Pub Date : 2024-06-05DOI: 10.1051/0004-6361/202450463
P. Zasche
In this work, I report that large fraction of stars detected by A A, 674, A170 2023A&A...674A.170A and noted in that work as new discoveries are in fact known systems. This is especially true for the dense bulge fields with large blending of nearby sources. Among the published 245 stars determined to be doubly eclipsing (i.e. containing two eclipsing signals), I identified 53 blends. In other words, about a quarter of the systems noted by 2023A&A...674A.170A are not actually doubly eclipsing; rather, these are contaminations of known nearby sources that have already been detected by OGLE. Such a high proportion of reported false positives should not be readily ignored and ought to be addressed in future studies.
{"title":"Comment on Ádám et al. (2023) : Large fraction of already known systems reported","authors":"P. Zasche","doi":"10.1051/0004-6361/202450463","DOIUrl":"https://doi.org/10.1051/0004-6361/202450463","url":null,"abstract":"In this work, I report that large fraction of stars detected by A A, 674,\u0000A170 2023A&A...674A.170A and noted in that work as new discoveries are in fact known systems.\u0000This is especially true for the dense bulge fields with large blending of nearby sources. Among\u0000the published 245 stars determined to be doubly eclipsing (i.e. containing two eclipsing signals),\u0000I identified 53 blends. In other words, about a quarter of the systems noted by 2023A&A...674A.170A are not actually doubly eclipsing; rather, these are\u0000contaminations of known nearby sources that have already been detected by OGLE. Such a high\u0000proportion of reported false positives should not be readily ignored and ought to be addressed in\u0000future studies.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"4 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141265441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.1051/0004-6361/202348290
J. Rosales, J. Petrovic, R. Mennickent, D. R. G. Schleicher, G. Djurašević, N. W. C. Leigh
In this work we focus on the double periodic variable (DPV) star V4142,Sgr, aiming to provide a deeper understanding of its evolution, the formation of its accretion disk, and the operation of magnetic dynamos within the donor star. We analyze its characteristics in detail as well as the phenomena associated with DPV stars more generally. The model was implemented using the stellar evolution code MESA r22.11.1. The modeling process starts from the zero age main sequence and incorporates differential rotation to facilitate the creation of a stellar dynamo in the donor star. We adjusted the model by employing a chi-square algorithm, minimizing the deviation between theoretical and observed values based on previously published fundamental parameters for this system. Our analysis includes an evaluation of various parameters, such as initial masses, orbital periods, mixing parameters, the thermohaline parameter, and metallicities. We assessed the algorithm convergence and set the stopping criterion at 20 helium core depletion in the donor star. A comprehensive analysis was conducted at each evolutionary stage, utilizing the Tayler-Spruit formalism to understand the mechanism of magnetic dynamos. The model begins by adjusting fundamental parameters published for this system through a chi-squared optimization algorithm, adopting an initial orbital period of 15.0 days and initial masses for the donor and gainer star of $ M_ i,d odot $ and $ M_ i,g odot $, with a metallicity associated with this type of DPV of $ Z = 0.02 $. It successfully converges with six degrees of freedom and 5 confidence, resulting in a chi-squared value of 0.007. In addition, the best-fit model for V4142,Sgr shows it is in thermal-timescale mass transfer. Our analysis provides insights into the role of differential rotation in facilitating the formation of a stellar dynamo. Additionally, we have determined that our type-B gainer star is located in a region similar to other type-B DPVs that have undergone rejuvenation due to the transfer of matter. The size of the gainer star shrinks considerably, but it rejuvenates thanks to the material acquired from its donor companion. As for the donor star, the creation and amplification of magnetic fields are influenced by the mixing diffusivity, $ D_ ST $, which is activated by advection outside the overshooting zone.
{"title":"Double periodic variable V4142 Sgr: A key to approaching the stellar dynamo","authors":"J. Rosales, J. Petrovic, R. Mennickent, D. R. G. Schleicher, G. Djurašević, N. W. C. Leigh","doi":"10.1051/0004-6361/202348290","DOIUrl":"https://doi.org/10.1051/0004-6361/202348290","url":null,"abstract":"In this work we focus on the double periodic variable (DPV) star V4142,Sgr, aiming to provide a deeper understanding of its evolution, the formation of its accretion disk, and the operation of magnetic dynamos within the donor star. We analyze its characteristics in detail as well as the phenomena associated with DPV stars more generally. The model was implemented using the stellar evolution code MESA r22.11.1. The modeling process starts from the zero age main sequence and incorporates differential rotation to facilitate the creation of a stellar dynamo in the donor star. We adjusted the model by employing a chi-square algorithm, minimizing the deviation between theoretical and observed values based on previously published fundamental parameters for this system. Our analysis includes an evaluation of various parameters, such as initial masses, orbital periods, mixing parameters, the thermohaline parameter, and metallicities. We assessed the algorithm convergence and set the stopping criterion at 20 helium core depletion in the donor star. A comprehensive analysis was conducted at each evolutionary stage, utilizing the Tayler-Spruit formalism to understand the mechanism of magnetic dynamos. The model begins by adjusting fundamental parameters published for this system through a chi-squared optimization algorithm, adopting an initial orbital period of 15.0 days and initial masses for the donor and gainer star of $ M_ i,d odot $ and $ M_ i,g odot $, with a metallicity associated with this type of DPV of $ Z = 0.02 $. It successfully converges with six degrees of freedom and 5 confidence, resulting in a chi-squared value of 0.007. In addition, the best-fit model for V4142,Sgr shows it is in thermal-timescale mass transfer. Our analysis provides insights into the role of differential rotation in facilitating the formation of a stellar dynamo. Additionally, we have determined that our type-B gainer star is located in a region similar to other type-B DPVs that have undergone rejuvenation due to the transfer of matter. The size of the gainer star shrinks considerably, but it rejuvenates thanks to the material acquired from its donor companion. As for the donor star, the creation and amplification of magnetic fields are influenced by the mixing diffusivity, $ D_ ST $, which is activated by advection outside the overshooting zone.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"3 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141265328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.1051/0004-6361/202449375
A. von Stauffenberg, T. Trifonov, A. Quirrenbach, S. Reffert, A. Kaminski, S. Dreizler, I. Ribas, A. Reiners, M. Kürster, J. Twicken, D. Rapetti, J. A. Caballero, P. Amado, S. V. J. Béjar, C. Cifuentes, S. Góngora, A. Hatzes, T. Henning, D. Montes, J. C. Morales, A. Schweitzer
GJ,581 is a nearby M dwarf known to host a packed multiple planet system composed of two super-Earths and a Neptune-mass planet. We present new orbital analyses of the GJ,581 system, utilizing recent radial velocity (RV) data obtained from the CARMENES spectrograph combined with newly reprocessed archival data from the HARPS and HIRES spectrographs. Our aim was to analyze the post-discovery spectroscopic data of GJ,581, which were obtained with CARMENES. In addition, we used publicly available HIRES and HARPS spectroscopic data to seek evidence of the known and disputed exoplanets in this system. We aimed to investigate the stellar activity of GJ,581 and update the planetary system's orbital parameters using state-of-the-art numerical models and techniques. We performed a periodogram analysis of the available precise CARMENES, HIRES, and HARPS RVs and of stellar activity indicators. We conducted detailed orbital analyses by testing various orbital configurations consistent with the RV data. We studied the posterior probability distribution of the parameters fit to the data and we explored the long-term stability and overall orbital dynamics of the GJ,581 system. We refined the orbital parameters of the GJ,581 system using the most precise and complete set of Doppler data available. Consistent with the existing literature, our analysis confirms that the system is unequivocally composed of only three planets detectable in the present data, dismissing the putative planet GJ,581,d as an artifact of stellar activity. Our N-body fit reveals that the system's inclination is $i = $,deg, which implies that the planets could be up to 30 more massive than their previously reported minimum masses. Furthermore, we report that the GJ,581 system exhibits long-term stability, as indicated by the posterior probability distribution, characterized by secular dynamical interactions without the involvement of mean motion resonances.
{"title":"The CARMENES search for exoplanets around M dwarfs. Revisiting the GJ 581 multi-planetary system with new Doppler measurements from CARMENES, HARPS, and HIRES","authors":"A. von Stauffenberg, T. Trifonov, A. Quirrenbach, S. Reffert, A. Kaminski, S. Dreizler, I. Ribas, A. Reiners, M. Kürster, J. Twicken, D. Rapetti, J. A. Caballero, P. Amado, S. V. J. Béjar, C. Cifuentes, S. Góngora, A. Hatzes, T. Henning, D. Montes, J. C. Morales, A. Schweitzer","doi":"10.1051/0004-6361/202449375","DOIUrl":"https://doi.org/10.1051/0004-6361/202449375","url":null,"abstract":"GJ,581 is a nearby M dwarf known to host a packed multiple planet system composed of two super-Earths and a Neptune-mass planet. We present new orbital analyses of the GJ,581 system, utilizing recent radial velocity (RV) data obtained from the CARMENES spectrograph combined with newly reprocessed archival data from the HARPS and HIRES spectrographs. Our aim was to analyze the post-discovery spectroscopic data of GJ,581, which were obtained with CARMENES. In addition, we used publicly available HIRES and HARPS spectroscopic data to seek evidence of the known and disputed exoplanets in this system. We aimed to investigate the stellar activity of GJ,581 and update the planetary system's orbital parameters using state-of-the-art numerical models and techniques. We performed a periodogram analysis of the available precise CARMENES, HIRES, and HARPS RVs and of stellar activity indicators. We conducted detailed orbital analyses by testing various orbital configurations consistent with the RV data. We studied the posterior probability distribution of the \u0000 parameters fit to the data and we explored the long-term stability and overall orbital dynamics of \u0000 the GJ,581 system. We refined the orbital parameters of the GJ,581 system using the most precise and complete set of Doppler data available. Consistent with the existing literature, our analysis confirms that the system is unequivocally composed of only three planets detectable in the present data, dismissing the putative planet GJ,581,d as an artifact of stellar activity. Our N-body fit reveals that the system's inclination is $i = $,deg, which implies that the planets could be up to 30 more massive than their previously reported minimum masses. Furthermore, we report that the GJ,581 system exhibits long-term stability, as indicated by the posterior probability distribution, characterized by secular dynamical interactions without the involvement of mean motion resonances.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"2 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141265428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.1051/0004-6361/202450450
V. Bozza
The microlensing of stars in our Galaxy has long been used to detect and characterize stellar populations, exoplanets, brown dwarfs, stellar remnants, and all other objects that may magnify the source stars with their gravitational fields. The interpretation of microlensing light curves is relatively simple for single lenses and single sources, but it becomes more and more complicated when we add more objects and take their relative motions into account. RTModel is a modeling platform that has been very active in the real-time investigations of microlensing events, providing preliminary models that have proven very useful for driving follow-up resources towards the most interesting events. The success of RTModel comes from its ability to carry out a thorough and focused exploration of the parameter space in a relatively short time. This modeling process is based on three key ideas. First, the initial conditions are chosen from a template library including all possible caustic crossing and approaches. The fits are then made using the Levenberg-Marquardt algorithm with the addition of a bumper mechanism to explore multiple minima. Finally, the basic computations of microlensing magnification are performed by the fast and robust VBBinaryLensing package. In this paper, we illustrate all the algorithms of RTModel in detail with the intention to foster new approaches in view of future microlensing pipelines aimed at massive microlensing analyses.
{"title":"RTModel : Platform for real-time modeling and massive analyses of microlensing events","authors":"V. Bozza","doi":"10.1051/0004-6361/202450450","DOIUrl":"https://doi.org/10.1051/0004-6361/202450450","url":null,"abstract":"The microlensing of stars in our Galaxy has long been used to detect and characterize stellar populations, exoplanets, brown dwarfs, stellar remnants, and all other objects that may magnify the source stars with their gravitational fields. The interpretation of microlensing light curves is relatively simple for single lenses and single sources, but it becomes more and more complicated when we add more objects and take their relative motions into account. RTModel is a modeling platform that has been very active in the real-time investigations of microlensing events, providing preliminary models that have proven very useful for driving follow-up resources towards the most interesting events. The success of RTModel comes from its ability to carry out a thorough and focused exploration of the parameter space in a relatively short time. This modeling process is based on three key ideas. First, the initial conditions are chosen from a template library including all possible caustic crossing and approaches. The fits are then made using the Levenberg-Marquardt algorithm with the addition of a bumper mechanism to explore multiple minima. Finally, the basic computations of microlensing magnification are performed by the fast and robust VBBinaryLensing package. In this paper, we illustrate all the algorithms of RTModel in detail with the intention to foster new approaches in view of future microlensing pipelines aimed at massive microlensing analyses.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"12 13","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141265472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.1051/0004-6361/202449661
Illya Plotnikov, A. J. Marle, C. Gu'epin, A. Marcowith, Pierrick Martin
The possibility of slow diffusion regions as the origin for extended TeV emission halos around some pulsars (such as PSR J0633+1746 and PSR B0656+14) challenges the standard scaling of the electron diffusion coefficient in the interstellar medium. Self-generated turbulence by electron-positron pairs streaming out of the pulsar wind nebula was proposed as a possible mechanism to produce the enhanced turbulence required to explain the morphology and brightness of these TeV halos. We perform fully kinetic 1D3V particle-in-cell simulations of this instability, considering the case where streaming electrons and positrons have the same density. This implies purely resonant instability as the beam does not carry any current. We compare the linear phase of the instability with analytical theory and find very reasonable agreement. The non-linear phase of the instability is also studied, which reveals that the intensity of saturated waves is consistent with a momentum exchange criterion between a decelerating beam and growing magnetic waves. With the adopted parameters, the instability-driven wavemodes cover both the Alfv'enic (fluid) and kinetic scales. The spectrum of the produced waves is non-symmetric, with left-handed circular polarisation waves being strongly damped when entering the ion-cyclotron branch, while right-handed waves are suppressed at smaller wavelength when entering the Whistler branch. The low-wavenumber part of the spectrum remains symmetric when in the Alfv'enic branch. As a result, positrons behave dynamically differently compared to electrons. The final drift velocity of positrons can maintain a larger value than the ambient Alfv'en speed $V_A$ while the drift of electrons can drop below $V_A$. We also observed a second harmonic plasma emission in the wave spectrum. An MHD-PIC approach is warranted to probe hotter beams and investigate the Alfv'en branch physics. We provide a few such test simulations to support this assertion. This work confirms that the self-confinement scenario develops essentially according to analytical expectations, but some of the adopted approximations (like the distribution of non-thermal particles in the beam) need to be revised and other complementary numerical techniques should be used to get closer to more realistic configuration.
一些脉冲星（如 PSR J0633+1746 和 PSR B0656+14）周围的扩展 TeV 发射晕可能起源于慢扩散区域，这对星际介质中电子扩散系数的标准比例提出了挑战。从脉冲星风星云中流出的电子-正电子对自发产生的湍流被认为是一种可能的机制，可以产生解释这些TeV晕的形态和亮度所需的增强湍流。我们对这种不稳定性进行了全动力学1D3V粒子入胞模拟，考虑了流电子和正电子具有相同密度的情况。这意味着纯共振不稳定性，因为光束不携带任何电流。我们将不稳定性的线性相位与分析理论进行了比较，发现两者非常吻合。我们还研究了不稳定性的非线性阶段，发现饱和波的强度与减速光束和增长磁波之间的动量交换准则一致。在所采用的参数下，不稳定驱动的波模涵盖了Alfv'enic （流体）尺度和动力学尺度。产生的波谱是非对称的，左旋圆极化波在进入离子-回旋支路时受到强烈阻尼，而右旋波在进入惠斯勒支路时则在较小波长上受到抑制。当进入 Alfv'enic 支时，频谱的低波长部分保持对称。因此，正电子的动力学行为与电子不同。正电子的最终漂移速度可以保持一个比环境Alfv'en 速度更大的值$V_A$，而电子的漂移速度可以降到$V_A$以下。我们还在波谱中观测到了二次谐波等离子体发射。我们有理由采用MHD-PIC方法来探测更热的光束并研究Alfv'en 分支物理学。我们提供了一些这样的测试模拟来支持这一论断。这项工作证实，自约束情景基本上是按照分析预期发展的，但所采用的一些近似值（如非热粒子在束流中的分布）需要修改，并应使用其他补充数值技术来接近更现实的配置。
{"title":"Kinetic simulations of electron-positron induced streaming instability in the context of gamma-ray halos around pulsars","authors":"Illya Plotnikov, A. J. Marle, C. Gu'epin, A. Marcowith, Pierrick Martin","doi":"10.1051/0004-6361/202449661","DOIUrl":"https://doi.org/10.1051/0004-6361/202449661","url":null,"abstract":"The possibility of slow diffusion regions as the origin for extended TeV emission halos around some pulsars (such as PSR J0633+1746 and PSR B0656+14) challenges the standard scaling of the electron diffusion coefficient in the interstellar medium. Self-generated turbulence by electron-positron pairs streaming out of the pulsar wind nebula was proposed as a possible mechanism to produce the enhanced turbulence required to explain the morphology and brightness of these TeV halos. We perform fully kinetic 1D3V particle-in-cell simulations of this instability, considering the case where streaming electrons and positrons have the same density. This implies purely resonant instability as the beam does not carry any current. We compare the linear phase of the instability with analytical theory and find very reasonable agreement. The non-linear phase of the instability is also studied, which reveals that the intensity of saturated waves is consistent with a momentum exchange criterion between a decelerating beam and growing magnetic waves. With the adopted parameters, the instability-driven wavemodes cover both the Alfv'enic (fluid) and kinetic scales. The spectrum of the produced waves is non-symmetric, with left-handed circular polarisation waves being strongly damped when entering the ion-cyclotron branch, while right-handed waves are suppressed at smaller wavelength when entering the Whistler branch. The low-wavenumber part of the spectrum remains symmetric when in the Alfv'enic branch. As a result, positrons behave dynamically differently compared to electrons. The final drift velocity of positrons can maintain a larger value than the ambient Alfv'en speed $V_A$ while the drift of electrons can drop below $V_A$. We also observed a second harmonic plasma emission in the wave spectrum. An MHD-PIC approach is warranted to probe hotter beams and investigate the Alfv'en branch physics. We provide a few such test simulations to support this assertion. This work confirms that the self-confinement scenario develops essentially according to analytical expectations, but some of the adopted approximations (like the distribution of non-thermal particles in the beam) need to be revised and other complementary numerical techniques should be used to get closer to more realistic configuration.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"7 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141382790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.1051/0004-6361/202449680
K. Daugevicius, E. Krisciunas, Erikas Cicenas, Rima Stonkute, V. Vansevičius
Recently, it has been noticed that the discrepancies in the integrated colour indices (CIs) between star clusters and models are mostly due to the projection of bright stars in the apertures. In order to reduce this problem, the method of adaptive aperture photometry has been proposed. This method has been applied to star clusters from the M,31 Panchromatic $Hubble$ Andromeda Treasury (PHAT) survey, and studies show that the adaptive aperture photometry performs better than the conventional approach. The aim of this study is to determine the best achievable limits on the accuracy and applicability of the aperture photometry method for studying star clusters in the local Universe. We computed a large network of artificial 3D star clusters spanning the parameter space of the M,31 clusters. We then simulated images of these clusters by projecting each onto a 2D plane from 100 directions. Star cluster images were generated in six passbands to match the PHAT survey. To investigate the limiting accuracy of aperture photometry and the limits of its applicability to star cluster studies, we measured the simulated images and performed parameter determination tests. We demonstrate that star clusters with and without post-main-sequence stars have significant photometric differences. We show that in order to obtain reliable physical parameters of star clusters, the CIs must be measured using an aperture with a radius larger than the cluster’s half-light radius. Furthermore, we demonstrate that the parameter determination of young clusters (sim 10,Myr) is problematic regardless of the aperture size used. Therefore, it is advisable to determine the parameters of these clusters using colour-magnitude diagram fitting methods, when possible. We also show that the randomness of the viewing angle can lead to a CI uncertainty of up to 0.1,mag, depending on cluster parameters and aperture size.
{"title":"Deriving physical parameters of unresolved star clusters. VIII. Limits of aperture photometry for star cluster studies","authors":"K. Daugevicius, E. Krisciunas, Erikas Cicenas, Rima Stonkute, V. Vansevičius","doi":"10.1051/0004-6361/202449680","DOIUrl":"https://doi.org/10.1051/0004-6361/202449680","url":null,"abstract":"Recently, it has been noticed that the discrepancies in the integrated colour indices (CIs) between star clusters and models are mostly due to the projection of bright stars in the apertures. In order to reduce this problem, the method of adaptive aperture photometry has been proposed. This method has been applied to star clusters from the M,31 Panchromatic $Hubble$ Andromeda Treasury (PHAT) survey, and studies show that the adaptive aperture photometry performs better than the conventional approach. The aim of this study is to determine the best achievable limits on the accuracy and applicability of the aperture photometry method for studying star clusters in the local Universe. We computed a large network of artificial 3D star clusters spanning the parameter space of the M,31 clusters. We then simulated images of these clusters by projecting each onto a 2D plane from 100 directions. Star cluster images were generated in six passbands to match the PHAT survey. To investigate the limiting accuracy of aperture photometry and the limits of its applicability to star cluster studies, we measured the simulated images and performed parameter determination tests. We demonstrate that star clusters with and without post-main-sequence stars have significant photometric differences. We show that in order to obtain reliable physical parameters of star clusters, the CIs must be measured using an aperture with a radius larger than the cluster’s half-light radius. Furthermore, we demonstrate that the parameter determination of young clusters (sim 10,Myr) is problematic regardless of the aperture size used. Therefore, it is advisable to determine the parameters of these clusters using colour-magnitude diagram fitting methods, when possible. We also show that the randomness of the viewing angle can lead to a CI uncertainty of up to 0.1,mag, depending on cluster parameters and aperture size.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"12 42","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141265641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.1051/0004-6361/202449329
L. N. Martínez-Ramírez, G. Calistro Rivera, E. Lusso, F. Bauer, E. Nardini, J. Buchner, J.I. Michael Brown, C.B. Juan Pineda, J. Matthew Temple, Manda Banerji, M. Stalevski, F. Joseph Hennawi
We present new advancements in the modeling of the spectral energy distributions (SEDs) of active galaxies by introducing the radio-to-X-ray fitting capabilities of the publicly available Bayesian code AGNfitter . The new code release, called AGNfitter-rx models the broad-band photometry covering the radio, infrared (IR), optical, ultraviolet (UV), and X-ray bands consistently using a combination of theoretical and semi-empirical models of the active galactic nucleus (AGN) and host-galaxy emission. This framework enables the detailed characterization of four physical components of the active nuclei, namely the accretion disk, the hot dusty torus, the relativistic jets and core radio emission, and the hot corona, and can be used to model three components within the host galaxy: stellar populations, cold dust, and the radio emission from the star-forming regions. Applying AGNfitter-rx to a diverse sample of 36 AGN SEDs at $z 0.7$ from the AGN SED ATLAS, we investigated and compared the performance of state-of-the-art torus and accretion disk emission models in terms of fit quality and inferred physical parameters. We find that clumpy torus models that include polar winds and semi-empirical accretion disk templates including emission-line features significantly increase the fit quality in 67 of the sources by reducing by $2 fit residuals in the $1.5-5 1mm m$ and $0.7 1mm m$ regimes. We demonstrate that, by applying AGNfitter-rx to photometric data, we are able to estimate the inclination and opening angles of the torus, consistent with spectroscopic classifications within the AGN unified model, as well as black hole masses congruent with virial estimates based on Halpha . We investigate wavelength-dependent AGN fractions across the spectrum for Type 1 and Type 2 AGNs, finding dominant AGN fractions in radio, mid-infrared, and X-ray bands, which are in agreement with the findings from empirical methods for AGN selection. The wavelength coverage and the flexibility for the inclusion of state-of-the-art theoretical models make AGNfitter-rx a unique tool for the further development of SED modeling for AGNs in present and future radio-to-X-ray galaxy surveys.
{"title":"AGNfitter-rx : Modeling the radio-to-X-ray spectral energy distributions of AGNs","authors":"L. N. Martínez-Ramírez, G. Calistro Rivera, E. Lusso, F. Bauer, E. Nardini, J. Buchner, J.I. Michael Brown, C.B. Juan Pineda, J. Matthew Temple, Manda Banerji, M. Stalevski, F. Joseph Hennawi","doi":"10.1051/0004-6361/202449329","DOIUrl":"https://doi.org/10.1051/0004-6361/202449329","url":null,"abstract":"We present new advancements in the modeling of the spectral energy distributions (SEDs) of active galaxies by introducing the radio-to-X-ray fitting capabilities of the publicly available Bayesian code AGNfitter . The new code release, called AGNfitter-rx models the broad-band photometry covering the radio, infrared (IR), optical, ultraviolet (UV), and X-ray bands consistently using a combination of theoretical and semi-empirical models of the active galactic nucleus (AGN) and host-galaxy emission. This framework enables the detailed characterization of four physical components of the active nuclei, namely the accretion disk, the hot dusty torus, the relativistic jets and core radio emission, and the hot corona, and can be used to model three components within the host galaxy: stellar populations, cold dust, and the radio emission from the star-forming regions. Applying AGNfitter-rx to a diverse sample of 36 AGN SEDs at $z 0.7$ from the AGN SED ATLAS, we investigated and compared the performance of state-of-the-art torus and accretion disk emission models in terms of fit quality and inferred physical parameters. We find that clumpy torus models that include polar winds and semi-empirical accretion disk templates including emission-line features significantly increase the fit quality in 67 of the sources by reducing by $2 fit residuals in the $1.5-5 1mm m$ and $0.7 1mm m$ regimes. We demonstrate that, by applying AGNfitter-rx to photometric data, we are able to estimate the inclination and opening angles of the torus, consistent with spectroscopic classifications within the AGN unified model, as well as black hole masses congruent with virial estimates based on Halpha . We investigate wavelength-dependent AGN fractions across the spectrum for Type 1 and Type 2 AGNs, finding dominant AGN fractions in radio, mid-infrared, and X-ray bands, which are in agreement with the findings from empirical methods for AGN selection. The wavelength coverage and the flexibility for the inclusion of state-of-the-art theoretical models make AGNfitter-rx a unique tool for the further development of SED modeling for AGNs in present and future radio-to-X-ray galaxy surveys.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141265310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.1051/0004-6361/202449653
Bruno Dom'inguez, Siddharth Chaini, Karlo Mrakovvci'c, Brandon Sallee, vZeljko Ivezi'c
We validate the 2010ApJ...716....1B kinematic models for the Milky Way's disk and halo stars with Gaia Data Release 3 data. Bond et al. constructed models for stellar velocity distributions using stellar radial velocities measured by the Sloan Digital Sky Survey (SDSS) and stellar proper motions derived from SDSS and the Palomar Observatory Sky Survey astrometric measurements. These models describe velocity distributions as functions of position in the Galaxy, with separate models for disk and halo stars that were labeled using SDSS photometric and spectroscopic metallicity measurements. We find that the Bond et al. model predictions are in good agreement with recent measurements of stellar radial velocities and proper motions by the Gaia survey. In particular, the model accurately predicts the skewed non-Gaussian distribution of rotational velocity for disk stars and its vertical gradient, as well as the dispersions for all three velocity components. Additionally, the spatial invariance of velocity ellipsoid for halo stars when expressed in spherical coordinates is also confirmed by Gaia data at galacto-centric radial distances of up to 15 kpc.
{"title":"Validation of the Bond et al. (2010) SDSS-derived kinematic models for the Milky Way's disk and halo stars with Gaia Data Release 3 proper motion and radial velocity data","authors":"Bruno Dom'inguez, Siddharth Chaini, Karlo Mrakovvci'c, Brandon Sallee, vZeljko Ivezi'c","doi":"10.1051/0004-6361/202449653","DOIUrl":"https://doi.org/10.1051/0004-6361/202449653","url":null,"abstract":"We validate the 2010ApJ...716....1B kinematic models for the Milky Way's disk and halo stars with Gaia Data Release 3 data.\u0000Bond et al. constructed models for stellar velocity distributions using stellar radial velocities measured by the Sloan Digital Sky Survey (SDSS) and stellar proper motions derived from SDSS and the Palomar Observatory Sky Survey astrometric measurements. These models describe velocity distributions as functions of position in the Galaxy, with separate models for\u0000disk and halo stars that were labeled using SDSS photometric and spectroscopic metallicity measurements.\u0000We find that the Bond et al. model predictions are in good agreement with recent measurements of stellar radial velocities\u0000and proper motions by the Gaia survey. In particular, the model accurately predicts the skewed non-Gaussian distribution of rotational velocity for disk\u0000stars and its vertical gradient, as well as the dispersions for all three velocity components.\u0000Additionally, the spatial invariance of velocity ellipsoid for halo stars when expressed in spherical coordinates is also confirmed by Gaia data at galacto-centric radial distances of up to 15 kpc.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"1 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141385956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.1051/0004-6361/202450153
P. Benke, A. Gokus, M. Lisakov, L. Gurvits, F. Eppel, J. Hessdorfer, M. Kadler, Y. Kovalev, E. Ros, F. Rosch
High-redshift blazars provide valuable input to studies of the evolution of active galactic nuclei (AGN) jets and provide constraints on cosmological models. Detections at high energies ($0.1< E <100$ GeV) of these distant sources are rare, but when they exhibit bright gamma-ray flares, we are able to study them. However, contemporaneous multi-wavelength observations of high-redshift objects ($z>4$) during their different periods of activity have not been carried out so far. An excellent opportunity for such a study arose when the blazar TXS,1508+572 ($z=4.31$) exhibited a gamma -ray flare in 2022 February in the $0.1-300$ GeV range with a flux 25 times brighter than the one reported in the in the fourth catalog of the Fermi Large Area Telescope. Our goal is to monitor the morphological changes, spectral index and opacity variations that could be associated with the preceding gamma -ray flare in TXS,1508+572 to find the origin of the high-energy emission in this source. We also plan to compare the source characteristics in the radio band to the blazars in the local Universe ($z<0.1$). In addition, we aim to collect quasi-simultaneous data to our multi-wavelength observations of the object, making TXS,1508+572 the first blazar in the early Universe ($z>4$) with contemporaneous multi-frequency data available in its high state. In order to study the parsec-scale structure of the source, we performed three epochs of very-long-baseline interferometry (VLBI) follow-up observations with the Very Long Baseline Array (VLBA) supplemented with the Effelsberg $100$-m Telescope at $15$, $22$, and $43$,GHz, which corresponds to $80$, $117$, and $228$,GHz in the rest frame of TXS,1508+572 . In addition, one $86$,GHz ($456$,GHz) measurement was performed by the VLBA and the Green Bank Telescope during the first epoch. We present total intensity images from our multi-wavelength VLBI monitoring that reveal significant morphological changes in the parsec-scale structure of TXS,1508+572 . The jet proper motion values range from $0.12$ mas/yr to $0.27$ mas/yr, which corresponds to apparent superluminal motion $ app -- $32.2,c$. This is consistent with the high Lorentz factors inferred from the spectral energy distribution (SED) modeling for this source. The core shift measurement reveals no significant impact by the high-energy flare on the distance of the $43$-GHz radio core with respect to the central engine, that means this region is probably not affected by e.g., injection of new plasma as seen in other well-studied sources like CTA,102. We determine the average distance from the $43$-GHz radio core to the central supermassive black hole to be $46.1 that corresponds to a projected distance of $0.32 pc. We estimate the equipartition magnetic field strength $1$ pc from the central engine to be on the order of $0.8$ G, and the non-equipartition magnetic field strength at the same distance to be about $1.7$ G, which values agree well with the magnetic field strength
高红移蓝星为研究活动星系核（AGN）喷流的演变提供了宝贵的资料，并为宇宙学模型提供了约束条件。迄今为止，还没有在高能量（0.1 美元< E 4 美元）下对它们的不同活动时期进行过探测。2022年2月，类星体TXS,1508+572（$z=4.31$）在0.1-300$ GeV范围内发生了一次伽马射线耀斑，其光通量比费米大口径望远镜的第四期星表中报告的光通量亮25倍，这为我们的研究提供了一个极好的机会。我们的目标是监测可能与TXS,1508+572之前的伽马射线耀斑有关的形态变化、光谱指数和不透明度变化，以找到该源高能发射的起源。我们还计划将该源在射电波段的特征与本地宇宙（$z4$）中的燃烧星进行比较，并同时提供其高能状态下的多频数据。为了研究该源的parsec尺度结构，我们利用埃菲尔斯贝格100美元米望远镜辅以甚长基线阵列（VLBA），在15美元、22美元和43美元（GHz）的频率上进行了三个纪元的甚长基线干涉测量（VLBI）跟踪观测，对应于TXS,1508+572静止帧上的80美元、117美元和228美元（GHz）。此外，在第一个纪元期间，VLBA和绿岸望远镜还进行了一次86美元/千兆赫（456美元/千兆赫）的测量。我们展示了多波长 VLBI 监测得到的总强度图像，这些图像揭示了 TXS,1508+572 星系尺度结构的显著形态变化。喷流的正确运动值范围从0.12$mas/yr到0.27$mas/yr，对应于明显的超光速运动$app--$32.2,c$。这与该星源的光谱能量分布（SED）建模推断出的高洛伦兹因子是一致的。核心偏移的测量结果显示，高能耀斑对$43$-GHz射电核心相对于中央引擎的距离没有明显的影响，这意味着这个区域很可能没有受到新等离子体注入的影响，就像在CTA,102等其他研究得很好的源中看到的那样。我们确定从 $43$-GHz 射电核心到中央超大质量黑洞的平均距离为 46.1 美元，相当于 0.32 pc 的预测距离。我们估计距离中心引擎 1 美元 pc 的等分磁场强度约为 0.8 美元 G，而相同距离的非等分磁场强度约为 1.7 美元 G，这些数值与在中低红移 AGN 中测得的磁场强度非常吻合。根据我们的VLBI分析，我们认为在2022年2月观测到的伽马射线活动是由TXS,1508+572的喷流和流经这个部分的新等离子体之间的冲击-震荡相互作用引起的。例如，在CTA,102中也观测到了类似的现象，即静止成分与新出现成分之间的冲击-震荡相互作用。不过，在这种情况下，核心区域也受到了耀斑的影响，因为核心偏移在整个观测过程中保持一致。
{"title":"Very-long-baseline interferometry study of the flaring blazar TXS 1508+572 in the early Universe","authors":"P. Benke, A. Gokus, M. Lisakov, L. Gurvits, F. Eppel, J. Hessdorfer, M. Kadler, Y. Kovalev, E. Ros, F. Rosch","doi":"10.1051/0004-6361/202450153","DOIUrl":"https://doi.org/10.1051/0004-6361/202450153","url":null,"abstract":"High-redshift blazars provide valuable input to studies of the evolution of active galactic nuclei (AGN) jets and provide constraints on cosmological models. Detections at high energies ($0.1< E <100$ GeV) of these distant sources are rare, but when they exhibit bright gamma-ray flares, we are able to study them. However, contemporaneous multi-wavelength observations of high-redshift objects ($z>4$) during their different periods of activity have not been carried out so far. An excellent opportunity for such a study arose when the blazar TXS,1508+572 ($z=4.31$) exhibited a gamma -ray flare in 2022 February in the $0.1-300$ GeV range with a flux 25 times brighter than the one reported in the in the fourth catalog of the Fermi Large Area Telescope. Our goal is to monitor the morphological changes, spectral index and opacity variations that could be associated with the preceding gamma -ray flare in TXS,1508+572 to find the origin of the high-energy emission in this source. We also plan to compare the source characteristics in the radio band to the blazars in the local Universe ($z<0.1$). In addition, we aim to collect quasi-simultaneous data to our multi-wavelength observations of the object, making TXS,1508+572 the first blazar in the early Universe ($z>4$) with contemporaneous multi-frequency data available in its high state. In order to study the parsec-scale structure of the source, we performed three epochs of very-long-baseline interferometry (VLBI) follow-up observations with the Very Long Baseline Array (VLBA) supplemented with the Effelsberg $100$-m Telescope at $15$, $22$, and $43$,GHz, which corresponds to $80$, $117$, and $228$,GHz in the rest frame of TXS,1508+572 . In addition, one $86$,GHz ($456$,GHz) measurement was performed by the VLBA and the Green Bank Telescope during the first epoch. We present total intensity images from our multi-wavelength VLBI monitoring that reveal significant morphological changes in the parsec-scale structure of TXS,1508+572 . The jet proper motion values range from $0.12$ mas/yr to $0.27$ mas/yr, which corresponds to apparent superluminal motion $ app -- $32.2,c$. This is consistent with the high Lorentz factors inferred from the spectral energy distribution (SED) modeling for this source. The core shift measurement reveals no significant impact by the high-energy flare on the distance of the $43$-GHz radio core with respect to the central engine, that means this region is probably not affected by e.g., injection of new plasma as seen in other well-studied sources like CTA,102. We determine the average distance from the $43$-GHz radio core to the central supermassive black hole to be $46.1 that corresponds to a projected distance of $0.32 pc. We estimate the equipartition magnetic field strength $1$ pc from the central engine to be on the order of $0.8$ G, and the non-equipartition magnetic field strength at the same distance to be about $1.7$ G, which values agree well with the magnetic field strength ","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"45 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141384407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.1051/0004-6361/202449998
Carlos Rodrigo, Patricia Cruz, J. F. Aguilar, Alba Aller, Enrique Solano, M. C. Gálvez-Ortiz, F. Jiménez-Esteban, P. Mas-Buitrago, Amelia Bayo, M. Cortés-Contreras, R. Murillo-Ojeda
This paper is focused on the segregation of FGK dwarf and giant stars through narrow-band photometric data using the Spanish Virtual Observatory (SVO) Filter Profile Service and associated photometric tools. We selected spectra from the MILES, STELIB, and ELODIE stellar libraries, and used SVO photometric tools to derive the synthetic photometry in 15 J-PAS narrow filters, which were especially selected to cover spectral features sensitive to gravity changes. Using machine-learning techniques as the Gaussian mixture model and the support vector machine, we defined several criteria based on J-PAS colours to discriminate between dwarf and giant stars. We selected five colour-colour diagrams that presented the most promising separation between both samples. Our results show an overall accuracy in the studied sample of sim 0.97 for FGK stars, although a dependence on the luminosity type and the stellar effective temperature was found. We also defined a colour-temperature relation for dwarf stars with effective temperatures between 4,000 and 7,000,K, which allows one to estimate the stellar effective temperature from four J-PAS filters ($J0450$, $J0510$, $J0550$, and $J0620$). Additionally, we extended the study to M-type giant and dwarf stars, achieving a similar accuracy to that for FGK stars.
{"title":"Photometric segregation of dwarf and giant FGK stars using the SVO Filter Profile Service and photometric tools","authors":"Carlos Rodrigo, Patricia Cruz, J. F. Aguilar, Alba Aller, Enrique Solano, M. C. Gálvez-Ortiz, F. Jiménez-Esteban, P. Mas-Buitrago, Amelia Bayo, M. Cortés-Contreras, R. Murillo-Ojeda","doi":"10.1051/0004-6361/202449998","DOIUrl":"https://doi.org/10.1051/0004-6361/202449998","url":null,"abstract":"This paper is focused on the segregation of FGK dwarf and giant stars through narrow-band photometric data using the Spanish Virtual Observatory (SVO) Filter Profile Service and associated photometric tools. We selected spectra from the MILES, STELIB, and ELODIE stellar libraries, and used SVO photometric tools to derive the synthetic photometry in 15 J-PAS narrow filters, which were especially selected to cover spectral features sensitive to gravity changes. Using machine-learning techniques as the Gaussian mixture model and the support vector machine, we defined several criteria based on J-PAS colours to discriminate between dwarf and giant stars. We selected five colour-colour diagrams that presented the most promising separation between both samples. Our results show an overall accuracy in the studied sample of sim 0.97 for FGK stars, although a dependence on the luminosity type and the stellar effective temperature was found. \u0000 We also defined a colour-temperature relation for dwarf stars with effective temperatures between 4,000 and 7,000,K, which allows one to estimate the stellar effective temperature from four J-PAS filters ($J0450$, $J0510$, $J0550$, and $J0620$). Additionally, we extended the study to M-type giant and dwarf stars, achieving a similar accuracy to that for FGK stars.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"76 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141385376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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