Astronomy & Astrophysics最新文献

{"title":"Unraveling the untwisting process and upward mass transfer of a twisted prominence driven by vortex motion","authors":"X.F. Zhang, G.P. Zhou, C.L. Jin, Y.Z. Zhang, G.W. Li, Z.H. Shang, L.P. Li, S.B. Yang, S.H. Yang, J.X. Wang","doi":"10.1051/0004-6361/202348070","DOIUrl":"https://doi.org/10.1051/0004-6361/202348070","url":null,"abstract":"Solar filaments or prominences are common features in the Sun's atmosphere that contain cool chromospheric material suspended within the hot corona. However, the intricate topology of these structures and the mechanisms driving their instability and upward material transfer are not well understood. Investigating these issues is essential for gaining insight into the fundamental laws that govern solar activity. This study is to analyze a specific twisted prominence observed on February 10, 2021, and to explore its dynamics, including stability, motion, and material transfer. The study also aims to propose a mechanism, based on the K'arm'an Vortex Street instability, to explain the destabilization of the prominence. The study utilizes high-resolution H$_ alpha $ observations from the 1-m New Vacuum Solar Telescope and space-borne observations from the Solar Dynamics Observatory. These observations capture the characteristics and behavior of the twisted prominence. We analyzed the data to investigate the equilibrium state, subsequent destabilization, vortex motion, oscillations, resonations, untwisting, and upward mass loading of the prominence. We also detected and measured the speeds of outflows surrounding the prominence. The study reveals that the observed twisted prominence exhibited a stretched and twisted structure at its apex, distinguishing it from familiar cloudy prominences. Following a period of more than 30 hours in equilibrium, the prominence underwent destabilization, leading to a series of dynamic phenomena, such as vortex motion, oscillations, resonations, untwisting, and the upward transfer of mass. Consequently, material from the top of the prominence was carried upward and deposited into the overlying magnetic arcades. Noteworthy, outflows surrounding the prominence were characterized by speeds exceeding 40 km s$^ Based on these findings, we propose, for the first time, a mechanism rooted in the K'arm'an Vortex Street instability to explain the destabilization of the prominence. The estimated typical Strouhal Number of 0.23pm 0.06, which is related to vortex shedding, falls within the expected range for the K'arm'an Vortex Street effect, as predicted by simulations. These discoveries provide new insights into the dynamics and fundamental topology of solar prominences and reveal a previously unknown mechanism for mass loading into the upper atmosphere.","PeriodicalId":8585,"journal":{"name":"Astronomy & Astrophysics","volume":"44 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141809516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A solar rotation signature in cosmic dust: Frequency analysis of dust particle impacts on the Wind spacecraft","authors":"L.R. Baalmann, S. Hunziker, A. Péronne, J.W. Kirchner, K. Glassmeier, D.M. Malaspina, L. Wilson III, C. Strähl, S. Chadda, V.J. Sterken","doi":"10.1051/0004-6361/202450069","DOIUrl":"https://doi.org/10.1051/0004-6361/202450069","url":null,"abstract":"Dust particle impacts on the Wind spacecraft were detected with its plasma wave instrument Wind/WAVES. Frequency analysis on the resulting dust impact time series has revealed spectral peaks indicative of a solar rotation signature. We investigated whether this solar rotation signature is embedded in the interplanetary or in the interstellar dust (ISD) and whether it is caused by co-rotating interaction regions (CIRs), by the sector structure of the interplanetary magnetic field (IMF), or by external effects. We performed frequency analysis on different subsets of the data to investigate the origin of these spectral peaks, comparing segments of Wind's orbit when the spacecraft moved against or with the ISD inflow direction and comparing the time periods of the ISD focusing phase and the ISD defocusing phase of the solar magnetic cycle. A superposed epoch analysis of the number of dust impacts during CIRs was used to investigate the systematic effect of CIRs. Case studies of time periods with frequent or infrequent occurrences of CIRs were performed and compared to synthetic data of cosmic dust impacts affected by CIRs. We performed similar case studies for time periods with a stable or chaotic IMF sector structure. The superposed epoch analysis was repeated for a time series of the spacecraft floating potential. Spectral peaks were found at the solar rotation period of $ sim d $ and its harmonics at $13.5 d $ and $9 d $. This solar rotation signature may affect both interplanetary and interstellar dust. The appearance of this signature correlates with the occurrence of CIRs but not with the stability of the IMF sector structure. The CIRs cause, on average, a reduction in the number of dust impact detections. Periodic changes of the spacecraft's floating potential were found to partially counteract this reduction by enhancing the instrument's sensitivity to dust impacts; these changes of the floating potential are thus unlikely to be the cause of the solar rotation signature.","PeriodicalId":8585,"journal":{"name":"Astronomy & Astrophysics","volume":"51 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141809552","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 Pristine survey. XXIV. The Galactic underdogs: Dynamic tales of a Milky Way metal-poor population","authors":"Isaure Gonz'alez Rivera de La Vernhe, Vanessa Hill, G. Kordopatis, Felipe Gran, Emma Fern'andez-Alvar, Anke Ardern-Arentsen, Guillaume F. Thomas, F. Sestito, Camila Navarrete, N. Martin, E. Starkenburg, Akshara Viswanathan, G. Battaglia, K. Venn, S. Vitali","doi":"10.1051/0004-6361/202450513","DOIUrl":"https://doi.org/10.1051/0004-6361/202450513","url":null,"abstract":"Metal-poor stars hold key information on the early Milky Way.\u0000 Through the identification and characterisation of substructures, one can understand internal mechanisms (including merger and accretion events), which are indispensable to reconstruct the formation history of the Galaxy. To allow an investigation of a population of very metal-poor stars ( Fe/H < -1.7) with disc-like orbits (planar and prograde), high angular momenta ($L_z$/$J_ tot $ > 0.5) and rotational velocities ($V_ $) proposed in the literature, we used a sample of sim 3M giant stars with Gaia DR3 BP/RP information and Pristine-Gaia metallicities down to -4.0 dex that we aimed to decontaminate. To achieve this, we constructed a sample as free as possible from spurious photometric estimates, an issue commonly encountered for high $V_ metal-poor stars. We created a statistically robust sample of sim 36 000 Pristine-Gaia very metal-poor ( Fe/H < -1.7) giant stars, using APOGEE and LAMOST data (adding GALAH and GSP-spec for verification) to estimate and remove contamination. We investigated the spatial and kinematic properties of the decontaminated sample, making use of $V_ as well as the action space, which are both powerful tools to disentangle stellar populations. The global distribution of very metal-poor stars in our sample shows the typical kinematics, orbital properties, and spatial distributions of a halo; however, as in previous works, we found a pronounced asymmetry in the $L_z$ and $V_ distributions, in favour of prograde stars. We showed that this excess is predominantly due to prograde-planar stars (10 $$ of the very metal-poor population), which can be detected down to Fe/H = -2.9 at a 2sigma confidence level. This prograde-planar population contains stars with $V_ $ and $Z_ max $ < 1.5,kpc. While the overall orbital configurations max $ - $R_ max $ or action space distributions) of our sample match that of a halo, the highly prograde and planar subset (2 $$ of the very metal-poor population) also bears characteristics classically associated with a thick disc: (i) a spatial distribution compatible with a short-scaled thick disc, (ii) a $Z_ max $ - $R_ max $ distribution similar to the one expected from the thick disc prediction of the Gaia Universe Model Snapshot, and (iii) a challenge to erase its signature assuming a stationary or prograde halo with $ V_ phi $ sim 30-40 km.s$^ $. Altogether, these results seem to rule out that these highly prograde and planar stars are part of a thin disc population and, instead, support a contribution from a metal-weak thick disc. Higher resolution spectra are needed to fully disentangle the origin(s) of the population.","PeriodicalId":8585,"journal":{"name":"Astronomy &amp; Astrophysics","volume":"66 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141806499","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":"Properties of observable mixed inertial and gravito-inertial modes in gamma Doradus stars","authors":"Marion Galoy, François Lignières, J'erome Ballot","doi":"10.1051/0004-6361/202449965","DOIUrl":"https://doi.org/10.1051/0004-6361/202449965","url":null,"abstract":"The space missions Kepler and TESS provided a large number of highly detailed time series \u0000 for \u0000 main-sequence stars, including gamma Doradus stars. Additionally, numerous gamma Doradus stars are to be observed in the near future thanks to the upcoming PLATO mission. \u0000 \u0000 In gamma Doradus stars, gravito-inertial modes in the radiative zone and inertial modes in the convective core can interact resonantly, \u0000 \u0000 which translates into the appearance of dip structures in the period spacing of modes. Those dips are information-rich, as they are related to the star core characteristics. Our aim is to characterise these dips according to stellar properties and thus to develop new\u0000 seismic diagnostic tools to constrain the internal structure of gamma Doradus stars, especially their cores. We used the two-dimensional oscillation code TOP to compute sectoral prograde and axisymmetric dipolar modes in gamma Doradus stars at different rotation rates and evolutionary stages. We then characterised the dips we obtained by their width and location on the period spacing diagram. We found that the width and the location of the dips \u0000 depend quasi-linearly on the ratio of the rotation rate and the Brunt-Väisälä frequency at the core interface. This allowed us to determine empirical relations between the width and location of dips as well as the resonant inertial mode frequency in the core\u0000 and the Brunt-Väisälä frequency at the interface between the convective core and the radiative zone. \u0000 We propose an approximate theoretical model to support and discuss these empirical relations. The empirical relations we established could be applied to dips observed in data, which would allow for the estimation of frequencies of resonant inertial modes in the core and of the Brunt-Väisälä jump at the interface between the core and the radiative zone. As those two parameters are both related to the evolutionary stage of the star, their determination could lead to more accurate estimations of stellar ages.","PeriodicalId":8585,"journal":{"name":"Astronomy &amp; Astrophysics","volume":"67 21","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141806783","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":"XMM-Newton and NuSTAR discovery of a likely IP candidate XMMU J173029.8--330920 in the Galactic disc","authors":"Samaresh Mondal, G. Ponti, Luke Filor, Tong Bao, F. Haberl, Ciro Salcedo, S. Campana, C. Hailey, K. Mori, N. Rea","doi":"10.1051/0004-6361/202449228","DOIUrl":"https://doi.org/10.1051/0004-6361/202449228","url":null,"abstract":"We aim to characterise the population of low-luminosity X-ray sources in the Galactic plane by studying their X-ray spectra and periodic signals in the light curves. We are performing an X-ray survey of the Galactic disc using and the source XMMU J173029.8--330920 was serendipitously discovered in our campaign. We performed a follow-up observation of the source using our pre-approved target of opportunity time. We used various phenomenological models in xspec for the X-ray spectral modelling. We also computed the Lomb-Scargle periodogram to search for X-ray periodicity. A Monte Carlo method was used to simulate 1000 artificial light curves in order to estimate the significance of the detected period. We also searched for X-ray, optical, and infrared counterparts of the source in various catalogues. The spectral modelling indicates the presence of an intervening cloud with $N_ H $ that partially absorbs the incoming X-ray photons. The X-ray spectra are best fit by a model representing emission from a collisionally ionised diffuse gas with a plasma temperature of $kT=26^ $ keV. Furthermore, an Fe $K_ alpha $ line at $6.47^ $ keV was detected with an equivalent width of the line of $312 eV. We discovered a coherent pulsation with a period of $521.7 s. The 3--10 keV pulsed fraction of the source is around sim 50--60. The hard X-ray emission with plasma temperature $kT=26^ $ keV, iron $K_ alpha $ emission at 6.4 keV, and a periodic behaviour of $521.7 s suggest XMMU J173029.8--33092 to be an intermediate polar. We estimated the mass of the central white dwarf to be $0.94-1.4 odot $ by assuming a distance to the source of $ kpc.","PeriodicalId":8585,"journal":{"name":"Astronomy &amp; Astrophysics","volume":"56 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141807010","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":"MINDS: The DR Tau disk. II. Probing the hot and cold H_2O reservoirs in the JWST-MIRI spectrum","authors":"M. Temmink, F. Ewine van Dishoeck, D. Gasman, L. Sierra Grant, B. Tabone, M. Gudel, Thomas K. Henning, D. Barrado, A. Caratti o Garatti, M. Adrian Glauser, I. Kamp, M. Aditya Arabhavi, H. Jang, N. Kurtovic, G. Perotti, K. Schwarz, M. Vlasblom","doi":"10.1051/0004-6361/202450355","DOIUrl":"https://doi.org/10.1051/0004-6361/202450355","url":null,"abstract":"The Medium Resolution Spectrometer (MRS) of the Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) gives insights into the chemical richness and complexity of the inner regions of planet-forming disks. Several disks that are compact in the millimetre dust emission have been found by Spitzer to be particularly bright in H_2O which is thought to be caused by the inward drift of icy pebbles. Here, we analyse the H_2O -rich spectrum of the compact disk DR Tau using high-quality JWST-MIRI observations. We infer the H_2O column densities (in cm$^ $) using methods presented in previous works, as well as introducing a new method to fully characterise the pure rotational spectrum. We aim to further characterise the abundances of H_2O in the inner regions of this disk and its abundance relative to CO . We also search for emission of other molecular species, such as CH_4 NH_3 CS H_2 SO_2 and larger hydrocarbons; commonly detected species, such as CO CO_2 HCN and C_2H_2 have been investigated in our previous paper. We first use 0D local thermodynamic equilibrium (LTE) slab models to investigate the excitation properties observed in different wavelength regions across the entire spectrum, probing both the ro-vibrational and rotational transitions. To further analyse the pure rotational spectrum (geq 10 $ mu $m), we use the spectrum of a large, structured disk (CI Tau) as a template to search for differences with our compact disk. Finally, we fit multiple components to characterise the radial (and vertical) temperature gradient(s) present in the spectrum of DR Tau. The 0D slab models indicate a radial gradient in the disk, as the excitation temperature (emitting radius) decreases (increases) with increasing wavelength, which is confirmed by the analysis involving the large disk template. To explain the derived emitting radii, we need a larger inclination for the inner disk ($i agreeing with our previous analysis on CO . From our multi-component fit, we find that at least three temperature components ($T_1 K, $T_2 K, and $T_3 K) are required to reproduce the observed rotational spectrum of H_2O arising from the inner $R_ em au. By comparing line ratios, we derived an upper limit on the column densities (in $) for the first two components of $ (N) within sim 1.2 au. We note that the models with a pure temperature gradient provide as robust results as the more complex models, which include spatial line shielding. No robust detection of the isotopologue H_2 ^ O can be made and upper limits are provided for other molecular species. Our analysis confirms the presence of a pure radial temperature gradient present in the inner disk of DR Tau, which can be described by at least three components. This gradient scales roughly as $ R_ em $ in the emitting layers, in the inner 2 au. As the observed H_2O is mainly optically thick, a lower limit on the abundance ratio of H_2O CO sim 0.17 is derived, suggesting a potential depletion of H_2O . Similarly to","PeriodicalId":8585,"journal":{"name":"Astronomy &amp; Astrophysics","volume":"86 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141807830","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":"Testing the volume integrals of travel-time sensitivity kernels for flows","authors":"Michal Švanda, Daniel Chmúrny","doi":"10.1051/0004-6361/202451016","DOIUrl":"https://doi.org/10.1051/0004-6361/202451016","url":null,"abstract":"Helioseismic inversions largely rely on sensitivity kernels, in which 3D spatial functions describe how the changes in the solar interior translate into the change in helioseismic observables. These sensitivity kernels in most cases come from the forward modelling that is used in the most advanced solar models. We aim to test the sensitivity kernels by comparing their volume integrals with measured values from helioseismic travel times. By manipulating the tracking rate, we mimicked the additional zonal velocity in the Dopplergram datacubes. These datacubes were then processed by a standard travel-time measurements pipeline. We investigated the dependence of the east-west travel time averaged over a box around the disc centre on the implanted tracking velocity. The slope of this dependence is directly proportional to the total volume integral of the sensitivity kernel that corresponds to the travel-time geometry that is used. The agreement between measurements and models for travel times that are computed with a ridge filtering is very good to acceptable. The dependence we sought to determine indeed resembles a linear function, and its slope agrees with the expected volume integral from the forward-modelled sensitivity kernel. The agreement is poorer for the phase-speed filtered datacubes. The disagreement is particularly strong for the slowest phase speeds (filters td1--td4). For the higher phase speeds, our result indicates that the measured kernel integrals are systematically larger than expected from the forward modelling. We admit our testing procedure may not be appropriate for high phase speeds and higher radial modes.","PeriodicalId":8585,"journal":{"name":"Astronomy &amp; Astrophysics","volume":"27 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141809019","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":"Low-dimensional signal representations for massive black hole binary signals analysis from LISA data","authors":"Elie Leroy, Jérôme Bobin, Herve Moutarde","doi":"10.1051/0004-6361/202449987","DOIUrl":"https://doi.org/10.1051/0004-6361/202449987","url":null,"abstract":"The space-based gravitational wave observatory LISA will provide a wealth of information to analyze massive black hole binaries with high chirp masses, beyond $10^5$ solar masses. The large number of expected MBHBs (one event a day on average) increases the risk of overlapping between events. As well, the data will be contaminated with non-stationary artifacts, such as glitches and data gaps, which are expected to strongly impact the MBHB analysis, which mandates the development of dedicated detection and retrieval methods on long time intervals. Building upon a methodological approach we introduced for galactic binaries, in this article we investigate an original non-parametric recovery of MBHB signals from measurements with instrumental noise typical of LISA in order to tackle detection and signal reconstruction tasks on long time intervals. We investigated different approaches based on sparse signal modeling and machine learning. In this framework, we focused on recovering MBHB waveforms on long time intervals, which is a building block to further tackling more general signal recovery problems, from gap mitigation to unmixing overlapped signals. To that end, we introduced a hybrid method called SCARF (sparse chirp adaptive representation in Fourier), which combines a deep learning modeling of the merger of the MBHB with a specific adaptive time-frequency representation of the inspiral. Numerical experiments have been carried out on simulations of single MBHB events that account for the LISA response and with realistic realizations of noise. We checked the performances of the proposed hybrid method for the fast detection and recovery of the MBHB.","PeriodicalId":8585,"journal":{"name":"Astronomy &amp; Astrophysics","volume":"23 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141810298","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":"Non-linear torsional Alfv'en waves evolving in stratified viscous plasmas: Coronal hole plumes","authors":"S.M. Hejazi, S. Vasheghani Farahani, K. Hajisharifi, H. Mehdian","doi":"10.1051/0004-6361/202450550","DOIUrl":"https://doi.org/10.1051/0004-6361/202450550","url":null,"abstract":"We model solar atmospheric structures characterised by parallel structuring. We focus on Alfv'en waves in the weakly non-linear regime to highlight the efficiency of non-linear wave steepening when dissipative effects are prominent. We also consider the local and equilibrium conditions involved in shock formation and the shock's contributions to coronal seismology. Coronal plumes were modelled analytically by implementing the magnetohydrodynamic (MHD) theory in cylindrical geometry. Here, the stratification and viscosity are present internal to the plume, whilst effects of the external medium, together with equilibrium conditions, are implied where the magnetic fields are parallel to the plume axis. We implemented a second-order thin flux tube approximation to obtain a wave equation that points to effects tied to non-linear, dissipative, and stratification terms, as well as terms representing atmospheric conditions. The impact of shear viscosity on non-linear Alfv'en waves extracted by the Cohen-Kulsrud-Burgers-type equation proves more efficient when propagated to higher altitudes. The dissipative effects linked to the dimensionless viscosity indicate that the dissipative effects are not linear. Meanwhile, the delay in shock formation enables energy conversions at higher altitudes, thereby maintaining coronal heating at higher levels. The efficiency of parallel structuring and viscous damping is enhanced by such transverse structuring, as it is directly proportional to the external plasma-beta . It is observed that Alfv'en pulses may undergo a backward shock, either in the lower levels of coronal plasma or as they propagate toward higher regions, implying a conversion of energy occurring at various altitudes. A peak was observed, indicating that the interplay reverses at heights around $1.5$ solar radii. Such effects are shown to play a key role in the context of coronal seismology.","PeriodicalId":8585,"journal":{"name":"Astronomy &amp; Astrophysics","volume":"14 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141807352","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":"ViCTORIA project: The LOFAR-MeerKAT view of active galactic nuclei in Virgo cluster early-type galaxies","authors":"A. Spasic, H. Edler, Y. Su, M. Brüggen, F. de Gasperin, T. Pasini, V. Heesen, M. Simonte, A. Boselli, H. Röttgering, M. Fossati","doi":"10.1051/0004-6361/202450365","DOIUrl":"https://doi.org/10.1051/0004-6361/202450365","url":null,"abstract":"The evolution of active galactic nuclei (AGNs) is closely connected to their host galaxies and surroundings. Via feedback processes, AGNs can counteract the cooling of the intracluster medium (ICM) and suppress star formation in their host galaxies. Radio observations at low frequencies provide a glimpse into the history of AGN activity. The Virgo cluster is a substantial reservoir of nearby galaxies and provides an ideal laboratory for the study of AGNs as well as their feedback mechanisms. The aim of our work is to characterise the AGN population within the Virgo cluster down to low radio luminosities, constrain the AGN duty cycle, and investigate environmental feedback in cluster member galaxies. We analysed 144,MHz and 1.3,GHz radio observations of early-type galaxies from the ACS Virgo Cluster Survey (ACSVCS) taken with LOFAR and MeerKAT. We detect 12 of these galaxies at 144,MHz, five of which show clearly extended radio emission. The radio luminosity shows a strong dependence on the stellar mass of the host galaxy, in agreement with previous results. As a notable outlier, the massive elliptical galaxy NGC,4365 ($M_*=2.2 ,M_ is not detected as compact source in the LOFAR observations. Instead, it is surrounded by diffuse, low-surface brightness emission, which hints towards a past phase of stronger nuclear activity. Furthermore, we find a cavity in NGC,4472 (= M,49) inflated by the wide-angle tail only visible in the LOFAR data, which implies that the cavity was created by a past outburst. The corresponding cavity power is of the same order of magnitude as the jet power in the present duty cycle of the AGN.","PeriodicalId":8585,"journal":{"name":"Astronomy &amp; Astrophysics","volume":"2 13","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141807484","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}