The Astrophysical Journal最新文献

{"title":"Fractality of Magnetic Helicity Distribution in the Solar Corona","authors":"Anda Xiong, Shangbin Yang, Quan Wang and Xin Liu","doi":"10.3847/1538-4357/adaaed","DOIUrl":"https://doi.org/10.3847/1538-4357/adaaed","url":null,"abstract":"We find a universal power-law scaling of magnetic helicity distribution in the solar corona. Magnetic helicity is a dynamical invariant for ideal magnetohydrodynamics (MHD) and characterizes complex magnetic field structure by measuring the degree of knottiness of its field lines. We treat turbulent solar magnetic field as a superposition of random waves and develop a statistical topology method regarding the randomly tangled field lines. Based on the statistical behavior of the field lines, we consider their topology-specified structure and theoretically derive power laws for the distribution of magnetic flux and helicity. We find a power law of −7/4 to the magnetic helicity distribution when the field line topology is equivalent to handle and −5/4 when the field line topology is local open curve. We verify the universality of this new magnetic helicity fractality by observation to a number of 185 sunspots in newly emerging active regions during the 23rd and 24th solar cycle. This new distribution law reveals the fractal structure of the solar magnetic field.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"76 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451704","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":"MUSEQuBES: The Kinematics of O vi-bearing Gas in and around Low-redshift Galaxies","authors":"Sayak Dutta, Sowgat Muzahid, Joop Schaye, Sebastiano Cantalupo, Hsiao-Wen Chen and Sean Johnson","doi":"10.3847/1538-4357/adabbd","DOIUrl":"https://doi.org/10.3847/1538-4357/adabbd","url":null,"abstract":"We present a detailed study of the kinematics of O vi-bearing gas around 60 low-mass (median = 8.9) galaxies at low redshift (0.1 < z < 0.7) using background quasars (median impact parameter ≈115 kpc) as part of the MUSE Quasar-fields Blind Emitters Survey (MUSEQuBES). We find that the majority of the O vi absorbers detected within the virial radius have line-of-sight velocities smaller than the escape velocities and are thus consistent with being gravitationally bound, irrespective of the halo mass. However, the fraction of such absorbers declines at larger impact parameters. The Doppler b parameter and the velocity width (Δv90) of the O vi absorbers exhibit large scatter inside the virial radius of the host galaxies, but the scatter declines sharply at impact parameter D ≳ 2Rvir. For high-mass galaxies ( > 9), O vi absorption displays a larger kinematic spread, quantified by the pixel-velocity two-point correlation function (TPCF). However, the difference becomes marginal when the pixel velocities are scaled by the galaxies’ circular velocities. We do not find any significant difference between the TPCF of isolated and group galaxies when the stellar mass is controlled for. A significant fraction of groups (4/6) with four or more member galaxies do not show any detectable O vi absorption, likely due to the passive nature of the nearest galaxies.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143452192","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":"Comparison of Global H i and Hα Line Profiles in MaNGA Galaxy Pairs with FAST","authors":"Gaoxiang Jin, Y. Sophia Dai, Cheng Cheng, Cong Kevin Xu, Jia-Sheng Huang and Lihwai Lin","doi":"10.3847/1538-4357/ada935","DOIUrl":"https://doi.org/10.3847/1538-4357/ada935","url":null,"abstract":"We present case studies comparing the global H i and Hα emission line profiles of six galaxy pairs. The six pairs are selected to have different nuclear activities, with two hosting an active galactic nucleus, and in different merging stages—two of each from the premerging, merging, and postmerging stages. We observe their global H i spectra with the Five-hundred-meter Aperture Spherical radio Telescope, achieving a noise level of ~0.5 mJy. Five out of the six pair systems have secure detections of H i emissions (signal-to-noise ratio > 10). The H i fraction and star formation efficiency of the six pairs do not deviate from isolated galaxies. For the H i line profiles, common unique asymmetry is observed, indicating disturbances of the atomic gas from the galaxy interaction. The global Hα spectra of the merger systems are constructed from the optical integral field spectroscopic observations by integrating the flux in corresponding line-of-sight velocity bins. The Hα spectra tend to show multiple components in the premerger phase and single-component line profiles in the postmerger systems, while all H i spectra show single-component line profiles regardless of merger stages. The H i and Hα spectra show offsets in the central velocities, which appear to decrease from >100 km s−1 in the premerger pair to <10 km s−1 in the postmergers. This trend is consistent with the scenario that, despite the significantly different distributions and kinematics of the atomic and ionized gases, the merging process may contribute to the mixing and eventually align various gas contents.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143452141","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":"Multifrequency Models of Black Hole Photon Rings from Low-luminosity Accretion Disks","authors":"Tejahni Desire, Alejandro Cárdenas-Avendaño and Andrew Chael","doi":"10.3847/1538-4357/adac4d","DOIUrl":"https://doi.org/10.3847/1538-4357/adac4d","url":null,"abstract":"Images of black holes encode both astrophysical and gravitational properties. Detecting highly lensed features in images can differentiate between these two effects. We present an accretion disk emission model coupled to the Adaptive Analytical Ray Tracing (AART) code that allows a fast parameter space exploration of black hole photon ring images produced from synchrotron emission from 10 to 670 GHz. As an application, we systematically study several disk models and compute their total flux density, average radii, and optical depth. The model parameters are chosen around fiducial values calibrated to general relativistic magnetohydrodynamic (GRMHD) simulations and observations of M87*. For the parameter space studied, we characterize the transition between optically thin and thick regimes and the frequency at which the first photon ring is observable. Our results highlight the need for careful definitions of photon ring radius in the image domain, as in certain models the highly lensed photon ring is dimmer than the direct emission at certain angles. We find that at low frequencies the ring radii are set by the electron temperature, while at higher frequencies the magnetic field strength plays a more significant role, demonstrating how multifrequency analysis can also be used to infer plasma parameters. Lastly, we show how our implementation can qualitatively reproduce multifrequency black hole images from GRMHD simulations when adding time variability to our disk model through Gaussian random fields. This approach provides a new method for simulating observations from the Event Horizon Telescope and the proposed Black Hole Explorer space mission.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451657","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":"Study on the Responses in the Transition Region of Coronal Extreme-ultraviolet Waves","authors":"Xiaoqian Wang, Ruisheng Zheng, Yihan Liu, Xuechao Zhang, Liang Zhang, Jun Li and Yao Chen","doi":"10.3847/1538-4357/adb035","DOIUrl":"https://doi.org/10.3847/1538-4357/adb035","url":null,"abstract":"Coronal extreme-ultraviolet (EUV) waves are globally propagating disturbances in the solar atmosphere. The existence of coronal EUV waves was predicted by chromospheric Moreton–Ramsey waves. It is widely accepted that Moreton–Ramsey waves represent the chromospheric imprints of coronal EUV waves that compress downward during their lateral propagations. Hence, coronal EUV waves should inevitably compress the interlayer between the corona and the chromosphere, the transition region (TR), before reaching the chromosphere. However, the responses in the TR of coronal EUV waves lack enough attention. Here, we focus on the wave signatures in He ii 304 Å for a sample of 640 coronal EUV waves from 2010 to 2021, aiming to establish a “bridge” connecting coronal EUV waves and chromospheric Moreton–Ramsey waves. It is found that ∼14.4% of all coronal EUV waves have TR responses, and ∼34.5% of “disk events” with TR responses have chromospheric imprints. We specifically analyze the wave front characteristics of disk events with TR responses (58). Statistical analysis shows that TR responses for coronal EUV waves have an average speed of 495.58 ± 27.62 km s−1, an average duration of 488.4 ± 12 s, an average angular width of 71 22, and an average intensity enhancement ratio (IER) of 30.39%. Moreover, all TR responses with chromospheric imprints display a greater inclination angle (>50°) and a larger IER (>30%). All the results suggest that TR responses can be indicators of missing Moreton–Ramsey waves and clarify the resolution of the mystery of the rarity of Moreton–Ramsey waves.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451700","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":"Could the Neutrino Emission of TXS 0506+056 Come from the Accretion Flow of the Supermassive Black Hole?","authors":"Qi-Rui Yang, Ruo-Yu Liu and Xiang-Yu Wang","doi":"10.3847/1538-4357/adaea4","DOIUrl":"https://doi.org/10.3847/1538-4357/adaea4","url":null,"abstract":"High-energy neutrinos from the blazar TXS 0506+056 are usually thought to arise from the relativistic jet pointing to us. However, the composition of jets of active galactic nuclei (AGNs), whether they are baryon dominated or Poynting flux dominated, is largely unknown. In the latter case, no comic rays and neutrinos would be expected from the AGN jets. In this work, we study whether the neutrino emission from TXS 0506+056 could be powered by the accretion flow of the supermassive black hole. Protons could be accelerated by magnetic reconnection or turbulence in the inner accretion flow. To explain the neutrino flare of TXS 0506+056 in the years 2014–2015, a super-Eddington accretion is needed. During the steady state, a sub-Eddington accretion flow could power a steady neutrino emission that may explain the long-term neutrino flux from TXS 0506+056. We consider the neutrino production in both magnetically arrested accretion (MAD) flow and the standard and normal evolution (SANE) regime of accretion. In the MAD scenario, due to a high magnetic field, a large dissipation radius is required to avoid the cooling of protons and secondary pions.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143451833","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":"LEIA Discovery of the Longest-lasting and Most Energetic Stellar X-Ray Flare Ever Detected","authors":"Xuan Mao, He-Yang Liu, Song Wang, Zhixing Ling, Weimin Yuan, Huaqing Cheng, Haiwu Pan, Dongyue Li, Fabio Favata, Tuo Ji, Jujia Zhang, Xinlin Zhao, Jing Wang, Mingjun Liu, Yuan Liu, Zhiming Cai, Alberto J. Castro-Tirado, Yanfeng Dai, Licai Deng, Xu Ding, Kaifan Ji, Chichuan Jin, Yajuan Lei, Huali Li, Jun Lin, Huaqiu Liu, Shuai Liu, Hui Sun, Shengli Sun, Xiaojin Sun, Jianrong Shi, Jianguo Wang, Jingxiu Wang, Wenxin Wang, Jianyan Wei, Liping Xin, Dingrong Xiong, Chen Zhang, Wenda Zhang, Yonghe Zhang, Xiaofeng Zhang, Donghua Zhao and Guiping Zhou","doi":"10.3847/1538-4357/ada698","DOIUrl":"https://doi.org/10.3847/1538-4357/ada698","url":null,"abstract":"The Lobster Eye Imager for Astronomy (LEIA) detected a new X-ray transient on 2022 November 7, identified as a superflare event occurring on a nearby K-type giant star HD 251108. The flux increase was also detected in follow-up observations at X-ray, UV, and optical wavelengths. The flare lasted for about 40 days in soft X-ray observations, reaching a peak luminosity of ∼1.1 × 1034 erg s−1 in 0.5–4.0 keV, which is roughly 60 times the quiescent luminosity. Optical brightening was observed for only one night. The X-ray light curve is well described by a double fast rise and exponential decay model, attributed to the cooling process of a loop arcade structure formed subsequent to the initial large loop with a half-length of ∼1.9 × 1012 cm. Time-resolved X-ray spectra were fitted by a four-temperature apec model (with three components being the quiescent background), showing significant evolution of plasma temperature and emission measure over time. The estimated energy released in the LEIA band is ∼3 × 1039 erg, suggesting that this is likely the most energetic X-ray stellar flare with the longest duration detected to date.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143452053","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":"Turbulence and Magnetic Field Alignment in Small Molecular Clouds: The Role of Cloud Size, Mass, and Density","authors":"Bhaskarjyoti Barman, Himadri Sekhar Das and Pritibhajan Byakti","doi":"10.3847/1538-4357/ada562","DOIUrl":"https://doi.org/10.3847/1538-4357/ada562","url":null,"abstract":"In this study, we investigate the relationship between turbulence (ΔV) and different physical parameters in 22 isolated small molecular clouds and their cores, extending the analysis to a hierarchical scenario from core to cloud. Using 12CO line width as a tracer of turbulence, we find that ΔV correlates with both cloud size and mass, following and . Further, the surface density of the clouds (Σcl) influences the ΔV–Lcl relation, with . This indicates that gravitational energy drives turbulence in clouds, indicating possible virial equilibrium. We observe that Lcl correlates with Mcl and volume gas density of the cloud (ρcl), implying nearly constant Σcl across the clouds. In cloud cores, C18O line-width data show complex behavior, with no direct correlation between ΔV and core size (Lco). However, a positive correlation emerges when the surface density of the core is included in Lco. Notably, the relation between volume gas density (ρco) and core size (Lco) deviates from constant core surface density. Our analysis reveals that turbulent pressure increases with gravitational pressure to maintain global equilibrium. Finally, on the core-to-cloud scale, physical relationships remain continuous, reflecting the interconnected nature of clouds and cores. Extending our previous work, where we demonstrated a nonlinear dependence of turbulence on the alignment of the local magnetic field in molecular clouds with the Galactic plane, we now compare observations with a theoretical model based on kinetic theory. Our result confirms that higher turbulence causes greater magnetic misalignment consistent with the derived second-order polynomial relationship.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443229","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":"Modeling Tidal Streams and Tidal Tails around Galaxies Using Deep Wendelstein Imaging Data","authors":"Jan-Niklas Pippert, Matthias Kluge and Ralf Bender","doi":"10.3847/1538-4357/adabda","DOIUrl":"https://doi.org/10.3847/1538-4357/adabda","url":null,"abstract":"From the Λ cold dark matter paradigm, it is expected that galaxies merge and grow in their environments. These processes form various tidal features depending on the merger mass ratio, orbital parameters, and gas richness. We inspected 170 -band Abell cluster observations from the 2.1 m Fraunhofer-Teleskop Wendelstein and identify 111 of such features from which we select nine streams and five tails. A fast and innovative technique was developed for determining their photometric properties. The model is a Gaussian, including higher-order moments to describe the light profile in slices perpendicular to the elongation direction. From these models, FWHM apertures are generated. The method was developed, tested, and applied on the selected features and corresponding g- and r-band data from the Legacy Survey DR10. Regarding the novel modeling approach, we can measure surface and total brightnesses with precisions of 4% and 7%, respectively. Mean stream width precision, which also translates to the mean Re along the feature is on average within 3% uncertainty. The measured streams have on average a surface brightness of mag arcsec−2 and are dimmer than the tails in our sample ( mag arcsec−2). We infer that the progenitors of our streams can come from dwarfs, early-type galaxies or disks, based on the streams structural parameters. Furthermore, brightnesses and colors of the streams and tails are consistent with those of galaxies that populate the red sequence in the Coma cluster within 2σ.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"209 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443234","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 AURORA Survey: A New Era of Emission-line Diagrams with JWST/NIRSpec","authors":"Alice E. Shapley, Ryan L. Sanders, Michael W. Topping, Naveen A. Reddy, Danielle A. Berg, Rychard J. Bouwens, Gabriel Brammer, Adam C. Carnall, Fergus Cullen, Romeel Davé, James S. Dunlop, Richard S. Ellis, N. M. Förster Schreiber, Steven R. Furlanetto, Karl Glazebrook, Garth D. Illingworth, Tucker Jones, Mariska Kriek, Derek J. McLeod, Ross J. McLure, Desika Narayanan, Pascal Oesch, Anthony J. Pahl, Max Pettini, Daniel Schaerer, Daniel P. Stark, Charles C. Steidel, Mengtao Tang, Leonardo Clarke, Callum T. Donnan and Emily Kehoe","doi":"10.3847/1538-4357/adad68","DOIUrl":"https://doi.org/10.3847/1538-4357/adad68","url":null,"abstract":"We present results on the emission-line properties of z = 1.4–7.5 star-forming galaxies in the Assembly of Ultradeep Rest-optical Observations Revealing Astrophysics (AURORA) Cycle 1 JWST/NIRSpec program. Based on its depth, continuous wavelength coverage from 1 to 5 μm, and medium spectral resolution (R ∼ 1000), AURORA includes detections of a large suite of nebular emission lines spanning a broad range in rest-frame wavelength. We investigate the locations of AURORA galaxies in multiple different emission-line diagrams, including traditional BPT diagrams of [O iii]λ5007/Hβ versus [N ii]λ6583/Hα, [S ii]λλ6717, 6731/Hα, and [O i]λ6300/Hα, and the ionization–metallicity diagram of [O iii]λ5007/[O ii]λ3727 (O32) versus ([O iii]λ5007+[O ii]λ3727)/Hβ (R23). We also consider a bluer rest-frame ionization–metallicity diagram introduced recently to characterize z > 10 galaxies, [Ne iii]λ3869/[O ii]λ3727 versus ([Ne iii]λ3869+[O ii]λ3727)/Hδ, as well as longer-wavelength diagnostic diagrams extending into the rest-frame near-IR: [O iii]λ5007/Hβ versus [S iii]λλ9069, 9532/[S ii]λλ6717, 6731 (S32), and He iλ1.083 μm/Paγ and [S iii]λ9532/Paγ versus [Fe ii]λ1.257μm/Paβ. With a significant boost in signal-to-noise ratio and large, representative samples of individual galaxy detections, the AURORA emission-line diagrams presented here definitively confirm a physical picture in which chemically young, α-enhanced, massive stars photoionize the interstellar medium (ISM) in distant galaxies with a harder ionizing spectrum at fixed nebular metallicity than in their z ∼ 0 counterparts. We also uncover previously unseen evolution prior to z ∼ 2 in the [O iii]λ5007/Hβ versus [N ii]λ6583/Hα diagram, which motivates deep NIRSpec observations at even higher redshift. Finally, we present the first statistical sample of rest-frame near-IR emission-line diagnostics in star-forming galaxies at high redshift. In order to truly interpret rest-frame near-IR line ratios including [Fe ii]λ1.257 μm, we must obtain better constraints on dust depletion in the high-redshift ISM.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443235","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}