Pub Date : 2025-12-17DOI: 10.1051/0004-6361/202557647
M. Mallo, M. Agúndez, C. Cabezas, O. Roncero, J. Cernicharo, G. Molpeceres
Cyclopentadiene (c-C5H6) is considered a key molecule in the formation of polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium (ISM). The synthesis of PAHs from simpler precursors is known as the “bottom-up” theory, which, so far, has been dominated by reactions between organic radicals. However, this mechanism struggles to account for the origin of the smallest cycles themselves. However, it struggles to account for the origin of the smallest cycles themselves. Ion-molecule reactions emerge as promising alternative pathways to explain the formation of these molecules. We investigated the reaction network of the main ionic precursor of cyclopentadiene, c-C5H7+. To this end, we established an integrated protocol that combines astrochemical modelling to identify viable formation routes under cold ISM conditions, automated reaction path searches, and kinetic simulations to obtain accurate descriptions of the reaction pathways and reliable rate constants. In particular, we examined the reaction between ethylene (C2H4) and the linear propargyl cation (CH2CCH+). Our results reveal that the formation of c-C5H7+ by radiative association is inefficient, contrary to our initial expectations. Instead, the system predominantly evolves through bimolecular channels yielding c-C5H5+ and CH3CCH2+, with the formation of c-C5H5+; this offers new insights into the reactivity that supports molecular growth in the ISM.
{"title":"Ion-molecule routes towards cycles in TMC-1","authors":"M. Mallo, M. Agúndez, C. Cabezas, O. Roncero, J. Cernicharo, G. Molpeceres","doi":"10.1051/0004-6361/202557647","DOIUrl":"https://doi.org/10.1051/0004-6361/202557647","url":null,"abstract":"Cyclopentadiene (c-C<sub>5<sub/>H<sub>6<sub/>) is considered a key molecule in the formation of polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium (ISM). The synthesis of PAHs from simpler precursors is known as the “bottom-up” theory, which, so far, has been dominated by reactions between organic radicals. However, this mechanism struggles to account for the origin of the smallest cycles themselves. However, it struggles to account for the origin of the smallest cycles themselves. Ion-molecule reactions emerge as promising alternative pathways to explain the formation of these molecules. We investigated the reaction network of the main ionic precursor of cyclopentadiene, c-C<sub>5<sub/>H<sub>7<sub/><sup>+<sup/>. To this end, we established an integrated protocol that combines astrochemical modelling to identify viable formation routes under cold ISM conditions, automated reaction path searches, and kinetic simulations to obtain accurate descriptions of the reaction pathways and reliable rate constants. In particular, we examined the reaction between ethylene (C<sub>2<sub/>H<sub>4<sub/>) and the linear propargyl cation (CH<sub>2<sub/>CCH<sup>+<sup/>). Our results reveal that the formation of c-C<sub>5<sub/>H<sub>7<sub/><sup>+<sup/> by radiative association is inefficient, contrary to our initial expectations. Instead, the system predominantly evolves through bimolecular channels yielding c-C<sub>5<sub/>H<sub>5<sub/><sup>+<sup/> and CH<sub>3<sub/>CCH<sub>2<sub/><sup>+<sup/>, with the formation of c-C<sub>5<sub/>H<sub>5<sub/><sup>+<sup/>; this offers new insights into the reactivity that supports molecular growth in the ISM.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"16 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-17DOI: 10.1051/0004-6361/202557227
Nicola Schneider, Simon Dannhauer, Eduard Keilmann, Slawa Kabanovic, Theodoros Topkaras, Volker Ossenkopf-Okada, Ronan Higgins, Andreas Brunthaler, Won-Ju Kim, Fernando Comerón, Markus Röllig, Timea Csengeri, Robert Simon, Yoko Okada, Matthias Justen, Sergio A. Dzib, Gisela N. Ortiz-León
A proplyd is defined as a young stellar object (YSO) surrounded by a circumstellar disk of gas and dust and embedded in a molecular envelope undergoing photo-evaporation by external ultraviolet (UV) radiation. Since the discovery of the Orion proplyds, one question has arisen as to how inside-out photo-evaporation and external irradiation can influence the evolution of these systems. For such an investigation, it is essential to determine the molecular and atomic gas masses, as well as the photo-evaporation and free-fall timescales. Understanding the dynamics within the photo-dissociation regions (PDRs) of a potential envelope–disc system, as well as the surrounding gas in relation to photo-evaporative flows, requires spectrally resolved line observations. Thus, we chose to investigate an isolated, globule-shaped object (~0.37 pc × 0.11 pc at a distance of 1.4 kpc), located near the centre of the Cygnus OB2 cluster and named proplyd #7 in optical observations. In the literature, there is no consensus on the nature of this source. Observations point toward a massive star (with or without disc) with a H II region or a G-type T Tauri star with a photo-evaporating disc, embedded in a molecular envelope. We obtained a map of the [O I] line at 63 μm with 6″ angular resolution and employed archival data of the [C II] 158 μm line (14" resolution), using the upGREAT heterodyne receiver aboard SOFIA. We also collected IRAM 30m CO data at 1 mm (11″ resolution). All the lines were detected across the whole object. The peak integrated [O I] emission of ~5 K km s<sup>−1<sup/> is located ~10″ west of an embedded YSO. The [O I] and [C II] data near the source show bulk emission at ~11 km s<sup>−1<sup/> and a line wing at ~13 km s<sup>−1<sup/>, while the <sup>12<sup/>CO 2→1 data reveal additional blue-shifted high-velocity emission. The widespread [O I] emission prompts the question of its origin since the [O I] line can serve as a cooling line for a PDR or for shocks associated with a disc. From both local and non-local thermodynamic equilibrium (LTE and non-LTE) calculations, we obtained a column density of N<sub>OI<sub/> ≈ 10<sup>18<sup/> cm<sup>−2<sup/> at a density of 4–8 × 10<sup>3<sup/> cm<sup>−3<sup/>. The [O I] line is, thus, sub-thermally excited. The KOSMA-<i>τ<i/> PDR model can explain the emissions in the tail with a low external UV field (<350 G<sub>°<sub/>, mostly consistent with our UV field estimates), but not at the location of the YSO. There, the high line intensities and increased line widths for all lines and a possible bipolar CO outflow suggest the presence of a protostellar disc. However, the existence of a thermal H II region, revealed by combining existing and new radio continuum data, points towards a massive star – and not a T Tauri-type one. The circumstellar environment of proplyd #7 consists mostly of molecular gas. We derived molecular and atomic gas masses of ~20 M<sub>⊙<sub/> and a few M<sub>⊙<sub/>, respectively. The photo
proplyd被定义为一种年轻的恒星物体（YSO），它被一个由气体和尘埃组成的星周圆盘包围，并嵌入在一个分子包膜中，在外部紫外线（UV）辐射下进行光蒸发。自从猎户座星系的发现以来，一个问题出现了，即由内而外的光蒸发和外部辐射如何影响这些系统的进化。对于这样的研究，必须确定分子和原子气体的质量，以及光蒸发和自由落体的时间尺度。了解潜在的包膜-圆盘系统的光解离区域（pdr）内的动力学，以及与光蒸发流动相关的周围气体，需要光谱分辨线观测。因此，我们选择研究一个孤立的球状物体（距离1.4 kpc的~0.37 pc × 0.11 pc），它位于天鹅座OB2星团的中心附近，在光学观测中被命名为proplyd #7。在文献中，对这一来源的性质没有达成共识。观测指向一个有H II区域的大质量恒星（有或没有圆盘），或一个有光蒸发盘的g型T金牛座恒星，镶嵌在一个分子包膜中。我们使用SOFIA上的upGREAT外差接收器，获得了63 μm [O ；I]线的地图，角分辨率为6″，并使用[C II] 158 μm线的存档数据（14”分辨率）。我们还收集了1 mm（11″分辨率）的IRAM 30m CO数据。所有的线条都是在整个物体上检测到的。~5 K km s−1的[O I]峰值积分发射位于嵌入YSO以西~10″处。来源附近的[O I]和[C II]数据显示在~11 km s−1处有大量发射和~13 km s−1处有线翼，而12CO 2→1数据显示额外的蓝移高速发射。广泛的[O I]辐射引发了它的起源问题，因为[O I]线可以作为PDR或与圆盘相关的冲击的冷却线。从局部和非局部热力学平衡（LTE和非LTE）计算中，我们得到了密度为4-8 × 103 cm−3时NOI≈1018 cm−2的柱密度。因此，[O I]线是次热激发的。KOSMA-τ PDR模型可以解释低外部紫外场（°，与我们的紫外场估计基本一致）尾部的发射，但不能解释YSO位置的发射。在那里，高线强度和所有线的线宽增加以及可能的双极CO流出表明存在原恒星盘。然而，结合现有的和新的射电连续体数据，发现了一个热H II区域的存在，指向一颗大质量恒星——而不是金牛座T型恒星。propld #7的星周环境主要由分子气体组成。我们得到的分子和原子气体质量分别为~ 20m⊙和几个M⊙。光蒸发（仅考虑外部光照）寿命为1.6±105 yr，小于自由落体寿命（5.2±105 yr）；因此，我们发现7号原行星可能没有足够的时间产生更多的恒星。这一观点得到了文献模拟结果的支持。
{"title":"Globules and pillars in Cygnus X","authors":"Nicola Schneider, Simon Dannhauer, Eduard Keilmann, Slawa Kabanovic, Theodoros Topkaras, Volker Ossenkopf-Okada, Ronan Higgins, Andreas Brunthaler, Won-Ju Kim, Fernando Comerón, Markus Röllig, Timea Csengeri, Robert Simon, Yoko Okada, Matthias Justen, Sergio A. Dzib, Gisela N. Ortiz-León","doi":"10.1051/0004-6361/202557227","DOIUrl":"https://doi.org/10.1051/0004-6361/202557227","url":null,"abstract":"A proplyd is defined as a young stellar object (YSO) surrounded by a circumstellar disk of gas and dust and embedded in a molecular envelope undergoing photo-evaporation by external ultraviolet (UV) radiation. Since the discovery of the Orion proplyds, one question has arisen as to how inside-out photo-evaporation and external irradiation can influence the evolution of these systems. For such an investigation, it is essential to determine the molecular and atomic gas masses, as well as the photo-evaporation and free-fall timescales. Understanding the dynamics within the photo-dissociation regions (PDRs) of a potential envelope–disc system, as well as the surrounding gas in relation to photo-evaporative flows, requires spectrally resolved line observations. Thus, we chose to investigate an isolated, globule-shaped object (~0.37 pc × 0.11 pc at a distance of 1.4 kpc), located near the centre of the Cygnus OB2 cluster and named proplyd #7 in optical observations. In the literature, there is no consensus on the nature of this source. Observations point toward a massive star (with or without disc) with a H II region or a G-type T Tauri star with a photo-evaporating disc, embedded in a molecular envelope. We obtained a map of the [O I] line at 63 μm with 6″ angular resolution and employed archival data of the [C II] 158 μm line (14\" resolution), using the upGREAT heterodyne receiver aboard SOFIA. We also collected IRAM 30m CO data at 1 mm (11″ resolution). All the lines were detected across the whole object. The peak integrated [O I] emission of ~5 K km s<sup>−1<sup/> is located ~10″ west of an embedded YSO. The [O I] and [C II] data near the source show bulk emission at ~11 km s<sup>−1<sup/> and a line wing at ~13 km s<sup>−1<sup/>, while the <sup>12<sup/>CO 2→1 data reveal additional blue-shifted high-velocity emission. The widespread [O I] emission prompts the question of its origin since the [O I] line can serve as a cooling line for a PDR or for shocks associated with a disc. From both local and non-local thermodynamic equilibrium (LTE and non-LTE) calculations, we obtained a column density of N<sub>OI<sub/> ≈ 10<sup>18<sup/> cm<sup>−2<sup/> at a density of 4–8 × 10<sup>3<sup/> cm<sup>−3<sup/>. The [O I] line is, thus, sub-thermally excited. The KOSMA-<i>τ<i/> PDR model can explain the emissions in the tail with a low external UV field (<350 G<sub>°<sub/>, mostly consistent with our UV field estimates), but not at the location of the YSO. There, the high line intensities and increased line widths for all lines and a possible bipolar CO outflow suggest the presence of a protostellar disc. However, the existence of a thermal H II region, revealed by combining existing and new radio continuum data, points towards a massive star – and not a T Tauri-type one. The circumstellar environment of proplyd #7 consists mostly of molecular gas. We derived molecular and atomic gas masses of ~20 M<sub>⊙<sub/> and a few M<sub>⊙<sub/>, respectively. The photo","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"15 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-17DOI: 10.1051/0004-6361/202556704
P. Janin-Potiron, M. Gray, B. Neichel, M. Dumont, J.-F. Sauvage, C. T. Heritier, P. Jouve, R. Fetick, T. Fusco
Context. As the Extremely Large Telescope (ELT) approaches operational status, optimising its imaging performance is critical. A differential piston, arising from either the adaptive optics (AO) control loop, thermomechanical effects, or other sources, significantly degrades the image quality and is detrimental to the telescope’s overall performance.Aims. In a numerical simulation set-up, we propose a method for estimating the differential piston between the petals of the ELT’s M4 mirror using images from a 2 × 2 Shack-Hartmann wavefront sensor (SH-WFS), commonly used in the ELT’s tomographic AO mode. We aim to identify the limitations of this approach by evaluating its sensitivity to various observing conditions and sources of noise.Methods. Using a deep learning model based on a ResNet architecture, we trained a neural network (NN) on simulated datasets to estimate the differential piston. We assessed the robustness of the method under various conditions, including variations in Strehl ratio, polychromaticity, and detector noise. The performance was quantified using the root mean square error (RMSE) of the estimated differential piston aberration.Results. This method demonstrates the ability to extract differential piston information from 2 × 2 SH-WFS images. Temporal averaging of frames makes the differential piston signal emerge from the turbulence-induced speckle field and leads to a significant improvement in the RMSE calculation. As expected, better seeing conditions result in improved accuracy. Polychromaticity only degrades the performance by less than 5%, compared to the monochromatic case. In a realistic scenario, detector noise is not a limiting factor, as the primary limitation rather arises from the need for sufficient speckle averaging. The network was also shown to be applicable to input images other than the 2 × 2 SH-WFS data.
{"title":"Estimating differential pistons for the Extremely Large Telescope using focal plane imaging and a residual network","authors":"P. Janin-Potiron, M. Gray, B. Neichel, M. Dumont, J.-F. Sauvage, C. T. Heritier, P. Jouve, R. Fetick, T. Fusco","doi":"10.1051/0004-6361/202556704","DOIUrl":"https://doi.org/10.1051/0004-6361/202556704","url":null,"abstract":"<i>Context.<i/> As the Extremely Large Telescope (ELT) approaches operational status, optimising its imaging performance is critical. A differential piston, arising from either the adaptive optics (AO) control loop, thermomechanical effects, or other sources, significantly degrades the image quality and is detrimental to the telescope’s overall performance.<i>Aims.<i/> In a numerical simulation set-up, we propose a method for estimating the differential piston between the petals of the ELT’s M4 mirror using images from a 2 × 2 Shack-Hartmann wavefront sensor (SH-WFS), commonly used in the ELT’s tomographic AO mode. We aim to identify the limitations of this approach by evaluating its sensitivity to various observing conditions and sources of noise.<i>Methods.<i/> Using a deep learning model based on a ResNet architecture, we trained a neural network (NN) on simulated datasets to estimate the differential piston. We assessed the robustness of the method under various conditions, including variations in Strehl ratio, polychromaticity, and detector noise. The performance was quantified using the root mean square error (RMSE) of the estimated differential piston aberration.<i>Results.<i/> This method demonstrates the ability to extract differential piston information from 2 × 2 SH-WFS images. Temporal averaging of frames makes the differential piston signal emerge from the turbulence-induced speckle field and leads to a significant improvement in the RMSE calculation. As expected, better seeing conditions result in improved accuracy. Polychromaticity only degrades the performance by less than 5%, compared to the monochromatic case. In a realistic scenario, detector noise is not a limiting factor, as the primary limitation rather arises from the need for sufficient speckle averaging. The network was also shown to be applicable to input images other than the 2 × 2 SH-WFS data.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"1 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-17DOI: 10.1051/0004-6361/202554492
P. M. W. Kalberla
Context. Neutral atomic hydrogen (H I) absorption lines can be used to probe the cold neutral medium (CNM) at high Galactic latitudes. Cold H I with a significant optical depth from the GASKAP-H I survey is found to be located predominantly if not exclusively within filamentary structures that can be identified as caustics with the Hessian operator. Most of these H I filaments (57%) are also observable in the far-infrared (FIR) and trace the orientation of magnetic field lines.Aims. We considered whether molecular hydrogen (H2) might also be preferentially associated with CNM filaments.Methods. We analyzed 241 H2 absorption lines against stars and determined whether the lines of sight intersected H I or FIR filaments. Using Far Ultraviolet Spectroscopic Explorer (FUSE) H2 data in the velocity range −50 < vLSR < 50 km s−1, we traced 65 additional H2 lines for filamentary H I and FIR structures in velocity and probed the H2 absorption for coincidences in position and velocity.Results. For 305 out of 306 positions, the lines of sight with H2 absorption intersect H I filaments. In 120 cases, there is also evidence for a correlation with dusty FIR filaments. All of the 65 available sight lines with known velocities intersect H I filaments. In 64 cases, the H2 velocities are consistent with H I filament velocities. For FIR filaments, an agreement is found for only 13 out of 14 H2 absorption lines.Conclusions. For the majority of H2 absorption lines, there is evidence that H2 is associated with cold H I filaments. Evidence of an association with FIR filaments is less compelling. Confusion along the line of sight limits the detectability of FIR filaments. For a comparable degree of UV excitation in the disk and lower Galactic halo, the formation rate of H2 appears to be enhanced in H I filaments with increased CNM densities.
{"title":"Molecular hydrogen in filaments at high Galactic latitudes","authors":"P. M. W. Kalberla","doi":"10.1051/0004-6361/202554492","DOIUrl":"https://doi.org/10.1051/0004-6361/202554492","url":null,"abstract":"<i>Context<i/>. Neutral atomic hydrogen (H I) absorption lines can be used to probe the cold neutral medium (CNM) at high Galactic latitudes. Cold H I with a significant optical depth from the GASKAP-H I survey is found to be located predominantly if not exclusively within filamentary structures that can be identified as caustics with the Hessian operator. Most of these H I filaments (57%) are also observable in the far-infrared (FIR) and trace the orientation of magnetic field lines.<i>Aims<i/>. We considered whether molecular hydrogen (H<sub>2<sub/>) might also be preferentially associated with CNM filaments.<i>Methods<i/>. We analyzed 241 H<sub>2<sub/> absorption lines against stars and determined whether the lines of sight intersected H I or FIR filaments. Using <i>Far Ultraviolet Spectroscopic Explorer (FUSE)<i/> H<sub>2<sub/> data in the velocity range −50 < <i>v<i/><sub>LSR<sub/> < 50 km s<sup>−1<sup/>, we traced 65 additional H<sub>2<sub/> lines for filamentary H I and FIR structures in velocity and probed the H<sub>2<sub/> absorption for coincidences in position and velocity.<i>Results<i/>. For 305 out of 306 positions, the lines of sight with H<sub>2<sub/> absorption intersect H I filaments. In 120 cases, there is also evidence for a correlation with dusty FIR filaments. All of the 65 available sight lines with known velocities intersect H I filaments. In 64 cases, the H<sub>2<sub/> velocities are consistent with H I filament velocities. For FIR filaments, an agreement is found for only 13 out of 14 H<sub>2<sub/> absorption lines.<i>Conclusions<i/>. For the majority of H<sub>2<sub/> absorption lines, there is evidence that H<sub>2<sub/> is associated with cold H I filaments. Evidence of an association with FIR filaments is less compelling. Confusion along the line of sight limits the detectability of FIR filaments. For a comparable degree of UV excitation in the disk and lower Galactic halo, the formation rate of H<sub>2<sub/> appears to be enhanced in H I filaments with increased CNM densities.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"147 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145771741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1051/0004-6361/202555537
F. Ahlborn, J. M. Joel Ong, J. Van Beeck, E. P. Bellinger, S. Hekker, S. Basu
Context.Accurate estimates of internal red giant rotation rates are crucial for constraining and improving current models of stellar rotation. Asteroseismic rotational inversions provide a means of estimating these internal rotation rates.Aims. In this work, we focus on the observed differences in the rotationally induced frequency shifts between prograde and retrograde modes. These effects have been overlooked in previous studies estimating internal rotation rates of red giants using inversions. We systematically study the limits of applicability of linear rotational inversions as a function of the evolution on the red giant branch and of the underlying rotation rates.Methods. We determine oscillation mode frequencies in the presence of rotation using the lowest-order perturbative approach and describe the differences between prograde and retrograde modes arising from the coupling of multiple mixed modes, also known as near-degeneracy effects. We computed synthetic rotational splittings, taking these near-degeneracy effects into account. We used red giant models with one solar mass, a large frequency separation between 16 and 9 μHz, and core rotation rates between 500 and 1500 nHz, covering the regime of observed parameters of Kepler red giant stars. Finally, we used these synthetic data to quantify the systematic errors in the internal rotation rates estimated by means of rotational inversions in the presence of near-degeneracy effects.Results. We show that the systematic errors in the estimated rotation rates introduced by near-degeneracy effects surpass the observational uncertainties for more evolved and faster-rotating stars. For a core rotation rate of 500 nHz, linear inversions remain applicable over the range of models considered here, while for a core rotation rate of 1000 nHz, systematic errors become significant below a large frequency separation of 13 μHz.Conclusions. The estimated rotation rates of some previously analysed red giants suffer from significant systematic errors that have not yet been accounted for. Nonetheless, reliable analyses with existing inversion methods are feasible for a number of red giants, and we expect there to be unexplored targets within the parameter ranges determined here. Finally, exploiting the observational potential of near-degeneracy effects is an important step towards obtaining more accurate estimates of internal red-giant rotation rates.
{"title":"Impact of near-degeneracy effects on linear rotational inversions for red giant stars","authors":"F. Ahlborn, J. M. Joel Ong, J. Van Beeck, E. P. Bellinger, S. Hekker, S. Basu","doi":"10.1051/0004-6361/202555537","DOIUrl":"https://doi.org/10.1051/0004-6361/202555537","url":null,"abstract":"<i>Context.<i/>Accurate estimates of internal red giant rotation rates are crucial for constraining and improving current models of stellar rotation. Asteroseismic rotational inversions provide a means of estimating these internal rotation rates.<i>Aims.<i/> In this work, we focus on the observed differences in the rotationally induced frequency shifts between prograde and retrograde modes. These effects have been overlooked in previous studies estimating internal rotation rates of red giants using inversions. We systematically study the limits of applicability of linear rotational inversions as a function of the evolution on the red giant branch and of the underlying rotation rates.<i>Methods.<i/> We determine oscillation mode frequencies in the presence of rotation using the lowest-order perturbative approach and describe the differences between prograde and retrograde modes arising from the coupling of multiple mixed modes, also known as near-degeneracy effects. We computed synthetic rotational splittings, taking these near-degeneracy effects into account. We used red giant models with one solar mass, a large frequency separation between 16 and 9 μHz, and core rotation rates between 500 and 1500 nHz, covering the regime of observed parameters of <i>Kepler<i/> red giant stars. Finally, we used these synthetic data to quantify the systematic errors in the internal rotation rates estimated by means of rotational inversions in the presence of near-degeneracy effects.<i>Results.<i/> We show that the systematic errors in the estimated rotation rates introduced by near-degeneracy effects surpass the observational uncertainties for more evolved and faster-rotating stars. For a core rotation rate of 500 nHz, linear inversions remain applicable over the range of models considered here, while for a core rotation rate of 1000 nHz, systematic errors become significant below a large frequency separation of 13 μHz.<i>Conclusions.<i/> The estimated rotation rates of some previously analysed red giants suffer from significant systematic errors that have not yet been accounted for. Nonetheless, reliable analyses with existing inversion methods are feasible for a number of red giants, and we expect there to be unexplored targets within the parameter ranges determined here. Finally, exploiting the observational potential of near-degeneracy effects is an important step towards obtaining more accurate estimates of internal red-giant rotation rates.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"22 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145765619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1051/0004-6361/202555615
I. Rabago, G. Lodato, S. Facchini, Z. Zhu
In binary systems with a strongly misaligned disk, the central binary stars can travel a significant vertical distance above and below the disk’s orbital plane. This can cause large changes in illumination of the disk over the course of the binary orbital period. We use both analytic and radiative transfer models to examine the effect of changes in stellar illumination on the appearance of the disk, specifically in the case of the polar disk HD 98800B. We find that the observed flux from the disk can vary significantly over the binary orbital period, producing a periodically varying light curve that peaks twice each binary orbit. The amount of flux variation is strongly influenced by the disk geometry. We suggest that these flux variations produce several observable signatures, and that these observables may provide constraints on different properties of the disk, such as its vertical structure, geometry, and cooling rate.
{"title":"Brightness variability in polar circumbinary disks","authors":"I. Rabago, G. Lodato, S. Facchini, Z. Zhu","doi":"10.1051/0004-6361/202555615","DOIUrl":"https://doi.org/10.1051/0004-6361/202555615","url":null,"abstract":"In binary systems with a strongly misaligned disk, the central binary stars can travel a significant vertical distance above and below the disk’s orbital plane. This can cause large changes in illumination of the disk over the course of the binary orbital period. We use both analytic and radiative transfer models to examine the effect of changes in stellar illumination on the appearance of the disk, specifically in the case of the polar disk HD 98800B. We find that the observed flux from the disk can vary significantly over the binary orbital period, producing a periodically varying light curve that peaks twice each binary orbit. The amount of flux variation is strongly influenced by the disk geometry. We suggest that these flux variations produce several observable signatures, and that these observables may provide constraints on different properties of the disk, such as its vertical structure, geometry, and cooling rate.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"132 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145765622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1051/0004-6361/202557339
Michael L. Weber, Eleftheria Sarafidou, Christian Rab, Oliver Gressel, Barbara Ercolano
Context. Disc winds driven by thermal and magnetic processes are thought to play a critical role in protoplanetary disc evolution. However, the relative contribution of each mechanism remains uncertain, particularly in light of their observational signatures.Aims. We investigate whether spatially resolved emission and synthetic spectral line profiles can be used to distinguish between thermally and magnetically driven winds in protoplanetary discs.Methods. We modelled three disc wind scenarios with different levels of magnetisation: a relatively strongly magnetised wind (β4), a rather weakly magnetised wind (β6), and a purely photoevaporative wind (PE). Using radiative transfer post-processing, we generated synthetic emission maps and line profiles for [OI] 6300 Å, [NeII] 12.81 μm, and o-H2 2.12 μm, and compared them with observational trends in the literature.Results. We find that the β4 model generally produces broader and more blueshifted low-velocity components across all tracers, consistent with compact emission regions and steep velocity gradients. The β6 and PE models yield narrower profiles with smaller blueshifts, in better agreement with most observed narrow low-velocity components (NLVCs). We also find that some line profile diagnostics, such as the inclination at maximum centroid velocity, are not robust discriminants. However, the overall blueshift and full width at half maximum of the low-velocity components provide reliable constraints. The β4 model reproduces the most extreme blueshifted NLVCs in observations, while most observed winds are more consistent with the β6 and PE models.Conclusions. Our findings reinforce previous conclusions that most observed NLVCs are compatible with weakly magnetised or purely photo-evaporative flows. The combination of line kinematics and emission morphology offers meaningful constraints on wind-driving physics, and synthetic line modelling remains a powerful tool for probing disc wind mechanisms.
{"title":"From thermal to magnetic driving: Spectral diagnostics of simulation-based magneto-thermal disc wind models","authors":"Michael L. Weber, Eleftheria Sarafidou, Christian Rab, Oliver Gressel, Barbara Ercolano","doi":"10.1051/0004-6361/202557339","DOIUrl":"https://doi.org/10.1051/0004-6361/202557339","url":null,"abstract":"<i>Context<i/>. Disc winds driven by thermal and magnetic processes are thought to play a critical role in protoplanetary disc evolution. However, the relative contribution of each mechanism remains uncertain, particularly in light of their observational signatures.<i>Aims<i/>. We investigate whether spatially resolved emission and synthetic spectral line profiles can be used to distinguish between thermally and magnetically driven winds in protoplanetary discs.<i>Methods<i/>. We modelled three disc wind scenarios with different levels of magnetisation: a relatively strongly magnetised wind (<i>β<i/>4), a rather weakly magnetised wind (<i>β<i/>6), and a purely photoevaporative wind (<i>PE<i/>). Using radiative transfer post-processing, we generated synthetic emission maps and line profiles for [OI] 6300 Å, [NeII] 12.81 μm, and o-H<sub>2<sub/> 2.12 μm, and compared them with observational trends in the literature.<i>Results<i/>. We find that the <i>β<i/>4 model generally produces broader and more blueshifted low-velocity components across all tracers, consistent with compact emission regions and steep velocity gradients. The <i>β<i/>6 and <i>PE<i/> models yield narrower profiles with smaller blueshifts, in better agreement with most observed narrow low-velocity components (NLVCs). We also find that some line profile diagnostics, such as the inclination at maximum centroid velocity, are not robust discriminants. However, the overall blueshift and full width at half maximum of the low-velocity components provide reliable constraints. The <i>β<i/>4 model reproduces the most extreme blueshifted NLVCs in observations, while most observed winds are more consistent with the <i>β<i/>6 and <i>PE<i/> models.<i>Conclusions<i/>. Our findings reinforce previous conclusions that most observed NLVCs are compatible with weakly magnetised or purely photo-evaporative flows. The combination of line kinematics and emission morphology offers meaningful constraints on wind-driving physics, and synthetic line modelling remains a powerful tool for probing disc wind mechanisms.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"4 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145765623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1051/0004-6361/202555294
H. Stiele, A. K. H. Kong
Context. The X-ray source population of M 31 has been intensively studied in numerous investigations using X-ray telescopes. A notable example is the Deep XMM-Newton survey of M 31, which covered the entire D25 ellipse down to a limiting luminosity of ~1035 erg s−1 in the 0.2–4.5 keV band.Aims. We aimed to identify UV counterparts of the X-ray sources detected with XMM-Newton using the M 31 UVIT catalogue, which is based on AstroSat observations.Methods. We studied the UV colour-colour diagram of the counterparts and fitted the UV spectra with simple phenomenological models that provide formally acceptable fits for about 35 per cent of the sources. We also analysed the X-ray spectral properties and their temporal evolution, based on the X-ray spectral fits of the XMM2Athena project. We updated the classification of XMM-Newton sources with UVIT counterparts, where necessary, by verifying cross-correlations with more recent studies.Results. In the UV colour-colour diagram, we find one source that is classified as ‘hard’ in a region where, apart from this source, only foreground stars are located. Apart from foreground stars (23) and hard sources (13), sources located in globular clusters (6) are most numerous among those with UV counterparts that yield statistically acceptable fits with our simple models. We used UVIT data together with XMM-Newton optical monitor data to investigate the spectral energy distributions of the sources. This enabled us to suggest classifications for sources previously classified as hard sources in earlier studies. We provide an updated classification for 24 of the 291 XMM-Newton sources with UVIT counterparts. The list thus contains (including candidates of each class): 105 foreground stars, 22 globular clusters, 11 supernova remnants, nine X-ray binaries, of which six are suggested as high-mass X-ray binary candidates, eight galaxies, eight AGNs, seven supersoft source candidates, two sources that are either an X-ray binary or a galaxy, and another one that is either a galaxy or a globular cluster. A total of 107 sources can still only be classified as hard, while nine remain unclassified.
{"title":"AstroSat UVIT counterparts of XMM-Newton X-ray sources in M31","authors":"H. Stiele, A. K. H. Kong","doi":"10.1051/0004-6361/202555294","DOIUrl":"https://doi.org/10.1051/0004-6361/202555294","url":null,"abstract":"<i>Context<i/>. The X-ray source population of M 31 has been intensively studied in numerous investigations using X-ray telescopes. A notable example is the Deep XMM-Newton survey of M 31, which covered the entire D<sub>25<sub/> ellipse down to a limiting luminosity of ~10<sup>35<sup/> erg s<sup>−1<sup/> in the 0.2–4.5 keV band.<i>Aims<i/>. We aimed to identify UV counterparts of the X-ray sources detected with XMM-Newton using the M 31 UVIT catalogue, which is based on AstroSat observations.<i>Methods<i/>. We studied the UV colour-colour diagram of the counterparts and fitted the UV spectra with simple phenomenological models that provide formally acceptable fits for about 35 per cent of the sources. We also analysed the X-ray spectral properties and their temporal evolution, based on the X-ray spectral fits of the XMM2Athena project. We updated the classification of XMM-Newton sources with UVIT counterparts, where necessary, by verifying cross-correlations with more recent studies.<i>Results<i/>. In the UV colour-colour diagram, we find one source that is classified as ‘hard’ in a region where, apart from this source, only foreground stars are located. Apart from foreground stars (23) and hard sources (13), sources located in globular clusters (6) are most numerous among those with UV counterparts that yield statistically acceptable fits with our simple models. We used UVIT data together with XMM-Newton optical monitor data to investigate the spectral energy distributions of the sources. This enabled us to suggest classifications for sources previously classified as hard sources in earlier studies. We provide an updated classification for 24 of the 291 XMM-Newton sources with UVIT counterparts. The list thus contains (including candidates of each class): 105 foreground stars, 22 globular clusters, 11 supernova remnants, nine X-ray binaries, of which six are suggested as high-mass X-ray binary candidates, eight galaxies, eight AGNs, seven supersoft source candidates, two sources that are either an X-ray binary or a galaxy, and another one that is either a galaxy or a globular cluster. A total of 107 sources can still only be classified as hard, while nine remain unclassified.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"23 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145765625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1051/0004-6361/202557210
Mykyta Bilodid, Maryna Ishchenko, Peter Berczik
Context. The history of our Galaxy is shaped by significant merger events, which contribute to its mass and to the distribution of stars, but which also bring globular clusters that act as the main tracers of the accretion history of the Milky Way.Aims. We investigated Gaia-Enceladus/Sausage globular cluster samples and studied their orbital and dynamical evolution over cosmological timescales in external time-variable potential. We estimated the limits of distribution of the escaped stars from the globular clusters’ orbital evolution in energy angular momentum space.Methods. To reconstruct the orbital evolution of the known globular clusters of the dwarf galaxy Gaia-Enceladus/Sausage, we used the parallel N-body code φ-GPU. We investigated the relationship between globular clusters and their progenitor by analysing their orbital parameters and phase-space distribution during 9 Gyr of evolution in the past. We created a N-body model of Gaia-Enceladus/Sausage globular clusters and analysed their dynamical evolution and distribution of the escaped stars today.Results. We summarised the samples of the Gaia-Enceladus/Sausage globular clusters and created two main categories: ‘most probable’ and ‘tentative’, with 15 and 9 clusters, respectively. We analysed the evolution of their kinematic, orbital, and phase-space parameters in the external time-variable potential. We defined phase-space distribution limits of stars that escape from globular clusters during 9 Gyr of evolution: a specific energy from −18 to −12.2 ×104 km2 s−2, Lz from −0.98 to 0.72 ×103 kpc km s−1, and Lperp from 0 to 1.8 ×103 kpc km s−1. The limits of the GE/S debris in Galactic area based on orbital parameters of the GC’s escaped stars are: for apocentre and pericetre distances of 10–28 and 1–4 kpc, <18 kpc in Galactocentric radius and <|15| kpc in the Z direction. Generally we compared the phase-space distribution of escaped stars from the GCs GE/S debris energy-angular momentum limits with the observed very metal-poor stars, which belong to the GE/S itself and produce consistent results.
上下文。我们银河系的历史是由重大的合并事件塑造的，这些合并事件影响了它的质量和恒星的分布，但也带来了球状星团，它们是银河系吸积历史的主要示踪剂。我们研究了Gaia-Enceladus/Sausage球状星团样本，并在外部时变势下研究了它们在宇宙时间尺度上的轨道和动力学演化。我们估计了球状星团轨道演化中逃逸恒星在能量角动量空间的分布极限。为了重建Gaia-Enceladus/Sausage矮星系中已知球状星团的轨道演化，我们使用了平行n体代码φ-GPU。通过分析过去9 Gyr演化过程中球状星团的轨道参数和相空间分布，探讨了球状星团与其前身的关系。我们建立了Gaia-Enceladus/Sausage球状星团的n体模型，并分析了它们的动态演化和逃逸恒星的分布。我们总结了盖亚-土卫二/香肠球状星团的样本，并创建了两个主要类别：“最可能”和“暂定”，分别有15个和9个星团。我们分析了它们的运动、轨道和相空间参数在外部时变电位下的演变。我们定义了在9 Gyr演化过程中逃离球状星团的恒星的相空间分布极限：比能量为- 18至- 12.2 ×104 km2 s−2，Lz为- 0.98至0.72 ×103 kpc km s−1，Lperp为0至1.8 ×103 kpc km s−1。根据GC逃逸恒星的轨道参数，银河系区域的GE/S碎片的极限为：在10-28和1-4 kpc的距离内，星系中心半径<18 kpc， Z方向< 15| kpc。一般来说，我们比较了从GCs - GE/S碎片中逸出的恒星的相空间分布与观测到的非常缺金属的恒星，这些恒星属于GE/S本身，并得出了一致的结果。
{"title":"Globular clusters of the Gaia Enceladus/Sausage","authors":"Mykyta Bilodid, Maryna Ishchenko, Peter Berczik","doi":"10.1051/0004-6361/202557210","DOIUrl":"https://doi.org/10.1051/0004-6361/202557210","url":null,"abstract":"<i>Context<i/>. The history of our Galaxy is shaped by significant merger events, which contribute to its mass and to the distribution of stars, but which also bring globular clusters that act as the main tracers of the accretion history of the Milky Way.<i>Aims<i/>. We investigated <i>Gaia<i/>-Enceladus/Sausage globular cluster samples and studied their orbital and dynamical evolution over cosmological timescales in external time-variable potential. We estimated the limits of distribution of the escaped stars from the globular clusters’ orbital evolution in energy angular momentum space.<i>Methods<i/>. To reconstruct the orbital evolution of the known globular clusters of the dwarf galaxy <i>Gaia<i/>-Enceladus/Sausage, we used the parallel <i>N<i/>-body code <i>φ<i/>-GPU. We investigated the relationship between globular clusters and their progenitor by analysing their orbital parameters and phase-space distribution during 9 Gyr of evolution in the past. We created a <i>N<i/>-body model of <i>Gaia<i/>-Enceladus/Sausage globular clusters and analysed their dynamical evolution and distribution of the escaped stars today.<i>Results<i/>. We summarised the samples of the <i>Gaia<i/>-Enceladus/Sausage globular clusters and created two main categories: ‘most probable’ and ‘tentative’, with 15 and 9 clusters, respectively. We analysed the evolution of their kinematic, orbital, and phase-space parameters in the external time-variable potential. We defined phase-space distribution limits of stars that escape from globular clusters during 9 Gyr of evolution: a specific energy from −18 to −12.2 ×10<sup>4<sup/> km<sup>2<sup/> s<sup>−2<sup/>, L<sub>z<sub/> from −0.98 to 0.72 ×10<sup>3<sup/> kpc km s<sup>−1<sup/>, and L<sub>perp<sub/> from 0 to 1.8 ×10<sup>3<sup/> kpc km s<sup>−1<sup/>. The limits of the GE/S debris in Galactic area based on orbital parameters of the GC’s escaped stars are: for apocentre and pericetre distances of 10–28 and 1–4 kpc, <18 kpc in Galactocentric radius and <|15| kpc in the Z direction. Generally we compared the phase-space distribution of escaped stars from the GCs GE/S debris energy-angular momentum limits with the observed very metal-poor stars, which belong to the GE/S itself and produce consistent results.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"43 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145765620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1051/0004-6361/202453255
P. Popesso, I. Marini, K. Dolag, G. Lamer, B. Csizi, V. Biffi, A. Robothan, M. Bravo, A. Biviano, S. Vladutescu-Zopp, L. Lovisari, S. Ettori, M. Angelinelli, S. Driver, V. Toptun, A. Dev, D. Mazengo, A. Merloni, Y. Zhang, J. Comparat, G. Ponti, T. Mroczkowski, E. Bulbul
<i>Context.<i/> In this study, we present the average X-ray properties of massive halos at <i>z<i/> < 0.2 over the largest halo mass range ever probed so far, bridging the gap from Milky Way-like halos to massive clusters.<i>Aims.<i/> The results show the average X-ray properties of galaxy groups, obtained through the stacking analysis in the eFEDS area of the GAMA galaxy group sample at <i>z<i/> < 0.2. The results have been rigorously tested using a synthetic dataset that mirrors the observed eROSITA X-ray and GAMA optical data based on the lightcones of the Magneticum simulations.<i>Methods.<i/> We used a halo mass proxy based on group total luminosity, avoiding systematics linked to velocity dispersion and richness cuts. The stacking is done in bins of halo mass and tested in the synthetic dataset for AGN and X-ray binaries contamination, systematics due to the halo mass proxy, and uncertainty in the optical group center.<i>Results.<i/> We provide the average X-ray surface brightness profile in six bins of mass, ranging from Milky Way-like systems to poor clusters at <i>M<i/><sub>200<sub/> ∼ 10<sup>14<sup/> <i>M<i/><sub>⊙<sub/>. We find that the scatter in the <i>L<i/><sub>X<sub/> − <i>M<i/> relation is driven by gas concentration in groups, as undetected X-ray systems at fixed halo mass exhibit lower central gas concentrations than detected ones, aligning with Magneticum predictions. However, there is a discrepancy regarding dark matter concentration: Magneticum predictions suggest that undetected groups are more concentrated, implying they are older and more relaxed, whereas previous observational findings suggest the opposite. We present new measurements of the <i>L<i/><sub>X, 500<sub/> − <i>M<i/><sub>500<sub/> and <i>L<i/><sub>X, 200<sub/> − <i>M<i/><sub>200<sub/> relations, from Milky Way-like halos to massive clusters. Our results indicate that a single power law fits the data across three decades of halo mass, and they align well with previous studies focused on specific halo mass ranges. Magneticum best matches the observed gas distribution across the entire halo mass range, while IllustrisTNG, EAGLE, Simba, and FLAMINGO show larger discrepancies at different mass ranges. This highlights that simulations such as Magneticum, which are not calibrated on <i>z<i/> = 0 galaxy properties, reproduce gas properties well but still lead to overly massive galaxies at the centers of massive halos. Conversely, simulations calibrated on <i>z<i/> = 0 galaxy properties fail to reproduce the gas properties.<i>Conclusions.<i/> This evidence reveals a potential gap in our understanding of the relationship between galaxies and their host structures. Therefore, this work emphasizes the need for a deeper investigation into the connection between gas and dark matter distributions and their impact on central galaxy properties. Such an inquiry is crucial to comprehensively understanding the role and interplay of gravitational forces and feedback-related proces
{"title":"Average X-ray properties of galaxy groups: From Milky Way-like halos to massive clusters","authors":"P. Popesso, I. Marini, K. Dolag, G. Lamer, B. Csizi, V. Biffi, A. Robothan, M. Bravo, A. Biviano, S. Vladutescu-Zopp, L. Lovisari, S. Ettori, M. Angelinelli, S. Driver, V. Toptun, A. Dev, D. Mazengo, A. Merloni, Y. Zhang, J. Comparat, G. Ponti, T. Mroczkowski, E. Bulbul","doi":"10.1051/0004-6361/202453255","DOIUrl":"https://doi.org/10.1051/0004-6361/202453255","url":null,"abstract":"<i>Context.<i/> In this study, we present the average X-ray properties of massive halos at <i>z<i/> < 0.2 over the largest halo mass range ever probed so far, bridging the gap from Milky Way-like halos to massive clusters.<i>Aims.<i/> The results show the average X-ray properties of galaxy groups, obtained through the stacking analysis in the eFEDS area of the GAMA galaxy group sample at <i>z<i/> < 0.2. The results have been rigorously tested using a synthetic dataset that mirrors the observed eROSITA X-ray and GAMA optical data based on the lightcones of the Magneticum simulations.<i>Methods.<i/> We used a halo mass proxy based on group total luminosity, avoiding systematics linked to velocity dispersion and richness cuts. The stacking is done in bins of halo mass and tested in the synthetic dataset for AGN and X-ray binaries contamination, systematics due to the halo mass proxy, and uncertainty in the optical group center.<i>Results.<i/> We provide the average X-ray surface brightness profile in six bins of mass, ranging from Milky Way-like systems to poor clusters at <i>M<i/><sub>200<sub/> ∼ 10<sup>14<sup/> <i>M<i/><sub>⊙<sub/>. We find that the scatter in the <i>L<i/><sub>X<sub/> − <i>M<i/> relation is driven by gas concentration in groups, as undetected X-ray systems at fixed halo mass exhibit lower central gas concentrations than detected ones, aligning with Magneticum predictions. However, there is a discrepancy regarding dark matter concentration: Magneticum predictions suggest that undetected groups are more concentrated, implying they are older and more relaxed, whereas previous observational findings suggest the opposite. We present new measurements of the <i>L<i/><sub>X, 500<sub/> − <i>M<i/><sub>500<sub/> and <i>L<i/><sub>X, 200<sub/> − <i>M<i/><sub>200<sub/> relations, from Milky Way-like halos to massive clusters. Our results indicate that a single power law fits the data across three decades of halo mass, and they align well with previous studies focused on specific halo mass ranges. Magneticum best matches the observed gas distribution across the entire halo mass range, while IllustrisTNG, EAGLE, Simba, and FLAMINGO show larger discrepancies at different mass ranges. This highlights that simulations such as Magneticum, which are not calibrated on <i>z<i/> = 0 galaxy properties, reproduce gas properties well but still lead to overly massive galaxies at the centers of massive halos. Conversely, simulations calibrated on <i>z<i/> = 0 galaxy properties fail to reproduce the gas properties.<i>Conclusions.<i/> This evidence reveals a potential gap in our understanding of the relationship between galaxies and their host structures. Therefore, this work emphasizes the need for a deeper investigation into the connection between gas and dark matter distributions and their impact on central galaxy properties. Such an inquiry is crucial to comprehensively understanding the role and interplay of gravitational forces and feedback-related proces","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"15 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145765624","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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