts as add-on material. Our results highlight the advantage of using data combination to ensure high-quality science images of spatially resolved objects.
Location: Japan
Location: Japan
Location: No location found
No related grants have been discovered for Yusuke MIYAMOTO.