Faculty Profiles - INUTSUKA, Shu-ichiro

Papers - INUTSUKA, Shu-ichiro

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3D magnetic-field morphology of the Perseus molecular cloud Reviewed International coauthorship Open Access

Tahani, M; Lupypciw, W; Glover, J; Plume, R; West, JL; Kothes, R; Inutsuka, S; Lee, MY; Robishaw, T; Knee, LBG; Brown, JC; Doi, Y; Grenier, IA; Haverkorn, M

ASTRONOMY & ASTROPHYSICS Vol. 660 2022.4

Language：English Publisher：Astronomy and Astrophysics

Context. Despite recent observational and theoretical advances in mapping the magnetic fields associated with molecular clouds, their three-dimensional (3D) morphology remains unresolved. Multi-wavelength and multi-scale observations will allow us to paint a comprehensive picture of the magnetic fields of these star-forming regions. Aims. We reconstructed the 3D magnetic field morphology associated with the Perseus molecular cloud and compared it with predictions of cloud-formation models. These cloud-formation models predict a bending of magnetic fields associated with filamentary molecular clouds. We compared the orientation and direction of this field bending with our 3D magnetic-field view of the Perseus cloud. Methods. We used previous line-of-sight and plane-of-sky magnetic field observations as well as Galactic magnetic field models to reconstruct the complete 3D magnetic field vectors and morphology associated with the Perseus cloud. Results. We approximated the 3D magnetic field morphology of the cloud as a concave arc that points in the decreasing longitude direction in the plane of the sky (from our point of view). This field morphology preserves a memory of the Galactic magnetic field. In order to compare this morphology to cloud-formation model predictions, we assume that the cloud retains a memory of its most recent interaction. After incorporating velocity observations, we find that the line-of-sight magnetic field observations are consistent with predictions of shock-cloud-interaction models. Conclusions. To our knowledge, this is the first time that the 3D magnetic fields of a molecular cloud have been reconstructed. We find the 3D magnetic field morphology of the Perseus cloud to be consistent with the predictions of the shock-cloud-interaction model that describes the formation mechanism of filamentary molecular clouds.

DOI： 10.1051/0004-6361/202141170

Velocity structure of the 50 pc long NGC 6334 filamentary cloud Hints of multiple compressions and their impact on the cloud properties Reviewed International coauthorship Open Access

Arzoumanian, D; Russeil, D; Zavagno, A; Chen, MCY; André, P; Inutsuka, SI; Misugi, Y; Sanchez-Monge, A; Schilke, P; Men'shchikov, A; Kohno, M

ASTRONOMY & ASTROPHYSICS Vol. 660 2022.4

Language：English Publisher：Astronomy and Astrophysics

Context. The interstellar medium is observed to be organized in filamentary structures, and in neutral (H I) and ionized (H II) bubbles. The expanding nature of these bubbles shapes the surrounding medium and possibly plays a role in the formation and evolution of the interstellar filaments. The impact of the expansion of these bubbles on the interstellar medium is not well understood. Aims. Our aim is to describe the kinematics of a filamentary molecular cloud forming high-mass stars and hosting multiple H II regions in order to study the possible environmental impact on the properties of molecular filaments. Methods. We present APEX 13CO and C18O(2-1) mapping observations of the 10 × 50 pc NGC 6334 molecular cloud complex. We investigated the gas velocity structure along and across the 50 pc long cloud and toward velocity-coherent filaments (VCFs). Results. The NGC 6334 complex is observed to have a coherent velocity structure smoothly varying by ∼5 km s-1 over its 50 pc elongation parallel to the Galactic plane. We identify a sample of 75 VCFs in the C18O(2-1) position-position-velocity cube and present the properties of 47 VCFs with a length ³1 pc (five beams). We measure a large number of velocity gradients along the VCFs. The amplitudes of these velocity gradients and the velocity dispersion measured along the crests increase with the column density of the VCFs. We derive the column density and velocity power spectra of the VCFs. These power spectra are well represented with power laws showing similar slopes for the two quantities (with a mean of about -2), although some differ by up to a factor of 2. The position velocity diagrams perpendicular to three VCFs (selected from different physical environments) show the V-shaped velocity pattern corresponding to a bent structure in velocity space with the filament at the tip of the V surrounded by an extended structure connected to it with a velocity gradient. This velocity structure is qualitatively similar to that resulting from numerical simulations of filament formation from large-scale compression from propagating shock fronts. In addition, the radial profiles perpendicular to these VCFs hint to small-scale internal impacts from neighboring H II bubbles on two of them, while the third is mostly unaffected. Conclusions. The observed opposite curvature in velocity space (V- and A-shaped) toward the VCFs points to various origins of large-scale external compressions from propagating H I bubbles. This suggests the plausible importance of multiple H I compressions, separated in space and time, in the formation and evolution of molecular clouds and their star formation history. These atomic compressions due to past and distant star formation events are complemented by the impact of H II bubbles from present time and local star formation activity.

DOI： 10.1051/0004-6361/202141699

Orion A's complete 3D magnetic field morphology Reviewed International coauthorship Open Access

Tahani, M; Glover, J; Lupypciw, W; West, JL; Kothes, R; Plume, R; Inutsuka, S; Lee, MY; Grenier, IA; Knee, LBG; Brown, JC; Doi, Y; Robishaw, T; Haverkorn, M

ASTRONOMY & ASTROPHYSICS Vol. 660 2022.4

Language：English Publisher：Astronomy and Astrophysics

Magnetic fields permeate the interstellar medium and are important in the star formation process. Determining the three-dimensional (3D) magnetic fields of molecular clouds will allow us to better understand their role in the evolution of these clouds and the formation of stars. We fully reconstruct the approximate 3D magnetic field morphology of the Orion A molecular cloud (on scales of a few to ∼100 pc) using Galactic magnetic field models, as well as available line-of-sight and plane-of-sky magnetic field observations. While previous studies identified the 3D magnetic field morphology of the Orion A cloud as an arc shape, in this study we provide the orientation of this arc-shaped field and its plane-of-sky direction for the first time. We find that this 3D field is a tilted, semi-convex (from our point of view) structure and mostly points in the direction of decreasing latitude and longitude on the plane of the sky from our vantage point. The previously identified bubbles and events in this region were key in shaping this arc-shaped magnetic field morphology.

DOI： 10.1051/0004-6361/202243322

Filament coalescence and hub structure in Mon R2 Implications for massive star and cluster formation Open Access

Kumar, MSN; Arzoumanian, D; Men'shchikov, A; Palmeirim, P; Matsumura, M; Inutsuka, S

ASTRONOMY & ASTROPHYSICS Vol. 658 2022.2

Language：Japanese Publisher：Astronomy and Astrophysics

There is growing evidence of the role of hub-filament systems (HFS) in the formation of stars from low to high masses. As of today, however, the detailed structures of these systems are still not well described. Here we study the Mon R2 star-forming region, which has a rich network of filaments joining in a star cluster forming hub, and aim to understand the hub structure and to examine the mass fraction residing in the hub and in the filaments, which is a key factor that influences massive star formation. We conducted a multi-scale, multi-component analysis of the Herschel column density maps (resolution of 18.2′′ or ∼0.07 pc at 830 pc) of the region using a newly developed algorithm getsf to identify the structural components, namely, extended cloud, filaments, and sources. We find that cascades of lower column density filaments coalesce to form higher-density filaments eventually merging inside the hub (0.8 pc radius). As opposed to the previous view of the hub as a massive clump with ∼1 pc radius, we find it to be a network of short high-density filaments. We analyse the orientations and mass per unit length (M/L) of the filaments as a function of distance from the hub centre. The filaments are radially aligned towards the centre of the hub. The total mass reservoir in the Mon R2 HFS (5 pc × 5 pc) is split between filaments (54%), an extended cloud (37%), and sources (9%). The M/L of filaments increases from ∼10 M· pc-1 at 1.5 pc from the hub to ∼100 M· pc-1 at its centre, while the number of filaments per annulus of 0.2 pc width decreases from 20 to two in the same range. The observed radial column density structure of the HFS (filament component only) displays a power-law dependence of NH2 r-2.17 up to a radius of ∼2.5 pc from the central hub, resembling a global collapse of the HFS. We present a scenario where the HFS can be supported by magnetic fields which interact, merge, and reorganise themselves as the filaments coalesce. We plotted the plane-of-the-sky magnetic field line geometry using archival Planck data to support our scenario. In the new view of the hub as a network of high-density filaments, we suggest that only the stars located in the network can benefit from the longitudinal flows of gas to become massive, which may explain the reason for the formation of many low-mass stars in cluster centres. We show the correlation of massive stars in the region to the intertwined network-like hub, based on which we updated the implications of the filaments to clusters (F2C) model for massive star formation.

DOI： 10.1051/0004-6361/202140363

B-fields in Star-forming Region Observations (BISTRO): Magnetic Fields in the Filamentary Structures of Serpens Main Open Access

Kwon, W; Pattle, K; Sadavoy, S; Hull, CLH; Johnstone, D; Ward-Thompson, D; Di Francesco, J; Koch, PM; Furuya, R; Doi, Y; Le Gouellec, VJM; Hwang, J; Lyo, AR; Soam, A; Tang, XD; Hoang, T; Kirchschlager, F; Eswaraiah, C; Fanciullo, L; Kim, KH; Onaka, T; Könyves, V; Kang, JH; Lee, CW; Tamura, M; Bastien, P; Hasegawa, T; Lai, SP; Qiu, KP; Berry, D; Arzoumanian, D; Bourke, TL; Byun, DY; Chen, WP; Chen, HRV; Chen, MK; Chen, ZW; Ching, TC; Cho, J; Choi, Y; Choi, M; Chrysostomou, A; Chung, EJ; Coudé, S; Dai, S; Diep, PN; Duan, Y; Duan, HY; Eden, D; Fiege, J; Fissel, LM; Franzmann, E; Friberg, P; Friesen, R; Fuller, G; Gledhill, T; Graves, S; Greaves, J; Griffin, M; Gu, QL; Han, I; Hatchell, J; Hayashi, S; Houde, M; Inoue, T; Inutsuka, S; Iwasaki, K; Jeong, IG; Kang, MJ; Karoly, J; Kataoka, A; Kawabata, K; Kemper, F; Kim, KT; Kim, G; Kim, MR; Kim, S; Kim, J; Kirk, J; Kobayashi, MIN; Kusune, T; Kwon, J; Lacaille, K; Law, CY; Lee, CF; Lee, YH; Lee, H; Lee, JE; Lee, SS; Li, DL; Li, D; Li, HB; Lin, SJ; Liu, SY; Liu, HL; Liu, JH; Liu, T; Lu, X; Mairs, S; Matsumura, M; Matthews, B; Moriarty-Schieven, G; Nagata, T; Nakamura, F; Nakanishi, H; Ngoc, NB; Ohashi, N; Park, G; Parsons, H; Peretto, N; Priestley, F; Pyo, TS; Qian, L; Rao, R; Rawlings, J; Rawlings, MG; Retter, B; Richer, J; Rigby, A; Saito, H; Savini, G; Seta, M; Shimajiri, Y; Shinnaga, H; Tahani, M; Tang, YW; Tomisaka, K; Tram, L; Tsukamoto, Y; Viti, S; Wang, HC; Wang, JW; Whitworth, A; Wu, JT; Xie, JJ; Yen, HW; Yoo, H; Yuan, J; Yun, HS; Zenko, T; Zhang, YP; Zhang, CP; Zhang, GY; Zhou, JJ; Zhu, L; de Looze, I; André, P; Dowell, CD; Eyres, S; Falle, S; Robitaille, JF; van Loo, S

ASTROPHYSICAL JOURNAL Vol. 926 ( 2 ) 2022.2

Language：Japanese Publisher：Astrophysical Journal

We present 850 μm polarimetric observations toward the Serpens Main molecular cloud obtained using the POL-2 polarimeter on the James Clerk Maxwell Telescope as part of the B-fields In STar-forming Region Observations survey. These observations probe the magnetic field morphology of the Serpens Main molecular cloud on about 6000 au scales, which consists of cores and six filaments with different physical properties such as density and star formation activity. Using the histogram of relative orientation (HRO) technique, we find that magnetic fields are parallel to filaments in less-dense filamentary structures where NH2<0.93×1022 cm-2 (magnetic fields perpendicular to density gradients), while they are perpendicular to filaments (magnetic fields parallel to density gradients) in dense filamentary structures with star formation activity. Moreover, applying the HRO technique to denser core regions, we find that magnetic field orientations change to become perpendicular to density gradients again at NH2≈4.6×1022 cm-2. This can be interpreted as a signature of core formation. At NH2≈16×1022 cm-2, magnetic fields change back to being parallel to density gradients once again, which can be understood to be due to magnetic fields being dragged in by infalling material. In addition, we estimate the magnetic field strengths of the filaments (B POS = 60-300 μG)) using the Davis-Chandrasekhar-Fermi method and discuss whether the filaments are gravitationally unstable based on magnetic field and turbulence energy densities.

DOI： 10.3847/1538-4357/ac4bbe

The Effects of Cosmic-Ray Diffusion and Radiative Cooling on the Galactic Wind of the Milky Way Open Access

Shimoda, J; Inutsuka, S

ASTROPHYSICAL JOURNAL Vol. 926 ( 1 ) 2022.2

Language：Japanese Publisher：Astrophysical Journal

The effects of cosmic-ray diffusion and radiative cooling on the structure of the Galactic wind are studied using a steady-state approximation. It is known that realistic cooling processes suppress the wind from launching. The effects of cosmic-ray diffusion are also supposed to be unfavorable for launching the wind. Both of these effects have not been studied simultaneously in a steady-state approximation of the wind. We find 327,254 solutions of the steady-state Galactic wind and confirm that: the effect of the cosmic-ray pressure depends on the Alfvén Mach number, the mass flux carried by the wind does not depend on the cosmic-ray pressure directly (but depends on the thermal pressure), and the typical conditions found in the Galaxy may correspond to the wind solution that provides metal-polluted matter at a height of ∼300 kpc from the disk.

DOI： 10.3847/1538-4357/ac4110

Coagulation Instability in Protoplanetary Disks: A Novel Mechanism Connecting Collisional Growth and Hydrodynamical Clumping of Dust Particles Open Access

Tominaga, RT; Inutsuka, S; Kobayashi, H

ASTROPHYSICAL JOURNAL Vol. 923 ( 1 ) 2021.12

Language：Japanese Publisher：Astrophysical Journal

We present a new instability driven by a combination of coagulation and radial drift of dust particles. We refer to this instability as "coagulation instability"and regard it as a promising mechanism to concentrate dust particles and assist planetesimal formation in the very early stages of disk evolution. Because of dust-density dependence of collisional coagulation efficiency, dust particles efficiently (inefficiently) grow in a region of positive (negative) dust density perturbations, leading to a small radial variation of dust sizes and as a result radial velocity perturbations. The resultant velocity perturbations lead to dust concentration and amplify dust density perturbations. This positive feedback makes a disk unstable. The growth timescale of coagulation instability is a few tens of orbital periods even when dust-to-gas mass ratio is on the order of 10-3. In a protoplanetary disk, radial drift and coagulation of dust particles tend to result in dust depletion. The present instability locally concentrates dust particles even in such a dust-depleted region. The resulting concentration provides preferable sites for dust-gas instabilities to develop, which leads to further concentration. Dust diffusion and aerodynamical feedback tend to stabilize short-wavelength modes, but do not completely suppress the growth of coagulation instability. Therefore, coagulation instability is expected to play an important role in setting up the next stage for other instabilities, such as streaming instability or secular gravitational instability, to further develop toward planetesimal formation.

DOI： 10.3847/1538-4357/ac173a

The JCMT BISTRO Survey: Evidence for Pinched Magnetic Fields in Quiescent Filaments of NGC 1333 Open Access

Doi, Y; Tomisaka, K; Hasegawa, T; Coudé, S; Arzoumanian, D; Bastien, P; Matsumura, M; Tahani, M; Sadavoy, S; Hull, CLH; Johnstone, D; Di Francesco, J; Shimajiri, Y; Furuya, RS; Kwon, J; Tamura, M; Ward-Thompson, D; Le Gouellec, VJM; Hoang, T; Kirchschlager, F; Hwang, J; Eswaraiah, C; Koch, PM; Whitworth, AP; Pattle, K; Kwon, W; Kang, J; Inutsuka, S; Bourke, TL; Tang, XD; Fanciullo, L; Lee, CW; Liu, HL; Lyo, AR; Qiu, KP; Lai, SP

ASTROPHYSICAL JOURNAL LETTERS Vol. 923 ( 1 ) 2021.12

Language：Japanese Publisher：Astrophysical Journal Letters

We investigate the internal 3D magnetic structure of dense interstellar filaments within NGC 1333 using polarization data at 850 μm from the B-fields In STar-forming Region Observations survey at the James Clerk Maxwell Telescope. Theoretical models predict that the magnetic field lines in a filament will tend to be dragged radially inward (i.e., pinched) toward the central axis due to the filament's self-gravity. We study the cross-sectional profiles of the total intensity (I) and polarized intensity (PI) of dust emission in four segments of filaments unaffected by local star formation that are expected to retain a pristine magnetic field structure. We find that the filaments' FWHMs in PI are not the same as those in I, with two segments being appreciably narrower in PI (FWHM ratio ≃0.7-0.8) and one segment being wider (FWHM ratio ≃1.3). The filament profiles of the polarization fraction (P) do not show a minimum at the spine of the filament, which is not in line with an anticorrelation between P and I normally seen in molecular clouds and protostellar cores. Dust grain alignment variation with density cannot reproduce the observed P distribution. We demonstrate numerically that the I and PI cross-sectional profiles of filaments in magnetohydrostatic equilibrium will have differing relative widths depending on the viewing angle. The observed variations of FWHM ratios in NGC 1333 are therefore consistent with models of pinched magnetic field structures inside filaments, especially if they are magnetically near-critical or supercritical.

DOI： 10.3847/2041-8213/ac3cc1

Dispersal of protoplanetary discs by the combination of magnetically driven and photoevaporative winds (vol 492, pg 3849, 2020) Open Access

Kunitomo Masanobu, Suzuki Takeru K., Inutsuka Shu-ichiro

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY Vol. 508 ( 2 ) page： 2492 - 2492 2021.12

Dispersal of protoplanetary discs by the combination of magnetically driven and photoevaporative winds (vol 492, pg 3849, 2020) Open Access

Kunitomo Masanobu, Suzuki Takeru K., Inutsuka Shu-ichiro

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY Vol. 508 ( 2 ) page： 2492 - 2492 2021.10

"Ashfall" Induced by Molecular Outflow in Protostar Evolution Open Access

Tsukamoto, Y; Machida, MN; Inutsuka, S

ASTROPHYSICAL JOURNAL LETTERS Vol. 920 ( 2 ) 2021.10

Language：Japanese Publisher：Astrophysical Journal Letters

Dust growth and its associated dynamics play key roles in the first phase of planet formation in young stellar objects. Observations have detected signs of dust growth in very young protoplanetary disks. Furthermore, signs of planet formation, gaps in the disk at a distance of several tens of au from the central protostar, are also reported. From a theoretical point of view, however, planet formation in the outer regions is difficult due to the rapid inward drift of dust, called the radial drift barrier. Here, on the basis of three-dimensional magnetohydrodynamical simulations of disk evolution with dust growth, we propose a mechanism called the "ashfall"phenomenon, induced by a powerful molecular outflow driven by a magnetic field that may circumvent the radial drift barrier. We find that the large dust that grows to a size of about a centimeter in the inner region of a disk is entrained by an outflow from the disk. Then, large dust decoupled from gas is ejected from the outflow due to centrifugal force, enriching the grown dust in the envelope and eventually falls onto the outer edge of the disk. The overall process is similar to the behavior of ashfall from volcanic eruptions. In the ashfall phenomenon, the Stokes number of dust increases by reaccreting to the less dense disk outer edge. This may allow the dust grains to overcome the radial drift barrier. Consequently, the ashfall phenomenon can provide a crucial assist for making the formation of the planetesimals in outer regions of the disk possible, and hence the formation of wide-orbit planets and gaps.

DOI： 10.3847/2041-8213/ac2b2f

The JCMT Transient Survey: Four-year Summary of Monitoring the Submillimeter Variability of Protostars Open Access

Lee, YH; Johnstone, D; Lee, JE; Herczeg, G; Mairs, S; Contreras-Peña, C; Hatchell, J; Naylor, T; Bell, GS; Bourke, TL; Broughton, C; Francis, L; Gupta, A; Harsono, D; Liu, SY; Park, G; Plovie, S; Moriarty-Schieven, GH; Scholz, A; Sharma, T; Teixeira, PS; Wang, YT; Aikawa, Y; Bower, GC; Chen, HRV; Bae, J; Baek, G; Chapman, S; Chen, WP; Du, FJ; Dutta, S; Forbrich, J; Guo, Z; Inutsuka, S; Kang, M; Kirk, H; Kuan, YJ; Kwon, W; Lai, SP; Lalchand, B; Lane, JMM; Lee, CF; Liu, T; Morata, O; Pearson, S; Pon, A; Sahu, D; Shang, H; Stamatellos, D; Tang, SY; Xu, ZY; Yoo, H; Rawlings, JMC

ASTROPHYSICAL JOURNAL Vol. 920 ( 2 ) 2021.10

Language：Japanese Publisher：Astrophysical Journal

We present the four-year survey results of monthly submillimeter monitoring of eight nearby (<500 pc) star-forming regions by the JCMT Transient Survey. We apply the Lomb-Scargle Periodogram technique to search for and characterize variability on 295 submillimeter peaks brighter than 0.14 Jy beam-1, including 22 disk sources (Class II), 83 protostars (Class 0/I), and 190 starless sources. We uncover 18 secular variables, all of them protostars. No single-epoch burst or drop events and no inherently stochastic sources are observed. We classify the secular variables by their timescales into three groups: Periodic, Curved, and Linear. For the Curved and Periodic cases, the detectable fractional amplitude, with respect to mean peak brightness, is ∼4% for sources brighter than ∼0.5 Jy beam-1. Limiting our sample to only these bright sources, the observed variable fraction is 37% (16 out of 43). Considering source evolution, we find a similar fraction of bright variables for both Class 0 and Class I. Using an empirically motivated conversion from submillimeter variability to variation in mass accretion rate, six sources (7% of our full sample) are predicted to have years-long accretion events during which the excess mass accreted reaches more than 40% above the total quiescently accreted mass: two previously known eruptive Class I sources, V1647 Ori and EC 53 (V371 Ser), and four Class 0 sources, HOPS 356, HOPS 373, HOPS 383, and West 40. Considering the full protostellar ensemble, the importance of episodic accretion on few years timescale is negligible - only a few percent of the assembled mass. However, given that this accretion is dominated by events on the order of the observing time window, it remains uncertain as to whether the importance of episodic events will continue to rise with decades-long monitoring.

DOI： 10.3847/1538-4357/ac1679

SPH simulations for shape deformation of rubble-pile asteroids through spinup: The challenge for making top-shaped asteroids Ryugu and Bennu Open Access

Sugiura, K; Kobayashi, H; Watanabe, S; Genda, H; Hyodo, R; Inutsuka, S

ICARUS Vol. 365 2021.9

Associated Molecular and Atomic Clouds with X-Ray Shell of Superbubble 30 Doradus C in the LMC Open Access

Yamane, Y; Sano, H; Filipovic, MD; Tokuda, K; Fujii, K; Babazaki, Y; Mitsuishi, I; Inoue, T; Aharonian, F; Inaba, T; Inutsuka, S; Maxted, N; Mizuno, N; Onishi, T; Rowell, G; Tsuge, K; Voisin, F; Yoshiike, S; Fukuda, T; Kawamura, A; Bamba, A; Tachihara, K; Fukui, Y

ASTROPHYSICAL JOURNAL Vol. 918 ( 1 ) 2021.9

Language：Japanese Publisher：Astrophysical Journal

30 Doradus C is a superbubble that emits the brightest non-thermal X- and TeV gamma-rays in the Local Group. To explore the detailed connection between the high-energy radiation and the interstellar medium, we have carried out new CO and Hi observations using the Atacama Large Millimeter/Submillimeter Array (ALMA), Atacama Submillimeter Telescope Experiment, and the Australia Telescope Compact Array with resolutions of up to 3 pc. The ALMA data of 12CO(J = 1-0) emission revealed 23 molecular clouds, with typical diameters of ∼6-12 pc and masses of ∼600-10,000 M o˙. A comparison with the X-rays of XMM-Newton at ∼3 pc resolution shows that X-rays are enhanced toward these clouds. The CO data were combined with the Hi to estimate the total interstellar protons. A comparison of the interstellar proton column density and the X-rays revealed that the X-rays are enhanced with the total proton column density. These are most likely to be caused by the shock-cloud interaction, which is modeled by magnetohydrodynamical simulations (Inoue et al. 2012). We also note a trend for the X-ray photon index to vary with distance from the center of the high-mass star cluster. This suggests that the cosmic-ray electrons are accelerated by one or multiple supernovae in the cluster. Based on these results, we discuss the role of the interstellar medium in cosmic-ray particle acceleration.

DOI： 10.3847/1538-4357/ac0adb

The JCMT BISTRO Survey: An 850/450 <i>μ</i>m Polarization Study of NGC 2071IR in Orion B Open Access

Lyo, AR; Kim, J; Sadavoy, S; Johnstone, D; Berry, D; Pattle, K; Kwon, W; Bastien, P; Onaka, T; Di Francesco, J; Kang, JH; Furuya, R; Hull, CLH; Tamura, M; Koch, PM; Ward-Thompson, D; Hasegawa, T; Hoang, T; Arzoumanian, D; Lee, CW; Lee, CF; Byun, DY; Kirchschlager, F; Doi, Y; Kim, KT; Hwang, J; Diep, PN; Fanciullo, L; Lee, SS; Park, G; Yoo, H; Chung, EJ; Whitworth, A; Mairs, S; Soam, A; Liu, T; Tang, XD; Coudé, S; André, P; Bourke, TL; Chen, HRV; Chen, ZW; Chen, WP; Chen, MK; Ching, TC; Cho, J; Choi, M; Choi, Y; Chrysostomou, A; Dai, S; Dowell, CD; Duan, HY; Duan, Y; Eden, D; Eswaraiah, C; Eyres, S; Fiege, J; Fissel, LM; Franzmann, E; Friberg, P; Friesen, R; Fuller, G; Gledhill, T; Graves, S; Greaves, J; Griffin, M; Gu, QL; Han, I; Hatchell, J; Hayashi, S; Houde, M; Inoue, T; Inutsuka, S; Iwasaki, K; Jeong, IG; Kang, MJ; Kataoka, A; Kawabata, K; Kemper, F; Kim, G; Kim, MR; Kim, S; Kim, KH; Kirk, J; Kobayashi, MIN; Könyves, V; Kusune, T; Kwon, J; Lacaille, K; Lai, SP; Law, CY; Lee, JE; Lee, YH; Lee, H; Li, DL; Li, D; Li, HB; Liu, HL; Liu, JH; Liu, SY; Lu, X; Matsumura, M; Matthews, B; Moriarty-Schieven, G; Nagata, T; Nakamura, F; Nakanishi, H; Ngoc, NB; Ohashi, N; Parsons, H; Peretto, N; Priestley, F; Pyo, TS; Qian, L; Qiu, K; Rao, R; Rawlings, J; Rawlings, MG; Retter, B; Richer, J; Rigby, A; Saito, H; Savini, G; Scaife, A; Seta, M; Shimajiri, Y; Shinnaga, H; Tahani, M; Tang, YW; Tomisaka, K; Tram, LN; Tsukamoto, Y; Viti, S; Wang, JW; Wang, HC; Xie, JJ; Yen, HW; Yuan, JH; Yun, HS; Zenko, T; Zhang, GY; Zhang, CP; Zhang, YP; Zhou, JJ; Zhu, L; de Looze, I; Dowell, CD; Falle, S; Robitaille, JF; van Loo, S

ASTROPHYSICAL JOURNAL Vol. 918 ( 2 ) 2021.9

Language：Japanese Publisher：Astrophysical Journal

We present the results of simultaneous 450 μm and 850 μm polarization observations toward the massive star-forming region NGC 2071IR, a target of the BISTRO (B-fields in STar-forming Region Observations) Survey, using the POL-2 polarimeter and SCUBA-2 camera mounted on the James Clerk Maxwell Telescope. We find a pinched magnetic field morphology in the central dense core region, which could be due to a rotating toroidal disklike structure and a bipolar outflow originating from the central young stellar object IRS 3. Using the modified Davis–Chandrasekhar–Fermi method, we obtain a plane-of-sky magnetic field strength of 563 ± 421 μG in the central ∼0.12 pc region from 850 μm polarization data. The corresponding magnetic energy density of 2.04 × 10<sup>-8</sup> erg cm<sup>-3</sup> is comparable to the turbulent and gravitational energy densities in the region. We find that the magnetic field direction is very well aligned with the whole of the IRS 3 bipolar outflow structure. We find that the median value of polarization fractions is 3.0% at 450 μm in the central 3′ region, which is larger than the median value of 1.2% at 850 μm. The trend could be due to the better alignment of warmer dust in the strong radiation environment. We also find that polarization fractions decrease with intensity at both wavelengths, with slopes, determined by fitting a Rician noise model of 0.59 ± 0.03 at 450 μm and 0.36 ± 0.04 at 850 μm, respectively. We think that the shallow slope at 850 μm is due to grain alignment at the center being assisted by strong radiation from the central young stellar objects.

DOI： 10.3847/1538-4357/ac0ce9

Classification of Filament Formation Mechanisms in Magnetized Molecular Clouds Open Access

Abe, D; Inoue, T; Inutsuka, S; Matsumoto, T

ASTROPHYSICAL JOURNAL Vol. 916 ( 2 ) 2021.8

Language：Japanese Publisher：Astrophysical Journal

Recent observations of molecular clouds show that dense filaments are the sites of present-day star formation. Thus, it is necessary to understand the filament formation process because these filaments provide the initial condition for star formation. Theoretical research suggests that shock waves in molecular clouds trigger filament formation. Since several different mechanisms have been proposed for filament formation, the formation mechanism of the observed star-forming filaments requires clarification. In the present study, we perform a series of isothermal magnetohydrodynamics simulations of filament formation. We focus on the influences of shock velocity and turbulence on the formation mechanism and identified three different mechanisms for the filament formation. The results indicate that when the shock is fast, at shock velocity v sh ≃ 7 km s-1, the gas flows driven by the curved shock wave create filaments irrespective of the presence of turbulence and self-gravity. However, at a slow shock velocity v sh ≃ 2.5 km s-1, the compressive flow component involved in the initial turbulence induces filament formation. When both the shock velocities and turbulence are low, the self-gravity in the shock-compressed sheet becomes important for filament formation. Moreover, we analyzed the line-mass distribution of the filaments and showed that strong shock waves can naturally create high-line-mass filaments such as those observed in the massive star-forming regions in a short time. We conclude that the dominant filament formation mode changes with the velocity of the shock wave triggering the filament formation.

DOI： 10.3847/1538-4357/ac07a1

Conditions for Justifying Single-fluid Approximation for Charged and Neutral Dust Fluids and a Smoothed Particle Magnetohydrodynamics Method for Dust-Gas Mixture Open Access

Tsukamoto, Y; Machida, MN; Inutsuka, S

ASTROPHYSICAL JOURNAL Vol. 913 ( 2 ) 2021.6

Language：Japanese Publisher：Astrophysical Journal

We describe a numerical scheme for magnetohydrodynamics simulations of dust-gas mixture by extending smoothed particle magnetohydrodynamics. We employ the single-species particle approach to describe dust-gas mixture with several modifications from the previous studies. We assume that the charged and neutral dust can be treated as single-fluid, that the electromagnetic force acts on the gas, and that that acting on the charged dust is negligible. The validity of these assumptions in the context of protostar formation is not obvious and is extensively evaluated. By investigating the electromagnetic force and electric current with terminal velocity approximation, it is found that as the dust size increases, the contribution of dust to them becomes smaller and negligible. We conclude that our assumption that the electromagnetic force on the dusts is negligible is valid for the dust size with a d ⪆ 10 μm. On the other hand, they do not produce the numerical artifact for the dust a d ≲ 10 μm in the envelope and disk, where the perfect coupling between gas and dust is realized. However, we also found that our assumptions may break down in outflow (or under an environment with very strong magnetic field and low density) for the dust a d ≲ 10 μm. We conclude that our assumptions are valid in almost all cases where macroscopic dust dynamics is important in the context of protostar formation. We conduct numerical tests of dusty waves, dusty magnetohydrodynamics shocks, and gravitational collapse of magnetized cloud cores with our simulation code. The results show that our numerical scheme well reproduces the dust dynamics in the magnetized medium.

DOI： 10.3847/1538-4357/abf5db

Two-component Magnetic Field along the Line of Sight to the Perseus Molecular Cloud: Contribution of the Foreground Taurus Molecular Cloud Open Access

Doi, Y; Hasegawa, T; Bastien, P; Tahani, M; Arzoumanian, D; Coudé, S; Matsumura, M; Sadavoy, S; Hull, CLH; Shimajiri, Y; Furuya, RS; Johnstone, D; Plume, R; Inutsuka, S; Kwon, J; Tamura, M

ASTROPHYSICAL JOURNAL Vol. 914 ( 2 ) 2021.6

Language：Japanese Publisher：Astrophysical Journal

Optical stellar polarimetry in the Perseus molecular cloud direction is known to show a fully mixed bimodal distribution of position angles across the cloud. We study the Gaia trigonometric distances to each of these stars and reveal that the two components in position angles trace two different dust clouds along the line of sight. One component, which shows a polarization angle of -37.°6 ± 35.°2 and a higher polarization fraction of 2.0 ± 1.7 %, primarily traces the Perseus molecular cloud at a distance of 300 pc. The other component, which shows a polarization angle of +66.°8 ± 19.°1 and a lower polarization fraction of 0.8 ± 0.6 %, traces a foreground cloud at a distance of 150 pc. The foreground cloud is faint, with a maximum visual extinction of ≤1 mag. We identify that foreground cloud as the outer edge of the Taurus molecular cloud. Between the Perseus and Taurus molecular clouds, we identify a lower-density ellipsoidal dust cavity with a size of 100-160 pc. This dust cavity is located at l = 170°, b = -20°, and d = 240 pc, which corresponds to an HI shell generally associated with the Per OB2 association. The two-component polarization signature observed toward the Perseus molecular cloud can therefore be explained by a combination of the plane-of-sky orientations of the magnetic field both at the front and at the back of this dust cavity.

DOI： 10.3847/1538-4357/abfcc5

OMC-1 dust polarization in ALMA Band 7: diagnosing grain alignment mechanisms in the vicinity of Orion Source I Open Access

Pattle Kate, Lai Shih-Ping, Wright Melvyn, Coude Simon, Plambeck Richard, Thiem Hoang, Tang Ya-Wen, Bastien Pierre, Eswaraiah Chakali, Furuya Ray S., Hwang Jihye, Inutsuka Shu-ichiro, Kim Kee-Tae, Kirchschlager Florian, Kwon Woojin, Lee Chang Won, Liu Sheng-Yuan, Lyo Aran, Ohashi Nagayoshi, Rawlings Mark G., Tahani Mehrnoosh, Tamura Motohide, Soam Archana, Wang Jia-Wei, Ward-Thompson Derek

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY Vol. 503 ( 3 ) page： 3414 - 3433 2021.5

The JCMT BISTRO Survey: Revealing the Diverse Magnetic Field Morphologies in Taurus Dense Cores with Sensitive Submillimeter Polarimetry Open Access

Chakali, E; Li, D; Furuya, RS; Hasegawa, T; Ward-Thompson, D; Qiu, KP; Ohashi, N; Pattle, K; Sadavoy, S; Hull, CLH; Berry, D; Doi, Y; Ching, TC; Lai, SP; Wang, JW; Koch, PM; Kwon, J; Kwon, W; Bastien, P; Arzoumanian, D; Coudé, S; Soam, A; Fanciullo, L; Yen, HW; Liu, JH; Hoang, T; Chen, WP; Shimajiri, Y; Liu, T; Chen, ZW; Li, HB; Lyo, AR; Hwang, J; Johnstone, D; Rao, R; Ngoc, NB; Diep, PN; Mairs, S; Parsons, H; Tamura, M; Tahani, M; Chen, HRV; Nakamura, F; Shinnaga, H; Tang, YW; Cho, J; Lee, CW; Inutsuka, SI; Inoue, T; Iwasaki, K; Qian, L; Xie, JJ; Li, DL; Liu, HL; Zhang, CP; Chen, MK; Zhang, GY; Zhu, L; Zhou, JJ; André, P; Liu, SY; Yuan, JH; Lu, X; Peretto, N; Bourke, TL; Byun, DY; Dai, S; Duan, Y; Duan, HY; Eden, D; Matthews, B; Fiege, J; Fissel, LM; Kim, KT; Lee, CF; Kim, J; Pyo, TS; Choi, Y; Choi, M; Chrysostomou, A; Chung, EJ; Tram, L; Franzmann, E; Friberg, P; Friesen, R; Fuller, G; Gledhill, T; Graves, S; Greaves, J; Griffin, M; Gu, QL; Han, I; Hatchell, J; Hayashi, S; Houde, M; Kawabata, K; Jeong, IG; Kang, JH; Kang, SJ; Kang, M; Kataoka, A; Kemper, F; Rawlings, M; Rawlings, J; Retter, B; Richer, J; Rigby, A; Saito, H; Savini, G; Scaife, A; Seta, M; Kim, G; Kim, KH; Kim, MR; Kirchschlager, F; Kirk, J; Kobayashi, MIN; Konyves, V; Kusune, T; Lacaille, K; Law, CY; Lee, SS; Lee, YH; Matsumura, M; Moriarty-Schieven, G; Nagata, T; Nakanishi, H; Onaka, T; Park, G; Tang, XD; Tomisaka, K; Tsukamoto, Y; Viti, S; Wang, HC; Whitworth, A; Yoo, H; Yun, HS; Zenko, T; Zhang, YP; de Looze, I; Dowell, CD; Eyres, S; Falle, S; Robitaille, JF; van Loo, S

ASTROPHYSICAL JOURNAL LETTERS Vol. 912 ( 2 ) 2021.5

Language：Japanese Publisher：Astrophysical Journal Letters

We have obtained sensitive dust continuum polarization observations at 850 μm in the B213 region of Taurus using POL-2 on SCUBA-2 at the James Clerk Maxwell Telescope as part of the B-fields in STar-forming Region Observations (BISTRO) survey. These observations allow us to probe magnetic field (B-field) at high spatial resolution (∼2000 au or ∼0.01 pc at 140 pc) in two protostellar cores (K04166 and K04169) and one prestellar core (Miz-8b) that lie within the B213 filament. Using the Davis-Chandrasekhar-Fermi method, we estimate the B-field strengths in K04166, K04169, and Miz-8b to be 38 ± 14, 44 ± 16, and 12 ± 5 μG, respectively. These cores show distinct mean B-field orientations. The B-field in K04166 is well ordered and aligned parallel to the orientations of the core minor axis, outflows, core rotation axis, and large-scale uniform B-field, in accordance with magnetically regulated star formation via ambipolar diffusion taking place in K04166. The B-field in K04169 is found to be ordered but oriented nearly perpendicular to the core minor axis and large-scale B-field and not well correlated with other axes. In contrast, Miz-8b exhibits a disordered B-field that shows no preferred alignment with the core minor axis or large-scale field. We found that only one core, K04166, retains a memory of the large-scale uniform B-field. The other two cores, K04169 and Miz-8b, are decoupled from the large-scale field. Such a complex B-field configuration could be caused by gas inflow onto the filament, even in the presence of a substantial magnetic flux.

DOI： 10.3847/2041-8213/abeb1c

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