Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

Abstract

We derive the entire dust extinction (AV) map for the Large Magellanic Cloud (LMC) estimated from the color excess at near-infrared wavelengths. Using the percentile method we recently adopted to evaluate AV distribution along the line of sight, we derive three-dimensional (3D) AV maps of the three massive star-forming regions of N44, N79, and N11 based on the IRSF/SIRIUS point source catalog. The 3D AV maps are compared with the hydrogen column densities N(H) of three different velocity components where one is of the LMC disk velocity and the other two are of velocities lower than the disk velocity. As a result, we obtain a 3D dust geometry suggesting that gas collision is ongoing between the different velocity components. We also find differences in the timing of the gas collision between the massive star-forming regions, which indicates that the gas collision in N44, N79, and N11 occurred later than that in 30 Doradus. In addition, a difference of a factor of two in AV/N(H) is found between the velocity components for N44, while a significant difference is not found for N79 and N11. From the 3D geometry and AV/N(H) in each star-forming region, we suggest that the massive star formation in N44 was induced by an external trigger of tidal interaction between the LMC and the Small Magellanic Cloud, while that in N79 and N11 is likely to have been induced by internal triggers such as gas converging from the galactic spiral arm and expansion of a supershell, although the possibility of tidal interaction cannot be ruled out.

DOI： 10.1093/pasj/psac025

Web of Science

Language：English  

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

To reveal the causes of infrared absorption in the wavelength region between electronic and lattice absorptions, we measured the temperature dependence of the absorption coefficient of p-type low-resistivity ($$\sim 10^2~ \Omega \mathrm{cm}$$) CdZnTe crystals. We measured the absorption coefficients of CdZnTe crystals in four wavelength bands ($$\lambda =6.45$$, 10.6, 11.6, 15.1$$~\mu $$m) over the temperature range of $$T=8.6$$-300 K with an originally developed system. The CdZnTe absorption coefficient was measured to be $$\alpha =0.3$$-0.5 $$\mathrm{cm}^{-1}$$ at $$T=300$$ K and $$\alpha =0.4$$-0.9 $$\mathrm{cm}^{-1}$$ at $$T=8.6$$ K in the investigated wavelength range. With an absorption model based on transitions of free holes and holes trapped at an acceptor level, we conclude that the absorption due to free holes at $$T=150$$-300 K and that due to trapped-holes at $$T<50$$ K are dominant absorption causes in CdZnTe. We also discuss a method to predict the CdZnTe absorption coefficient at cryogenic temperature based on the room-temperature resistivity.

DOI： 10.1007/s11664-021-09361-1

Web of Science

Other Link： https://link.springer.com/article/10.1007/s11664-021-09361-1/fulltext.html

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Astronomical Society  

DOI： 10.3847/1538-4357/ac1e2c

Web of Science

Other Link： https://iopscience.iop.org/article/10.3847/1538-4357/ac1e2c/pdf

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/pasj/psab052

Web of Science

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1051/0004-6361/202140483

Web of Science

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

SMI (SPICA Mid-infrared Instrument) is one of the three focal-plane science instruments for SPICA. SMI is the Japanese-led instrument proposed and managed by a university consortium. SMI covers the wavelength range from 10 to 36 mu m with four separate channels: the low-resolution (R = 60 - 160) spectroscopy function for 17 - 36 mu m, the broad-band (R = 5) imaging function at 34 mu m, the mid-resolution (R = 1400 - 2600) spectroscopy function for 18 - 36 mu m, and the high-resolution (R = 29000) spectroscopy function for 10 - 18 mu m. In this presentation, we will show the latest design and specifications of SMI as a result of feasibility studies.

DOI： 10.1117/12.2561157

Web of Science

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

<title>Abstract</title>
Centaurus A (Cen A) is one of the most famous galaxies hosting an active galactic nucleus (AGN), where the interaction between AGN activities and surrounding interstellar and intergalactic media has been investigated. Recent studies reported detections of Hα emission from clouds in the galactic halo toward the northeast and southwest of the nucleus of Cen A, suggesting that AGN jets may have triggered star formation there. We performed near-infrared line mapping of Cen A with the IRSF 1.4 m telescope, using the narrow-band filter tuned for Paβ, from which we find that Paβ emission is not detected significantly from either of the northeast or southwest regions. The upper limit of the Paβ/Hα ratio in the northeast region is compatible with that expected for a typical H ii region, in line with the scenario that AGNs have triggered star formation there. On the other hand, the upper limit of Paβ/Hα in the southwest region is significantly lower than that expected for a typical H ii region. A possible explanation of the low Paβ/Hα ratio in the southwest region is the scattering of Hα and Paβ photons from the center of Cen A by dust grains in the halo clouds. From the upper limit of Paβ/Hα in the southwest region, we obtain constraints on the dust size distribution, which is found to be compatible with those seen in the interstellar medium of our Galaxy.

DOI： 10.1093/pasj/psaa081

Web of Science

Language：English  

DOI： 10.1093/pasj/psaa094

Web of Science

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Astronomical Society  

DOI： 10.3847/1538-4357/ab9cb3

Web of Science

Other Link： https://iopscience.iop.org/article/10.3847/1538-4357/ab9cb3

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.1088/1538-3873/ab8aa8

Web of Science

Other Link： https://iopscience.iop.org/article/10.1088/1538-3873/ab8aa8

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

<title>Abstract</title>
Galactic infrared (IR) bubbles, which can be seen as shell-like structures at mid-IR wavelengths, are known to possess massive stars within their shell boundaries. In our previous study (Hanaoka, 2019, PASJ, 71, 6), we expanded the research area to the whole Galactic plane ($0^{\circ } \le l \le 360^{\circ }$, $|b| \le 5^{\circ }$) and studied systematic differences in the shell morphology and the IR luminosity of the IR bubbles between inner and outer Galactic regions. In this study, utilizing high spatial-resolution data of AKARI and WISE in the mid-IR and Herschel in the far-IR, we investigate the spatial distributions of dust components around each IR bubble to discuss the relation between the star-formation activity and the dust properties of the IR bubbles. For the 247 IR bubbles studied in Hanaoka (2019, PASJ, 71, 6), 165 IR bubbles are investigated in this study, which have the Herschel data ($|b|\le 1^{\circ }$) and known distances. We created their spectral energy distributions on a pixel-by-pixel basis around each IR bubble, and decomposed them with a dust model consisting of polycyclic aromatic hydrocarbons (PAHs), hot dust, warm dust and cold dust. As a result, we find that the offsets of dust heating sources from the shell centers in inner Galactic regions are systematically larger than those in outer Galactic regions. Many of the broken bubbles in inner Galactic regions show large angles between the offset and the direction of the broken shell from the center. Moreover, the spatial variations of the PAH intensity and cold dust emissivity around the IR bubbles in inner Galactic regions are larger than those in outer Galactic regions. We discuss these results in light of the interstellar environments and the formation mechanism of the massive stars associated with the IR bubbles.

DOI： 10.1093/pasj/psz123

Web of Science

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

We measured the transmittance of low-resistivity (∼10 2 ωcm) and high-resistivity (> 10 10 ωcm) CdZnTe, which are candidates for Immersion grating (IG) in 10-18μm wavelength, at cryogenic temperature. IG is a compact diffraction grating and we are developing a cryogenically operated 10-18μm IG for SMI/HR (SPICA Mid-Infrared Instrument / High-Resolution spectrometer) of SPICA (SPace Infrared telescope for Cosmology and Astrophysics) We performed two experiments: Transmittance measurement with a convergent light Fourier transform spectrometer, and with a collimated lamp beam system. Our result shows that the low-resistivity CdZnTe has large absorption (> 0.5 cm {-1}) and the high-resistivity CdZnTe has low absorption (< 0.1 cm {-1}) at 8.5K at 10-18 μm. The high-resistivity CdZnTe is promising as an IG material although higher precision measurement is needed to determine whether it meets the absorption coefficient requirement (< 0.01 cm {-1}) at cryogenic temperature.

DOI： 10.1117/12.2562042

Web of Science

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

<title>ABSTRACT</title>
We present a dust extinction AV map of the Large Magellanic Cloud (LMC) in the H i ridge region using the InfraRed Survey Facility (IRSF) near-infrared (IR) data, and compare the AV map with the total hydrogen column density N(H) maps derived from the CO and H i observations. In the LMC H i ridge region, the two-velocity H i components (plus an intermediate velocity component) are identified, and the young massive star cluster is possibly formed by collision between them. In addition, one of the components is suggested to be an inflow gas from the Small Magellanic Cloud (SMC) which is expected to have even lower metallicity gas (Fukui et al. 2017, PASJ, 69, L5). To evaluate dust/gas ratios in the H i ridge region in detail, we derive the AV map from the near-IR color excess of the IRSF data updated with the latest calibration, and fit the resultant AV map with a combination of the N(H) maps of the different velocity components to decompose it successfully into the three components. As a result, we find difference by a factor of 2 in AV/N(H) between the components. In additon, the CO-to-H2 conversion factor also indicates difference between the components, implying a difference in the metallicity. Our results are likely to support the scenario that the gas in the LMC H i ridge region is contaminated with an inflow gas from the SMC with a geometry consistent with the on-going collision between the two-velocity components.

DOI： 10.1093/pasj/psz078

Web of Science

Language：English   Publishing type：Research paper (scientific journal)   Publisher：EDP Sciences  

<italic>Context</italic>. Although heavily obscured active galactic nuclei (AGNs) have been found by many observational studies, the properties of the surrounding dust are poorly understood. Using AKARI/IRC spectroscopy, we discovered a new heavily obscured AGN in LEDA 1712304 which shows a deep spectral absorption feature due to silicate dust.


<italic>Aims.</italic> We study the infrared (IR) spectral properties of circumnuclear silicate dust in LEDA 1712304.


<italic>Methods.</italic> We performed IR spectral fitting, considering silicate dust properties such as composition, porosity, size, and crystallinity. Spectral energy distribution fitting was also performed on the flux densities in the UV to submillimeter range to investigate the global spectral properties.


<italic>Results.</italic> The best-fit model indicates 0.1 <italic>μ</italic>m-sized porous amorphous olivine (Mg_{2<italic>x</italic>}Fe_{2−2<italic>x</italic>}SiO₄; <italic>x</italic> = 0.4) with 4% crystalline pyroxene. The optical depth is <italic>τ</italic>_sil ∼ 2.3, while the total IR luminosity and stellar mass are estimated to be <italic>L</italic>_IR = (5 ± 1)×10¹⁰ <italic>L</italic>_⊙ and <italic>M</italic>_star = (2.7 ± 0.8)×10⁹ <italic>M</italic>_⊙, respectively. In such low <italic>L</italic>_IR and <italic>M</italic>_star ranges, there are few galaxies that show such a large <italic>τ</italic>_sil.


<italic>Conclusion.</italic> The silicate dust in the AGN torus of LEDA 1712304 has properties that are notably similar to those in other AGNs overall, but slightly different in the wing shape of the absorption profile. The porosity of the silicate dust suggests dust coagulation or processing in the circumnuclear environments, while the crystallinity suggests that the silicate dust is relatively fresh.

DOI： 10.1051/0004-6361/201935483

Web of Science

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：EDP Sciences  

<italic>Context.</italic> The properties of the dust in the cold and hot gas phases of early-type galaxies (ETGs) are key to understanding ETG evolution.


<italic>Aims.</italic> We aim to conduct a systematic study of the dust in a large sample of local ETGs, focusing on relations between the dust and the molecular, atomic, and X-ray gas of the galaxies, as well as their environment.


<italic>Methods.</italic> We estimated the dust temperatures and masses of the 260 ETGs from the ATLAS^3D survey, using fits to their spectral energy distributions primarily constructed from AKARI measurements. We also used literature measurements of the cold (CO and H <sc>I</sc>) and X-ray gas phases.


<italic>Results.</italic> Our ETGs show no correlation between their dust and stellar masses, suggesting inefficient dust production by stars and/or dust destruction in X-ray gas. The global dust-to-gas mass ratios of ETGs are generally lower than those of late-type galaxies, likely due to dust-poor H <sc>I</sc> envelopes in ETGs. They are also higher in Virgo Cluster ETGs than in group and field ETGs, but the same ratios measured in the central parts of the galaxies only are independent of galaxy environment. Slow-rotating ETGs have systematically lower dust masses than fast-rotating ETGs. The dust masses and X-ray luminosities are correlated in fast-rotating ETGs, whose star formation rates are also correlated with the X-ray luminosities.


<italic>Conclusions.</italic> The correlation between dust and X-rays in fast-rotating ETGs appears to be caused by residual star formation, while slow-rotating ETGs are likely well evolved, and have therefore exhausted their dust. These results appear consistent with the postulated evolution of ETGs, whereby fast-rotating ETGs form by mergers of late-type galaxies and associated bulge growth, while slow-rotating ETGs form by (dry) mergers of fast-rotating ETGs. Central cold dense gas appears to be resilient against ram pressure stripping, suggesting that Virgo Cluster ETGs may not suffer strong related suppression of star formation.

DOI： 10.1051/0004-6361/201833911

Web of Science

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/pasj/psy126

Web of Science

arXiv

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/mnras/sty800

Web of Science

Scopus

arXiv

Language：English  

DOI： 10.1117/12.2313093

Language：English  

Language：English  

Language：English  

Language：English  

Authorship：Lead author   Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1117/12.2313093

Web of Science

Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

Using the AKARI, Wide-field Infrared Survey Explorer (WISE), Infrared Astronomical Satellite (IRAS), Sloan Digital Sky Survey (SDSS) and Hubble Space Telescope (HST) data, we investigated the relation of polycyclic aromatic hydrocarbon (PAH) mass (M-PAH), very small grain mass (M-VSG), big grain mass (M-BG) and stellar mass (M-star) with galaxy merger for 55 star-forming galaxies at redshift z &lt; 0.2. Using the SDSS image at z &lt; 0.1 and the HST image at z &gt; 0.1, we divided the galaxies into merger galaxies and non-merger galaxies with the morphological parameter asymmetry A, and quantified merging stages of galaxies based on the morphological indicators, the second-order momentum of the brightest 20 per cent region M-20 and the Gini coefficient. We find that M-PAH/M-BG of merger galaxies tend to be lower than that of non-merger galaxies and there are no systematic differences of M-VSG/M-BG and M-BG/M-star between merger galaxies and non-merger galaxies. We find that galaxies with very low M-PAH/M-BG seem to be merger galaxies at late stages. These results suggest that PAHs are partly destroyed at late stages of merging processes. Furthermore, we investigated MPAH/MBG variations in radiation field intensity strength G(0) and the emission line ratio of [O I] lambda 6300/H alpha that is a shock tracer for merger galaxies and find that M-PAH/M-BG decreases with increasing both G(0) and [O I]/H alpha. PAH destruction is likely to be caused by two processes: strong radiation fields and large-scale shocks during merging processes of galaxies.

DOI： 10.1093/mnras/stx1902

Web of Science

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：EDP SCIENCES S A  

Context. The star formation properties of early-type galaxies (ETGs) are currently the subject of considerable interest, particularly whether they differ from the star formation properties of gas-rich spirals.
Aims. We perform a systematic study of star formation in a large sample of local ETGs with polycyclic aromatic hydrocarbon (PAH) and dust emission, focusing on the star formation rates (SFRs) and star formation efficiencies (SFEs) of the galaxies.
Methods. Our sample is composed of the 260 ETGs from the ATLAS(3D) survey, from which we used the cold gas measurements (HI and CO). We estimated the SFRs from stellar, PAH, and dust fits to spectral energy distributions created from new AKARI measurements and with literature data from WISE and 2MASS.
Results. The mid-infrared luminosities of non-CO-detected galaxies are well correlated with their stellar luminosities, showing that they trace (circum) stellar dust emission. CO-detected galaxies show an excess above these correlations, uncorrelated with their stellar luminosities, indicating that they likely contain PAHs and dust of interstellar origin. PAH and dust luminosities of CO-detected galaxies show tight correlations with their molecular gas masses; the derived current SFRs are typically 0.01-1 M circle dot yr(-1). These SFRs systematically decrease with stellar age at fixed stellar mass, while they correlate nearly linearly with stellar mass at fixed age. The majority of local ETGs follow the same star formation law as local star-forming galaxies and their current SFEs do not depend on either stellar mass or age.
Conclusions. Our results clearly indicate that molecular gas is fueling current star formation in local ETGs, which appear to acquire this gas via mechanisms regulated primarily by stellar mass. The current SFEs of local ETGs are similar to those of local star-forming galaxies, indicating that their low SFRs are likely due to smaller cold gas fractions rather than a suppression of star formation.

DOI： 10.1051/0004-6361/201630158

Web of Science

arXiv

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Korean Astronomical Society  

DOI： 10.5303/pkas.2017.32.1.151

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Korean Astronomical Society  

DOI： 10.5303/pkas.2017.32.1.363

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DOI： 10.5303/PKAS.2017.32.1.135

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DOI： 10.1093/pasj/psw028

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.pss.2015.04.009

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DOI： 10.1117/12.2055084

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DOI： 10.1117/12.2025259

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DOI： 10.5303/PKAS.2012.27.4.381

Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.1117/12.926879

Language：English  

DOI： 10.1117/12.926029

Event date： 2022.12

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2019.9

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Event date： 2018.6

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