Pub Date : 2025-12-09DOI: 10.1051/0004-6361/202555130
Jonathan Petersson, Michaela Hirschmann, Robin G. Tress, Marion Farcy, Simon C. O. Glover, Ralf S. Klessen, Thorsten Naab, Christian Partmann, David J. Whitworth
Aims. We study the individual and cumulative impact of stellar feedback on massive black hole (MBH) growth in a simulated low-mass dwarf galaxy. Furthermore, we explore the influence of the MBH’s initial mass (103−6 M⊙) on the gas accretion, and whether or not artificially induced gas inflows can ‘boost’ further gas accretion onto the MBH.Methods. A suite of high-resolution radiation-hydrodynamic simulations called NOCTUA were performed, using the AREPONOCTUA numerical framework. The chemical evolution of the interstellar medium (ISM) was modelled in a time-dependent non-equilibrium way. Two types of stellar feedback were considered: individually traced type II supernova (SNII) explosions, and radiatively transferred (on-the-fly) ionising stellar radiation (ISR) from OB stars. As part of AREPONOCTUA, we develop and apply a novel physically motivated model for MBH gas accretion, taking into account the angular momentum of the gas in the radiatively efficient regime, to estimate the gas accretion rate onto the MBH from its sub-grid accretion disc.Results. Without any stellar feedback, an initial 104 M⊙ MBH is able to steadily grow over time, roughly doubling its mass after 800 Myr. Surprisingly, the growth of the MBH more than doubles when only ISR feedback is considered, compared to the no stellar feedback run. This is due to the star formation rate (SFR) being highly suppressed (to a similar level or slightly above that when SNII feedback is considered), enabling a higher cumulative net gas inflow onto the MBH from not only the cold neutral and molecular medium phases, but also the unstable and warm neutral medium phases of the ISM. With SNII feedback included, the gas accretion onto the MBH is episodic over time, and is already suppressed by more than an order of magnitude during the first 150 Myr. When combining SNII with ISR feedback, the growth of the MBH remains suppressed due to SNII explosions, but to a lesser extent compared to the SNII-only feedback run, due to a slightly lower SFR, and thus a reduced number of SNII events.Conclusions. We conclude that SNII feedback is a strong regulator and suppressor of MBH growth, and that only an initial 105 M⊙ MBH is able to consistently accrete gas in the radiatively efficient regime (in the presence of SNII feedback). Combined with the fact that artificially induced gas inflows are unable to boost further gas accretion onto the MBH (even for an initial 106 M⊙ MBH), this suggests that it is primarily the nearby gravitational potential around the MBH that determines how much the MBH can grow via gas accretion over time (at least in an isolated non-cosmological environment).
{"title":"NOCTUA suite of simulations","authors":"Jonathan Petersson, Michaela Hirschmann, Robin G. Tress, Marion Farcy, Simon C. O. Glover, Ralf S. Klessen, Thorsten Naab, Christian Partmann, David J. Whitworth","doi":"10.1051/0004-6361/202555130","DOIUrl":"https://doi.org/10.1051/0004-6361/202555130","url":null,"abstract":"<i>Aims.<i/> We study the individual and cumulative impact of stellar feedback on massive black hole (MBH) growth in a simulated low-mass dwarf galaxy. Furthermore, we explore the influence of the MBH’s initial mass (10<sup>3−6<sup/> M<sub>⊙<sub/>) on the gas accretion, and whether or not artificially induced gas inflows can ‘boost’ further gas accretion onto the MBH.<i>Methods.<i/> A suite of high-resolution radiation-hydrodynamic simulations called NOCTUA were performed, using the AREPONOCTUA numerical framework. The chemical evolution of the interstellar medium (ISM) was modelled in a time-dependent non-equilibrium way. Two types of stellar feedback were considered: individually traced type II supernova (SNII) explosions, and radiatively transferred (on-the-fly) ionising stellar radiation (ISR) from OB stars. As part of AREPONOCTUA, we develop and apply a novel physically motivated model for MBH gas accretion, taking into account the angular momentum of the gas in the radiatively efficient regime, to estimate the gas accretion rate onto the MBH from its sub-grid accretion disc.<i>Results.<i/> Without any stellar feedback, an initial 10<sup>4<sup/> M<sub>⊙<sub/> MBH is able to steadily grow over time, roughly doubling its mass after 800 Myr. Surprisingly, the growth of the MBH more than doubles when only ISR feedback is considered, compared to the no stellar feedback run. This is due to the star formation rate (SFR) being highly suppressed (to a similar level or slightly above that when SNII feedback is considered), enabling a higher cumulative net gas inflow onto the MBH from not only the cold neutral and molecular medium phases, but also the unstable and warm neutral medium phases of the ISM. With SNII feedback included, the gas accretion onto the MBH is episodic over time, and is already suppressed by more than an order of magnitude during the first 150 Myr. When combining SNII with ISR feedback, the growth of the MBH remains suppressed due to SNII explosions, but to a lesser extent compared to the SNII-only feedback run, due to a slightly lower SFR, and thus a reduced number of SNII events.<i>Conclusions.<i/> We conclude that SNII feedback is a strong regulator and suppressor of MBH growth, and that only an initial 10<sup>5<sup/> M<sub>⊙<sub/> MBH is able to consistently accrete gas in the radiatively efficient regime (in the presence of SNII feedback). Combined with the fact that artificially induced gas inflows are unable to boost further gas accretion onto the MBH (even for an initial 10<sup>6<sup/> M<sub>⊙<sub/> MBH), this suggests that it is primarily the nearby gravitational potential around the MBH that determines how much the MBH can grow via gas accretion over time (at least in an isolated non-cosmological environment).","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"39 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711526","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}
Pub Date : 2025-12-09DOI: 10.1051/0004-6361/202553882
Baoyi Zeng, Marc-Antoine Martinod, Denis Defrère
Context. Accurate null depth retrieval is critical in nulling interferometry. However, achieving accurate null depth calibration is challenging due to various noise sources, instrumental imperfections, and the complexity of real observational environments. These challenges necessitate advanced calibration techniques that can efficiently handle such uncertainties while maintaining a high accuracy.Aims. This paper aims to incorporate machine-learning techniques with a Bayesian inference to improve the accuracy and efficiency of null depth retrieval in nulling interferometry. Specifically, it explores the use of neural posterior estimation (NPE) to develop models that overcome the computational limitations of conventional methods, such as numerical self-calibration (NSC), providing a more robust solution for accurate null depth calibration.Methods. An NPE-based model was developed, with a simulator that incorporates real data to better represent specific conditions. The model was tested on both synthetic and observational data from the LBTI nuller for evaluation.Results. The NPE model successfully demonstrated improved efficiency, achieving results comparable to current methods in use. It achieved a null depth retrieval accuracy down to a few 10−4 on real observational data, matching the performance of conventional approaches while offering significant computational advantages, reducing the data retrieval time to one-quarter of the time required by self-calibration methods.Conclusions. The NPE model presents a practical and scalable solution for null depth calibration in nulling interferometry, offering substantial improvements in efficiency over existing methods with a better precision and application to other interferometric techniques.
{"title":"A scalable and accurate framework for self-calibrating null depth retrieval using neural posterior estimation","authors":"Baoyi Zeng, Marc-Antoine Martinod, Denis Defrère","doi":"10.1051/0004-6361/202553882","DOIUrl":"https://doi.org/10.1051/0004-6361/202553882","url":null,"abstract":"<i>Context<i/>. Accurate null depth retrieval is critical in nulling interferometry. However, achieving accurate null depth calibration is challenging due to various noise sources, instrumental imperfections, and the complexity of real observational environments. These challenges necessitate advanced calibration techniques that can efficiently handle such uncertainties while maintaining a high accuracy.<i>Aims<i/>. This paper aims to incorporate machine-learning techniques with a Bayesian inference to improve the accuracy and efficiency of null depth retrieval in nulling interferometry. Specifically, it explores the use of neural posterior estimation (NPE) to develop models that overcome the computational limitations of conventional methods, such as numerical self-calibration (NSC), providing a more robust solution for accurate null depth calibration.<i>Methods<i/>. An NPE-based model was developed, with a simulator that incorporates real data to better represent specific conditions. The model was tested on both synthetic and observational data from the LBTI nuller for evaluation.<i>Results<i/>. The NPE model successfully demonstrated improved efficiency, achieving results comparable to current methods in use. It achieved a null depth retrieval accuracy down to a few 10<sup>−4<sup/> on real observational data, matching the performance of conventional approaches while offering significant computational advantages, reducing the data retrieval time to one-quarter of the time required by self-calibration methods.<i>Conclusions<i/>. The NPE model presents a practical and scalable solution for null depth calibration in nulling interferometry, offering substantial improvements in efficiency over existing methods with a better precision and application to other interferometric techniques.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"144 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711530","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}
Pub Date : 2025-12-09DOI: 10.1051/0004-6361/202555043
Herbert Gunell, Gabriella Stenberg Wieser, Anja Moeslinger, Charlotte Goetz, Romain Canu-Blot, Pierre Henri
In the plasma environment of a comet, waves are generated on vastly different temporal and spatial scales. Wave observations were carried out during the cometary flybys in the 1980s and 1990s as well as by the Rosetta spacecraft which accompanied comet 67P/Churyumov-Gerasimenko between 2014 and 2016. Waves are thought to contribute to the transfer of energy in the ionised coma. One of the fundamental plasma waves observed in space is the Langmuir wave, which appears at or above the electron plasma frequency. The Mutual Impedance Probe of the Rosetta Plasma Consortium (RPC-MIP) recorded frequency spectra of electric field fluctuations in the cometary plasma, and we used these spectra in order to detect and identify Langmuir waves. Langmuir waves were found during the part of the Rosetta mission when the comet was less than 2.65-2.8 AU from the Sun. The Langmuir waves appear near, but always outside, the diamagnetic cavity boundary, in a region where, at much lower frequencies, steepened magnetosonic waves also are present.
{"title":"Langmuir waves observed at comet 67P/Churyumov-Gerasimenko","authors":"Herbert Gunell, Gabriella Stenberg Wieser, Anja Moeslinger, Charlotte Goetz, Romain Canu-Blot, Pierre Henri","doi":"10.1051/0004-6361/202555043","DOIUrl":"https://doi.org/10.1051/0004-6361/202555043","url":null,"abstract":"In the plasma environment of a comet, waves are generated on vastly different temporal and spatial scales. Wave observations were carried out during the cometary flybys in the 1980s and 1990s as well as by the Rosetta spacecraft which accompanied comet 67P/Churyumov-Gerasimenko between 2014 and 2016. Waves are thought to contribute to the transfer of energy in the ionised coma. One of the fundamental plasma waves observed in space is the Langmuir wave, which appears at or above the electron plasma frequency. The Mutual Impedance Probe of the Rosetta Plasma Consortium (RPC-MIP) recorded frequency spectra of electric field fluctuations in the cometary plasma, and we used these spectra in order to detect and identify Langmuir waves. Langmuir waves were found during the part of the Rosetta mission when the comet was less than 2.65-2.8 AU from the Sun. The Langmuir waves appear near, but always outside, the diamagnetic cavity boundary, in a region where, at much lower frequencies, steepened magnetosonic waves also are present.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"7 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711531","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}
Pub Date : 2025-12-09DOI: 10.1051/0004-6361/202554393
Anthony Noll, Sarbani Basu, Saskia Hekker
Context. Red clump (RC) stars still pose open questions regarding several physical processes, such as the mixing around the core or the nuclear reactions, which are ill-constrained by theory and experiments. The oscillations of RC stars, which are of a mixed gravito-acoustic nature, allow us to directly investigate the interior of these stars and thereby better understand their physics. In particular, the measurement of their period spacing is a good probe of the structure around the core.Aims. We aim to explain the distribution of period spacings in RC stars observed by Kepler by testing different prescriptions of core-boundary mixing and the nuclear reaction rate.Methods. Using the MESA stellar evolution code, we computed several grids of core-helium-burning tracks, with varying masses and metallicities. Each of these grids has been computed assuming a certain core boundary mixing scheme, or 12C(α, γ)16O reaction rate. We then sampled these grids, in a Monte-Carlo fashion, using observational spectroscopic metallicity and seismic mass priors, in order to retrieve a period spacing distribution, which we compared to the observations.Results. We find that the best-fitting distribution is obtained when using a “maximal overshoot” core-boundary scheme, which has similar seismic properties as a model whose modes are trapped outside a semi-convective region, and which does not exhibit core-breathing pulses at the end of the core-helium-burning phase. If no mode trapping is assumed, then no core boundary mixing scheme is compatible with the observations. Moreover, we find that extending the core with overshoot worsens the fit. Additionally, reducing the 12C(α, γ)16O reaction rate (by around 15%) improves the fit to the observed distribution. Finally, we note that an overpopulation of early RC stars with period spacing values around 250 s is predicted by the models but not found in the observations.Conclusions. Assuming a semi-convective region and mode trapping, along with a slightly lower than nominal 12C(α, γ)16O rate, allowed us to reproduce most of the features of the observed period spacing distribution, except for those of early RC stars.
{"title":"Ensemble seismic study of the properties of the core of red clump stars","authors":"Anthony Noll, Sarbani Basu, Saskia Hekker","doi":"10.1051/0004-6361/202554393","DOIUrl":"https://doi.org/10.1051/0004-6361/202554393","url":null,"abstract":"<i>Context.<i/> Red clump (RC) stars still pose open questions regarding several physical processes, such as the mixing around the core or the nuclear reactions, which are ill-constrained by theory and experiments. The oscillations of RC stars, which are of a mixed gravito-acoustic nature, allow us to directly investigate the interior of these stars and thereby better understand their physics. In particular, the measurement of their period spacing is a good probe of the structure around the core.<i>Aims.<i/> We aim to explain the distribution of period spacings in RC stars observed by <i>Kepler<i/> by testing different prescriptions of core-boundary mixing and the nuclear reaction rate.<i>Methods.<i/> Using the MESA stellar evolution code, we computed several grids of core-helium-burning tracks, with varying masses and metallicities. Each of these grids has been computed assuming a certain core boundary mixing scheme, or <sup>12<sup/>C(<i>α<i/>, <i>γ<i/>)<sup>16<sup/>O reaction rate. We then sampled these grids, in a Monte-Carlo fashion, using observational spectroscopic metallicity and seismic mass priors, in order to retrieve a period spacing distribution, which we compared to the observations.<i>Results.<i/> We find that the best-fitting distribution is obtained when using a “maximal overshoot” core-boundary scheme, which has similar seismic properties as a model whose modes are trapped outside a semi-convective region, and which does not exhibit core-breathing pulses at the end of the core-helium-burning phase. If no mode trapping is assumed, then no core boundary mixing scheme is compatible with the observations. Moreover, we find that extending the core with overshoot worsens the fit. Additionally, reducing the <sup>12<sup/>C(<i>α<i/>, <i>γ<i/>)<sup>16<sup/>O reaction rate (by around 15%) improves the fit to the observed distribution. Finally, we note that an overpopulation of early RC stars with period spacing values around 250 s is predicted by the models but not found in the observations.<i>Conclusions.<i/> Assuming a semi-convective region and mode trapping, along with a slightly lower than nominal <sup>12<sup/>C(<i>α<i/>, <i>γ<i/>)<sup>16<sup/>O rate, allowed us to reproduce most of the features of the observed period spacing distribution, except for those of early RC stars.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"169 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711524","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}
1ES 1927+654 has exhibited a spectroscopic changing-look transition following dramatic ultraviolet/optical (UV/optical) and X-ray variability in recent years. X-ray observations have revealed a rapid flux decline, when the hard X-ray power-law component disappeared, the soft thermal emission reached a minimum ∼150 days after the UV/optical peak, and both components reemerged with the source re-brightening. This extreme variability suggests the destruction and subsequent reformation of the inner disk and corona. Here, we report the discovery of quasiperiodic X-ray variability with a period of ∼12 days (significance > 3.2σ), which persisted for about 220 days, based on high-cadence monitoring during the inner disk-corona rebuilding phase. The signal is coherent with a very high quality factor of ∼58. We interpret this periodicity as a signature of radiation-pressure instability in the accretion disk, which occurs when the accretion rate and magnetic field strength reach appropriate values. This mechanism has been proposed as an explanation for quasiperiodic eruptions, a recently discovered intriguing phenomenon associated with galactic nuclei. Our findings provide a representative example of disk instability at moderate accretion rates. This phenomenon was long predicted by accretion theory, but rarely observed in active galactic nuclei (AGNs). Our research suggests that extreme events in AGNs, such as tidal disruption events, could serve as novel probes for testing and refining accretion theory.
{"title":"Microhertz oscillations during the reformation of the inner disk-corona in the changing-look active galactic nucleus 1ES 1927+654","authors":"Wenjie Zhang, Xin Pan, Mingjun Liu, Tao Wu, Xinwen Shu, Luming Sun, Lei Yang, Bifang Liu, Chichuan Jin, Yuan Liu, Weimin Yuan","doi":"10.1051/0004-6361/202556066","DOIUrl":"https://doi.org/10.1051/0004-6361/202556066","url":null,"abstract":"1ES 1927+654 has exhibited a spectroscopic changing-look transition following dramatic ultraviolet/optical (UV/optical) and X-ray variability in recent years. X-ray observations have revealed a rapid flux decline, when the hard X-ray power-law component disappeared, the soft thermal emission reached a minimum ∼150 days after the UV/optical peak, and both components reemerged with the source re-brightening. This extreme variability suggests the destruction and subsequent reformation of the inner disk and corona. Here, we report the discovery of quasiperiodic X-ray variability with a period of ∼12 days (significance > 3.2<i>σ<i/>), which persisted for about 220 days, based on high-cadence monitoring during the inner disk-corona rebuilding phase. The signal is coherent with a very high quality factor of ∼58. We interpret this periodicity as a signature of radiation-pressure instability in the accretion disk, which occurs when the accretion rate and magnetic field strength reach appropriate values. This mechanism has been proposed as an explanation for quasiperiodic eruptions, a recently discovered intriguing phenomenon associated with galactic nuclei. Our findings provide a representative example of disk instability at moderate accretion rates. This phenomenon was long predicted by accretion theory, but rarely observed in active galactic nuclei (AGNs). Our research suggests that extreme events in AGNs, such as tidal disruption events, could serve as novel probes for testing and refining accretion theory.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"6 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711523","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}
Pub Date : 2025-12-09DOI: 10.1051/0004-6361/202556215
C.-Z. Jiang, J.-X. Wang, H. Sou, W.-K. Ren
Context. The single-epoch virial method is a fundamental tool for estimating supermassive black hole (SMBH) masses in large samples of active galactic nuclei (AGNs) and has been extensively employed in studies of SMBH–galaxy coevolution across cosmic time. However, since this method is calibrated using reverberation-mapped AGNs, its validity across the entire AGN population remains uncertain.Aims. We aim to examine the breathing effect–the variability of emission line widths with continuum luminosity–beyond reverberation-mapped AGNs, to assess the validity and estimate potential systematic uncertainties of single-epoch virial black hole mass estimates.Methods. We constructed an unprecedentedly large multi-epoch spectroscopic dataset of quasars from Sloan Digital Sky Survey data release 16 (SDSS DR16), focusing on four key broad emission lines (Hα, Hβ, Mg II, and C IV). We assessed how breathing behavior evolves with the rest-frame time interval between observations.Results. We detect no significant breathing signal in Hα, Hβ, or Mg II at any observed timescale. In contrast, C IV exhibits a statistically significant anti-breathing trend, most prominent at intermediate timescales. Notably, for Hβ, which has shown breathing in previous reverberation-mapped samples, we recover the effect only in the small subset of quasars with clearly detected broad-line region (BLR) lags and only during the epochs when such lags are measurable–suggesting that both the lag and breathing signals are intermittent, possibly due to a weak correlation between optical and ionizing continua. These results highlight the complex, variable, and timescale-dependent nature of line profile variability and underscore its implications for single-epoch black hole mass estimates.
{"title":"A timescale-resolved analysis of the breathing effect in quasar broad-line regions","authors":"C.-Z. Jiang, J.-X. Wang, H. Sou, W.-K. Ren","doi":"10.1051/0004-6361/202556215","DOIUrl":"https://doi.org/10.1051/0004-6361/202556215","url":null,"abstract":"<i>Context.<i/> The single-epoch virial method is a fundamental tool for estimating supermassive black hole (SMBH) masses in large samples of active galactic nuclei (AGNs) and has been extensively employed in studies of SMBH–galaxy coevolution across cosmic time. However, since this method is calibrated using reverberation-mapped AGNs, its validity across the entire AGN population remains uncertain.<i>Aims.<i/> We aim to examine the breathing effect–the variability of emission line widths with continuum luminosity–beyond reverberation-mapped AGNs, to assess the validity and estimate potential systematic uncertainties of single-epoch virial black hole mass estimates.<i>Methods.<i/> We constructed an unprecedentedly large multi-epoch spectroscopic dataset of quasars from Sloan Digital Sky Survey data release 16 (SDSS DR16), focusing on four key broad emission lines (H<i>α<i/>, H<i>β<i/>, Mg II, and C IV). We assessed how breathing behavior evolves with the rest-frame time interval between observations.<i>Results.<i/> We detect no significant breathing signal in H<i>α<i/>, H<i>β<i/>, or Mg II at any observed timescale. In contrast, C IV exhibits a statistically significant anti-breathing trend, most prominent at intermediate timescales. Notably, for H<i>β<i/>, which has shown breathing in previous reverberation-mapped samples, we recover the effect only in the small subset of quasars with clearly detected broad-line region (BLR) lags and only during the epochs when such lags are measurable–suggesting that both the lag and breathing signals are intermittent, possibly due to a weak correlation between optical and ionizing continua. These results highlight the complex, variable, and timescale-dependent nature of line profile variability and underscore its implications for single-epoch black hole mass estimates.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"29 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711525","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}
Pub Date : 2025-12-09DOI: 10.1051/0004-6361/202555203
A. P. Jones, N. Ysard
Context. Hydrogenated amorphous carbon materials, a-C(:H), are heterogeneous structures consisting of carbon atoms in different hybridisation states and bonding configurations and are thought to constitute a significant and observationally important fraction of the interstellar dust material. The stability of interstellar a-C(:H) nanoparticles against photo-thermo-dissociation and Coulomb fragmentation needs to take their intrinsic heterogeneity into account.Aims. This work aims to characterise semi-conducting a-C(:H) nanoparticle structures and, in particular, their property-characterising aromatic domain size distribution and so predict how they will behave in intense UV radiation fields that can fragment them through dissociative and charge effects as a result of carbon-carbon bond-breaking.Methods. Using a statistical approach, we determined the typical sizes of the aromatic domains, their size distribution, how they are network-bonded, and where they are to be found within the structure. We consider the effects of thermal excitation, photo-dissociation and charging of a-C(:H) nanoparticles, and the products of their fragmentation.Results. The derived UV photon-induced fragmentation lifetimes for nanometre-sized a-C(:H) nanoparticles, with radii ∼0.4-0.5 nm radius and containing ∼40-60 carbon atoms, are of the order of 106-107 yr in the diffuse interstellar medium and likely 102-104 times shorter in photodissociation regions, depending on the local radiation field intensity. Grains larger than this are stable against photodissociation. In HII regions only a-C(:H) nanoparticles with radii greater than 0.7 nm (≳150 carbon atoms) are likely to survive.Conclusions. The photon-driven fragmentation of sub-nanometre a-C(:H) particles was determined to be important in the diffuse interstellar medium and also in high excitation regions, such as photodissociation and H II regions. However, in these same regions Coulomb fragmentation is unlikely to be an important dust destruction process.
上下文。氢化非晶碳材料，a- c (:H)，是由不同杂化状态和成键构型的碳原子组成的非均相结构，被认为构成了星际尘埃物质中重要的观测部分。星际a-C（:H）纳米粒子对光热解离和库仑破碎的稳定性需要考虑其固有的非均质性。这项工作的目的是表征半导体a- c （:H）纳米颗粒结构，特别是表征其芳域尺寸分布的性质，从而预测它们在强烈的紫外线辐射场中的行为，这种辐射场可以通过碳-碳键断裂引起的解离和电荷效应将它们碎片化。使用统计方法，我们确定了芳香结构域的典型尺寸，它们的尺寸分布，它们是如何网络键合的，以及它们在结构中的位置。研究了a-C（:H）纳米颗粒及其破碎产物的热激发、光解离和充电的影响。导出的半径为~ 0.4-0.5 nm、含有~ 40-60个碳原子的纳米尺寸的a-C（:H）纳米粒子的紫外光子诱导碎片寿命在弥漫性星际介质中为106-107年，在光解区域可能短102-104倍，这取决于局部辐射场强度。比这大的颗粒抗光解作用是稳定的。在HII区，只有半径大于0.7 nm的a-C（:H）纳米粒子（约150个碳原子）才有可能存活。亚纳米a-C（:H）粒子的光子驱动破碎在弥漫性星际介质和高激发区（如光解离和H II区）中很重要。然而，在这些相同的区域，库仑破碎不太可能是一个重要的尘埃破坏过程。
{"title":"The essential elements of dust evolution: a-C(:H) nanoparticle sub-structures and photo-fragmentation","authors":"A. P. Jones, N. Ysard","doi":"10.1051/0004-6361/202555203","DOIUrl":"https://doi.org/10.1051/0004-6361/202555203","url":null,"abstract":"<i>Context.<i/> Hydrogenated amorphous carbon materials, a-C(:H), are heterogeneous structures consisting of carbon atoms in different hybridisation states and bonding configurations and are thought to constitute a significant and observationally important fraction of the interstellar dust material. The stability of interstellar a-C(:H) nanoparticles against photo-thermo-dissociation and Coulomb fragmentation needs to take their intrinsic heterogeneity into account.<i>Aims.<i/> This work aims to characterise semi-conducting a-C(:H) nanoparticle structures and, in particular, their property-characterising aromatic domain size distribution and so predict how they will behave in intense UV radiation fields that can fragment them through dissociative and charge effects as a result of carbon-carbon bond-breaking.<i>Methods.<i/> Using a statistical approach, we determined the typical sizes of the aromatic domains, their size distribution, how they are network-bonded, and where they are to be found within the structure. We consider the effects of thermal excitation, photo-dissociation and charging of a-C(:H) nanoparticles, and the products of their fragmentation.<i>Results.<i/> The derived UV photon-induced fragmentation lifetimes for nanometre-sized a-C(:H) nanoparticles, with radii ∼0.4-0.5 nm radius and containing ∼40-60 carbon atoms, are of the order of 10<sup>6<sup/>-10<sup>7<sup/> yr in the diffuse interstellar medium and likely 10<sup>2<sup/>-10<sup>4<sup/> times shorter in photodissociation regions, depending on the local radiation field intensity. Grains larger than this are stable against photodissociation. In HII regions only a-C(:H) nanoparticles with radii greater than 0.7 nm (≳150 carbon atoms) are likely to survive.<i>Conclusions.<i/> The photon-driven fragmentation of sub-nanometre a-C(:H) particles was determined to be important in the diffuse interstellar medium and also in high excitation regions, such as photodissociation and H II regions. However, in these same regions Coulomb fragmentation is unlikely to be an important dust destruction process.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"65 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711528","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}
The 2024 X-ray/UV observation campaign of NGC 3783, led by XRISM, revealed the launch of an ultrafast outflow (UFO) with a radial velocity of 0.19c (57 000 km s−1). This event is synchronized with the sharp decay, within less than half a day, of a prominent soft X-ray/UV flare. Accounting for the look-elsewhere effect, the XRISM Resolve data alone indicate a low probability of 2 × 10−5 that this UFO detection is due to random chance. The UFO features narrow H-like and He-like Fe lines with a velocity dispersion of ∼1000 km s−1, suggesting that it originates from a dense clump. Beyond this primary detection, there are hints of weaker outflow signatures throughout the rise and fall phases of the soft flare. Their velocities increase from 0.05c to 0.3c over approximately three days, and they may be associated with a larger stream in which the clump is embedded. The radiation pressure is insufficient to drive the acceleration of this rapidly evolving outflow. The observed evolution of the outflow kinematics instead closely resembles that of solar coronal mass ejections, implying magnetic driving and, conceivably, reconnection near the accretion disk as the likely mechanisms behind both the UFO launch and the associated soft flare.
由XRISM领导的2024年NGC 3783 x射线/紫外观测活动揭示了一个径向速度为0.19c （57000 km s - 1）的超快流出物（UFO）的发射。这一事件与一个突出的软x射线/紫外线耀斑在不到半天的时间内急剧衰减同步。考虑到寻找其他地方的影响，XRISM Resolve数据单独表明，这种不明飞行物探测是由于随机机会的低概率为2 × 10−5。UFO具有窄的类h和类he铁线，速度色散为~ 1000 km s−1，表明它起源于密集的团块。除了这个初步探测之外，在软耀斑的上升和下降阶段，还有一些较弱的流出信号的暗示。在大约三天的时间里，它们的速度从0.05摄氏度增加到0.3摄氏度，它们可能与一个更大的溪流有关，而这个溪流中嵌入了团块。辐射压力不足以加速这种快速演化的外流。观测到的外流运动的演变与太阳日冕物质抛射非常相似，这意味着磁场驱动，可以想象，吸积盘附近的重新连接可能是不明飞行物发射和相关软耀斑背后的可能机制。
{"title":"Delving into the depths of NGC 3783 with XRISM","authors":"Liyi Gu, Keigo Fukumura, Jelle Kaastra, Megan Eckart, Ralf Ballhausen, Ehud Behar, Camille Diez, Matteo Guainazzi, Timothy Kallman, Erin Kara, Chen Li, Missagh Mehdipour, Misaki Mizumoto, Shoji Ogawa, Christos Panagiotou, Matilde Signorini, Atsushi Tanimoto, Keqin Zhao, Hirofumi Noda, Jon Miller, Satoshi Yamada","doi":"10.1051/0004-6361/202557189","DOIUrl":"https://doi.org/10.1051/0004-6361/202557189","url":null,"abstract":"The 2024 X-ray/UV observation campaign of NGC 3783, led by XRISM, revealed the launch of an ultrafast outflow (UFO) with a radial velocity of 0.19<i>c<i/> (57 000 km s<sup>−1<sup/>). This event is synchronized with the sharp decay, within less than half a day, of a prominent soft X-ray/UV flare. Accounting for the look-elsewhere effect, the XRISM Resolve data alone indicate a low probability of 2 × 10<sup>−5<sup/> that this UFO detection is due to random chance. The UFO features narrow H-like and He-like Fe lines with a velocity dispersion of ∼1000 km s<sup>−1<sup/>, suggesting that it originates from a dense clump. Beyond this primary detection, there are hints of weaker outflow signatures throughout the rise and fall phases of the soft flare. Their velocities increase from 0.05<i>c<i/> to 0.3<i>c<i/> over approximately three days, and they may be associated with a larger stream in which the clump is embedded. The radiation pressure is insufficient to drive the acceleration of this rapidly evolving outflow. The observed evolution of the outflow kinematics instead closely resembles that of solar coronal mass ejections, implying magnetic driving and, conceivably, reconnection near the accretion disk as the likely mechanisms behind both the UFO launch and the associated soft flare.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"38 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711538","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}
Pub Date : 2025-12-08DOI: 10.1051/0004-6361/202554541
N. Blind, N. Restori, B. Chazelas, C. Lovis, J. Kühn, C. Mordasini
Context. Proxima Cen b is the prime target in a search for life around a nearby exoplanet based on characterization of its atmosphere in reflected light. Due to its very high star-companion contrast (≤10−6), High Dispersion Coronagraphy is the most promising technique to perform such a characterization.Aims. With a maximum separation of 37 mas, Proxima b can be observed with one of the VLT’s UT in the visible. This requires a coronagraph that provides high contrast (≤10−4) very close to the star (≤2 λ/D ) over a broad spectral range (∼30%)and with high transmission of the companion (≥50%). We searched for an optimal solution that benefits from the properties of single-mode fibers.Methods. We introduce the Phase Induced Amplitude Apodizer and Nuller (PIAAN), a coronagraphic integral field unit, designed to feed a diffraction-limited spectrograph. It uses pupil remapping optics with moderate apodization combined with a single-mode fiber integral field unit. It exploits the properties of single-mode fibers to null starlight without reducing the companion coupling. The study focuses on a proper tolerance analysis and proposes a wavefront optimization strategy. A prototype has been built to demonstrate its performance.Results. We show that the PIAAN can theoretically provide contrasts of 7 · 10−7 and a transmission of 72% at 2 λ/D over a bandwidth of 30%. We built and characterized a prototype and demonstrate the proposed wavefront control strategy. The prototype reached contrast levels of 3 · 10−5 over the full bandwidth, as expected from the tolerance analysis.Conclusions. The new PIAAN coronagraph achieves performances that enable the study of exoplanets in reflected light. It is the main coronagraph candidate for the RISTRETTO instrument to observe Proxima Cen b on the VLT and its first technological milestone. It is also a solution of high interest for exploiting the spatial resolution and the large collecting area of future ELTs.
上下文。比邻星b是在附近系外行星周围寻找生命的主要目标，这是基于其大气反射光的特征。由于其极高的星伴对比度（≤10−6），高色散日冕术是最有希望进行这种表征的技术。比邻星b的最大距离为37 mas，可以用VLT的一个UT在可见光中观测到。这就要求日冕仪在宽光谱范围（~ 30%）内提供非常接近恒星（≤2 λ/D）的高对比度（≤10−4）和伴星的高透射率（≥50%）。我们从单模光纤的特性中寻找一个最佳的解决方案。我们介绍了相位诱导振幅Apodizer and Nuller (PIAAN)，这是一种日冕积分场单元，设计用于衍射限制光谱仪。它采用瞳孔重映射光学与中等屈光结合单模光纤积分场单元。它利用单模光纤的特性，在不降低伴生耦合的情况下消除星光。研究重点是适当的容差分析，并提出了波前优化策略。已经建立了一个原型来演示其性能。我们表明，PIAAN理论上可以提供7·10−7的对比度，在2 λ/D下，在30%的带宽下，传输率为72%。我们建立并表征了一个原型，并演示了所提出的波前控制策略。原型在全带宽上达到了3·10−5的对比度水平，正如公差分析所期望的那样。新的PIAAN日冕仪实现了在反射光下研究系外行星的性能。它是RISTRETTO仪器在VLT上观测比邻星b的主要日冕候选者，也是它的第一个技术里程碑。这也是开发未来elt的空间分辨率和大收集面积的高兴趣解决方案。
{"title":"The Phase Induced Amplitude Apodizer and Nuller","authors":"N. Blind, N. Restori, B. Chazelas, C. Lovis, J. Kühn, C. Mordasini","doi":"10.1051/0004-6361/202554541","DOIUrl":"https://doi.org/10.1051/0004-6361/202554541","url":null,"abstract":"<i>Context.<i/> Proxima Cen b is the prime target in a search for life around a nearby exoplanet based on characterization of its atmosphere in reflected light. Due to its very high star-companion contrast (≤10<sup>−6<sup/>), High Dispersion Coronagraphy is the most promising technique to perform such a characterization.<i>Aims.<i/> With a maximum separation of 37 mas, Proxima b can be observed with one of the VLT’s UT in the visible. This requires a coronagraph that provides high contrast (≤10<sup>−4<sup/>) very close to the star (≤2 <i>λ/D<i/> ) over a broad spectral range (∼30%)and with high transmission of the companion (≥50%). We searched for an optimal solution that benefits from the properties of single-mode fibers.<i>Methods.<i/> We introduce the Phase Induced Amplitude Apodizer and Nuller (PIAAN), a coronagraphic integral field unit, designed to feed a diffraction-limited spectrograph. It uses pupil remapping optics with moderate apodization combined with a single-mode fiber integral field unit. It exploits the properties of single-mode fibers to null starlight without reducing the companion coupling. The study focuses on a proper tolerance analysis and proposes a wavefront optimization strategy. A prototype has been built to demonstrate its performance.<i>Results.<i/> We show that the PIAAN can theoretically provide contrasts of 7 · 10<sup>−7<sup/> and a transmission of 72% at 2 <i>λ/D<i/> over a bandwidth of 30%. We built and characterized a prototype and demonstrate the proposed wavefront control strategy. The prototype reached contrast levels of 3 · 10<sup>−5<sup/> over the full bandwidth, as expected from the tolerance analysis.<i>Conclusions.<i/> The new PIAAN coronagraph achieves performances that enable the study of exoplanets in reflected light. It is the main coronagraph candidate for the RISTRETTO instrument to observe Proxima Cen b on the VLT and its first technological milestone. It is also a solution of high interest for exploiting the spatial resolution and the large collecting area of future ELTs.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"363 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145697371","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}
Pub Date : 2025-12-08DOI: 10.1051/0004-6361/202555555
K. Muinonen, A. Leppälä
Context. The scattering matrix averaged for a particle ensemble is a 4 × 4 Mueller matrix that describes, as a function of the scattering angle, θ, the relation between polarized light incident on and scattered by the ensemble. An empirical system is provided for the angular dependencies of the matrix elements for the commonly occurring case of arbitrarily shaped particles and their mirror particles that are both oriented randomly. The resulting Mueller matrix, F, is of a block-diagonal form and is given by six nonzero functions F11, F12 = F21, F22, F33, F34 = -F43, and F44.Aims. It is our goal to show that the complex angular dependencies of the Mueller matrix can be parameterized with the help of analytical basis functions. The empirical system strives to remove obstacles arising from, for example, measured or computed scattering matrices violating the strict symmetry relations among the elements. The system further allows for efficient application of the scattering matrices.Methods. The empirical system is based on insights from the physics of light scattering. The angular dependencies are taken to be functions of q = sin 1/2θ, a functional form frequently present in scattering problems. With the proposed modeling, common matrices can be represented by using a minimum of 28 free parameters in total; that is, less than five parameters as per the matrix element. Markov chain Monte Carlo schemes are provided for the estimation of the parameters and their uncertainties.Results. Examples of experimentally measured and theoretical scattering matrices are analyzed with the help of the empirical system. The Mueller matrix elements are typically matched, in a relative sense, with a root-mean-square value on the order of 1%. The example Mueller matrices provide a range of angular patterns, acting as a credible test bench for the system.Conclusions. The system with related numerical methods is successful in capturing the angular dependencies of the scattering matrix elements. The system allows for applications in both forward and inverse scattering problems concerning cosmic dust particles, with prospects for applications in scattering problems at large.
{"title":"Scattering of light by cosmic dust: Parameterized Mueller matrix","authors":"K. Muinonen, A. Leppälä","doi":"10.1051/0004-6361/202555555","DOIUrl":"https://doi.org/10.1051/0004-6361/202555555","url":null,"abstract":"<i>Context<i/>. The scattering matrix averaged for a particle ensemble is a 4 × 4 Mueller matrix that describes, as a function of the scattering angle, θ, the relation between polarized light incident on and scattered by the ensemble. An empirical system is provided for the angular dependencies of the matrix elements for the commonly occurring case of arbitrarily shaped particles and their mirror particles that are both oriented randomly. The resulting Mueller matrix, <b>F<b/>, is of a block-diagonal form and is given by six nonzero functions <i>F<i/><sub>11<sub/>, <i>F<i/><sub>12<sub/> = <i>F<i/><sub>21<sub/>, <i>F<i/><sub>22<sub/>, <i>F<i/><sub>33<sub/>, <i>F<i/><sub>34<sub/> = -<i>F<i/><sub>43<sub/>, and <i>F<i/><sub>44<sub/>.<i>Aims<i/>. It is our goal to show that the complex angular dependencies of the Mueller matrix can be parameterized with the help of analytical basis functions. The empirical system strives to remove obstacles arising from, for example, measured or computed scattering matrices violating the strict symmetry relations among the elements. The system further allows for efficient application of the scattering matrices.<i>Methods<i/>. The empirical system is based on insights from the physics of light scattering. The angular dependencies are taken to be functions of <i>q<i/> = sin 1/2<i>θ<i/>, a functional form frequently present in scattering problems. With the proposed modeling, common matrices can be represented by using a minimum of 28 free parameters in total; that is, less than five parameters as per the matrix element. Markov chain Monte Carlo schemes are provided for the estimation of the parameters and their uncertainties.<i>Results<i/>. Examples of experimentally measured and theoretical scattering matrices are analyzed with the help of the empirical system. The Mueller matrix elements are typically matched, in a relative sense, with a root-mean-square value on the order of 1%. The example Mueller matrices provide a range of angular patterns, acting as a credible test bench for the system.<i>Conclusions<i/>. The system with related numerical methods is successful in capturing the angular dependencies of the scattering matrix elements. The system allows for applications in both forward and inverse scattering problems concerning cosmic dust particles, with prospects for applications in scattering problems at large.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"03 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145697377","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}
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