Astronomy & Astrophysics最新文献

{"title":"The NICER view of Scorpius X-1","authors":"J. López-Miralles, S. E. Motta, J. C. A. Miller-Jones, J. Homan, J. Kajava, S. Migliari","doi":"10.1051/0004-6361/202555299","DOIUrl":"https://doi.org/10.1051/0004-6361/202555299","url":null,"abstract":"<i>Context.<i/> The neutron star X-ray binary Scorpius X-1 is one of the brightest <i>Z<i/>-type sources in our Galaxy, showing frequent periods of flaring activity and different types of relativistic outflows. Observations with RXTE have shown that the strongest X-ray variability appears in the transition to and from the flaring state. During this transition, it has been proposed that the appearance of two particular types of quasi-periodic oscillations (QPOs) might be connected with the ejection of the so-called ultra-relativistic flows.<i>Aims.<i/> In this paper, we present an analysis of the first NICER observations of Scorpius X-1 obtained during a multi-wavelength campaign conducted in February 2019, in order to characterise the properties of QPOs in this source as the system evolves through its various accretion states.<i>Methods.<i/> We computed a light curve and a hardness-intensity diagram to track the evolution of the source spectral properties, while we investigated the X-ray time variability with a dynamical power density spectrum. To trace the temporal evolution of QPOs, we segmented the dataset into shorter, continuous intervals, and computed and fitted the averaged power density spectrum for each interval.<i>Results.<i/> Our analysis shows that the overall behaviour of the source is consistent with the literature; strong QPOs around 6 Hz are detected on the normal branch, while transitions to and from the flaring branch – occurring over timescales of a few hundred seconds – are characterised by rapid, weaker quasi-periodic variability reaching frequencies up to 15 Hz. Despite limited statistical significance, we also identify faint, transient timing features above 20 Hz, which occasionally coexist with the prominent 6 Hz QPOs. Although tentative, the existence of these timing features in the NICER data is crucial for interpreting the simultaneous radio observations from the same multi-wavelength campaign, potentially reinforcing the connection between the ejection of relativistic outflows and the accretion states in Scorpius X-1.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"50 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145043201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-mass microquasars from binary to black hole scale","authors":"Rolf Walder, Doris Folini","doi":"10.1051/0004-6361/202556402","DOIUrl":"https://doi.org/10.1051/0004-6361/202556402","url":null,"abstract":"We present a 3D hydrodynamical simulation of a wind-accreting high-mass microquasar, from 30 binary separations (<i>d<i/>) to 256 black hole (BH) gravitational radii, over one-sixth of a full orbit in time, with system parameters inspired by Cyg X-1. The simulation allows key system components to emerge naturally as inter-dependent quasi-stationary parts of an inherently multi-scale flow. The BH accretion disk is highly eccentric, with spirally shaped accreting and decreting zones. Its flow field is consistent with elliptical orbits confocal at the BH. The disk structure relates to its feeding: a cold 3D accretion cone channels matter from opposite the L1 point and within 2/3<i>d<i/> from the BH toward the disk. Above and below the disk, a polytropic atmosphere establishes, with temperatures one-tenth of the virial temperature. A hot cocoon of shocked wind material engulfs the BH accretion structure on scales of <i>d<i/>/10. We hypothesize that the shocks may accelerate particles and the atmosphere may up-scatter photons to GeV energies and beyond. An Archimedian spiral is apparent out to at least 10<i>d<i/>, as the orbiting BH perturbs the homogeneous donor star wind. Our simulation offers a coherent cross-scale perspective that allows us to contextualize observations, interpretations, and specific models.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"59 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145043403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Beyond the first galaxies primordial black holes shine","authors":"Antonio Matteri, Andrea Ferrara, Andrea Pallottini","doi":"10.1051/0004-6361/202554728","DOIUrl":"https://doi.org/10.1051/0004-6361/202554728","url":null,"abstract":"The presence of nine candidate galaxies at <i>z<i/> = 17 and <i>z<i/> = 25 discovered by the <i>James Webb<i/> Space Telescope in relatively small sky areas, if confirmed, is virtually impossible to reconcile with the predictions of the current galaxy formation model. We show here that the implied UV luminosity density can be produced by a population of primordial black holes (PBHs) of mass <i>M<i/><sub>PBH<sub/> = 10<sup>4 − 5<sup/> <i>M<i/><sub>⊙<sub/> residing in low-mass halos (<i>M<i/><sub>h<sub/> ≈ 10<sup>7<sup/> <i>M<i/><sub>⊙<sub/>), and accreting at a moderate fraction of the Eddington luminosity, <i>λ<i/><sub>E<sub/> ≃ 0.36. These sources precede the first significant episodes of cosmic star formation. At later times, as star formation is ignited, PBH emission becomes comparable to, or subdominant with respect to, the galactic emission. This PBH+galaxy scenario reconciles the evolution of the UV luminosity function (LF) from <i>z<i/> = 25 to <i>z<i/> = 11. If ultra-early sources are powered purely by accretion, this strongly disfavours seed production mechanisms requiring the presence of stars (massive stars, Pop III stars, or clusters), or their UV radiation (direct collapse BHs), leaving PBHs as the only alternative solution available so far. Alternative explanations, such as isolated, large clusters (≈10<sup>7<sup/> <i>M<i/><sub>⊙<sub/>) of massive (<i>m<i/><sub>⋆<sub/> = 10<sup>3<sup/> <i>M<i/><sub>⊙<sub/>) Pop III stars are marginally viable, but require extreme and unlikely conditions that can be probed via UV and far-infrared (FIR) emission lines or gravitational waves.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"24 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145043034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A deep search for radio pulsations from the 1.3 M⊙ compact-object binary companion of young pulsar PSR J1906+0746","authors":"Yuyang Wang, Joeri van Leeuwen","doi":"10.1051/0004-6361/202555920","DOIUrl":"https://doi.org/10.1051/0004-6361/202555920","url":null,"abstract":"Double pulsar systems offer unrivaled advantages for the study of astrophysics and fundamental physics. Only one such system has been visible so far, however: PSR J0737−3039. Its component pulsar B has now rotated out of sight due to the general relativistic effect of geodetic precession. We know, however, that these precession cycles can also pivot pulsars into sight, and that this precession occurs at similar strength in PSR J1906+0746. This source is a young, unrecycled radio pulsar that orbits a compact object with mass ∼1.32 M<sub>⊙<sub/>. We present a renewed campaign to detect radio pulsations from this companion two decades after the previous search. The two key reasons driving this reattempt are the possibility that the companion radio beam has since precessed into our line of sight, and the improved sensitivity now offered by the FAST radio telescope. In 28 deep observations, we did not detect a credible companion pulsar signal. After comparing the possible scenarios, we conclude the companion is still most likely a pulsar that does not point at us. We next present estimates for the sky covered by such systems throughout their precession cycle. We find that for most system geometries, the all-time beaming fraction is unity, that is, observers in any direction can see the system at some point. We conclude that it is still likely that PSR J1906+0746 will be visible as a double pulsar in the future.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"77 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145043035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Tremaine-Weinberg method at high redshifts","authors":"Mahmood Roshan, Asiyeh Habibi, J. Alfonso L. Aguerri, Virginia Cuomo, Connor Bottrell, Luca Costantin, Enrico Maria Corsini, Taehyun Kim, Yun Hee Lee, Jairo Mendez-Abreu, Matthew Frosst, Adriana de Lorenzo-Cáceres, Lorenzo Morelli, Alessandro Pizzella","doi":"10.1051/0004-6361/202555547","DOIUrl":"https://doi.org/10.1051/0004-6361/202555547","url":null,"abstract":"This paper examines the reliability of the Tremaine-Weinberg (TW) method in measuring the pattern speed of barred galaxies at high redshifts. Measuring pattern speeds at high redshift may help to shed light on the time evolution of interactions between galactic bars and dark matter halos. The TW method has been extensively employed for nearby galaxies, and its accuracy in determining bar pattern speeds has been validated through numerical simulations. For nearby galaxies, the method yields acceptable results when the inclination angle of the galaxy and the position angle of the bar fall within appropriate ranges. However, the application of the TW method to high-redshift galaxies remains unexplored in both observations and simulations. For this study we generated mock observations of barred galaxies from the TNG50 cosmological simulation. These simulated observations were tailored to mimic the integral field unit (IFU) spectroscopy data that the Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope (JWST) would capture at a redshift of <i>ɀ<i/> ≃ 1.2. By applying the TW method to these mock observations and comparing the results with the known pattern speeds, we demonstrate that the TW method performs adequately for barred galaxies whose bars are sufficiently long to be detected by JWST at high redshifts. This work opens a new avenue for applying the TW method to investigate the properties of high-redshift barred galaxies.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"17 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145043037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Azimuthal offsets in spiral arms of nearby galaxies","authors":"Miguel Querejeta, Sharon E. Meidt, Yixian Cao, Dario Colombo, Eric Emsellem, Santiago García-Burillo, Ralf S. Klessen, Eric W. Koch, Adam K. Leroy, Marina Ruiz-García, Eva Schinnerer, Rowan Smith, Sophia Stuber, Mallory Thorp, Thomas G. Williams, Médéric Boquien, Daniel A. Dale, Chris Faesi, Damian R. Gleis, Kathryn Grasha, Annie Hughes, María J. Jiménez-Donaire, Kathryn Kreckel, Daizhong Liu, Justus Neumann, Hsi-An Pan, Francesca Pinna, Alessandro Razza, Toshiki Saito, Jiayi Sun, Antonio Usero","doi":"10.1051/0004-6361/202556175","DOIUrl":"https://doi.org/10.1051/0004-6361/202556175","url":null,"abstract":"Spiral arms play a central role in disc galaxies, but their dynamical nature remains a long-standing open question. Azimuthal offsets between molecular gas and star formation are expected if gas crosses spiral arms, as predicted by quasi-stationary density wave theory. In this work, we measure offsets between CO and H<i>α<i/> peaks in radial bins for 24 galaxies from the PHANGS survey that display a well-delineated spiral structure. The offsets exhibit substantial scatter, implying that star formation is not exclusively initiated at a coherent spiral shock. We define offsets such that positive values mean H<i>α<i/> peaks lie ahead of CO peaks in the direction of galactic rotation. With this convention, 14 galaxies show mean positive CO-H<i>α<i/> offsets, typically of a few hundred parsecs. In four of these 14 galaxies (17% of the total), offsets become smaller with increasing radius, as expected for a single quasi-stationary spiral density wave. Ten galaxies (42%) show positive mean offsets but no clear correlation with radius, which is compatible with multiple overlapping modes. In the remaining ten galaxies (42%), we find no significantly positive offsets, which could point to transient dynamical spirals or material arms, where gas and stars co-rotate with the spiral perturbation. Across the full sample, we find mostly positive offsets between CO peaks and the gravitational potential minimum, confirming that gas often crosses the spiral perturbation. For the four galaxies with clear positive offsets and a radial trend, we derived pattern speeds in good agreement with the literature. Overall, our results suggest that even well-delineated spirals in the local Universe can arise from a variety of underlying dynamical mechanisms.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"34 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145043036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In search of the Local Universe dynamical homogeneity scale with CF4++ peculiar velocities","authors":"H. M. Courtois, J. Mould, A. M. Hollinger, A. Dupuy, C. P. Zhang","doi":"10.1051/0004-6361/202553677","DOIUrl":"https://doi.org/10.1051/0004-6361/202553677","url":null,"abstract":"This article explores an update to the cosmography of the local Universe within <i>z<i/> = 0.1, incorporating galaxy peculiar velocity datasets from the first data releases of the WALLABY, FAST, and DESI surveys. The number of galaxies with peculiar velocities currently selected in each survey is 655, 4796, and 4191, respectively. The new CF4++ compendium enables a more comprehensive study of the nearby Universe bulk flow dynamics. We find a bulk flow of 315 ± 40 km s<sup>−1<sup/> at 150 <i>h<i/><sup>−1<sup/> Mpc. This analysis additionally reveals that the dynamical scale of homogeneity is not yet reached in the interval [200−300] <i>h<i/><sup>−1<sup/> Mpc from the observer. This new data also refines the structure of local superclusters, revealing more spherical shapes and more clearly defined boundaries for key regions such as the Great Attractor (Laniakea) and the Coma cluster. The addition of a few measurements has made a big difference in our ability to reveal the hidden Vela supercluster. To help colleagues obtain a peculiar velocity prediction for the object they are currently studying (e.g. SNIa, gravitational waves), we publicly release the CF4++ catalogue, as well as the reconstructed density and velocity fields used in this work.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"85 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145043400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The 10 kpc collar of early-type galaxies: Probing evolution by focusing on the inner stellar density profile","authors":"Rongfu Liu, Alessandro Sonnenfeld, Carlo Nipoti, Rui Li","doi":"10.1051/0004-6361/202553788","DOIUrl":"https://doi.org/10.1051/0004-6361/202553788","url":null,"abstract":"<i>Context.<i/> The post-quenching evolution process of early-type galaxies (ETGs), which is typically driven by mergers, is still not fully understood. The amount of growth in stellar mass and size incurred after quenching is still under debate.<i>Aims.<i/> In this work, we investigated the late evolution of ETGs, both observationally and theoretically, by focusing on the stellar mass density profile inside a fixed aperture, within 10 kpc from the galaxy center.<i>Methods.<i/> We first studied the stellar mass and the mass-weighted density slope within 10 kpc, respectively <i>M<i/><sub>*, 10<sub/> and Γ<sub>*, 10<sub/>, of a sample of ETGs from the GAMA survey. We measured the Γ<sub>*, 10<sub/> − <i>M<i/><sub>*, 10<sub/> relation and its evolution over the redshift range 0.17 ≤ <i>z<i/> ≤ 0.37. We then built a toy model for the merger evolution of galaxies, based on N-body simulations, to explore to what extent the observed growth in Γ<sub>*, 10<sub/> − <i>M<i/><sub>*, 10<sub/> relation is consistent with a dry-merger evolution scenario.<i>Results.<i/> From the observations, we do not detect evidence for an evolution of the Γ<sub>*, 10<sub/> − <i>M<i/><sub>*, 10<sub/> relation relation. We put an upper limit on the redshift derivative of the normalization (<i>μ<i/>) and slope (<i>β<i/>) of the Γ<sub>*, 10<sub/> − <i>M<i/><sub>*, 10<sub/> relation: |∂<i>μ<i/>/∂log(1 + <i>z<i/>)| ≤ 0.13 and |∂<i>β<i/>/∂log(1+<i>z<i/>)| ≤ 1.10, respectively. Simulations show that most mergers induce a decrease in Γ<sub>*, 10<sub/> and an increase in <i>M<i/><sub>*.10<sub/>, although some show a decrease in <i>M<i/><sub>*, 10<sub/>, particularly for the most extended galaxies and smaller merger mass ratios. By combining the observations with our merger toy model, we place an upper limit on the fractional stellar mass growth of <i>f<i/><sub>M<sub/> = 11.2% in the redshift range 0.17 ≤ <i>z<i/> ≤ 0.37.<i>Conclusions.<i/> While our measurement is limited by systematics, the application of our approach to samples with a larger redshift baseline, particularly with a time interval Δ<i>t<i/> ≥ 3.2 Gyr, should enable detection of a signal and improves our understanding of the late growth of ETGs.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"16 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145043040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identifying radio active galactic nuclei with machine learning and large-area surveys","authors":"Xu-Liang Fan, Jie Li","doi":"10.1051/0004-6361/202453082","DOIUrl":"https://doi.org/10.1051/0004-6361/202453082","url":null,"abstract":"<i>Context.<i/> Active galactic nuclei (AGNs) and star-forming galaxies (SFGs) are the primary sources in the extragalactic radio sky. But it is difficult to distinguish the radio emission produced by AGNs from that by SFGs, especially when the radio sources are faint. Best et al. (2023, MNRAS, 523, 1729) classified the radio sources in LoTSS Deep Fields DR1 through multiwavelength SED fitting. With the classification results of them, we performed a supervised machine learning to distinguish radio AGNs and radio SFGs.<i>Aims.<i/> We aim to provide a supervised classifier to identify radio AGNs, which can get both high purity and completeness simultaneously, and can easily be applied to datasets of large-area surveys.<i>Methods.<i/> The classifications of Best et al. (2023, MNRAS, 523, 1729) were used as the true labels for supervised machine learning. With the cross-matched sample of LoTSS Deep Fields DR1, AllWISE, and <i>Gaia<i/> DR3, the features of optical and mid-infrared magnitude and colors were applied to train the classifier. The performance of the classifier was evaluated mainly by the precision, recall, and <i>F<i/><sub>1<sub/> score of both AGNs and non-AGNs.<i>Results.<i/> By comparing the performance of six learning algorithms, CatBoost was chosen to construct the best classifier. The best classifier gets <i>precision<i/> = 0.974, <i>recall<i/> = 0.865, and <i>F<i/><sub>1<sub/> = 0.916 for AGNs, and <i>precision<i/> = 0.936, <i>recall<i/> = 0.988, and <i>F<i/><sub>1<sub/> = 0.961 for non-AGNs. After applying our classifier to the cross-matched sample of LoTSS DR2, AllWISE, and <i>Gaia<i/> DR3, we obtained a sample of 49716 AGNs and 102261 non-AGNs. The reliability of these classification results was confirmed by comparing them with the spectroscopic classification of SDSS. The precision and recall of AGN sample can be as high as 94.2% and 92.3%, respectively. We also trained a model to identify radio excess sources. The <i>F<i/><sub>1<sub/> scores are 0.610 and 0.965 for sources with and without radio excess, respectively.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"3 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145043404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sulfur oxides tracing streamers and shocks at low-mass protostellar disk–envelope interfaces","authors":"X.-C. Liu, E. F. van Dishoeck, M. R. Hogerheijde, M. L. van Gelder, Y. Chen, T. Liu, M. van’t Hoff, M. N. Drozdovskaya, E. Artur de la Villarmois, X.-F. Mai, Ł. Tychoniec","doi":"10.1051/0004-6361/202554186","DOIUrl":"https://doi.org/10.1051/0004-6361/202554186","url":null,"abstract":"Accretion shocks are thought to play a crucial role in the early stages of star and planet formation, but direct observational evidence of them remains elusive, particularly regarding the molecular tracers of these processes. In this work, we searched for features of accretion shocks by observing the emission of SO and SO<sub>2<sub/> using ALMA in Band 6 toward nearby Class I protostars. We analyzed the SO and SO<sub>2<sub/> emission from Oph IRS 63, DK Cha, and L1527, which have different disk inclination angles, ranging from nearly face-on to edge-on. SO emission is found to be concentrated in rings at the centrifugal barriers of the infalling envelopes. These rings are projected onto the plane of the sky as ellipses or parallel slabs, depending on the inclination angles. Spiral-like streamers with SO emission are also common, with warm (<i>T<i/><sub>ex<sub/> > 50 K) and even hot (<i>T<i/><sub>ex<sub/> ≳ 100 K) spots or segments of SO<sub>2<sub/> observed near the centrifugal barriers. Inspired by these findings, we present a model that consistently explains the accretion shock traced by SO and SO<sub>2<sub/>, where the shock occurs primarily in two regions: (1) the centrifugal barriers, and (2) the surface of the disk-like inner envelope outside the centrifugal barrier. The outer envelope gains angular momentum through outflows, causing it to fall onto the midplane at or outside the centrifugal barrier, leading to a disk-like inner envelope that is pressure-confined by the accretion shock and that moves in a rotating and infalling motion. We classify the streamers into two types – those in the midplane and those off the midplane. These streamers interact with the inner envelopes in different ways, resulting in different patterns of shocked regions. We suggest that the shock-related chemistry at the surfaces of the disk and the disk-like inner envelope warrants further special attention.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"59 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145043039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}