Pub Date : 2025-02-14DOI: 10.1051/0004-6361/202451280
C. Palmroos, N. Dresing, J. Gieseler, C. P. Gutiérrez, R. Vainio
Context. Solar energetic particle (SEP) events are a type of space weather phenomena in which highly energetic charged particles are released from the Sun into interplanetary space by violent and eruptive phenomena, such as solar flares and coronal mass ejections. In order to assess the origin of SEPs, an accurate timing of their arrival at spacecraft is of utmost importance. Several methods for determining the starting time of an SEP event at an observer exist, but the uncertainty of this starting time is not assessed in a systematic way by the vast majority of studies.Aims. Employing a newly developed hybrid method of Poisson-CUSUM combined with bootstrapping, we show that the uncertainty related to the onset of an event in any particular energy range is often more than the mere time resolution of the measuring apparatus, and furthermore, it is not necessarily symmetric with respect to the past and future of the determined onset. In addition, we provide a software tool to the scientific community that applies the presented method and automates the determination of SEP event onset times and their related uncertainties, and it finally allows one to easily perform a velocity dispersion analysis.Methods. By applying the Poisson-CUSUM method coupled with statistical bootstrapping to SEP event observations, we demonstrate the effectiveness of the method on synthetic and real data, and we compare them to an analysis conducted using a classical approach in which the uncertainty is assumed based on the time resolution of the data.Results. In the example case, the inferred SEP path length and injection time related to the event, acquired by the velocity dispersion analysis, differ from what is obtained without properly assessing the uncertainty related to the onset times in varying energies. We also present the software package, PyOnset, that automates many steps of the method along with providing powerful data-visualization methods and analysis tools. We release the code to the scientific community as open-source software.
{"title":"A new method for determining the onset times of solar energetic particles and their uncertainties: Poisson-CUSUM bootstrap hybrid method","authors":"C. Palmroos, N. Dresing, J. Gieseler, C. P. Gutiérrez, R. Vainio","doi":"10.1051/0004-6361/202451280","DOIUrl":"https://doi.org/10.1051/0004-6361/202451280","url":null,"abstract":"<i>Context<i/>. Solar energetic particle (SEP) events are a type of space weather phenomena in which highly energetic charged particles are released from the Sun into interplanetary space by violent and eruptive phenomena, such as solar flares and coronal mass ejections. In order to assess the origin of SEPs, an accurate timing of their arrival at spacecraft is of utmost importance. Several methods for determining the starting time of an SEP event at an observer exist, but the uncertainty of this starting time is not assessed in a systematic way by the vast majority of studies.<i>Aims<i/>. Employing a newly developed hybrid method of Poisson-CUSUM combined with bootstrapping, we show that the uncertainty related to the onset of an event in any particular energy range is often more than the mere time resolution of the measuring apparatus, and furthermore, it is not necessarily symmetric with respect to the past and future of the determined onset. In addition, we provide a software tool to the scientific community that applies the presented method and automates the determination of SEP event onset times and their related uncertainties, and it finally allows one to easily perform a velocity dispersion analysis.<i>Methods<i/>. By applying the Poisson-CUSUM method coupled with statistical bootstrapping to SEP event observations, we demonstrate the effectiveness of the method on synthetic and real data, and we compare them to an analysis conducted using a classical approach in which the uncertainty is assumed based on the time resolution of the data.<i>Results<i/>. In the example case, the inferred SEP path length and injection time related to the event, acquired by the velocity dispersion analysis, differ from what is obtained without properly assessing the uncertainty related to the onset times in varying energies. We also present the software package, PyOnset, that automates many steps of the method along with providing powerful data-visualization methods and analysis tools. We release the code to the scientific community as open-source software.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"5 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427420","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 : 2025-02-14DOI: 10.1051/0004-6361/202451693
J. Bienias, R. Szabó
Context. During the primary Kepler mission, between 2009 and 2013, about 150 000 pre-selected targets were observed with a 29.42 minute-long cadence. However, a survey of background stars that fall within the field of view of the downloaded apertures of the primary targets has revealed a number of interesting objects. In previous papers we have presented surveys of short-period eclipsing binaries and RR Lyrae stars.Aims. The current survey of the Kepler background is concentrated on identifying longer-period eclipsing binaries and pulsating stars. These will be the subject of later papers. In the course of this survey, in addition to eclipsing binaries and pulsating stars, seven exoplanet candidates have been uncovered and in this paper we report on these candidates.Methods. We used Lomb-Scargle, light curve transit search, and phase dispersion minimisation methods to reveal pixels that show significant periodicities, resulting in the identification of the seven exoplanet candidates. We prepared the light curves for analysis using Pytransit software and cross-matched the pixel coordinates with Gaia and other catalogues to identify the sources.Results. We identify seven hot Jupiter exoplanet candidates with planet radii ranging from 0.8878 to 1.5174 RJup and periods ranging from 2.5089 to 4.7918 days.
{"title":"Background exoplanet candidates in the original Kepler field","authors":"J. Bienias, R. Szabó","doi":"10.1051/0004-6361/202451693","DOIUrl":"https://doi.org/10.1051/0004-6361/202451693","url":null,"abstract":"<i>Context<i/>. During the primary <i>Kepler<i/> mission, between 2009 and 2013, about 150 000 pre-selected targets were observed with a 29.42 minute-long cadence. However, a survey of background stars that fall within the field of view of the downloaded apertures of the primary targets has revealed a number of interesting objects. In previous papers we have presented surveys of short-period eclipsing binaries and RR Lyrae stars.<i>Aims<i/>. The current survey of the <i>Kepler<i/> background is concentrated on identifying longer-period eclipsing binaries and pulsating stars. These will be the subject of later papers. In the course of this survey, in addition to eclipsing binaries and pulsating stars, seven exoplanet candidates have been uncovered and in this paper we report on these candidates.<i>Methods<i/>. We used Lomb-Scargle, light curve transit search, and phase dispersion minimisation methods to reveal pixels that show significant periodicities, resulting in the identification of the seven exoplanet candidates. We prepared the light curves for analysis using Pytransit software and cross-matched the pixel coordinates with <i>Gaia<i/> and other catalogues to identify the sources.<i>Results<i/>. We identify seven hot Jupiter exoplanet candidates with planet radii ranging from 0.8878 to 1.5174 <i>R<i/><sub><i>Jup<i/><sub/> and periods ranging from 2.5089 to 4.7918 days.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"209 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427436","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 : 2025-02-14DOI: 10.1051/0004-6361/202451705
E. Dreas, A. Pavan, R. Ciolfi, A. Celotti
Context. The concomitant observation of gravitational wave and electromagnetic signals from a binary neutron star (BNS) merger in 2017 confirmed that these events can produce relativistic jets responsible for short gamma-ray bursts (sGRBs). The complex interaction between the jet and the surrounding post-merger environment shapes the angular structure of the outflow, which is then imprinted in the prompt and afterglow sGRB emission.Aims. The outcome of relativistic (magneto)hydrodynamic simulations of jets piercing through post-merger environments is often used as input to compute afterglow signals that can be compared with observations. However, for reliable comparisons, the jet propagation should be followed until nearly ballistic regimes, in which the jet acceleration is essentially over and the angular structure is no longer evolving. This condition is typically reached in 2D simulations, but not in 3D ones. Our goal is to extend a (specific) jet simulation in 3D up to a nearly ballistic phase and analyse the overall dynamical evolution from the jet breakout.Methods. Our work is based on a previous 3D magnetohydrodynamic jet simulation employing a realistic environment imported from a BNS merger simulation, extended here far beyond the evolution time originally covered. After approximately 3 seconds of the jet evolution on the original spherical grid, we remapped the system into a uniform Cartesian grid and reached about 10 seconds without loss of resolution.Results. The specific jet considered here struggled to pierce the dense surroundings, resulting in a rather asymmetrical emerging outflow with a relatively low Lorentz factor. Analysis of the energy conversion processes and corresponding acceleration showed that at the end of our simulation, 98% of the energy is in kinetic form. Moreover, at that time the angular structure is frozen. We thus obtained suitable inputs for computing the afterglow emission. Our procedure is general and applicable to any jet simulation of the same kind.
{"title":"Approaching ballistic motion in 3D simulations of gamma-ray burst jets in realistic binary neutron star merger environments","authors":"E. Dreas, A. Pavan, R. Ciolfi, A. Celotti","doi":"10.1051/0004-6361/202451705","DOIUrl":"https://doi.org/10.1051/0004-6361/202451705","url":null,"abstract":"<i>Context.<i/> The concomitant observation of gravitational wave and electromagnetic signals from a binary neutron star (BNS) merger in 2017 confirmed that these events can produce relativistic jets responsible for short gamma-ray bursts (sGRBs). The complex interaction between the jet and the surrounding post-merger environment shapes the angular structure of the outflow, which is then imprinted in the prompt and afterglow sGRB emission.<i>Aims.<i/> The outcome of relativistic (magneto)hydrodynamic simulations of jets piercing through post-merger environments is often used as input to compute afterglow signals that can be compared with observations. However, for reliable comparisons, the jet propagation should be followed until nearly ballistic regimes, in which the jet acceleration is essentially over and the angular structure is no longer evolving. This condition is typically reached in 2D simulations, but not in 3D ones. Our goal is to extend a (specific) jet simulation in 3D up to a nearly ballistic phase and analyse the overall dynamical evolution from the jet breakout.<i>Methods.<i/> Our work is based on a previous 3D magnetohydrodynamic jet simulation employing a realistic environment imported from a BNS merger simulation, extended here far beyond the evolution time originally covered. After approximately 3 seconds of the jet evolution on the original spherical grid, we remapped the system into a uniform Cartesian grid and reached about 10 seconds without loss of resolution.<i>Results.<i/> The specific jet considered here struggled to pierce the dense surroundings, resulting in a rather asymmetrical emerging outflow with a relatively low Lorentz factor. Analysis of the energy conversion processes and corresponding acceleration showed that at the end of our simulation, 98% of the energy is in kinetic form. Moreover, at that time the angular structure is frozen. We thus obtained suitable inputs for computing the afterglow emission. Our procedure is general and applicable to any jet simulation of the same kind.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"28 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427442","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 : 2025-02-14DOI: 10.1051/0004-6361/202452541
Na-Na Gao, Jian-Fu Zhang
Context. The origin of cosmic rays (CRs) and how they propagate remain unclear. Studying the propagation of CRs in magnetohydrodynamic (MHD) turbulence can help to comprehend many open issues related to CR origin and the role of turbulent magnetic fields.Aims. To comprehend the phenomenon of slow diffusion in the near-source region, we study the interactions of CRs with the ambient turbulent magnetic field to reveal their universal laws.Methods. We numerically study the interactions of CRs with the ambient turbulent magnetic field, considering pulsar wind nebula as a general research case. Taking the magnetization parameter and turbulence spectral index as free parameters, together with radiative losses, we perform three group simulations to analyze the CR spectral, spatial distributions, and possible CR diffusion types.Results. Our studies demonstrate that (1) CR energy density decays with both its effective radius and kinetic energy in the form of power-law distributions; (2) the morphology of the CR spatial distribution strongly depends on the properties of magnetic turbulence and the viewing angle; (3) CRs suffer a slow diffusion near the source and a fast or normal diffusion away from the source; (4) the existence of a power-law relationship between the averaged CR energy density and the magnetization parameter is independent of both CR energy and radiative losses; and (5) radiative losses can suppress CR anisotropic diffusion and soften the power-law distribution of CR energy density.Conclusions. The distribution law established between turbulent magnetic fields and CRs presents an intrinsic property, providing a convenient way to understand complex astrophysical processes related to turbulence cascades.
{"title":"Anisotropic diffusion of high-energy cosmic rays in magnetohydrodynamic turbulence","authors":"Na-Na Gao, Jian-Fu Zhang","doi":"10.1051/0004-6361/202452541","DOIUrl":"https://doi.org/10.1051/0004-6361/202452541","url":null,"abstract":"<i>Context.<i/> The origin of cosmic rays (CRs) and how they propagate remain unclear. Studying the propagation of CRs in magnetohydrodynamic (MHD) turbulence can help to comprehend many open issues related to CR origin and the role of turbulent magnetic fields.<i>Aims.<i/> To comprehend the phenomenon of slow diffusion in the near-source region, we study the interactions of CRs with the ambient turbulent magnetic field to reveal their universal laws.<i>Methods.<i/> We numerically study the interactions of CRs with the ambient turbulent magnetic field, considering pulsar wind nebula as a general research case. Taking the magnetization parameter and turbulence spectral index as free parameters, together with radiative losses, we perform three group simulations to analyze the CR spectral, spatial distributions, and possible CR diffusion types.<i>Results.<i/> Our studies demonstrate that (1) CR energy density decays with both its effective radius and kinetic energy in the form of power-law distributions; (2) the morphology of the CR spatial distribution strongly depends on the properties of magnetic turbulence and the viewing angle; (3) CRs suffer a slow diffusion near the source and a fast or normal diffusion away from the source; (4) the existence of a power-law relationship between the averaged CR energy density and the magnetization parameter is independent of both CR energy and radiative losses; and (5) radiative losses can suppress CR anisotropic diffusion and soften the power-law distribution of CR energy density.<i>Conclusions.<i/> The distribution law established between turbulent magnetic fields and CRs presents an intrinsic property, providing a convenient way to understand complex astrophysical processes related to turbulence cascades.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427437","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 : 2025-02-14DOI: 10.1051/0004-6361/202452137
Keerthana Jegatheesan, Evelyn J. Johnston, Boris Häußler, Augusto E. Lassen, Rogério Riffel, Ana L. Chies-Santos
Elliptical galaxies often exhibit complex assembly histories, and are presumed to typically form through a combination of rapid, early star formation and the subsequent accretion of material, often resulting from mergers with other galaxies. To investigate theories of spheroidal galaxy formation, the objective of this work is to analyse the star formation histories (SFHs) of a sample of three isolated elliptical galaxies in the local Universe observed with MUSE at z < 0.06. With BUDDI, we decompose the integral field unit (IFU) datacubes into two components with Sérsic profiles, which roughly correspond to the two phases of in situ and ex situ star formation. To constrain the mode of growth in these galaxies, we derived the mass and light-weighted stellar ages and metallicities, and created 2D stellar population maps of each component using pPXF. We reconstructed the mass and light-weighted SFHs to constrain the contribution of different stellar populations to the mass and luminosity of the components through cosmic time. Our results show that the ellipticals in this sample have experienced an early and rapid phase of star formation, either through a rapid dissipative collapse or gas-rich major mergers concentrated in the inner component, which contributes to ∼50% of the galaxy stellar mass. The co-dominant outer component, however, had assembled the bulk of its stellar mass shortly after the inner component did, through accretion via dry mergers and possible gas accretion. This premise is supported by our observations of the inner component being primarily composed of old and metal-rich stars. The outer component has a combination of old and intermediate-age stars, with a moderate spread in metallicities. These results are analysed through the lens of the two-phase scenario, a framework developed over the years to explain the formation histories of elliptical galaxies.
{"title":"Dual-component stellar assembly histories in local elliptical galaxies via MUSE","authors":"Keerthana Jegatheesan, Evelyn J. Johnston, Boris Häußler, Augusto E. Lassen, Rogério Riffel, Ana L. Chies-Santos","doi":"10.1051/0004-6361/202452137","DOIUrl":"https://doi.org/10.1051/0004-6361/202452137","url":null,"abstract":"Elliptical galaxies often exhibit complex assembly histories, and are presumed to typically form through a combination of rapid, early star formation and the subsequent accretion of material, often resulting from mergers with other galaxies. To investigate theories of spheroidal galaxy formation, the objective of this work is to analyse the star formation histories (SFHs) of a sample of three isolated elliptical galaxies in the local Universe observed with MUSE at <i>z<i/> < 0.06. With BUDDI, we decompose the integral field unit (IFU) datacubes into two components with Sérsic profiles, which roughly correspond to the two phases of in situ and ex situ star formation. To constrain the mode of growth in these galaxies, we derived the mass and light-weighted stellar ages and metallicities, and created 2D stellar population maps of each component using pPXF. We reconstructed the mass and light-weighted SFHs to constrain the contribution of different stellar populations to the mass and luminosity of the components through cosmic time. Our results show that the ellipticals in this sample have experienced an early and rapid phase of star formation, either through a rapid dissipative collapse or gas-rich major mergers concentrated in the inner component, which contributes to ∼50% of the galaxy stellar mass. The co-dominant outer component, however, had assembled the bulk of its stellar mass shortly after the inner component did, through accretion via dry mergers and possible gas accretion. This premise is supported by our observations of the inner component being primarily composed of old and metal-rich stars. The outer component has a combination of old and intermediate-age stars, with a moderate spread in metallicities. These results are analysed through the lens of the two-phase scenario, a framework developed over the years to explain the formation histories of elliptical galaxies.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"14 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427438","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 : 2025-02-14DOI: 10.1051/0004-6361/202452384
Yolanda Jiménez-Teja, Javier Román, Kim HyeongHan, Jose M. Vílchez, Renato A. Dupke, Paulo Afrânio Augusto Lopes, Robert Michael Rich, Osmin Caceres, Chester Li
The detection and study of the intracluster light (ICL) in rich clusters of galaxies has been a longstanding challenge and key focus. Using the lowest-surface-brightness images of the Coma cluster of galaxies in the g and r bands, from the Halos and Environment of Nearby Galaxies (HERON) Coma Cluster Project, we obtained the most extensive image of ICL in a single cluster to date, spreading over 1.5 Mpc from the cluster core. The unprecedented wealth of spectroscopic data from the Dark Energy Spectroscopic Instrument (DESI) Early Data Release, along with a compilation from the NASA/IPAC Extragalactic Database and available data from the literature, enabled the identification of 2157 galaxy members within Coma; on this basis, 42 distinct groups were identified. The synergy between these high-quality data allowed us to: (1) calculate ICL fractions of 19.9 ± 0.5% and 19.6 ± 0.6% in the g and r bands, respectively, consistent with a dynamically active cluster; (2) unveil Coma’s faintest tidal features; and (3) provide a comprehensive picture of the dynamics and interactions within this complex system. Our findings indicate that the ICL connects several of these groups in a filamentous network, from which we can infer ongoing dynamical processes. In particular, we identified a faint stellar bridge linking the core of Coma with the galaxy NGC 4839, providing compelling evidence that this galaxy has already traversed the central region of the cluster.
{"title":"Deep view of the intracluster light in the Coma cluster of galaxies","authors":"Yolanda Jiménez-Teja, Javier Román, Kim HyeongHan, Jose M. Vílchez, Renato A. Dupke, Paulo Afrânio Augusto Lopes, Robert Michael Rich, Osmin Caceres, Chester Li","doi":"10.1051/0004-6361/202452384","DOIUrl":"https://doi.org/10.1051/0004-6361/202452384","url":null,"abstract":"The detection and study of the intracluster light (ICL) in rich clusters of galaxies has been a longstanding challenge and key focus. Using the lowest-surface-brightness images of the Coma cluster of galaxies in the <i>g<i/> and <i>r<i/> bands, from the Halos and Environment of Nearby Galaxies (HERON) Coma Cluster Project, we obtained the most extensive image of ICL in a single cluster to date, spreading over 1.5 Mpc from the cluster core. The unprecedented wealth of spectroscopic data from the Dark Energy Spectroscopic Instrument (DESI) Early Data Release, along with a compilation from the NASA/IPAC Extragalactic Database and available data from the literature, enabled the identification of 2157 galaxy members within Coma; on this basis, 42 distinct groups were identified. The synergy between these high-quality data allowed us to: (1) calculate ICL fractions of 19.9 ± 0.5% and 19.6 ± 0.6% in the <i>g<i/> and <i>r<i/> bands, respectively, consistent with a dynamically active cluster; (2) unveil Coma’s faintest tidal features; and (3) provide a comprehensive picture of the dynamics and interactions within this complex system. Our findings indicate that the ICL connects several of these groups in a filamentous network, from which we can infer ongoing dynamical processes. In particular, we identified a faint stellar bridge linking the core of Coma with the galaxy NGC 4839, providing compelling evidence that this galaxy has already traversed the central region of the cluster.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"12 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427416","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 : 2025-02-14DOI: 10.1051/0004-6361/202452567
Wei-Jian Lu, Ying-Ru Lin, Min Yao
We present the observation of a velocity shift in the broad absorption line (BAL) of C IV ion in quasar SDSS J145229.08+093204.9 (hereafter J1452+0932).This quasar exhibits three distinct BAL systems, designated as systems A, B, and C. Notably, system A, which possesses the highest velocity of approximately −23 000 km s−1, demonstrates a velocity shift of −1097 km s−1 in its C IV ion over a rest-frame period of approximately 1.7 years. To elucidate the nature of these variations, we conducted a comprehensive analysis focusing on the variation situation, location, ionisation state, and profile shape of the three BAL systems in J1452+0932. Our findings reveal that system A is situated closer to the central source compared to systems B and C. Furthermore, system A exhibits higher velocities, higher ionisation states, and smoother profile morphologies. These characteristics collectively suggest that the outflow generating system A is situated in a particularly extreme environment and experiences more pronounced impacts from background radiation energy than systems B and C. Consequently, we postulate that the observed velocity shift in system A may signify an actual line-of-sight acceleration of the outflow, induced by the radiation pressure emanating from the central source. Specifically, this scenario could occur if our line of sight intersects an outflow at a location where it is undergoing acceleration towards its terminal outflow velocity, or if a previously coasting outflow is undergoing renewed acceleration.
{"title":"Velocity shift of a C IV broad absorption line in quasar SDSS J145229.08+093204.9","authors":"Wei-Jian Lu, Ying-Ru Lin, Min Yao","doi":"10.1051/0004-6361/202452567","DOIUrl":"https://doi.org/10.1051/0004-6361/202452567","url":null,"abstract":"We present the observation of a velocity shift in the broad absorption line (BAL) of C IV ion in quasar SDSS J145229.08+093204.9 (hereafter J1452+0932).This quasar exhibits three distinct BAL systems, designated as systems A, B, and C. Notably, system A, which possesses the highest velocity of approximately −23 000 km s<sup>−1<sup/>, demonstrates a velocity shift of −1097 km s<sup>−1<sup/> in its C IV ion over a rest-frame period of approximately 1.7 years. To elucidate the nature of these variations, we conducted a comprehensive analysis focusing on the variation situation, location, ionisation state, and profile shape of the three BAL systems in J1452+0932. Our findings reveal that system A is situated closer to the central source compared to systems B and C. Furthermore, system A exhibits higher velocities, higher ionisation states, and smoother profile morphologies. These characteristics collectively suggest that the outflow generating system A is situated in a particularly extreme environment and experiences more pronounced impacts from background radiation energy than systems B and C. Consequently, we postulate that the observed velocity shift in system A may signify an actual line-of-sight acceleration of the outflow, induced by the radiation pressure emanating from the central source. Specifically, this scenario could occur if our line of sight intersects an outflow at a location where it is undergoing acceleration towards its terminal outflow velocity, or if a previously coasting outflow is undergoing renewed acceleration.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"12 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427418","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 : 2025-02-14DOI: 10.1051/0004-6361/202452479
Jianing Zhao, Haoyu Lu, Jinbin Cao, Christian Mazelle, Yasong Ge, Shibang Li, Nihan Chen, Yihui Song, Jianxuan Wang, Yuchen Cao
The global effects on Venusian magnetic topology and ion escape during the significant solar-wind disturbances caused by the interplanetary coronal mass ejection (ICME) remain an open area of research. This study examined a particularly intense ICME interaction with Venus on November 5, 2011, using a global multifluid magnetohydrodynamics (MHD) model. To evaluate Venus’s time-dependent response to the event, the model was driven by varying solar-wind input conditions. The numerical results indicate that there are more draped and open magnetic-field lines at low altitudes due to deeper interplanetary magnetic-field (IMF) penetration resulting from the enhanced solar-wind dynamic pressure during the ICME. Conversely, the closed magnetic-field lines gradually decrease after the ICME reaches Venus due to the reduction in magnetic reconnection influenced by a shift in the magnetic topology direction. In the magnetotail escape channel, the increased presence of open field lines intersecting the ionosphere promotes greater ion outflow, thereby facilitating ion escape. The escape rates of planetary ions are enhanced by about an order of magnitude under ICME sheath conditions. This comprehensive investigation of the global distribution of magnetic topology around Venus provides valuable insights into the magnetic-field properties and ion escape during disturbed conditions.
{"title":"Variations in Venusian magnetic topology during an interplanetary coronal mass ejection passage: A multifluid magnetohydrodynamics study","authors":"Jianing Zhao, Haoyu Lu, Jinbin Cao, Christian Mazelle, Yasong Ge, Shibang Li, Nihan Chen, Yihui Song, Jianxuan Wang, Yuchen Cao","doi":"10.1051/0004-6361/202452479","DOIUrl":"https://doi.org/10.1051/0004-6361/202452479","url":null,"abstract":"The global effects on Venusian magnetic topology and ion escape during the significant solar-wind disturbances caused by the interplanetary coronal mass ejection (ICME) remain an open area of research. This study examined a particularly intense ICME interaction with Venus on November 5, 2011, using a global multifluid magnetohydrodynamics (MHD) model. To evaluate Venus’s time-dependent response to the event, the model was driven by varying solar-wind input conditions. The numerical results indicate that there are more draped and open magnetic-field lines at low altitudes due to deeper interplanetary magnetic-field (IMF) penetration resulting from the enhanced solar-wind dynamic pressure during the ICME. Conversely, the closed magnetic-field lines gradually decrease after the ICME reaches Venus due to the reduction in magnetic reconnection influenced by a shift in the magnetic topology direction. In the magnetotail escape channel, the increased presence of open field lines intersecting the ionosphere promotes greater ion outflow, thereby facilitating ion escape. The escape rates of planetary ions are enhanced by about an order of magnitude under ICME sheath conditions. This comprehensive investigation of the global distribution of magnetic topology around Venus provides valuable insights into the magnetic-field properties and ion escape during disturbed conditions.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"53 4 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427435","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 : 2025-02-14DOI: 10.1051/0004-6361/202452588
Jiazheng Dou, Jiakang Han, Wen Zhao, Bin Hu
The ground-based cosmic microwave background (CMB) experiments are susceptible to various instrumental errors, especially for B-mode measurements. The difference between the response of two polarized detectors, referred to as the beam mismatch, would induce a T → P leakage when the detector pair is differenced to cancel the unpolarized signal. We applied the deprojection technique on the time-ordered mock data to mitigate the systematic contamination caused by beam mismatches by assuming the third-generation ground-based CMB experiment (S3). Our results show that the deprojection effectively recovered the input power spectra. We adopted the Needlet ILC (NILC) and constrained ILC (cILC) methods to reconstruct the foreground-cleaned TEB maps, and we evaluated the level of residual systematic errors after the foreground cleaning pipeline by comparing the power spectra between the systematics-added data after deprojection and the systematics-free data. The results show that the residual beam systematics cleaned by deprojection do not bias the CMB measurements of the T, E, and B modes nor the CMB lensing reconstruction or the estimation of the tensor-to-scalar ratio under the S3 sensitivity.
{"title":"Forecasts of effects of beam systematics and deprojection on the third-generation ground-based cosmic microwave background experiment","authors":"Jiazheng Dou, Jiakang Han, Wen Zhao, Bin Hu","doi":"10.1051/0004-6361/202452588","DOIUrl":"https://doi.org/10.1051/0004-6361/202452588","url":null,"abstract":"The ground-based cosmic microwave background (CMB) experiments are susceptible to various instrumental errors, especially for <i>B<i/>-mode measurements. The difference between the response of two polarized detectors, referred to as the beam mismatch, would induce a <i>T<i/> → <i>P<i/> leakage when the detector pair is differenced to cancel the unpolarized signal. We applied the deprojection technique on the time-ordered mock data to mitigate the systematic contamination caused by beam mismatches by assuming the third-generation ground-based CMB experiment (S3). Our results show that the deprojection effectively recovered the input power spectra. We adopted the Needlet ILC (NILC) and constrained ILC (cILC) methods to reconstruct the foreground-cleaned <i>TEB<i/> maps, and we evaluated the level of residual systematic errors after the foreground cleaning pipeline by comparing the power spectra between the systematics-added data after deprojection and the systematics-free data. The results show that the residual beam systematics cleaned by deprojection do not bias the CMB measurements of the <i>T<i/>, <i>E<i/>, and <i>B<i/> modes nor the CMB lensing reconstruction or the estimation of the tensor-to-scalar ratio under the S3 sensitivity.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"10 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427461","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 : 2025-02-14DOI: 10.1051/0004-6361/202452801
M. H. Jafarpour, S. Nasiri
Context. The magnetic field plays an essential role in the evolution of structures and the description of events in the solar atmosphere. Several models have been developed to reconstruct the magnetic field, due to the impossibility of its direct measurement in the solar corona. The model proposed here extrapolates the photospheric magnetogram data up to the corona using a constrained optimization method. In the upper photosphere and chromosphere, both the magnetic and nonmagnetic forces must be taken into account, and the magnetic field reconstruction must be done considering the plasma pressure and density. This is done by applying the Lagrange multiplier technique, as the constrained optimization method, to compute the magnetic field, plasma pressure, and density in magnetohydrostatic equilibria.Aims. This approach has previously been introduced to reconstruct a nonlinear force-free magnetic field. For this work we extended it to a more realistic issue to reconstruct the magnetic field and calculate the plasma pressure and density in a magnetohydrostatic environment.Methods. Our approach was to use the constrained optimization method, which is computationally more efficient and easy to implement. The Lagrange multiplier technique is a powerful mathematical tool that has been successfully applied to many areas of physics. We sought to minimize a Lagrangian, which minimizes the divergence term subject to the constraint magnetohydrostatic equilibrium equation. The plasma parameters and magnetic field were eventually computed following the iteration scheme along with appropriate boundary data.Results. In our previous work, we applied Lagrange multiplier techniques to reconstruct a force-free magnetic field for the solar atmosphere. For this wok, we extended the same optimization technique to extrapolate magnetic field and plasma parameters in magnetohydrostatic equilibria. The results for the magnetic field and plasma parameters were calculated and compared with those obtained by other models in the magnetohydrostatic equilibrium environment as well as the semi-analytical solution as a reference model.Conclusions. A force-free magnetic field and a suitable distribution for pressure and density were used as the initial input for their corresponding evolution equations. After 20 000 iterations, the convergence of the Lagrangian in our model was slightly better than that of the comparison model. The indicators such as the relative magnetic energy and magnetic field lines were investigated, which are in agreement with the reference model compared to the comparison model.
{"title":"Constrained optimization approach for magnetohydrostatic equilibria on the solar atmosphere","authors":"M. H. Jafarpour, S. Nasiri","doi":"10.1051/0004-6361/202452801","DOIUrl":"https://doi.org/10.1051/0004-6361/202452801","url":null,"abstract":"<i>Context<i/>. The magnetic field plays an essential role in the evolution of structures and the description of events in the solar atmosphere. Several models have been developed to reconstruct the magnetic field, due to the impossibility of its direct measurement in the solar corona. The model proposed here extrapolates the photospheric magnetogram data up to the corona using a constrained optimization method. In the upper photosphere and chromosphere, both the magnetic and nonmagnetic forces must be taken into account, and the magnetic field reconstruction must be done considering the plasma pressure and density. This is done by applying the Lagrange multiplier technique, as the constrained optimization method, to compute the magnetic field, plasma pressure, and density in magnetohydrostatic equilibria.<i>Aims<i/>. This approach has previously been introduced to reconstruct a nonlinear force-free magnetic field. For this work we extended it to a more realistic issue to reconstruct the magnetic field and calculate the plasma pressure and density in a magnetohydrostatic environment.<i>Methods<i/>. Our approach was to use the constrained optimization method, which is computationally more efficient and easy to implement. The Lagrange multiplier technique is a powerful mathematical tool that has been successfully applied to many areas of physics. We sought to minimize a Lagrangian, which minimizes the divergence term subject to the constraint magnetohydrostatic equilibrium equation. The plasma parameters and magnetic field were eventually computed following the iteration scheme along with appropriate boundary data.<i>Results<i/>. In our previous work, we applied Lagrange multiplier techniques to reconstruct a force-free magnetic field for the solar atmosphere. For this wok, we extended the same optimization technique to extrapolate magnetic field and plasma parameters in magnetohydrostatic equilibria. The results for the magnetic field and plasma parameters were calculated and compared with those obtained by other models in the magnetohydrostatic equilibrium environment as well as the semi-analytical solution as a reference model.<i>Conclusions<i/>. A force-free magnetic field and a suitable distribution for pressure and density were used as the initial input for their corresponding evolution equations. After 20 000 iterations, the convergence of the Lagrangian in our model was slightly better than that of the comparison model. The indicators such as the relative magnetic energy and magnetic field lines were investigated, which are in agreement with the reference model compared to the comparison model.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"49 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427419","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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