Pub Date : 2025-02-18DOI: 10.1051/0004-6361/202453302
Dhanraj Risbud, Vikrant V. Jadhav, Pavel Kroupa
Context. Tidal tails of open clusters are the result of stellar evaporation from the cluster through the Galactic potential and internal dynamics. With the recent availability of high-precision data, tidal tails are being detected for most of the nearby open clusters.Aims. We identify the tidal tail members for all open clusters within a distance of 400 pc that are older than 100 Myr and have >100 members. To do this, we use model-independent methods.Methods. We used the convergent-point (CP) method to identify the co-moving stars near the open clusters using Gaia DR3 data. A new method called the self-compact convergent-point method was proposed and applied to some of the clusters. It performed better overall in tracing the tails. We also analysed the colour-magnitude diagrams and orbital energy to diagnose possible contamination.Results. Nineteen out of 21 clusters have tidal tails. Five of them were discovered for the first time through this work. The typical span of the tidal tails is 20–200 pc, and 30–700 member stars lie in the region inside the tidal radius and the tidal tails. Four out of 19 tidal tails are tilted away from direction of the Galactic centre. This contradicts the known theory of the tidal-tail formation. The luminosity functions of the tails and clusters are consistent with each other and with the canonical stellar interstellar mass function, but systematically higher radial velocities for the trailing tail than for the leading tail were observed for the first time.Conclusions. The CP method is useful for detecting tidal tails on a scale of ≈100 pc for clusters closer than 400 pc. A further analysis of theoretical N-body models is required to understand the incompleteness and biases in the current sample of tidal tails.
{"title":"Tidal tails of nearby open clusters","authors":"Dhanraj Risbud, Vikrant V. Jadhav, Pavel Kroupa","doi":"10.1051/0004-6361/202453302","DOIUrl":"https://doi.org/10.1051/0004-6361/202453302","url":null,"abstract":"<i>Context<i/>. Tidal tails of open clusters are the result of stellar evaporation from the cluster through the Galactic potential and internal dynamics. With the recent availability of high-precision data, tidal tails are being detected for most of the nearby open clusters.<i>Aims<i/>. We identify the tidal tail members for all open clusters within a distance of 400 pc that are older than 100 Myr and have >100 members. To do this, we use model-independent methods.<i>Methods<i/>. We used the convergent-point (CP) method to identify the co-moving stars near the open clusters using <i>Gaia<i/> DR3 data. A new method called the self-compact convergent-point method was proposed and applied to some of the clusters. It performed better overall in tracing the tails. We also analysed the colour-magnitude diagrams and orbital energy to diagnose possible contamination.<i>Results<i/>. Nineteen out of 21 clusters have tidal tails. Five of them were discovered for the first time through this work. The typical span of the tidal tails is 20–200 pc, and 30–700 member stars lie in the region inside the tidal radius and the tidal tails. Four out of 19 tidal tails are tilted away from direction of the Galactic centre. This contradicts the known theory of the tidal-tail formation. The luminosity functions of the tails and clusters are consistent with each other and with the canonical stellar interstellar mass function, but systematically higher radial velocities for the trailing tail than for the leading tail were observed for the first time.<i>Conclusions<i/>. The CP method is useful for detecting tidal tails on a scale of ≈100 pc for clusters closer than 400 pc. A further analysis of theoretical <i>N<i/>-body models is required to understand the incompleteness and biases in the current sample of tidal tails.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"24 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435735","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 : 2025-02-18DOI: 10.1051/0004-6361/202452985
I. Kraus, Ph.-A. Bourdin, J. Zender, M. Bergmann, A. Hanslmeier
Context. The solar corona maintains temperatures of a million Kelvin or more. The plasma heating mechanisms responsible for these extreme temperatures are still unclear. Large regions of magnetic activity in the photosphere cause extreme ultraviolet (EUV) emission in the corona. Even smaller regions with bipolar and multipolar magnetic fields can generate coronal bright points (CBPs).Aims. We performed a statistical analysis of 346 CBPs. We used Solar Dynamics Observatory (SDO) images to track CBPs on a continuous basis. Therefore, we were able to collect a database of information on the CPB’s lifetime, shape, polarity, flux emergence, and merging behavior, as well as their magnetic evolution, using the SDO Helioseismic and Magnetic Imager (SDO-HMI) instrument.Methods. We searched the SDO data archive for the longest continuous interval of uninterrupted observations in 2015. The longest such interval contains 12 consecutive days of full-disk images from the EUV channels of the SDO-AIA instrument. To analyze the properties of CBPs, we employed an automated tracking algorithm to follow the evolution of the CBPs. Furthermore, we manually checked the shape, underlying magnetic polarities, and merging behavior of each CBP.Results. We provide statistics on the magnetic polarity, emergence, and merging of CBPs. We established a relationship between the CBP’s merging behavior and both its shape and magnetic polarities. Brighter CBPs are visible in all SDO-AIA channels and exhibit strong radiative energy losses. The category of CBPs with a bipolar field has the highest probability of being emissive in all SDO-AIA channels. The majority of CBPs have two opposite polarities below them.Conclusions. The merging of two CBPs is an unusual phenomenon that is related to complex multipolar magnetic regions. Moreover, loop-shaped CBPs usually appear above bipolar fields. Faint CBPs have shorter lifetimes and are less likely to merge with another CBP.
{"title":"Coronal bright point statistics","authors":"I. Kraus, Ph.-A. Bourdin, J. Zender, M. Bergmann, A. Hanslmeier","doi":"10.1051/0004-6361/202452985","DOIUrl":"https://doi.org/10.1051/0004-6361/202452985","url":null,"abstract":"<i>Context.<i/> The solar corona maintains temperatures of a million Kelvin or more. The plasma heating mechanisms responsible for these extreme temperatures are still unclear. Large regions of magnetic activity in the photosphere cause extreme ultraviolet (EUV) emission in the corona. Even smaller regions with bipolar and multipolar magnetic fields can generate coronal bright points (CBPs).<i>Aims.<i/> We performed a statistical analysis of 346 CBPs. We used Solar Dynamics Observatory (SDO) images to track CBPs on a continuous basis. Therefore, we were able to collect a database of information on the CPB’s lifetime, shape, polarity, flux emergence, and merging behavior, as well as their magnetic evolution, using the SDO Helioseismic and Magnetic Imager (SDO-HMI) instrument.<i>Methods.<i/> We searched the SDO data archive for the longest continuous interval of uninterrupted observations in 2015. The longest such interval contains 12 consecutive days of full-disk images from the EUV channels of the SDO-AIA instrument. To analyze the properties of CBPs, we employed an automated tracking algorithm to follow the evolution of the CBPs. Furthermore, we manually checked the shape, underlying magnetic polarities, and merging behavior of each CBP.<i>Results.<i/> We provide statistics on the magnetic polarity, emergence, and merging of CBPs. We established a relationship between the CBP’s merging behavior and both its shape and magnetic polarities. Brighter CBPs are visible in all SDO-AIA channels and exhibit strong radiative energy losses. The category of CBPs with a bipolar field has the highest probability of being emissive in all SDO-AIA channels. The majority of CBPs have two opposite polarities below them.<i>Conclusions.<i/> The merging of two CBPs is an unusual phenomenon that is related to complex multipolar magnetic regions. Moreover, loop-shaped CBPs usually appear above bipolar fields. Faint CBPs have shorter lifetimes and are less likely to merge with another CBP.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"15 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435774","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: 10.1051/0004-6361/202452416
Yadi Yang, Xi Luo, Xiaojian Song, Weiwei Xu, Marius S. Potgieter
Aims. Alpha Magnetic Spectrometer (AMS), installed on the International Space Station, delivers precision measurements of cosmic proton fluxes and electron fluxes, providing unique inputs to further improve our understanding of the solar modulation of cosmic protons and electrons. The latest measurements published by AMS show significant decreases in daily cosmic proton fluxes and electron fluxes in the second half of 2017 (approximately from June 11, 2017 to December 23, 2017). A special structure, known as a loop, appears in the electron-proton hysteresis during this period. These declining fluxes, as well as their recovery toward solar minimum modulation, could be attributed to solar wind structures such as global merged interaction regions (GMIRs), which can affect cosmic ray flux for several months, as well as coronal mass ejections (CMEs). We aim to find the reason for the decrease and clarify the solar modulation mechanism underlying the loop structure.Methods. We developed a 3D numerical model based on Parker transport equation, which is solved as a set of stochastic differential equations, combined with diffusion barriers propagating away from the Sun. Correspondingly, the relevant parameters can be tuned up.Results. The unusual changes in cosmic proton fluxes and electron fluxes in the second half of 2017 could be caused by CMEs and GMIRs. The decreases in these fluxes in 2017, with rigidities below 11 GV, have been successfully reproduced. Daily variations at Earth in terms of the diffusion coefficients (and their mean-free paths) were subsequently obtained. Furthermore, our simulation reveals that the electron-proton hysteresis loop structure in 2017 results from the different responses of protons and electrons to solar modulation, especially with respect to drift and diffusion processes in the heliosphere.
{"title":"A numerical study of unusual flux decreases for cosmic ray protons and electrons observed by Alpha Magnetic Spectrometer in 2017","authors":"Yadi Yang, Xi Luo, Xiaojian Song, Weiwei Xu, Marius S. Potgieter","doi":"10.1051/0004-6361/202452416","DOIUrl":"https://doi.org/10.1051/0004-6361/202452416","url":null,"abstract":"<i>Aims.<i/> Alpha Magnetic Spectrometer (AMS), installed on the International Space Station, delivers precision measurements of cosmic proton fluxes and electron fluxes, providing unique inputs to further improve our understanding of the solar modulation of cosmic protons and electrons. The latest measurements published by AMS show significant decreases in daily cosmic proton fluxes and electron fluxes in the second half of 2017 (approximately from June 11, 2017 to December 23, 2017). A special structure, known as a loop, appears in the electron-proton hysteresis during this period. These declining fluxes, as well as their recovery toward solar minimum modulation, could be attributed to solar wind structures such as global merged interaction regions (GMIRs), which can affect cosmic ray flux for several months, as well as coronal mass ejections (CMEs). We aim to find the reason for the decrease and clarify the solar modulation mechanism underlying the loop structure.<i>Methods.<i/> We developed a 3D numerical model based on Parker transport equation, which is solved as a set of stochastic differential equations, combined with diffusion barriers propagating away from the Sun. Correspondingly, the relevant parameters can be tuned up.<i>Results.<i/> The unusual changes in cosmic proton fluxes and electron fluxes in the second half of 2017 could be caused by CMEs and GMIRs. The decreases in these fluxes in 2017, with rigidities below 11 GV, have been successfully reproduced. Daily variations at Earth in terms of the diffusion coefficients (and their mean-free paths) were subsequently obtained. Furthermore, our simulation reveals that the electron-proton hysteresis loop structure in 2017 results from the different responses of protons and electrons to solar modulation, especially with respect to drift and diffusion processes in the heliosphere.","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":"143427443","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: 10.1051/0004-6361/202452526
Juris Kalvāns
Context. Matter that falls onto a protoplanetary disk (PPD) from a protostellar envelope is heated before it cools again. This induces sublimation and subsequent re-adsorption of ices that accumulated during the prestellar phase.Aims. We explore the fate of ices on multiple-sized dust grains in a parcel of infalling matter.Methods. A comprehensive kinetic chemical model using five grain-size bins with different temperatures was applied for an infalling parcel. The parcel was heated to 150 K and then cooled over a total timescale of 20 kyr. Effects on ice loss and re-accumulation by the changed gas density, the maximum temperature, the irradiation intensity, the size-dependent grain temperature trend, and the distribution of the ice mass among the grain-size bins were investigated.Results. A massive selective redistribution of ices exclusively onto the surface of the coldest grain-size bin occurs in all models. The redistribution starts already during the heating stage, where ices that are sublimated from warmer grains re-adsorb onto colder grains before complete sublimation. During the cooling stage, the sublimated molecules re-freeze again onto the coldest grains. In the case of full sublimation, this re-adsorption is delayed and occurs at lower temperatures because a bare grain surface has lower molecular desorption energies in our model.Conclusions. Most protostellar envelope grains enter the PPD ice poor (bare). Ices are carried by a single coldest grain-size bin, here representing 12% of the total grain surface area. This bare ice-grain dualism can affect the rate of the grain coagulation. The ice components are stratified on the grains according to their sublimation temperatures.
{"title":"Redistribution of ices between grain populations in protostellar envelopes","authors":"Juris Kalvāns","doi":"10.1051/0004-6361/202452526","DOIUrl":"https://doi.org/10.1051/0004-6361/202452526","url":null,"abstract":"<i>Context<i/>. Matter that falls onto a protoplanetary disk (PPD) from a protostellar envelope is heated before it cools again. This induces sublimation and subsequent re-adsorption of ices that accumulated during the prestellar phase.<i>Aims<i/>. We explore the fate of ices on multiple-sized dust grains in a parcel of infalling matter.<i>Methods<i/>. A comprehensive kinetic chemical model using five grain-size bins with different temperatures was applied for an infalling parcel. The parcel was heated to 150 K and then cooled over a total timescale of 20 kyr. Effects on ice loss and re-accumulation by the changed gas density, the maximum temperature, the irradiation intensity, the size-dependent grain temperature trend, and the distribution of the ice mass among the grain-size bins were investigated.<i>Results<i/>. A massive selective redistribution of ices exclusively onto the surface of the coldest grain-size bin occurs in all models. The redistribution starts already during the heating stage, where ices that are sublimated from warmer grains re-adsorb onto colder grains before complete sublimation. During the cooling stage, the sublimated molecules re-freeze again onto the coldest grains. In the case of full sublimation, this re-adsorption is delayed and occurs at lower temperatures because a bare grain surface has lower molecular desorption energies in our model.<i>Conclusions<i/>. Most protostellar envelope grains enter the PPD ice poor (bare). Ices are carried by a single coldest grain-size bin, here representing 12% of the total grain surface area. This bare ice-grain dualism can affect the rate of the grain coagulation. The ice components are stratified on the grains according to their sublimation temperatures.","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":"143427434","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: 10.1051/0004-6361/202450943
M. Ginolin, M. Rigault, Y. Copin, B. Popovic, G. Dimitriadis, A. Goobar, J. Johansson, K. Maguire, J. Nordin, M. Smith, M. Aubert, C. Barjou-Delayre, U. Burgaz, B. Carreres, S. Dhawan, M. Deckers, F. Feinstein, D. Fouchez, L. Galbany, C. Ganot, T. de Jaeger, Y.-L. Kim, D. Kuhn, L. Lacroix, T. E. Müller-Bravo, P. Nugent, B. Racine, P. Rosnet, D. Rosselli, F. Ruppin, J. Sollerman, J. H. Terwel, A. Townsend, R. Dekany, M. Graham, M. Kasliwal, S. L. Groom, J. Purdum, B. Rusholme, S. van der Walt
Context. As type Ia supernova cosmology transitions from a statistics-dominated to a systematics-dominated era, it is crucial to understand the remaining unexplained uncertainties that affect their luminosity, such as those stemming from astrophysical biases. Type Ia supernovae are standardisable candles whose absolute magnitude reaches a scatter of typically 0.15 mag when empirical correlations with their light-curve stretch and colour and with their environmental properties are accounted for.Aims. We investigate the dependence of the standardisation process of type Ia supernovae on the astrophysical environment to ultimately reduce their scatter in magnitude. We focus on colour standardisation.Methods. We used the volume-limited ZTF SN Ia DR2 sample, which offers unprecedented statistics for the low-redshift (z < 0.06) range. We first studied the colour distribution with a focus on the effects of dust to then select a dustless subsample of objects that originated in environments with a low stellar mass and in the outskirts of their host galaxies. We then examined the colour-residual relation and its associated parameter β. Finally, we investigated the colour dependence of the environment-dependent magnitude offsets (steps) to separate their intrinsic and extrinsic components.Results. Our sample of nearly 1000 supernovae probes the red tail of the colour distribution up to c = 0.8. The dustless sample exhibits a significantly shorter red tail (4.3σ) than the whole sample, but the distributions around c ∼ 0 are similar for both samples. This suggests that the reddening above c ≥ 0.2 is dominated by interstellar dust absorption of the host and that the remaining colour scatter has an intrinsic origin. The colour-residual relation is linear with light-curve colour. We found indications of a potential evolution of β with the stellar host mass, with β ∼ 3.6 for low-mass galaxies, compared to β = 3.05 ± 0.06 for the full sample. Finally, in contrast to recent claims from the literature, we found no evolution of steps as a function of light-curve colour. This suggests that dust may not be the dominating mechanism for the dependence on the environment of the magnitude of type Ia supernovae.
{"title":"ZTF SN Ia DR2: Colour standardisation of type Ia supernovae and its dependence on the environment","authors":"M. Ginolin, M. Rigault, Y. Copin, B. Popovic, G. Dimitriadis, A. Goobar, J. Johansson, K. Maguire, J. Nordin, M. Smith, M. Aubert, C. Barjou-Delayre, U. Burgaz, B. Carreres, S. Dhawan, M. Deckers, F. Feinstein, D. Fouchez, L. Galbany, C. Ganot, T. de Jaeger, Y.-L. Kim, D. Kuhn, L. Lacroix, T. E. Müller-Bravo, P. Nugent, B. Racine, P. Rosnet, D. Rosselli, F. Ruppin, J. Sollerman, J. H. Terwel, A. Townsend, R. Dekany, M. Graham, M. Kasliwal, S. L. Groom, J. Purdum, B. Rusholme, S. van der Walt","doi":"10.1051/0004-6361/202450943","DOIUrl":"https://doi.org/10.1051/0004-6361/202450943","url":null,"abstract":"<i>Context.<i/> As type Ia supernova cosmology transitions from a statistics-dominated to a systematics-dominated era, it is crucial to understand the remaining unexplained uncertainties that affect their luminosity, such as those stemming from astrophysical biases. Type Ia supernovae are standardisable candles whose absolute magnitude reaches a scatter of typically 0.15 mag when empirical correlations with their light-curve stretch and colour and with their environmental properties are accounted for.<i>Aims.<i/> We investigate the dependence of the standardisation process of type Ia supernovae on the astrophysical environment to ultimately reduce their scatter in magnitude. We focus on colour standardisation.<i>Methods.<i/> We used the volume-limited ZTF SN Ia DR2 sample, which offers unprecedented statistics for the low-redshift (<i>z<i/> < 0.06) range. We first studied the colour distribution with a focus on the effects of dust to then select a dustless subsample of objects that originated in environments with a low stellar mass and in the outskirts of their host galaxies. We then examined the colour-residual relation and its associated parameter <i>β<i/>. Finally, we investigated the colour dependence of the environment-dependent magnitude offsets (steps) to separate their intrinsic and extrinsic components.<i>Results.<i/> Our sample of nearly 1000 supernovae probes the red tail of the colour distribution up to <i>c<i/> = 0.8. The dustless sample exhibits a significantly shorter red tail (4.3<i>σ<i/>) than the whole sample, but the distributions around <i>c<i/> ∼ 0 are similar for both samples. This suggests that the reddening above <i>c<i/> ≥ 0.2 is dominated by interstellar dust absorption of the host and that the remaining colour scatter has an intrinsic origin. The colour-residual relation is linear with light-curve colour. We found indications of a potential evolution of <i>β<i/> with the stellar host mass, with <i>β<i/> ∼ 3.6 for low-mass galaxies, compared to <i>β<i/> = 3.05 ± 0.06 for the full sample. Finally, in contrast to recent claims from the literature, we found no evolution of steps as a function of light-curve colour. This suggests that dust may not be the dominating mechanism for the dependence on the environment of the magnitude of type Ia supernovae.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"68 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427412","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: 10.1051/0004-6361/202450951
M. Aubert, P. Rosnet, B. Popovic, F. Ruppin, M. Smith, M. Rigault, G. Dimitriadis, A. Goobar, J. Johansson, C. Barjou-Delayre, U. Burgaz, B. Carreres, F. Feinstein, D. Fouchez, L. Galbany, M. Ginolin, T. de Jaeger, M. M. Kasliwal, Y.-L. Kim, L. Lacroix, F. J. Masci, T. E. Müller-Bravo, B. Racine, C. Ravoux, N. Regnault, R. L. Riddle, D. Rosselli, B. Rusholme, R. Smith, J. Sollerman, J. H. Terwel, A. Townsend
Context. The unprecedented statistics of detected Type Ia supernovae (SNe Ia) brought by the Zwicky Transient Facility (ZTF) enable us to probe the impact of the large-scale structure (LSS) on the properties of these objects.Aims. The goal of this paper is to explore the possible impact of the under-dense part of the LSS on the intrinsic SALT2 light-curve properties of SNe Ia and uncover possible biases in SN Ia analyses.Methods. With a volume-limited selection of ZTF-Cosmo-DR2 SNe Ia overlapping with the SDSS-DR7 survey footprint, we investigated the distribution of their properties with regard to voids detected in the SDSS-DR7 galaxy sample. We further used Voronoi volumes as a proxy for local density environments within the LSS.Results. We find a moderate dependency of the stretch on the localisation around the void centre and none when considering colour. The local Voronoi volumes mostly affect the fraction of low- and high-stretch supernovae.Conclusions. With the presently available statistics, we consider that the impact of high- or low-local-density environment can be considered as a proxy for the colour of the host galaxy. Under-dense environments should not cause any biases in analyses of supernova.
{"title":"ZTF SN Ia DR2: Exploring SN Ia properties in the vicinity of under-dense environments","authors":"M. Aubert, P. Rosnet, B. Popovic, F. Ruppin, M. Smith, M. Rigault, G. Dimitriadis, A. Goobar, J. Johansson, C. Barjou-Delayre, U. Burgaz, B. Carreres, F. Feinstein, D. Fouchez, L. Galbany, M. Ginolin, T. de Jaeger, M. M. Kasliwal, Y.-L. Kim, L. Lacroix, F. J. Masci, T. E. Müller-Bravo, B. Racine, C. Ravoux, N. Regnault, R. L. Riddle, D. Rosselli, B. Rusholme, R. Smith, J. Sollerman, J. H. Terwel, A. Townsend","doi":"10.1051/0004-6361/202450951","DOIUrl":"https://doi.org/10.1051/0004-6361/202450951","url":null,"abstract":"<i>Context.<i/> The unprecedented statistics of detected Type Ia supernovae (SNe Ia) brought by the Zwicky Transient Facility (ZTF) enable us to probe the impact of the large-scale structure (LSS) on the properties of these objects.<i>Aims.<i/> The goal of this paper is to explore the possible impact of the under-dense part of the LSS on the intrinsic SALT2 light-curve properties of SNe Ia and uncover possible biases in SN Ia analyses.<i>Methods.<i/> With a volume-limited selection of ZTF-Cosmo-DR2 SNe Ia overlapping with the SDSS-DR7 survey footprint, we investigated the distribution of their properties with regard to voids detected in the SDSS-DR7 galaxy sample. We further used Voronoi volumes as a proxy for local density environments within the LSS.<i>Results.<i/> We find a moderate dependency of the stretch on the localisation around the void centre and none when considering colour. The local Voronoi volumes mostly affect the fraction of low- and high-stretch supernovae.<i>Conclusions.<i/> With the presently available statistics, we consider that the impact of high- or low-local-density environment can be considered as a proxy for the colour of the host galaxy. Under-dense environments should not cause any biases in analyses of supernova.","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":"143427411","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: 10.1051/0004-6361/202453009
J. Jormanainen, T. Hovatta, E. Lindfors, A. Berdyugin, W. Chamani, V. Fallah Ramazani, H. Jermak, S. G. Jorstad, A. Lähteenmäki, C. McCall, K. Nilsson, P. Smith, I. A. Steele, J. Tammi, M. Tornikoski, F. Wierda
OJ 287 is a bright blazar with century-long observations, and one of the strongest candidates to host a supermassive black hole binary. Its polarisation behaviour between 2015 and 2017 (MJD 57300–58000) contains several interesting events that we re-contextualise in this study. We collected optical photometric and polarimetric data from several telescopes and obtained high-cadence light curves from this period. In the radio band, we collected millimetre-wavelength polarisation data from the AMAPOLA programme. We combined them with existing multi-frequency polarimetric radio results and the results of very long-baseline interferometry imaging with the Global mm-VLBI Array at 86 GHz. In December 2015, an optical flare was seen according to the general relativistic binary black hole model. We suggest that the overall activity near the accretion disk and the jet base during this time may be connected to the onset of a new moving component, K, seen in the jet in March 2017. With the additional optical data, we find a fast polarisation angle rotation of ∼210° coinciding with the December 2015 flare, hinting at a possible link between these events. Based on the 86 GHz images, we calculated a new speed of 0.12 mas/yr for K, which places it inside the core at the time of the 2015 flare. This speed also supports the scenario in which the passage of K through the quasi-stationary feature S1 could have been the trigger for the very high-energy gamma-ray flare of OJ 287 seen in February 2017. With the millimetre-polarisation data, we establish that these bands follow the centimetre-band data but show a difference during the time when K passes through S1. This indicates that the millimetre bands trace substructures of the jet that are still unresolved in the centimetre bands.
{"title":"The polarisation behaviour of OJ 287 viewed through radio, millimetre, and optical observations between 2015 and 2017","authors":"J. Jormanainen, T. Hovatta, E. Lindfors, A. Berdyugin, W. Chamani, V. Fallah Ramazani, H. Jermak, S. G. Jorstad, A. Lähteenmäki, C. McCall, K. Nilsson, P. Smith, I. A. Steele, J. Tammi, M. Tornikoski, F. Wierda","doi":"10.1051/0004-6361/202453009","DOIUrl":"https://doi.org/10.1051/0004-6361/202453009","url":null,"abstract":"OJ 287 is a bright blazar with century-long observations, and one of the strongest candidates to host a supermassive black hole binary. Its polarisation behaviour between 2015 and 2017 (MJD 57300–58000) contains several interesting events that we re-contextualise in this study. We collected optical photometric and polarimetric data from several telescopes and obtained high-cadence light curves from this period. In the radio band, we collected millimetre-wavelength polarisation data from the AMAPOLA programme. We combined them with existing multi-frequency polarimetric radio results and the results of very long-baseline interferometry imaging with the Global mm-VLBI Array at 86 GHz. In December 2015, an optical flare was seen according to the general relativistic binary black hole model. We suggest that the overall activity near the accretion disk and the jet base during this time may be connected to the onset of a new moving component, K, seen in the jet in March 2017. With the additional optical data, we find a fast polarisation angle rotation of ∼210° coinciding with the December 2015 flare, hinting at a possible link between these events. Based on the 86 GHz images, we calculated a new speed of 0.12 mas/yr for K, which places it inside the core at the time of the 2015 flare. This speed also supports the scenario in which the passage of K through the quasi-stationary feature S1 could have been the trigger for the very high-energy gamma-ray flare of OJ 287 seen in February 2017. With the millimetre-polarisation data, we establish that these bands follow the centimetre-band data but show a difference during the time when K passes through S1. This indicates that the millimetre bands trace substructures of the jet that are still unresolved in the centimetre bands.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"30 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427460","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: 10.1051/0004-6361/202451280
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}
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