Astronomy & Astrophysics最新文献

{"title":"Little impact of mergers and galaxy morphology on the production and escape of ionizing photons in the early Universe","authors":"S. Mascia, L. Pentericci, M. Llerena, A. Calabrò, J. Matthee, S. Flury, F. Pacucci, A. Jaskot, R. O. Amorín, R. Bhatawdekar, M. Castellano, N. Cleri, L. Costantin, K. Davis, C. Di Cesare, M. Dickinson, A. Fontana, Y. Guo, M. Giavalisco, B. W. Holwerda, W. Hu, M. Huertas-Company, Intae Jung, J. Kartaltepe, D. Kashino, A. M. Koekemoer, R. A. Lucas, J. Lotz, L. Napolitano, S. Jogee, S. Wilkins","doi":"10.1051/0004-6361/202553760","DOIUrl":"https://doi.org/10.1051/0004-6361/202553760","url":null,"abstract":"Compact, star-forming galaxies with high star formation rate surface densities (Σ<sub>SFR<sub/>) are often efficient Lyman continuum (LyC) emitters at <i>z<i/> ≤ 4.5, likely because intense stellar feedback creates low-density channels that allow photons to escape. Irregular or disturbed morphologies, such as those resulting from mergers, can also facilitate LyC escape by creating anisotropic gas distributions. We investigated the influence of galaxy morphology on LyC production and escape at redshifts 5 ≤ <i>z<i/> ≤ 7 using observations from various <i>James Webb Space Telescope<i/> (JWST) surveys. Our sample consists of 436 sources, which are predominantly low-mass (∼10<sup>8.15<sup/> <i>M<i/><sub>⊙<sub/>), star-forming galaxies with ionizing photon efficiency (<i>ξ<i/><sub>ion<sub/>) values consistent with canonical expectations. Since direct measurements of <i>f<i/><sub>esc<sub/> are not possible during the Epoch of Reionization (EoR), we predicted <i>f<i/><sub>esc<sub/> for high-redshift galaxies by applying survival analysis to a subsample of LyC emitters from the Low-Redshift Lyman Continuum Survey (LzLCS), selected to be direct analogs of reionization-era galaxies. We find that these galaxies exhibit, on average, modest predicted escape fractions (∼0.04). In addition, we evaluated the correlation between morphological features and LyC emission. Our findings indicate that neither <i>ξ<i/><sub>ion<sub/> nor the predicted <i>f<i/><sub>esc<sub/> values show a significant correlation with the presence of merger signatures. This suggests that in low-mass galaxies at <i>z<i/> ≥ 5, strong morphological disturbances are not the primary mechanism driving LyC emission and leakage. Instead, compactness and star formation activity likely play a more pivotal role in regulating LyC escape.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"34 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144995590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radio continuum and H I 21-cm line observations of the nearby luminous infrared galaxy IRAS 17526+3253","authors":"Jianfeng Wu, Zhongzu Wu, Yulia Sotnikova, Bo Zhang, Yongjun Chen, Timur Mufakharov, Zhiqiang Shen","doi":"10.1051/0004-6361/202553911","DOIUrl":"https://doi.org/10.1051/0004-6361/202553911","url":null,"abstract":"We present results from our European VLBI Network (EVN) and Giant Meterwave Radio Telescope (GMRT) observations of the radio continuum and spectral line emission in IRAS 17526+3253, along with an analysis of its arcsecond-scale radio properties using archival Very Large Array (VLA) data. The EVN observations detected radio continuum emission from both the northwest (NW) and southeast (SE) nuclei. The NW nucleus shows two components with high brightness temperatures and radio luminosities, likely indicating the presence of an active galactic nucleus (AGN) core and jet. Meanwhile, our EVN observation failed to detect the OH line emission, possibly due to radio frequency interference (RFI) and/or the emission being partly resolved out and below our detection limit. The multiband radio spectral energy distribution deviates from a single power law at low frequencies, suggesting low-frequency absorption. The GMRT spectral line data reveal both H I absorption and emission. The H I emission is diffuse and shows a velocity gradient from about 7500 km s<sup>−1<sup/> in the NW to 7800 km s<sup>−1<sup/> in the SE nucleus. On larger scales, the H I emission extends about 4′ along the NW–SE direction, with the SE extension matching the optical tidal tail. In addition, the weak H I absorption features show broad line profiles, possibly due to overlapping H I gas from the two nuclei. The aforementioned results are consistent with properties of intermediate-stage mergers reported in the literature.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"12 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144995564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ALMA survey of a massive node of the Cosmic Web at z ∼ 3","authors":"A. Pensabene, S. Cantalupo, W. Wang, C. Bacchini, F. Fraternali, M. Bischetti, C. Cicone, R. Decarli, G. Pezzulli, M. Galbiati, T. Lazeyras, N. Ledos, G. Quadri, A. Travascio","doi":"10.1051/0004-6361/202554769","DOIUrl":"https://doi.org/10.1051/0004-6361/202554769","url":null,"abstract":"Advancing our understanding of the formation and evolution of early massive galaxies and black holes requires detailed studies of dense structures in the high-redshift Universe. In this work, we present high angular resolution (≃0.​​″3) ALMA observations targeting the CO(4−3) line and the underlying 3 mm dust continuum toward the Cosmic Web node MQN01, a region identified through deep multiwavelength surveys as having one of the densest concentrations of galaxies and active galactic nuclei at cosmic noon. At the center of this structure, we identified a massive, rotationally supported disk galaxy located approximately at a projected-distance of ∼10 kpc and ∼ − 300 km s<sup>−1<sup/> from a hyper-luminous quasar at <i>z<i/> = 3.2510. By accurately modeling the cold gas kinematics, we determined a galaxy dynamical mass of 2.5 × 10<sup>11<sup/> <i>M<i/><sub>⊙<sub/> within the inner ≃4 kpc and a high degree of rotational support of <i>V<i/><sub>rot<sub/>/<i>σ<i/> ≈ 11. This makes it the first quasar companion galaxy confirmed as a massive, dynamically cold rotating disk at such an early cosmic epoch. Despite the small projected separation from the quasar host, we find no clear evidence of strong tidal interactions affecting the galaxy disk. This might suggest that the quasar is a satellite galaxy in the early stages of a merger. Furthermore, our spectroscopic analysis revealed a broad, blueshifted component in the CO(4−3) line profile of the quasar host, which may trace a powerful molecular outflow or kinematic disturbances induced by its interaction with the massive companion galaxy. Our findings show that rotationally supported cold disks are able to survive even in high-density environments of the early Universe.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"27 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144995570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PDRs4All","authors":"Dries Van De Putte, Els Peeters, Karl D. Gordon, John-David T. Smith, Thomas S.-Y. Lai, Alexandros Maragkoudakis, Bethany Schefter, Ameek Sidhu, Dhruvil Doshi, Olivier Berné, Jan Cami, Christiaan Boersma, Emmanuel Dartois, Emilie Habart, Takashi Onaka, Alexander G. G. M. Tielens","doi":"10.1051/0004-6361/202554991","DOIUrl":"https://doi.org/10.1051/0004-6361/202554991","url":null,"abstract":"<i>Context<i/>. Photodissociation regions (PDRs) exhibit strong emission bands between 3–20 μm known as the aromatic infrared bands (AIBs), and they originate from small carbonaceous species such as polycyclic aromatic hydrocarbons (PAHs) excited by UV radiation. The AIB spectra observed in Galactic PDRs are considered a local analog for those seen in extragalactic star-forming regions. Recently, the PDRs4All JWST program observed the Orion Bar PDR, revealing the subcomponents and profile variations of the AIBs in very high detail.<i>Aims<i/>. We present the Python version of PAHFIT, a spectral decomposition tool that separates the contributions by AIB subcomponents, thermal dust emission, gas lines, stellar light, and dust extinction. We aim to provide a configuration that enables highly detailed decompositions of JWST spectra of PDRs (3.1–26 μm) and to test if the same configuration is suitable to characterize AIB emission in extragalactic star forming regions.<i>Methods<i/>. We determined the central wavelength and FWHM of the AIB subcomponents by fitting selected segments of the Orion Bar spectra and compiled them into a “PDR pack” for PAHFIT. We tested the PDR pack by applying PAHFIT to the full 3.1–26 μm PDRs4All templates. We applied PAHFIT with this PDR pack and the default continuum model to seven spectra extracted from the central star forming ring of the galaxy NGC7469.<i>Results<i/>. We introduce an alternate dust continuum model to fit the Orion Bar spectra, as the default PAHFIT continuum model mismatches the intensity at 15–26 μm. Using the PDR pack and the alternate continuum model, PAHFIT reproduces the Orion Bar template spectra with residuals of a few percent. A similar performance is achieved when applying the PDR pack to the NGC7469 spectra. We provide PAHFIT-based diagnostics that trace the profile variations of the 3.3, 3.4, 5.7, 6.2, and 7.7 μm AIBs and thus the photochemical evolution of the AIB carriers. The 5.7 μm AIB emission originates from at least two subpopulations, one more prominent in highly irradiated environments and one preferring more shielded environments. Smaller PAHs as well as very small grains or PAH clusters both thrive in the more shielded environments of the molecular zone in the Orion Bar. Based on these new diagnostics, we show and quantify the strong similarity of the AIB profiles observed in NGC7469 to the Orion Bar template spectra.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"61 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144995531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extreme AGN feedback in the fossil galaxy group SDSSTG 4436","authors":"D. Eckert, F. Gastaldello, L. Lovisari, S. McGee, T. Pasini, M. Brienza, K. Kolokythas, E. O’Sullivan, A. Simionescu, M. Sun, M. Ayromlou, M. A. Bourne, Y. Chen, W. Cui, S. Ettori, A. Finoguenov, G. Gozaliasl, R. Kale, F. Mernier, B. D. Oppenheimer, G. Schellenberger, R. Seppi, E. Tempel","doi":"10.1051/0004-6361/202555212","DOIUrl":"https://doi.org/10.1051/0004-6361/202555212","url":null,"abstract":"Supermassive black hole feedback is the currently favoured mechanism to regulate the star formation rate of galaxies and prevent the formation of ultra-massive galaxies (<i>M<i/><sub>⋆<sub/> > 10<sup>12<sup/> <i>M<i/><sub>⊙<sub/>). However, the mechanism through which the outflowing energy is transferred to the surrounding medium strongly varies from one galaxy evolution model to another, such that a unified model for active galactic nucleus (AGN) feedback does not currently exist. The hot atmospheres of galaxy groups are highly sensitive laboratories of the feedback process, as the injected black hole energy is comparable to the binding energy of halo gas particles. Here we report multi-wavelength observations of the fossil galaxy group SDSSTG 4436. The hot atmosphere of this system exhibits a highly relaxed morphology centred on the giant elliptical galaxy NGC 3298. The X-ray emission from the system features a compact core (< 10 kpc) and a steep increase in the entropy and cooling time of the gas, with the cooling time reaching the age of the Universe ∼15 kpc from the centre of the galaxy. The observed entropy profile implies a total injected energy of ∼1.5 × 10<sup>61<sup/> ergs, which given the high level of relaxation could not have been injected by a recent merging event. Star formation in the central galaxy NGC 3298 is strongly quenched and its stellar population is very old (∼10.6 Gyr). The currently detected radio jets have low power and are confined within the central compact core. All the available evidence implies that this system was affected by giant AGN outbursts that raised the entropy of the neighbouring gas to the point that the gas no longer efficiently cools. Our findings imply that AGN outbursts can be energetic enough to unbind gas particles and lead to the disruption of cool cores.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"163 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144995567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Starburst-driven galactic outflows","authors":"Leonard E. C. Romano, Ellis R. Owen, Kentaro Nagamine","doi":"10.1051/0004-6361/202554590","DOIUrl":"https://doi.org/10.1051/0004-6361/202554590","url":null,"abstract":"<i>Aims.<i/> We investigate the role of cosmic ray (CR) halos in shaping the physical properties of starburst-driven galactic outflows.<i>Methods.<i/> We constructed a model for galactic outflows driven by a continuous central injection of energy, gas, and CRs, where the treatment of CRs accounts for the effect of CR pressure gradients on the flow dynamics. The model parameters were set by the effective properties of a starburst. By analyzing the asymptotic behavior of our model, we derived the launching criteria for starburst-driven galactic outflows and determined their corresponding outflow velocities.<i>Results.<i/> We find that in the absence of CRs, stellar feedback can only launch galactic outflows if the star formation rate (SFR) surface density exceeds a critical threshold proportional to the dynamical equilibrium pressure. In contrast, CRs can always drive slow outflows. Outflows driven by CRs dominate in systems with SFR surface densities below the critical threshold, but their influence diminishes in highly star-forming systems. However, in older systems with established CR halos, the CR contribution to outflows weakens once the outflow reaches the galactic scale height, making CRs ineffective in sustaining outflows in such environments.<i>Conclusions.<i/> Over cosmic time, galaxies accumulate relic CRs in their halos, providing additional non-thermal pressure support that suppresses low-velocity CR-driven outflows. We predict that such low-velocity outflows are expected only in young systems that have yet to build significant CR halos. In contrast, fast outflows in starburst galaxies, where the SFR surface density exceeds the critical threshold, are primarily driven by thermal energy and remain largely unaffected by CR halos.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"24 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144995226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two-way coupled particle-in-cell and magnetohydrodynamic simulation of 2D fan-spine reconnection","authors":"M. Haahr, B. V. Gudiksen, Å. Nordlund","doi":"10.1051/0004-6361/202555813","DOIUrl":"https://doi.org/10.1051/0004-6361/202555813","url":null,"abstract":"<i>Context.<i/> Magnetic reconnection is a key mechanism for energy release in the solar atmosphere, but its kinetic-scale microphysics remains difficult to model in large-scale solar geometries.<i>Aims.<i/> We investigate whether fully kinetic particle-in-cell (PIC) simulations can be stably and meaningfully embedded within global magnetohydrodynamic (MHD) models of the solar corona using a realistic fan-spine magnetic configuration.<i>Methods.<i/> We employed a two-way coupled PIC-MHD scheme implemented in the DISPATCH code framework. The PIC solver is embedded within a reconnecting current sheet in a solar-like topology. A physical adjustment of constants is used to bridge kinetic and fluid scales while maintaining self-consistent plasma ordering.<i>Results.<i/> The system evolves stably over more than 45 000 ion plasma periods, exhibiting clear kinetic signatures such as Hall-driven quadrupolar magnetic fields, a reconnection geometry reminiscent of the Petschek configuration, and supra-thermal particle populations. The reconnection rate in the PIC region remains steady and physically consistent, while coupling artefacts are effectively suppressed by fade-in/fade-out boundary weighting.<i>Conclusions.<i/> Our results demonstrate that fully kinetic reconnection can be embedded in global solar MHD models with physical fidelity and computational efficiency. This hybrid approach offers a practical pathway to multi-scale kinetic modelling in realistic astrophysical environments.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"34 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144995571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-linear evolution of the unstratified polydisperse dust settling instability","authors":"Hossam Aly, Sijme-Jan Paardekooper","doi":"10.1051/0004-6361/202554415","DOIUrl":"https://doi.org/10.1051/0004-6361/202554415","url":null,"abstract":"<i>Context<i/>. The dust settling instability (DSI) is a member of the resonant drag instability family, and is thus related to the streaming instability (SI). Linear calculations found that the unstratified monodisperse DSI has growth rates much higher than the SI even with lower initial dust-to-gas ratios. However, recent non-linear investigation found no evidence of strong dust clumping at the saturation level.<i>Aims<i/>. We seek to investigate the non-linear saturation of the mono- and polydisperse DSI. We examine the convergence behaviour with regard to both the numerical resolution as well as the number of species. By characterising the morphology of the dust evolution triggered by the DSI, we can shed more light on its role in planetesimal formation.<i>Methods<i/>. We performed a suite of 2D shearing box hydrodynamic simulations with the code IDEFIX, both in the mono- and polydisperse regimes. We focussed on the time evolution of the maximum dust density, noting the time at which the instability is triggered, and analysed the morphology of the resultant structure.<i>Results<i/>. In our monodisperse DSI simulations, the maximum dust density increases and the instability saturates earlier with a higher spatial resolution, with no signs of convergence yet. The polydisperse simulations do seem to converge with the number of species and produce maximum dust densities that are comparable to, albeit lower than, the monodisperse simulations. Different dust species tend to form adjacent but separate dust filaments, which may have implications on dust growth and further clumping.<i>Conclusions<i/>. The monodisperse DSI produces dust structure at densities high enough to likely lead to clumping. The polydisperse DSI produces lower but comparable dust densities at the same spatial resolution. Our idealised treatment suggests that the DSI is important for planetesimal formation, as it is less affected by the inclusion of a dust size distribution than the SI.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"113 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144995568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Forecast for a growth-rate measurement using peculiar velocities from LSST supernovae","authors":"D. Rosselli, B. Carreres, C. Ravoux, J. E. Bautista, D. Fouchez, A. G. Kim, B. Racine, F. Feinstein, B. O. Sánchez, A. Valade","doi":"10.1051/0004-6361/202556181","DOIUrl":"https://doi.org/10.1051/0004-6361/202556181","url":null,"abstract":"We investigate whether the cosmic growth-rate parameter <i>fσ<i/><sub>8<sub/> can be measured using peculiar velocities (PVs) derived from type Ia supernovae (SNe Ia) in the Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST). We produced simulations of different SN types using a realistic LSST observing strategy that incorporated noise, a photometric detection from the difference-image analysis (DIA) pipeline, and a PV field modeled from the Uchuu universe machine simulations. We tested three different observational scenarios that ranged from ideal conditions with spectroscopic host galaxy redshifts and spectroscopic SN typing to realistic photometric typing that resulted in a contamination with non-Ia SNe. Using a maximum likelihood technique, we showed that the LSST can measure <i>fσ<i/><sub>8<sub/> with a precision of 10% in the redshift range 0.02 < <i>z<i/> < 0.14 for our most realistic scenario. In three tomographic bins, the LSST will be able to constrain the growth-rate parameter with errors below 18% up to redshift <i>z<i/> = 0.14. We also tested the contamination effect on the maximum likelihood method and found that for a contamination fraction below ∼2%, we recovered unbiased measurements. The results of this analysis highlight that the LSST SN sample is expected to complement traditional redshift-space distortion measurements at high redshift. This will provide a novel avenue for testing general relativity and different dark energy models.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"49 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144995569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polarized, variable radio emission from the scallop-shell binary system DG CVn","authors":"Simranpreet Kaur, Daniele Viganò, Jackie Villadsen, Josep Miquel Girart, Víctor J. S. Béjar, Yutong Shan, Luke Bouma, Ekaterina Ilin, Òscar Morata, Miguel Pérez-Torres, Etienne Bonnassieux, Jorge R. Gherson","doi":"10.1051/0004-6361/202555222","DOIUrl":"https://doi.org/10.1051/0004-6361/202555222","url":null,"abstract":"DG CVn is an eruptive variable star and represents the closest member of the known sample of complex periodic variables, or scallop-shell stars. Over the years, this M dwarf binary system has shown significant flaring activity at a wide range of frequencies. Here, we present a detailed analysis of ∼14 hours of radio observations of this stellar system, taken with the Karl G. Jansky Very Large Array at band <i>L<i/>, centered at 1.5 GHz. In both 7-hour-long observations we have found a quiescent, weakly polarized component that could be ascribable to the incoherent, gyro-synchrotron emission coming from the magnetosphere surrounding one or both stars, along with multiple ∼90% right-circularly polarized bursts, some of which last for a few minutes and others of which last longer, ≳30 minutes Some of these bursts show a drift in frequency and time, possibly caused due to beaming effects or the motion of the plasma responsible for the emission. We assess the possible modulation of burst frequency with the primary and secondary periods, and discuss the properties of these bursts, favoring electron cyclotron maser over plasma emission as the likely underlying mechanism. We compare DG CVn’s dynamic spectrum to other young M dwarfs and find many similarities. A proper, dedicated, simultaneous radio/optical follow-up is needed to monitor the long-term variability and increase the statistics of bursts, in order to test whether the corotating absorbers detected in the optical can drive the observed radio emission, and whether the occurrence of radio bursts correlates with the rotational phase of either star.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"38 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144995228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}