The Astrophysical Journal Letters最新文献_第2页

The Impact of Alfvénic Shear Flow on Magnetic Reconnection and Turbulence alfv<s:1>剪切流对磁重联和湍流的影响

The Astrophysical Journal Letters Pub Date : 2025-10-06 DOI: 10.3847/2041-8213/ae0b56

Tamar Ervin, Alfred Mallet, Stefan Eriksson, M. Swisdak, James Juno, Orlando M. Romeo, Tai Phan, Trevor A. Bowen, Roberto Livi, Phyllis L. Whittlesey, Davin E. Larson and Stuart D. Bale

{"title":"The Impact of Alfvénic Shear Flow on Magnetic Reconnection and Turbulence","authors":"Tamar Ervin, Alfred Mallet, Stefan Eriksson, M. Swisdak, James Juno, Orlando M. Romeo, Tai Phan, Trevor A. Bowen, Roberto Livi, Phyllis L. Whittlesey, Davin E. Larson and Stuart D. Bale","doi":"10.3847/2041-8213/ae0b56","DOIUrl":"https://doi.org/10.3847/2041-8213/ae0b56","url":null,"abstract":"Magnetic reconnection is a fundamental and omnipresent energy conversion process in plasma physics. Novel observations of fields and particles from Parker Solar Probe (PSP) have shown the absence of reconnection in a large number of current sheets in the near-Sun solar wind. Using near-Sun observations from PSP encounters 4–11 (2020 January–2022 March), we investigate whether reconnection onset might be suppressed by velocity shear. We compare estimates of the tearing mode growth rate in the presence of shear flow for time periods identified as containing reconnecting current sheets versus nonreconnecting times, finding systematically larger growth rates for reconnection periods. Upon examination of the parameters associated with reconnection onset, we find that 85% of the reconnection events are embedded in slow, non-Alfvénic wind streams. We compare with fast, slow non-Alfvénic, and slow Alfvénic streams, finding that the growth rate is suppressed in highly Alfvénic fast and slow wind, and reconnection is not seen in these wind types, as would be expected from our theoretical expressions. These wind streams have strong Alfvénic flow shear, consistent with the idea of reconnection suppression by such flows. This could help explain the frequent absence of reconnection events in the highly Alfvénic, near-Sun solar wind observed by PSP. Finally, we find a steepening of both the trace and magnitude magnetic field spectra within reconnection periods in comparison to ambient wind. We tie this to the dynamics of relatively balanced turbulence within these reconnection periods and the potential generation of compressible fluctuations.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145235185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Electromagnetic Energy Extraction from Kerr Black Holes: Ab Initio Calculations 克尔黑洞的电磁能量提取：从头算

The Astrophysical Journal Letters Pub Date : 2025-10-05 DOI: 10.3847/2041-8213/ae06a6

Claudio Meringolo, Filippo Camilloni and Luciano Rezzolla

引用次数: 0

Numerical Simulations Confirm Wave-induced Shear Mixing in Stellar Interiors 数值模拟证实了恒星内部由波引起的剪切混合

The Astrophysical Journal Letters Pub Date : 2025-10-05 DOI: 10.3847/2041-8213/ae09ae

A. Varghese, R. P. Ratnasingam, L. Ramírez-Galeano, S. Mathis and T. M. Rogers

引用次数: 0

Spectroscopic Characterization of Interstellar Object 3I/ATLAS: Water Ice in the Coma 星际天体3I/ATLAS的光谱表征：彗发中的水冰

The Astrophysical Journal Letters Pub Date : 2025-10-05 DOI: 10.3847/2041-8213/ae08a7

Bin Yang, Karen J. Meech, Michael Connelley, Ruining Zhao and Jacqueline V. Keane

{"title":"Spectroscopic Characterization of Interstellar Object 3I/ATLAS: Water Ice in the Coma","authors":"Bin Yang, Karen J. Meech, Michael Connelley, Ruining Zhao and Jacqueline V. Keane","doi":"10.3847/2041-8213/ae08a7","DOIUrl":"https://doi.org/10.3847/2041-8213/ae08a7","url":null,"abstract":"We present optical and near-infrared spectroscopy of the interstellar object 3I/ATLAS, obtained with Gemini-S/GMOS and NASA IRTF/SpeX on 2025 July 5 and 14. The optical spectrum shows a red slope of ∼11% per 1000 Å between 0.5 and 0.8 μm, resembling typical D-type asteroids and distinct from ultrared trans-Neptunian objects. At longer wavelengths, the near-infrared continuum flattens to ∼3% per 1000 Å between 0.9 and 1.5 μm, with a broad absorption feature near 2.0 μm indicative of water-ice grains in the coma. Spectral modeling with a mixture of 63% amorphous carbon and 37% 1 μm-sized water ice reproduces both the continuum and the 2.0 μm band, while the 1.5 μm water-ice band is not detected, likely due to limited signal-to-noise in the IRTF data and dilution by refractory material. The close agreement between the GMOS and SpeX spectra, taken 9 days apart, indicates short-term stability in the coma’s optical properties. These observations demonstrate that 3I/ATLAS is an active interstellar comet containing abundant water ice, consistent with the theoretical expectation that its home planetary system had a high bulk fraction of water ice by mass.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"105 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145228827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Magnetic Turbulence Intermittency and Compressibility in the Inner Heliosheath and Very Local Interstellar Medium 内日鞘和极局域星际介质中的磁湍流间歇性和可压缩性

The Astrophysical Journal Letters Pub Date : 2025-10-02 DOI: 10.3847/2041-8213/ae09aa

L.-L. Zhao, V. Florinski, G. P. Zank, M. Opher, J. Richardson, W. S. Kurth, A. Silwal, X. Zhu, N. S. M. Subashchandar, J. G. Alonso Guzman and Z. Jin

{"title":"Magnetic Turbulence Intermittency and Compressibility in the Inner Heliosheath and Very Local Interstellar Medium","authors":"L.-L. Zhao, V. Florinski, G. P. Zank, M. Opher, J. Richardson, W. S. Kurth, A. Silwal, X. Zhu, N. S. M. Subashchandar, J. G. Alonso Guzman and Z. Jin","doi":"10.3847/2041-8213/ae09aa","DOIUrl":"https://doi.org/10.3847/2041-8213/ae09aa","url":null,"abstract":"We analyze Voyager 1 magnetic field data through 2024 to study fluctuations from the inner heliosheath into the very local interstellar medium (VLISM). We focus on inertial-range intermittency and magnetic compressibility and examine the effects of interstellar shocks and pressure fronts. The heliosheath shows consistently high fluctuation amplitude (δB/B0 ∼ 1) and compressibility, indicating the presence of compressive wave modes. The elevated sound speed from pickup ion pressure inhibits wave steepening within the heliosheath, but steepening may occur near or just beyond the heliopause, enabling partial transmission into the VLISM. Beyond the heliopause, magnetic compressibility decreases following the second pressure front at ∼149 au. Intermittency, measured via scale-dependent flatness, also decreases with distance but shows localized enhancements near pressure fronts and shocks in the VLISM. A pronounced peak in flatness at time lags around 105 s is observed downstream of the second pressure front, primarily in the parallel magnetic field component, indicating large-scale compressive structures. In contrast, the peak flatness downstream of the first pressure front (at ∼137 au) occurs at shorter time lags, likely due to differences in plasma conditions, structure scales, or elevated noise in the deeper VLISM. An overall decrease in intermittency, approaching near-Gaussian levels, is observed after the second pressure front. However, weak intermittency still persists at small time lags over the past 2 yr, indicating that intermittency does not fully vanish after the magnetic hump.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"126 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145209652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Characterization of Two Cool Galaxy Outflow Candidates Using Mid-infrared Emission from Polycyclic Aromatic Hydrocarbons 用多环芳烃的中红外辐射表征两个冷星系外流候选者

The Astrophysical Journal Letters Pub Date : 2025-10-02 DOI: 10.3847/2041-8213/ae08b7

Jessica Sutter, Karin Sandstrom, Ryan Chown, Oleg Egorov, Adam K. Leroy, Jérémy Chastenet, Alberto D. Bolatto, Thomas G. Williams, Daniel A. Dale, Amirnezam Amiri, Médéric Boquien, Yixian Cao, Simthembile Dlamini, Éric Emsellem, Hsi-An Pan, Debosmita Pathak, Hwihyun Kim, Ralf S. Klessen, Hannah Koziol, Erik Rosolowsky, Sumit K. Sarbadhicary, Eva Schinnerer, David A. Thilker, Leonardo Úbeda and Tony Weinbeck

{"title":"Characterization of Two Cool Galaxy Outflow Candidates Using Mid-infrared Emission from Polycyclic Aromatic Hydrocarbons","authors":"Jessica Sutter, Karin Sandstrom, Ryan Chown, Oleg Egorov, Adam K. Leroy, Jérémy Chastenet, Alberto D. Bolatto, Thomas G. Williams, Daniel A. Dale, Amirnezam Amiri, Médéric Boquien, Yixian Cao, Simthembile Dlamini, Éric Emsellem, Hsi-An Pan, Debosmita Pathak, Hwihyun Kim, Ralf S. Klessen, Hannah Koziol, Erik Rosolowsky, Sumit K. Sarbadhicary, Eva Schinnerer, David A. Thilker, Leonardo Úbeda and Tony Weinbeck","doi":"10.3847/2041-8213/ae08b7","DOIUrl":"https://doi.org/10.3847/2041-8213/ae08b7","url":null,"abstract":"We characterize two candidate cool galactic outflows in two relatively low-mass, highly inclined Virgo cluster galaxies: NGC 4424 and NGC 4694. Previous analyses of observations using the Atacama Large Millimeter/submillimeter Array carbon monoxide (CO) line emission maps did not classify these sources as cool outflow hosts. Using new high-sensitivity, high-spatial-resolution, JWST mid-infrared photometry in the polycyclic aromatic hydrocarbon (PAH)–tracing F770W band, we identify extended structures present off of the stellar disk. The identified structures are bright in the MIRI F770W and F2100W bands, suggesting they include PAHs as well as other dust grains. As PAHs have been shown to be destroyed in hot, ionized gas, these structures are likely to be outflows of cool (T ≤ 104 K) gas. This work represents an exciting possibility for using mid-infrared observations to identify and measure outflows in lower-mass, lower star formation galaxies.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145209650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The Landscape of Collapsar Outflows: Structure, Signatures, and Origins of Einstein Probe Relativistic Supernova Transients 坍缩星流出的景观：爱因斯坦探测器相对论性超新星瞬变的结构、特征和起源

The Astrophysical Journal Letters Pub Date : 2025-10-02 DOI: 10.3847/2041-8213/ae09af

Ore Gottlieb

{"title":"The Landscape of Collapsar Outflows: Structure, Signatures, and Origins of Einstein Probe Relativistic Supernova Transients","authors":"Ore Gottlieb","doi":"10.3847/2041-8213/ae09af","DOIUrl":"https://doi.org/10.3847/2041-8213/ae09af","url":null,"abstract":"The Einstein Probe is revolutionizing time-domain astrophysics through the discovery of new classes of X-ray transients associated with broad-line Type Ic supernovae. These events commonly exhibit bright early-time optical counterparts and sudden afterglow rebrightening within the first week—features that existing models fail to explain. In particular, structured jet and cocoon scenarios are inconsistent with the observed sharp rebrightening and multiday optical emission, while the refreshed shock model is ruled out owing to its inconsistency with collapsar hydrodynamics. Drawing on 3D general relativistic magnetohydrodynamic simulations, we present the multiscale angular and radial structure characterizing collapsar outflows. The resulting morphology features episodic, wobbling jets with a “top-hat” geometry, embedded within a smoother global cocoon and disk ejecta angular structure. The wobbling jets give rise to variations in radiative efficiency that can account for the observed alternation between X-ray-dominated and γ-ray-dominated jet emission. The top-hat structure of individual wobbling jet episodes naturally explains the sudden rebrightening observed when the emission from the top-hat jet cores enters the observer’s line of sight. The radial structure is consistent with that inferred from observations of stripped-envelope supernovae. It comprises a mildly relativistic cocoon (0.3 ≲ βΓ ≲ 3) that may power an early (∼1 day) rapidly decaying emission, followed by slower, black-hole-accretion-disk-driven outflows (β ≲ 0.3), which dominate the slowly evolving optical emission at t ≳ 1 day. This novel multicomponent outflow structure provides a unified explanation for the multiband light curves observed in Einstein Probe transients and is likely a common feature of broad-line Type Ic supernovae more broadly.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"53 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145209653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Absence of Radio Emission Reveals an Exceptionally Weak Explosion of the Putative Historical Supernova Pa 30 缺少射电辐射揭示了假定的历史超新星Pa 30异常微弱的爆炸

The Astrophysical Journal Letters Pub Date : 2025-10-02 DOI: 10.3847/2041-8213/ae092d

Yi-Xuan Shao, Ping Zhou, Xiao Zhang, Zhi-Yu Zhang, Yang Chen, Qin Han, Di Li, Xiang-Dong Li, Jian-Bin Weng and Yong Shao

{"title":"Absence of Radio Emission Reveals an Exceptionally Weak Explosion of the Putative Historical Supernova Pa 30","authors":"Yi-Xuan Shao, Ping Zhou, Xiao Zhang, Zhi-Yu Zhang, Yang Chen, Qin Han, Di Li, Xiang-Dong Li, Jian-Bin Weng and Yong Shao","doi":"10.3847/2041-8213/ae092d","DOIUrl":"https://doi.org/10.3847/2041-8213/ae092d","url":null,"abstract":"We present the first deep radio continuum observations of Pa 30, a nebula hosting a unique optical source driven by an ultrafast outflow with a velocity of 16,000 km s−1. The nebula was proposed to be the remnant of a white dwarf merger that occurred in 1181CE. We report no detection of the radio diffuse emission from Pa 30 or radio emission from the central source, setting 3σ upper limit flux densities of 0.84 and 0.29 mJy at 1.5 and 6 GHz, respectively, for Pa 30. The radio surface brightness of Pa 30 is ∼3 orders of magnitude smaller than that of typical supernova remnants (SNRs) with comparable angular size. If Pa 30 is an SNR, our observations show it to be the faintest known in the radio band. Considering that 10% of the supernova (SN) kinetic energy is transferred to cosmic rays (CRs), the absence of radio synchrotron emission suggests that the SN kinetic energy ≲3 × 1047(B/10 μG)−1.65 erg, which is 3–4 orders of magnitude lower than that of typical SNRs and the lowest measured among Galactic SNRs. There is also an indication of inefficient CR acceleration for this source. The low SN kinetic energy either implies the potential existence of many more radio-faint, subenergetic SNRs in our Galaxy or challenges the SNR interpretation of Pa 30.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145209651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Discovery of an Accretion Burst in a Free-floating Planetary-mass Object 在自由漂浮的行星质量物体中发现吸积爆发

The Astrophysical Journal Letters Pub Date : 2025-10-01 DOI: 10.3847/2041-8213/ae09a8

Victor Almendros-Abad, Aleks Scholz, Belinda Damian, Ray Jayawardhana, Amelia Bayo, Laura Flagg, Koraljka Mužić, Antonella Natta, Paola Pinilla and Leonardo Testi

{"title":"Discovery of an Accretion Burst in a Free-floating Planetary-mass Object","authors":"Victor Almendros-Abad, Aleks Scholz, Belinda Damian, Ray Jayawardhana, Amelia Bayo, Laura Flagg, Koraljka Mužić, Antonella Natta, Paola Pinilla and Leonardo Testi","doi":"10.3847/2041-8213/ae09a8","DOIUrl":"https://doi.org/10.3847/2041-8213/ae09a8","url":null,"abstract":"We report the discovery of a long-lasting burst of disk accretion in Cha J11070768-7626326 (Cha 1107-7626), a young, isolated, 5–10 MJupiter object. In spectra taken with XSHOOTER at ESO’s Very Large Telescope as well as NIRSpec and MIRI on the James Webb Space Telescope, the object transitions from quiescence in 2025 April–May to a strongly enhanced accretion phase in 2025 June–August. The line flux changes correspond to a 6–8-fold increase in the mass accretion rate, reaching 10−7MJupiteryr−1, the highest measured in a planetary-mass object. During the burst, the Hα line develops a double-peaked profile with redshifted absorption, as observed in stars and brown dwarfs undergoing magnetospheric accretion. The optical continuum increases by a factor of 3–6; the object is ∼1.5–2 mag brighter in the R band during the burst. Mid-infrared continuum fluxes rise by 10%–20%, with clear changes in the hydrocarbon emission lines from the disk. We detect water vapour emission at 6.5–7 μm, which were absent in quiescence. By the end of our observing campaign, the burst was still ongoing, implying a duration of at least 2 months. A 2016 spectrum also shows high accretion levels, suggesting that this object may undergo recurring bursts. The observed event is inconsistent with typical variability in accreting young stars and instead matches the duration, amplitude, and line spectrum of an EXor-type burst, making Cha1107-7626 the first substellar object with evidence of a potentially recurring EXor burst.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145203698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Scaling Law for the Orbital Architecture of Planetary Systems Formed by Gravitational Scattering and Collisions 由引力散射和碰撞形成的行星系统轨道结构的标度律

The Astrophysical Journal Letters Pub Date : 2025-09-30 DOI: 10.3847/2041-8213/ae06fc

Eiichiro Kokubo, Haruka Hoshino, Yuji Matsumoto and Re’em Sari

{"title":"A Scaling Law for the Orbital Architecture of Planetary Systems Formed by Gravitational Scattering and Collisions","authors":"Eiichiro Kokubo, Haruka Hoshino, Yuji Matsumoto and Re’em Sari","doi":"10.3847/2041-8213/ae06fc","DOIUrl":"https://doi.org/10.3847/2041-8213/ae06fc","url":null,"abstract":"In the standard formation models of terrestrial planets in the solar system and close-in super-Earths in nonresonant orbits recently discovered by exoplanet observations, planets are formed by giant impacts of protoplanets or planetary embryos after the dispersal of protoplanetary disk gas in the final stage. This study aims to theoretically clarify a fundamental scaling law for the orbital architecture of planetary systems formed by giant impacts. In the giant impact stage, protoplanets gravitationally scatter and collide with one another to form planets. Using N-body simulations, we investigate the orbital architecture of planetary systems formed from protoplanet systems by giant impacts. As the orbital architecture parameters, we focus on the mean orbital separation between two adjacent planets and the mean orbital eccentricity of planets in a planetary system. We find that the orbital architecture is determined by the ratio of the two-body surface escape velocity of planets vesc to the Keplerian circular velocity vK, k = vesc/vK. The mean orbital separation and eccentricity are about 2ka and 0.3k, respectively, where a is the system semimajor axis. With this scaling, the orbital architecture parameters of planetary systems are nearly independent of their total mass and semimajor axis.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145195141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0