The Astrophysical Journal Letters最新文献

{"title":"Decay of Turbulent Upper-hybrid Waves in Weakly Magnetized Solar Wind Plasmas","authors":"F. J. Polanco-Rodríguez, C. Krafft and P. Savoini","doi":"10.3847/2041-8213/adba64","DOIUrl":"https://doi.org/10.3847/2041-8213/adba64","url":null,"abstract":"Large-scale and long-term two-dimensional particle-in-cell simulations of high resolution are performed for the first time to study the dynamics of electrostatic decay of upper-hybrid wave turbulence generated by electron beams into Langmuir/ -mode ( ) waves in weakly to moderately magnetized plasmas, in conditions relevant to type III solar radio bursts. Simulations use parameters characteristic of beam–plasma interactions between ∼0.1 and 1 au. The impact of plasma magnetic field on decay is shown, and magnetic properties of waves are determined. During their energy transport through k wavevector scales, waves undergo several decay cascades, acquiring increasing magnetic energy until they reach electromagnetic -mode dispersion below the plasma frequency. Whereas the impact of magnetic field on decaying waves of large k = ∣k∣ is weak, important differences with respect to the unmagnetized plasma case manifest at small k-scales, where a boundary layer delimiting a spectral domain free of energy is revealed. It prevents decayed waves from reaching the -mode cutoff frequency and a high level of left-handed polarization, and it modifies the conditions for the appearance of modulational instabilities and strong turbulence phenomena at k ∼ 0. Ordinary -mode waves are generated jointly with -mode waves at comparable energy levels, via electromagnetic decay, whereas -mode emissions are much weaker in most cases. These results provide support for the interpretation of observations by satellites such as Parker Solar Probe and Solar Orbiter, and they supply a solid basis for tackling the more complex problem of dynamics of upper-hybrid wave turbulence in magnetized plasmas where random density fluctuations cannot be neglected.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143666020","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}

{"title":"A Massive H i-absorption-selected Galaxy at z ≈ 2.356","authors":"B. Kaur, N. Kanekar, M. Neeleman, Y. Zhu, J. X. Prochaska, M. Rafelski and G. Becker","doi":"10.3847/2041-8213/adb83d","DOIUrl":"https://doi.org/10.3847/2041-8213/adb83d","url":null,"abstract":"We use the Karl G. Jansky Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array to detect CO(1–0), CO(3–2), and rest-frame 349 GHz continuum emission from an H i-selected galaxy, DLA1020+2733g, at z ≈ 2.3568 in the field of the z = 2.3553 damped Lyα absorber (DLA) toward QSO J1020+2733. The VLA CO(1–0) detection yields a molecular gas mass of (2.84 ± 0.42) × 1011 × (αCO/4.36) M⊙, the largest ever measured in an H i-selected galaxy. The DLA metallicity is +0.28 ± 0.16, from the Zn iiλ2026 absorption line detected in a Keck Echellette Spectrograph and Imager spectrum. This continues the trend of high-metallicity DLAs being frequently associated with massive galaxies. We obtain a star formation rate (SFR) of ≲400 M⊙ yr−1 from the rest-frame 349 GHz continuum emission and a relatively long molecular gas depletion timescale of ≳0.6 Gyr. The excitation of the J = 3 rotational level is subthermal, with , suggesting that DLA1020+2733g has a low SFR surface density. The large velocity spread of the CO lines, ≈500 km s−1, and the long molecular gas depletion timescale suggest that DLA1020+2733g is likely to be a cold rotating-disk galaxy.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661405","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}

{"title":"3D MC. I. X-Ray Tomography Begins to Unravel the 3D Structure of a Molecular Cloud in our Galaxy’s Center","authors":"Samantha W. Brunker, Cara Battersby, Danya Alboslani, Maïca Clavel, Daniel L. Walker, Dani Lipman, H Perry Hatchfield and Régis Terrier","doi":"10.3847/2041-8213/adba5e","DOIUrl":"https://doi.org/10.3847/2041-8213/adba5e","url":null,"abstract":"Astronomers have used observations of the Galactic gas and dust via infrared, microwave, and radio to study molecular clouds in extreme environments such as the Galactic center. More recently, X-ray telescopes have opened up a new wavelength range in which to study these molecular clouds. Previous flaring events from Sgr A* propagate X-rays outwards in all directions, and these X-rays interact with the surrounding molecular gas, illuminating different parts of the clouds over time. We use a combination of X-ray observations from Chandra and molecular gas tracers (line data from Herschel and the Submillimeter Array) to analyze specific features in the Sticks cloud, one of three clouds in the Three Little Pigs system in the Central Molecular Zone (Galactic longitude and latitude of 0 106 and −0 082 respectively). We also present a novel X-ray tomography method we used to create 3D map of the Sticks cloud. By combining X-ray and molecular tracer observations, we are able to learn more about the environment inside the Sticks cloud.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661485","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}

{"title":"Upper Limits on the Mass of Cool Gas in the Circumgalactic Medium of Dwarf Galaxies","authors":"Yakov Faerman, Yong Zheng, 永 郑 and Benjamin D. Oppenheimer","doi":"10.3847/2041-8213/adba51","DOIUrl":"https://doi.org/10.3847/2041-8213/adba51","url":null,"abstract":"We use H i absorption measurements to constrain the amount of cool (≈104 K), photoionized gas in the circumgalactic medium (CGM) of dwarf galaxies with M* = 106.5−9.5M⊙ in the nearby Universe (z < 0.3). We show analytically that volume-filling gas gives an upper limit on the gas mass needed to reproduce a given H i column density profile. We introduce a power-law density profile for the gas distribution and fit our model to archival H i observations to infer the cool CGM gas mass, McCGM, as a function of halo mass. For volume-filling (fV = 1) models, we find McCGM = 5 × 108–2 × 109M⊙, constituting ≲10% of the halo baryon budget. For clumpy gas, with fV = 0.01, the masses are a factor of ≈11 lower, in agreement with our analytic approximation. Our assumption that the measured H i forms entirely in the cool CGM provides a conservative upper limit on McCGM, and possible contributions from the intergalactic medium or warm/hot CGM will further strengthen our result. We estimate the mass uncertainties due to the range of redshifts in our sample and the unknown gas metallicity to be ≈15% and ≈10%, respectively. Our results show that dwarf galaxies have only ≲15% of their baryon budget in stars and the cool CGM, with the rest residing in the warm/hot CGM or ejected from the dark matter halos.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"70 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661480","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}

{"title":"Natural Generation of Alfvén Waves from Three-dimensional Bursty Interchange Magnetic Reconnection in the Solar Corona","authors":"Liping Yang, Jiansen He, Xueshang Feng, Daniel Verscharen, Fan Guo, Hui Li, Hui Tian, Wenya Li, Fang Shen, Chuanpeng Hou, Mijie Shi, Honghong Wu and Ming Xiong","doi":"10.3847/2041-8213/adb8ce","DOIUrl":"https://doi.org/10.3847/2041-8213/adb8ce","url":null,"abstract":"Alfvén waves play a significant role in solar coronal heating, solar wind acceleration, and Alfvénic turbulence formation. As a fundamental process, magnetic reconnection has long been credited as a crucial source of Alfvén waves. However, how magnetic reconnection triggers Alfvén waves remains unclear. Here, employing high-resolution simulations of three-dimensional bursty interchange magnetic reconnection in the solar corona, we unveil that Alfvén waves are spontaneously excited in the reconnecting current sheet and propagate bidirectionally, mainly along unreconnected magnetic fields. Generated by the transient reconnection events, flux ropes with enhanced total pressure persistently displace the magnetic fields in their surrounding, launching the observed large-amplitude and quasi-linearly polarized Alfvén waves, which carry substantial energy for heating the quiet corona and accelerating the solar wind. Our findings underscore the natural association between Alfvén waves and intermittent magnetic reconnection, which can be generalized to various plasma systems in astrophysical and laboratorial environments.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143653949","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}

{"title":"Emergence of cHz Quasiperiodic Oscillations from a Low-angular-momentum Flow onto a Supermassive Black Hole","authors":"Indu K. Dihingia and Yosuke Mizuno","doi":"10.3847/2041-8213/adbc6d","DOIUrl":"https://doi.org/10.3847/2041-8213/adbc6d","url":null,"abstract":"Quasiperiodic oscillations (QPOs) are very common in black hole accretion systems that are seen from the modulations in luminosity. Many supermassive black hole sources (e.g., RE J1034+396, 1H 0707-495, MCG-6-30-15, 1ES 1927+654, Sgr A*) have been observed to exhibit QPO-like variability in the range of mHz in different energy bands (e.g., radio, near-IR, X-rays). Due to the shorter infalling time, low-angular-momentum accretion flows can have resonance close to the black hole, which will raise variability cHz or beyond QPOs for supermassive black holes. In this study, for the first time, we show that such resonance conditions can be achieved in simulations of low-angular-momentum accretion flows onto a black hole. The QPOs could have values beyond νQPO ≳ 0.1–1 × 107M⊙/MBH cHz and the harmonics have a ratio of 2:1. Hunting these cHz QPOs down will provide a smoking gun signature for the presence of low-angular-momentum accretion flows around black holes (e.g., Sgr A*, 1ES 1927+654).","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661488","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}

{"title":"The Large-scale Structure Supplies the Formation of Gas-star Misaligned Galaxies","authors":"Min Bao, Yanmei Chen, Qiusheng Gu, Huiyuan Wang, Yong Shi and Peng Wang","doi":"10.3847/2041-8213/adbc68","DOIUrl":"https://doi.org/10.3847/2041-8213/adbc68","url":null,"abstract":"Using the integral field unit data from the Mapping Nearby Galaxies at Apache Point Observatory survey, we build a sample of gas-star misaligned galaxies. The large-scale environment of misaligned galaxies is dominated by filaments and clusters, while it is less dense relative to the gas-star aligned control galaxies. The direction of the large-scale structure (LSS) is defined by its minor axis ( ), which indicates the slowest collapsing direction. For the aligned controls, the gas and stellar spins are preferentially perpendicular to , since these galaxies reside in high-mass host halos. For the misaligned galaxies, the gas spins also tend to be perpendicular to , suggesting that misaligned gas is recently accreted from the LSS. Meanwhile, there is no correlation between their stellar spins and . There are two possible explanations for this observational phenomenon: (1) the large-scale environments of misaligned galaxies evolve as they grow, with stellar angular momenta acquired in different environments having different orientations; (2) the correlation between stellar spins and the LSS is smeared out since a relatively higher portion of misaligned galaxies in sheet environments are statistically analyzed together with those in filament environments.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661489","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}

{"title":"Calibration of Complementary Metal-oxide-semiconductor Sensor–based Photometry to a Few-millimagnitude Precision: The Case of the Mini-SiTian Array","authors":"Kai Xiao, Yang Huang, Haibo Yuan, Zhirui Li, Yongkang Sun, Timothy C. Beers, Min He, Jifeng Liu, Hong Wu, Yongna Mao, Bowen Huang, Mingyang Ma, Chuanjie Zheng, Hongrui Gu, Beichuan Wang, Lin Yang and Shuai Xu","doi":"10.3847/2041-8213/adbd3c","DOIUrl":"https://doi.org/10.3847/2041-8213/adbd3c","url":null,"abstract":"We present a pioneering achievement in the high-precision photometric calibration of CMOS-based photometry, by application of the Gaia Blue Photometer or Red Photometer (XP) spectra–based synthetic photometry method to the mini-SiTian array (MST) photometry. Through 79 repeated observations of the f02 field on the night, we find good internal consistency in the calibrated MST GMST-band magnitudes for relatively bright stars, with a precision of about 4 mmag for GMST ∼ 13. Results from more than 30 different nights (over 3100 observations) further confirm this internal consistency, indicating that the 4 mmag precision is stable and achievable over timescales of months. An independent external validation using spectroscopic data from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope DR10 and high-precision photometric data using CCDs from Gaia DR3 reveals a zero-point consistency better than 1 mmag. Our results clearly demonstrate that CMOS photometry is on par with CCD photometry for high-precision results, highlighting the significant capabilities of CMOS cameras in astronomical observations, especially for large-scale telescope survey arrays.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661487","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}

{"title":"Constraining the Cosmic-Ray Energy Based on Observations of Nearby Galaxy Clusters by LHAASO","authors":"Zhen Cao, F. Aharonian, Y. X. Bai, Y. W. Bao, D. Bastieri, X. J. Bi, Y. J. Bi, W. Bian, A. V. Bukevich, C. M. Cai, W. Y. Cao, Zhe Cao, J. Chang, J. F. Chang, A. M. Chen, E. S. Chen, H. X. Chen, Liang Chen, Long Chen, M. J. Chen, M. L. Chen, Q. H. Chen, S. Chen, S. H. Chen, S. Z. Chen, T. L. Chen, X. B. Chen, X. J. Chen, Y. Chen, N. Cheng, Y. D. Cheng, M. C. Chu, M. Y. Cui, S. W. Cui, X. H. Cui, Y. D. Cui, B. Z. Dai, H. L. Dai, Z. G. Dai, Danzengluobu, Y. X. Diao, X. Q. Dong, K. K. Duan, J. H. Fan, Y. Z. Fan, J. Fang, J. H. Fang, K. Fang, C. F. Feng, H. Feng, L. Feng, S. H. Feng, X. T. Feng, Y. Feng, Y. L. Feng, S. Gabici, B. Gao, C. D. Gao, Q. Gao, W. Gao, W. K. Gao, M. M. Ge, T. T. Ge, L. S. Geng, G. Giacinti, G. H. Gong, Q. B. Gou, M. H. Gu, F. L. Guo, J. Guo, X. L. Guo, Y. Q. Guo, Y. Y. Guo, Y. A. Han, O. A. Hannuksela, M. Hasan, H. H. He, H. N. He, J. Y. He, X. Y. He, Y. He, S. Hernández-Cadena, Y. K. Hor, B. W. Hou, C. Hou, X. Hou, H. B. Hu, S. C. Hu, C. Huang, D. H. Hua..","doi":"10.3847/2041-8213/adb97d","DOIUrl":"https://doi.org/10.3847/2041-8213/adb97d","url":null,"abstract":"Galaxy clusters act as reservoirs of high-energy cosmic rays (CRs). As CRs propagate through the intracluster medium, they generate diffuse γ-rays detectable by arrays such as LHAASO. These γ-rays result from proton–proton (pp) collisions of very high-energy cosmic rays or inverse Compton (IC) scattering of positron-electron pairs created by pγ interactions of ultra-high-energy cosmic rays (UHECRs). We analyzed diffuse γ-ray emission from the Coma, Perseus, and Virgo clusters using LHAASO data. Diffuse emission was modeled as a disk of radius R500 for each cluster while accounting for point sources. No significant diffuse emission was detected, yielding 95% confidence level (C.L.) upper limits on the γ-ray flux: for WCDA (1–25 TeV) and KM2A (>25 TeV), less than (49.4, 13.7, 54.0) and (1.34, 1.14, 0.40) × 10−14 ph cm−2 s−1 for Coma, Perseus, and Virgo, respectively. The γ-ray upper limits can be used to derive model-independent constraints on the integral energy of cosmic ray protons above 10 TeV (corresponding to the LHAASO observational range >1 TeV under the pp scenario) to be less than (1.96, 0.59, 0.08) × 1061 erg. The absence of detectable annuli/ring-like structures, indicative of cluster accretion or merging shocks, imposes further constraints on models in which the UHECRs are accelerated in the merging shocks of galaxy clusters.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143653950","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}

{"title":"The First Chemical Census of the Milky Way’s Nuclear Star Cluster","authors":"Govind Nandakumar, Nils Ryde, Mathias Schultheis, R. Michael Rich, Paola di Matteo, Brian Thorsbro and Gregory Mace","doi":"10.3847/2041-8213/adbb6d","DOIUrl":"https://doi.org/10.3847/2041-8213/adbb6d","url":null,"abstract":"An important step in understanding the formation and evolution of the nuclear star cluster (NSC) is to investigate its chemistry and chemical evolution. Additionally, exploring the NSC’s relationship to the other structures in the Galactic center and the Milky Way disks is of great interest. Extreme optical extinction has previously prevented optical studies, but near-IR high-resolution spectroscopy is now possible. Here, we present a detailed chemical abundance analysis of 19 elements—more than 4 times as many as previously published—for nine stars in the NSC of the Milky Way, observed with the Immersion GRating INfrared Spectrometer on the Gemini South telescope. This study provides new, crucial observational evidence to shed light on the origin of the NSC. We demonstrate that it is possible to probe a variety of nucleosynthetic channels, reflecting different chemical evolution timescales. Our findings reveal that the NSC trends for the elements F, Mg, Al, Si, S, K, Ca, Ti, Cr, Mn, Co, Ni, Cu, and Zn, as well as for the s-process elements Ba, Ce, Nd, and Yb, generally follow the inner-bulge trends within uncertainties. This suggests a likely shared evolutionary history, and our results indicate that the NSC population is consistent with the chemical sequence observed in the inner Galaxy (the inner-disk sequence). However, we identify a significant and unexplained difference in the form of higher Na abundances in the NSC compared to the inner bulge. This is also observed in few Galactic globular clusters and may suggest a common enrichment process at work in all these systems.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":"51 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143635262","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}