Pub Date : 2026-03-25DOI: 10.3847/1538-4357/ae4695
Archana Aravindan, Thomas Bohn, Gabriela Canalizo, Shobita Satyapal, Vivian U, Weizhe Liu, William Matzko, Sara Doan, Matthew Malkan, Lee Armus, Tohru Nagao, Tanio Diaz-Santos, Aditya Togi, Thomas S. Y. Lai, Sean T. Linden, Marina Bianchin, Yiqing Song, Loreto Barcos-Muñoz, Aaron Evans, Hanae Inami, Kirsten Larson, Sabrina Stierwalt and Jason Surace
We present the first spatially resolved investigation of near-infrared coronal lines in dwarf galaxies hosting active galactic nuclei (AGN), using JWST/NIRSpec integral field spectroscopy. Coronal lines (CLs), which are forbidden transitions from highly ionized species with ionization potentials up to 450 eV, act as sensitive tracers of the AGN ionizing continuum and feedback processes. Across four dwarf galaxies with ionized gas outflows traced by the optical [O III] lines, we report the detection of 16 unique species of near-infrared CLs. Line ratio diagnostics indicate that photoionization from the AGN dominates the excitation of CLs. We find that the coronal line region in dwarf galaxies, traced by the various CLs, extends up to 0.5 kpc, and can constitute up to 10% of the size of the host galaxy. Correlations between CL luminosities and the properties of [O III] ionized gas outflows are consistent with a scenario in which AGN-driven outflows likely facilitate the detection of CLs and contribute to their extent. Several CLs, including [Si VI], [Si VII], and [Mg VIII], exhibit a secondary broad component with W80 (the line width enclosing 80% of the total flux) >300 km s−1. If we interpret this spatially compact gas as part of an outflow, this would indicate that the outflowing gas includes a wide range of ionization states. The estimated energetics imply this highly ionized component is compact yet powerful enough to perturb gas in the central regions of the host dwarfs. These results indicate that AGN in low-mass galaxies may produce outflows capable of influencing their structure and evolution.
{"title":"Probing Active Galactic Nuclei-driven Feedback in Dwarf Galaxies with Spatially Resolved Near-infrared Coronal Lines from JWST","authors":"Archana Aravindan, Thomas Bohn, Gabriela Canalizo, Shobita Satyapal, Vivian U, Weizhe Liu, William Matzko, Sara Doan, Matthew Malkan, Lee Armus, Tohru Nagao, Tanio Diaz-Santos, Aditya Togi, Thomas S. Y. Lai, Sean T. Linden, Marina Bianchin, Yiqing Song, Loreto Barcos-Muñoz, Aaron Evans, Hanae Inami, Kirsten Larson, Sabrina Stierwalt and Jason Surace","doi":"10.3847/1538-4357/ae4695","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4695","url":null,"abstract":"We present the first spatially resolved investigation of near-infrared coronal lines in dwarf galaxies hosting active galactic nuclei (AGN), using JWST/NIRSpec integral field spectroscopy. Coronal lines (CLs), which are forbidden transitions from highly ionized species with ionization potentials up to 450 eV, act as sensitive tracers of the AGN ionizing continuum and feedback processes. Across four dwarf galaxies with ionized gas outflows traced by the optical [O III] lines, we report the detection of 16 unique species of near-infrared CLs. Line ratio diagnostics indicate that photoionization from the AGN dominates the excitation of CLs. We find that the coronal line region in dwarf galaxies, traced by the various CLs, extends up to 0.5 kpc, and can constitute up to 10% of the size of the host galaxy. Correlations between CL luminosities and the properties of [O III] ionized gas outflows are consistent with a scenario in which AGN-driven outflows likely facilitate the detection of CLs and contribute to their extent. Several CLs, including [Si VI], [Si VII], and [Mg VIII], exhibit a secondary broad component with W80 (the line width enclosing 80% of the total flux) >300 km s−1. If we interpret this spatially compact gas as part of an outflow, this would indicate that the outflowing gas includes a wide range of ionization states. The estimated energetics imply this highly ionized component is compact yet powerful enough to perturb gas in the central regions of the host dwarfs. These results indicate that AGN in low-mass galaxies may produce outflows capable of influencing their structure and evolution.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506464","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}
Pub Date : 2026-03-25DOI: 10.3847/1538-4357/ae47db
Feng Chen
We present the application of the data-driven branch of the MURaM code to the extensively studied flare-productive Active Region 11158. We refine the hybrid model strategy—which has been described in the earlier papers of this series—to model the emergence of the active region during 4 solar days, starting shortly before 2011 February 11 until the eruption of an X2.2 flare on 2011 February 15. After 4 days of evolution, a major eruption of a magnetic flux rope occurs in the simulation approximately 3 hr (3% difference) before the real flare. The eruption leads to magnetic reconnection, which contributes to bulk heating in the chromosphere and corona. The deposition of the flare energy in the chromosphere causes strong condensations and evaporations, which fill hot postflare loops and bright flare ribbons that exhibit separation and extension similar to the observed ribbon evolution. The synthesized soft-X-ray flux corresponds to the X class, which is close to the real event. The upward eruption of the flux rope leads to a piston-driven shock and horizontal expansion that exert a strong downward impact on the lower atmosphere and generate an apparently fast-propagating chromospheric Moreton wave. We conclude that the data-driven radiative simulation of this active region can reproduce the key observational results of the real flare and demonstrate the great potential of this method for studying solar eruptions in a realistic corona environment.
{"title":"Data-driven Radiative Magnetohydrodynamics Simulations with the MURaM Code: The Emergence of Active Region 11158 and the X2.2 Flare","authors":"Feng Chen","doi":"10.3847/1538-4357/ae47db","DOIUrl":"https://doi.org/10.3847/1538-4357/ae47db","url":null,"abstract":"We present the application of the data-driven branch of the MURaM code to the extensively studied flare-productive Active Region 11158. We refine the hybrid model strategy—which has been described in the earlier papers of this series—to model the emergence of the active region during 4 solar days, starting shortly before 2011 February 11 until the eruption of an X2.2 flare on 2011 February 15. After 4 days of evolution, a major eruption of a magnetic flux rope occurs in the simulation approximately 3 hr (3% difference) before the real flare. The eruption leads to magnetic reconnection, which contributes to bulk heating in the chromosphere and corona. The deposition of the flare energy in the chromosphere causes strong condensations and evaporations, which fill hot postflare loops and bright flare ribbons that exhibit separation and extension similar to the observed ribbon evolution. The synthesized soft-X-ray flux corresponds to the X class, which is close to the real event. The upward eruption of the flux rope leads to a piston-driven shock and horizontal expansion that exert a strong downward impact on the lower atmosphere and generate an apparently fast-propagating chromospheric Moreton wave. We conclude that the data-driven radiative simulation of this active region can reproduce the key observational results of the real flare and demonstrate the great potential of this method for studying solar eruptions in a realistic corona environment.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506466","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}
Pub Date : 2026-03-25DOI: 10.3847/1538-4357/ae47f3
Tokuhiro Nimura and Toshikazu Ebisuzaki
This paper presents a new terrestrial planet formation theory demonstrating that Earth-mass planets form naturally in tandem protosolar disks. Our model builds upon tandem planet formation theory, incorporating magneto-rotational instability (MRI) suppression, porous particle aggregation, and standard planet formation mechanisms. In a tandem protosolar disk, planets form at two distinct locations: the inner and outer edges of the MRI-suppressed region, where solid particles accumulate. The inner edge produces rocky planets, while the outer edge forms gas giants. When planetesimals reach Earth mass at the inner MRI edge, they migrate outward due to torques from the gas disk. For a protosolar disk accretion rate of (case D), the total solid mass at the inner MRI edge reaches 1.99 M⊕, producing two Earth-mass planets. This result closely matches the distribution of the terrestrial planets in the solar system: Earth and Venus together comprise 92% of the total mass of terrestrial planets, providing strong support for our proposed formation mechanism.
{"title":"Earth-mass Planets in Tandem Disks","authors":"Tokuhiro Nimura and Toshikazu Ebisuzaki","doi":"10.3847/1538-4357/ae47f3","DOIUrl":"https://doi.org/10.3847/1538-4357/ae47f3","url":null,"abstract":"This paper presents a new terrestrial planet formation theory demonstrating that Earth-mass planets form naturally in tandem protosolar disks. Our model builds upon tandem planet formation theory, incorporating magneto-rotational instability (MRI) suppression, porous particle aggregation, and standard planet formation mechanisms. In a tandem protosolar disk, planets form at two distinct locations: the inner and outer edges of the MRI-suppressed region, where solid particles accumulate. The inner edge produces rocky planets, while the outer edge forms gas giants. When planetesimals reach Earth mass at the inner MRI edge, they migrate outward due to torques from the gas disk. For a protosolar disk accretion rate of (case D), the total solid mass at the inner MRI edge reaches 1.99 M⊕, producing two Earth-mass planets. This result closely matches the distribution of the terrestrial planets in the solar system: Earth and Venus together comprise 92% of the total mass of terrestrial planets, providing strong support for our proposed formation mechanism.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"59 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506469","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}
Pub Date : 2026-03-25DOI: 10.3847/1538-4357/ae4a97
Nazma Islam, Koji Mukai, Maurice A. Leutenegger and Gabriel W. Pratt
Nonmagnetic cataclysmic variables (CVs) show two distinct X-ray components: a hard, optically thin component and a soft, optically thick, blackbody-like component, both produced in the boundary layer between the accretion disk and the white dwarf (WD). An additional soft component originating from a more extended region has been reported in a few CVs. In a short Chandra exposure, we identified a tentative X-ray eclipse in UU Aqr, a nonmagnetic CV that shows deep optical eclipses. Using observations with the Nuclear Spectroscopic Telescope Array (NuSTAR) and the XMM-Newton, we detect total eclipses in the orbital intensity profiles of this system in the hard X-ray band (3–10 keV with XMM and 3–25 keV with NuSTAR). However, the soft X-ray band (0.3–2.0 keV) shows no evidence of an eclipse. Detailed eclipse modeling, energy-resolved power spectral analysis, and broadband spectral modeling indicate that the hard absorbed X-ray emission originates from a compact region near the WD, such as a boundary layer, while the soft, unabsorbed, and un-eclipsed X-ray emission originates in an extended region. Neither scattering of hard X-rays nor colliding winds can account for the observed un-eclipsed soft emission. We instead propose that this component is produced by shocks within vertically extended, radiatively driven accretion-disk winds. We also provide new estimates on the emitting regions, mass, and radius of the WD and the donor star using eclipse modeling.
{"title":"Unveiling the X-Ray Properties of the Eclipsing Cataclysmic Variable UU Aqr: Spatially and Spectrally Resolved Two-component Emission","authors":"Nazma Islam, Koji Mukai, Maurice A. Leutenegger and Gabriel W. Pratt","doi":"10.3847/1538-4357/ae4a97","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4a97","url":null,"abstract":"Nonmagnetic cataclysmic variables (CVs) show two distinct X-ray components: a hard, optically thin component and a soft, optically thick, blackbody-like component, both produced in the boundary layer between the accretion disk and the white dwarf (WD). An additional soft component originating from a more extended region has been reported in a few CVs. In a short Chandra exposure, we identified a tentative X-ray eclipse in UU Aqr, a nonmagnetic CV that shows deep optical eclipses. Using observations with the Nuclear Spectroscopic Telescope Array (NuSTAR) and the XMM-Newton, we detect total eclipses in the orbital intensity profiles of this system in the hard X-ray band (3–10 keV with XMM and 3–25 keV with NuSTAR). However, the soft X-ray band (0.3–2.0 keV) shows no evidence of an eclipse. Detailed eclipse modeling, energy-resolved power spectral analysis, and broadband spectral modeling indicate that the hard absorbed X-ray emission originates from a compact region near the WD, such as a boundary layer, while the soft, unabsorbed, and un-eclipsed X-ray emission originates in an extended region. Neither scattering of hard X-rays nor colliding winds can account for the observed un-eclipsed soft emission. We instead propose that this component is produced by shocks within vertically extended, radiatively driven accretion-disk winds. We also provide new estimates on the emitting regions, mass, and radius of the WD and the donor star using eclipse modeling.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506473","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}
Pub Date : 2026-03-25DOI: 10.3847/1538-4357/ae4d0c
Christopher J. Lindsay, J. M. Joel Ong, 加冕 王, Sarbani Basu, Samuel Grunblatt and Marc Hon
Constraining stellar models using asteroseismic and spectroscopic observations is a powerful method for precisely determining the fundamental properties of stars in different kinematic components of our Galaxy. We use spectroscopy and individual oscillation mode frequencies to perform a homogeneous modeling study of eight evolved metal-poor stars enhanced in α-elements. We compare a full treatment of α-enhancement against an ad hoc correction to the total metallicity and show that the stellar properties inferred from asteroseismic modeling using both sets of models agree with each other. Additionally, we find that the uncertainties on stellar parameters derived from both α-enhanced modeling methods are comparable. This is in qualitative disagreement with existing works showing red giant ages constrained by only the global asteroseismic parameters to depend strongly on the opacities and abundances assumed in 1D modeling. We also show that the observed frequency of maximum oscillation power (νmax) is larger than the value predicted from applying the νmax scaling relation to the masses, radii, and temperatures inferred from the detailed modeling. This discrepancy is pronounced at low metallicities, consistent with recent findings indicating a breakdown of the νmax scaling relation for metal-poor stars. Understanding the extent to which the νmax scaling relation fails for low-metallicity solar-like oscillators through detailed modeling will enable more accurate mass and age determinations for hundreds of giant stars in the Galactic halo for which only global asteroseismic parameters are available.
{"title":"The Effect of Different Methods for Accounting for α-enhancement on the Asteroseismic Modeling of Metal-poor Stars","authors":"Christopher J. Lindsay, J. M. Joel Ong, 加冕 王, Sarbani Basu, Samuel Grunblatt and Marc Hon","doi":"10.3847/1538-4357/ae4d0c","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4d0c","url":null,"abstract":"Constraining stellar models using asteroseismic and spectroscopic observations is a powerful method for precisely determining the fundamental properties of stars in different kinematic components of our Galaxy. We use spectroscopy and individual oscillation mode frequencies to perform a homogeneous modeling study of eight evolved metal-poor stars enhanced in α-elements. We compare a full treatment of α-enhancement against an ad hoc correction to the total metallicity and show that the stellar properties inferred from asteroseismic modeling using both sets of models agree with each other. Additionally, we find that the uncertainties on stellar parameters derived from both α-enhanced modeling methods are comparable. This is in qualitative disagreement with existing works showing red giant ages constrained by only the global asteroseismic parameters to depend strongly on the opacities and abundances assumed in 1D modeling. We also show that the observed frequency of maximum oscillation power (νmax) is larger than the value predicted from applying the νmax scaling relation to the masses, radii, and temperatures inferred from the detailed modeling. This discrepancy is pronounced at low metallicities, consistent with recent findings indicating a breakdown of the νmax scaling relation for metal-poor stars. Understanding the extent to which the νmax scaling relation fails for low-metallicity solar-like oscillators through detailed modeling will enable more accurate mass and age determinations for hundreds of giant stars in the Galactic halo for which only global asteroseismic parameters are available.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506475","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}
Pub Date : 2026-03-25DOI: 10.3847/1538-4357/ae48ef
Mark Dodici, Scott Tremaine and Yanqin Wu
Stellar binaries in galactic centers are relevant to several observable phenomena, including hypervelocity stars, X-ray binaries, and mergers of stars and compact objects; however, we know little about the properties of these binaries. Past works have suggested that a small fraction of them should contract to a few stellar radii or collide due to the cooperation of stellar tides and the eccentricity oscillations induced by the strong tidal field of the central massive black hole. We revisit this model with several updates. We first argue that when a binary’s pericenter separation is driven down to a few stellar radii, diffusive excitation of stellar tides should quickly contract the orbit, saving the stars from collision. Instead, the stars should end up as a very tight binary. We then show that vector resonant relaxation and perturbations from passing stars—effects not included in past models—dramatically increase the prevalence of such encounters. In numerical experiments, we find that one in five binaries around 1 pc from Sgr A* should tidally contract in this way while still on the main sequence. This rate climbs to three in five around 0.01 pc, inward of which it plateaus. We briefly discuss observable implications of these results, with particular attention to young stellar binaries in the Galactic Center.
{"title":"Dynamical Evolution of Stellar Binaries in Galactic Centers","authors":"Mark Dodici, Scott Tremaine and Yanqin Wu","doi":"10.3847/1538-4357/ae48ef","DOIUrl":"https://doi.org/10.3847/1538-4357/ae48ef","url":null,"abstract":"Stellar binaries in galactic centers are relevant to several observable phenomena, including hypervelocity stars, X-ray binaries, and mergers of stars and compact objects; however, we know little about the properties of these binaries. Past works have suggested that a small fraction of them should contract to a few stellar radii or collide due to the cooperation of stellar tides and the eccentricity oscillations induced by the strong tidal field of the central massive black hole. We revisit this model with several updates. We first argue that when a binary’s pericenter separation is driven down to a few stellar radii, diffusive excitation of stellar tides should quickly contract the orbit, saving the stars from collision. Instead, the stars should end up as a very tight binary. We then show that vector resonant relaxation and perturbations from passing stars—effects not included in past models—dramatically increase the prevalence of such encounters. In numerical experiments, we find that one in five binaries around 1 pc from Sgr A* should tidally contract in this way while still on the main sequence. This rate climbs to three in five around 0.01 pc, inward of which it plateaus. We briefly discuss observable implications of these results, with particular attention to young stellar binaries in the Galactic Center.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506470","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}
Pub Date : 2026-03-25DOI: 10.3847/1538-4357/ae4c42
Isabel Medlock, Daisuke Nagai, Nir Mandelker, Volker Springel, Frank C. van den Bosch, Elad Zinger and Barry T. Chiang
Cold, dense streams of gas are predicted to penetrate deeply into massive (≳1012M⊙) halos at cosmic noon (z ∼ 4–2), fueling galaxies to sustain high star formation rates. We investigate the prevalence of such cold streams in TNG50 over the range z = 4–0, using a novel algorithm to automatically detect cold streams in simulated halos. We qualitatively and quantitatively characterize the geometric and physical properties of the detected streams over cosmic time. We find that cold streams are ubiquitous in massive halos at cosmic noon, occurring in >80% of such systems down to z = 1, before becoming rare by z = 0. At their peak prevalence (z = 2–1), streams are often found in roughly coplanar, three-stream configurations. These streams generally exhibit a dense and cool core, surrounded by a diffuse and warmer envelope. However, we find that, in TNG50, these streams typically disrupt in the outer halo and do not penetrate efficiently to the central galaxy, with the total mass inflow from streams peaking at z = 2. Our results underscore the importance of cold streams in fueling galaxies at early times, but they highlight the need for higher-resolution simulations to fully capture their survival and impact at later epochs. Future cosmological zoom-in simulations, with better resolution in the CGM, will be essential to resolve turbulent mixing layers and feedback–inflow interactions that determine whether cold streams can reach the galactic disk.
{"title":"Statistical Properties of Cold Streams in Massive Star-forming Halos in TNG50","authors":"Isabel Medlock, Daisuke Nagai, Nir Mandelker, Volker Springel, Frank C. van den Bosch, Elad Zinger and Barry T. Chiang","doi":"10.3847/1538-4357/ae4c42","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4c42","url":null,"abstract":"Cold, dense streams of gas are predicted to penetrate deeply into massive (≳1012M⊙) halos at cosmic noon (z ∼ 4–2), fueling galaxies to sustain high star formation rates. We investigate the prevalence of such cold streams in TNG50 over the range z = 4–0, using a novel algorithm to automatically detect cold streams in simulated halos. We qualitatively and quantitatively characterize the geometric and physical properties of the detected streams over cosmic time. We find that cold streams are ubiquitous in massive halos at cosmic noon, occurring in >80% of such systems down to z = 1, before becoming rare by z = 0. At their peak prevalence (z = 2–1), streams are often found in roughly coplanar, three-stream configurations. These streams generally exhibit a dense and cool core, surrounded by a diffuse and warmer envelope. However, we find that, in TNG50, these streams typically disrupt in the outer halo and do not penetrate efficiently to the central galaxy, with the total mass inflow from streams peaking at z = 2. Our results underscore the importance of cold streams in fueling galaxies at early times, but they highlight the need for higher-resolution simulations to fully capture their survival and impact at later epochs. Future cosmological zoom-in simulations, with better resolution in the CGM, will be essential to resolve turbulent mixing layers and feedback–inflow interactions that determine whether cold streams can reach the galactic disk.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506474","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}
Pub Date : 2026-03-25DOI: 10.3847/1538-4357/ae4a19
Marcel F. Corchado Albelo, Maria D. Kazachenko, Ryan J. French, Vadim M. Uritsky, Emily Mason, Cole A. Tamburri, Rahul Yadav and Benjamin J. Lynch
Recent three-dimensional flare models suggest that flare ribbon substructure is linked to the fragmentation of the reconnecting current sheet in the corona. Flare ribbon substructure can therefore potentially serve as a unique diagnostic tool for physical processes in the flare current sheet. In this paper, we describe a new method to quantify the evolution of ribbon substructure that first extracts the ribbon’s bright leading edge and then quantifies its morphology using the box-counting dimension and correlation dimension mapping (CDM). We first test our method using synthetic observations. We then apply it to an M6.5-class solar flare on 2015 June 22 observed by the Interface Region Imaging Spectrograph (IRIS) 1330 Å slit-jaw imager. We find that when the flare ribbon boundary has more multiple-spatial-scale features (a higher box-counting dimension), hard X-ray emission and magnetic reconnection rates are the strongest. We also find that the flare ribbon complexity characterized by CDM has a moderate correlation with the IRIS Si IV 1402.77 Å nonthermal velocity (in the negative polarity ribbon) and reconnection flux rates (in ribbons of both magnetic polarities). We conclude that the buildup of the spatial complexity of the ribbons at multiple spatial scales can serve as an observational proxy for current-sheet fragmentation in the corona.
最近的三维耀斑模型表明，耀斑带的亚结构与日冕中重新连接的电流片的破碎有关。因此，耀斑带子结构可以潜在地作为耀斑电流表中物理过程的独特诊断工具。本文描述了一种量化条带子结构演变的新方法，该方法首先提取条带的明亮前沿，然后利用盒数维数和相关维数映射（CDM）对其形态进行量化。我们首先用综合观察来检验我们的方法。然后，我们将其应用于2015年6月22日由界面区域成像光谱仪（IRIS） 1330 Å狭颚成像仪观测到的m6.5级太阳耀斑。研究发现，当耀斑带边界具有更多的多空间尺度特征（盒计数维数较高）时，硬x射线发射和磁重联率最强。我们还发现，用CDM表征的耀斑带复杂度与IRIS Si IV 1402.77 Å非热速度（在负极性带中）和重联通量率（在两个磁极性带中）有适度的相关性。我们的结论是，在多个空间尺度上带状空间复杂性的积累可以作为日冕中电流片破碎的观测代理。
{"title":"Evolution of Spatial Complexity in Flare Ribbon Substructure and Its Relationship to Magnetic Reconnection Dynamics","authors":"Marcel F. Corchado Albelo, Maria D. Kazachenko, Ryan J. French, Vadim M. Uritsky, Emily Mason, Cole A. Tamburri, Rahul Yadav and Benjamin J. Lynch","doi":"10.3847/1538-4357/ae4a19","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4a19","url":null,"abstract":"Recent three-dimensional flare models suggest that flare ribbon substructure is linked to the fragmentation of the reconnecting current sheet in the corona. Flare ribbon substructure can therefore potentially serve as a unique diagnostic tool for physical processes in the flare current sheet. In this paper, we describe a new method to quantify the evolution of ribbon substructure that first extracts the ribbon’s bright leading edge and then quantifies its morphology using the box-counting dimension and correlation dimension mapping (CDM). We first test our method using synthetic observations. We then apply it to an M6.5-class solar flare on 2015 June 22 observed by the Interface Region Imaging Spectrograph (IRIS) 1330 Å slit-jaw imager. We find that when the flare ribbon boundary has more multiple-spatial-scale features (a higher box-counting dimension), hard X-ray emission and magnetic reconnection rates are the strongest. We also find that the flare ribbon complexity characterized by CDM has a moderate correlation with the IRIS Si IV 1402.77 Å nonthermal velocity (in the negative polarity ribbon) and reconnection flux rates (in ribbons of both magnetic polarities). We conclude that the buildup of the spatial complexity of the ribbons at multiple spatial scales can serve as an observational proxy for current-sheet fragmentation in the corona.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506687","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}
Pub Date : 2026-03-25DOI: 10.3847/1538-4357/ae4a1f
Zahra Sattari, Daniel D. Kelson, Bahram Mobasher, Nima Chartab, Vihang Mehta, Harry I. Teplitz and Shannon G. Patel
We present a spectroscopic study of low-mass galaxies (LMGs;108 ≤ M*/M⊙ ≤ 109) at z ∼ 0.15 in the Cosmic Evolution Survey field, and compare it to a control sample of intermediate-mass galaxies (IMGs; 109 ≤ M*/M⊙ ≤ 1010) at z ∼ 0.35. We examine their star formation rates (SFRs), dust attenuation properties, and the relationship between nebular and stellar reddening. For both samples, SFRs derived from Hα are strongly correlated with SFRs from fitting simple star formation histories (SFHs) to the galaxies’ spectral energy distributions. In fitting a joint SFR–M* relation, we obtain a slope of , indicating that fair ensembles of SFHs for galaxies at these stellar masses are well described by scale-free, self-similar forms. We also examine their dust attenuation properties and the relationship between nebular and stellar reddening, exploring how these quantities vary with stellar mass and specific star formation rate (sSFR). Nebular attenuation increases with stellar mass for IMGs but is lower and less mass dependent in LMGs, consistent with their reduced dust content. In all cases, stellar continuum attenuation is lower than nebular attenuation, as expected from the two-component dust model. The nebular-to-stellar color excess ratio in both samples is consistent with the canonical factor of 2.27. The ratio is mass independent, but rises with sSFR in IMGs and remains constant in LMGs. These results suggest that in LMGs, efficient dispersal of birth clouds keeps the differential attenuation approximately constant across sSFR. Thus, although LMGs follow the same global SFR–M* scaling as massive galaxies, their lower dust content and feedback-maintained ISM produce distinct attenuation behavior relative to IMGs.
{"title":"Optical Spectroscopy of Dwarf Galaxies at z ∼ 0.15 in the COSMOS Field: Star Formation and Dust Properties","authors":"Zahra Sattari, Daniel D. Kelson, Bahram Mobasher, Nima Chartab, Vihang Mehta, Harry I. Teplitz and Shannon G. Patel","doi":"10.3847/1538-4357/ae4a1f","DOIUrl":"https://doi.org/10.3847/1538-4357/ae4a1f","url":null,"abstract":"We present a spectroscopic study of low-mass galaxies (LMGs;108 ≤ M*/M⊙ ≤ 109) at z ∼ 0.15 in the Cosmic Evolution Survey field, and compare it to a control sample of intermediate-mass galaxies (IMGs; 109 ≤ M*/M⊙ ≤ 1010) at z ∼ 0.35. We examine their star formation rates (SFRs), dust attenuation properties, and the relationship between nebular and stellar reddening. For both samples, SFRs derived from Hα are strongly correlated with SFRs from fitting simple star formation histories (SFHs) to the galaxies’ spectral energy distributions. In fitting a joint SFR–M* relation, we obtain a slope of , indicating that fair ensembles of SFHs for galaxies at these stellar masses are well described by scale-free, self-similar forms. We also examine their dust attenuation properties and the relationship between nebular and stellar reddening, exploring how these quantities vary with stellar mass and specific star formation rate (sSFR). Nebular attenuation increases with stellar mass for IMGs but is lower and less mass dependent in LMGs, consistent with their reduced dust content. In all cases, stellar continuum attenuation is lower than nebular attenuation, as expected from the two-component dust model. The nebular-to-stellar color excess ratio in both samples is consistent with the canonical factor of 2.27. The ratio is mass independent, but rises with sSFR in IMGs and remains constant in LMGs. These results suggest that in LMGs, efficient dispersal of birth clouds keeps the differential attenuation approximately constant across sSFR. Thus, although LMGs follow the same global SFR–M* scaling as massive galaxies, their lower dust content and feedback-maintained ISM produce distinct attenuation behavior relative to IMGs.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"405 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506471","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}
Pub Date : 2026-03-25DOI: 10.3847/1538-4357/ae34af
Vadim Bernshteyn, Nicholas S. Conroy, Michi Bauböck, Paul Tiede, Abhishek V. Joshi, Ben S. Prather, Charles F. Gammie, The Event Horizon Telescope Collaboration, Kazunori Akiyama, Ezequiel Albentosa-Ruíz, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Richard Anantua, Keiichi Asada, Rebecca Azulay, Anne-Kathrin Baczko, David Ball, Bidisha Bandyopadhyay, John Barrett, Bradford A. Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Katherine L. Bouman, Geoffrey C. Bower, Michael Bremer, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Douglas F. Carlos, John E. Carlstrom, Andrew Chael, Chi-kwan Chan, Dominic O. Chang, Koushik Chatterjee, Ming-Tang Chen, Yongjun Chen, 永军 陈, Xiaopeng Cheng, Paul Chichura, Ilje Cho, John E. Conway, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, 玉竹 崔, Brandon Curd, Rohan Dahale, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jason Dexter, Vedant Dh..
Event Horizon Telescope (EHT) images of the supermassive black hole M87* depict an asymmetric ring of emission. General relativistic magnetohydrodynamic (GRMHD) models of M87* and its accretion disk predict that the amplitude and location of the ring’s peak brightness asymmetry should fluctuate due to turbulence in the source plasma. We compare the observed distribution of brightness asymmetry amplitudes to the simulated distribution in GRMHD models, across varying black hole spin a*. We show that, for strongly magnetized (MAD) models, three epochs of EHT data marginally disfavor ∣a*∣ ≲ 0.2. This is consistent with the Blandford–Znajek model for M87’s jet, which predicts that M87* should have nonzero spin. We show quantitatively how future observations could improve spin constraints and discuss how improved spin constraints could distinguish between differing jet-launching mechanisms and black hole growth scenarios.
{"title":"Ring Asymmetry and Spin in M87*","authors":"Vadim Bernshteyn, Nicholas S. Conroy, Michi Bauböck, Paul Tiede, Abhishek V. Joshi, Ben S. Prather, Charles F. Gammie, The Event Horizon Telescope Collaboration, Kazunori Akiyama, Ezequiel Albentosa-Ruíz, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Richard Anantua, Keiichi Asada, Rebecca Azulay, Anne-Kathrin Baczko, David Ball, Bidisha Bandyopadhyay, John Barrett, Bradford A. Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Katherine L. Bouman, Geoffrey C. Bower, Michael Bremer, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Douglas F. Carlos, John E. Carlstrom, Andrew Chael, Chi-kwan Chan, Dominic O. Chang, Koushik Chatterjee, Ming-Tang Chen, Yongjun Chen, 永军 陈, Xiaopeng Cheng, Paul Chichura, Ilje Cho, John E. Conway, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, 玉竹 崔, Brandon Curd, Rohan Dahale, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jason Dexter, Vedant Dh..","doi":"10.3847/1538-4357/ae34af","DOIUrl":"https://doi.org/10.3847/1538-4357/ae34af","url":null,"abstract":"Event Horizon Telescope (EHT) images of the supermassive black hole M87* depict an asymmetric ring of emission. General relativistic magnetohydrodynamic (GRMHD) models of M87* and its accretion disk predict that the amplitude and location of the ring’s peak brightness asymmetry should fluctuate due to turbulence in the source plasma. We compare the observed distribution of brightness asymmetry amplitudes to the simulated distribution in GRMHD models, across varying black hole spin a*. We show that, for strongly magnetized (MAD) models, three epochs of EHT data marginally disfavor ∣a*∣ ≲ 0.2. This is consistent with the Blandford–Znajek model for M87’s jet, which predicts that M87* should have nonzero spin. We show quantitatively how future observations could improve spin constraints and discuss how improved spin constraints could distinguish between differing jet-launching mechanisms and black hole growth scenarios.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2026-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147506463","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}
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