The Astrophysical Journal最新文献_第5页

Penetrative Convection in Rotating Tilted f-plane with Multiple Radiative and Convective Layers 多辐射层和对流层旋转倾斜f面中的穿透对流

The Astrophysical Journal Pub Date : 2025-07-14 DOI: 10.3847/1538-4357/ade2d6

Sethulakshmy Edathara Sreenivasan and Tao Cai

{"title":"Penetrative Convection in Rotating Tilted f-plane with Multiple Radiative and Convective Layers","authors":"Sethulakshmy Edathara Sreenivasan and Tao Cai","doi":"10.3847/1538-4357/ade2d6","DOIUrl":"https://doi.org/10.3847/1538-4357/ade2d6","url":null,"abstract":"In this paper, we conducted a linear instability analysis to investigate penetrative convection in rotating, tilted f-planes with multiple convectively stable and unstable layers. Our findings indicate that penetrative distance decreases with increasing rotational and stratification strengths. We also observed that teleconvection, multiroll convection, and cutoff convection, previously identified in two-layer models, are present in multilayer models. For a three-layer model, the flow exhibits an up-down symmetric pattern for penetrative convection at the poles. However, this symmetry is disrupted in tilted f-planes when the flow drifts in equatorward or poleward directions. At mid- to low latitudes, poleward flow tends to enhance penetration in the upper layers, while equatorward flow facilitates penetration in the lower layers. The disruption of up-down symmetry is also observed in multilayer models with more layers when oscillatory convection occurs. Our findings suggest that upward and downward penetration could be significantly different in stars or planets with multilayer structures. However, under a strong stable composition gradient, the instability is found to be reduced.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144630340","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}

引用次数: 0

FUOr-Aur 0544+3330: A New Young Stellar Object Outburst in the Outskirts of Auriga OB1, Viewed Face-on FUOr-Aur 0544+3330：在御夫座OB1外围的一个新的年轻恒星爆发，正面观察

The Astrophysical Journal Pub Date : 2025-07-14 DOI: 10.3847/1538-4357/ade14d

Lynne A. Hillenbrand, Adolfo S. Carvalho, Dan Stern, Michael Connelley, Facundo Pérez Paolino, Ahaan Shetty, Zachariah Milby and Howard Isaacson

{"title":"FUOr-Aur 0544+3330: A New Young Stellar Object Outburst in the Outskirts of Auriga OB1, Viewed Face-on","authors":"Lynne A. Hillenbrand, Adolfo S. Carvalho, Dan Stern, Michael Connelley, Facundo Pérez Paolino, Ahaan Shetty, Zachariah Milby and Howard Isaacson","doi":"10.3847/1538-4357/ade14d","DOIUrl":"https://doi.org/10.3847/1538-4357/ade14d","url":null,"abstract":"We present a newly appreciated FU Ori outburst event that began in 2019 and reached a peak in early 2021. Suspected young stellar object WISE J054452.25+333009.6 experienced substantial brightening, in excess of −5 mag at optical wavelengths and −2.5 mag at mid-infrared wavelengths. The time from near-quiescence to peak brightness was approximately 24 months. Optical and near-infrared spectra confirm that the outbursting source (hereby designated FUOr-Aur 0544+3330) shows all the hallmarks of the FU Ori class, including the Li i indicator of stellar youth. The mix of ionized and neutral atomic lines, alongside prominent molecular absorption features, is consistent with the expected change in spectral type from earlier in the optical to later types in the near-infrared. The closest analog among well-studied FU Ori objects is V1515 Cyg. Both sources have unusually narrow-lined absorption spectra that can be explained by a face-on disk orientation, such that disk-broadening is minimized and wind-induced blueshift (in e.g., Hα, NaD, Ca ii) is maximized. Both the optical through infrared spectral energy distribution and high-resolution spectrum are well-fit by a pure-accretion disk model. Adopting a distance of d = 1.5 kpc, the accretion and central star parameters are M⊙ yr−1, M* = 0.17 M⊙, and Rinner = 1.04 R⊙. Other fitted values are disk inclination i = 5.9 deg and source extinction AV = 1.83 mag. These parameters yield accretion luminosity Lacc = 8.4 L⊙ and maximum disk temperature K.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144640075","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}

引用次数: 0

Response of the LMC’s Bar to a Recent SMC Collision and Implications for the SMC’s Dark Matter Profile 大麦哲伦星系棒子对最近一次麦哲伦星系碰撞的响应及其对麦哲伦星系暗物质剖面的启示

The Astrophysical Journal Pub Date : 2025-07-14 DOI: 10.3847/1538-4357/ade0ae

Himansh Rathore, Gurtina Besla, Kathryne J. Daniel and Leandro Beraldo e Silva

{"title":"Response of the LMC’s Bar to a Recent SMC Collision and Implications for the SMC’s Dark Matter Profile","authors":"Himansh Rathore, Gurtina Besla, Kathryne J. Daniel and Leandro Beraldo e Silva","doi":"10.3847/1538-4357/ade0ae","DOIUrl":"https://doi.org/10.3847/1538-4357/ade0ae","url":null,"abstract":"The LMC’s stellar bar is offset from the outer disk center, tilted from the disk plane, and does not drive gas inflows. These properties are atypical of bars in gas-rich galaxies, yet the LMC bar’s strength and radius are similar to typical barred galaxies. Using N-body hydrodynamic simulations, we show that the LMC’s unusual bar is explainable if there was a recent collision (impact parameter ≈2 kpc) between the LMC and SMC. Pre-collision, the simulated bar is centered and coplanar. Post-collision, the simulated bar is offset (≈1.5 kpc) and tilted (≈8 6). The simulated bar offset reduces with time, and comparing with the observed offset (≈0.8 kpc) suggests the timing of the true collision to be 150–200 Myr ago. Then, 150 Myr post-collision, the LMC’s bar is centered with its dark matter (DM) halo, whereas the outer disk center is separated from the DM center by ≈1 kpc. The SMC collision produces a tilted-ring structure for the simulated LMC, consistent with observations. Post-collision, the simulated LMC bar’s pattern speed decreases by a factor of 2. We also provide a generalizable framework to quantitatively compare the LMC’s central gas distribution in different LMC–SMC interaction scenarios. We demonstrate that the SMC’s torques on the LMC’s bar during the collision are sufficient to explain the observed bar tilt, provided the SMC’s total mass within 2 kpc was (0.8–2.4) × 109M⊙. Therefore, the LMC bar’s tilt constrains the SMC’s pre-collision DM profile, and requires the SMC to be a DM-dominated galaxy.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144630330","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}

引用次数: 0

The Crucial Role of Third Body in Formation and Evolution of Contact Binary Systems: Evidence from CY Ari and IK Lyn 第三体在接触双星系统形成和演化中的关键作用：来自CY Ari和IK Lyn的证据

The Astrophysical Journal Pub Date : 2025-07-14 DOI: 10.3847/1538-4357/ade152

Hu-Shan Xu, Zhong-Tao Han, Wei-wei Na, Zhi-Hua Wang, Wen-wu Ma and Li-Ying Zhu

{"title":"The Crucial Role of Third Body in Formation and Evolution of Contact Binary Systems: Evidence from CY Ari and IK Lyn","authors":"Hu-Shan Xu, Zhong-Tao Han, Wei-wei Na, Zhi-Hua Wang, Wen-wu Ma and Li-Ying Zhu","doi":"10.3847/1538-4357/ade152","DOIUrl":"https://doi.org/10.3847/1538-4357/ade152","url":null,"abstract":"CY Ari and IK Lyn are two eclipsing binary systems that share the same spectral type but exhibit significantly different metallicities. Based on the Wilson–Devinney (W-D) method, the first photometric solutions are obtained by analyzing the new complete BVRcIc light curves. The completely eclipsing nature of the light curves allows for the determination of reliable photometric parameters for both systems. Analysis of the light curves indicates that the two systems are structurally similar. Both belong to W-type shallow contact binary systems, with nearly identical degrees of contact. The O − C analysis demonstrates that the orbital periods of CY Ari and IK Lyn are increasing over the long term, with the increase rate for IK Lyn being significantly higher than that for CY Ari. This discrepancy may arise from different mass transfer rates from the secondary star to the primary star. Additionally, a periodic oscillation with a period of 5.4 yr has been detected in CY Ari, potentially attributable to the light-time effect of an unseen third body. An analysis of the age and evolutionary stage elucidates the reasons behind the divergent evolutionary paths of CY Ari and IK Lyn. The presence of the third body accelerates the evolution of CY Ari by removing angular momentum from the central binary pair. Although CY Ari was formed later than IK Lyn, it has evolved into a similar stage. This study provides critical evidence of the significant role played by a third body in the formation and evolution of contact binary systems.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144630338","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}

引用次数: 0

A Galaxy with an Extremely Blue Ultraviolet Slope β = −3 at z = 9.25 Identified by JWST Spectroscopy: Evidence for a Weak Nebular Continuum and Efficient Ionizing Photon Escape? JWST光谱识别出z = 9.25处极蓝紫外斜率β =−3的星系：弱星云连续体和有效电离光子逃逸的证据？

The Astrophysical Journal Pub Date : 2025-07-14 DOI: 10.3847/1538-4357/adcecd

Hiroto Yanagisawa, Masami Ouchi, Kimihiko Nakajima, Yuichi Harikane, Seiji Fujimoto, Yoshiaki Ono, Hiroya Umeda, Minami Nakane, Hidenobu Yajima, Hajime Fukushima and Yi Xu

{"title":"A Galaxy with an Extremely Blue Ultraviolet Slope β = −3 at z = 9.25 Identified by JWST Spectroscopy: Evidence for a Weak Nebular Continuum and Efficient Ionizing Photon Escape?","authors":"Hiroto Yanagisawa, Masami Ouchi, Kimihiko Nakajima, Yuichi Harikane, Seiji Fujimoto, Yoshiaki Ono, Hiroya Umeda, Minami Nakane, Hidenobu Yajima, Hajime Fukushima and Yi Xu","doi":"10.3847/1538-4357/adcecd","DOIUrl":"https://doi.org/10.3847/1538-4357/adcecd","url":null,"abstract":"We investigate UV continuum slopes β of 863 galaxies at 4 < z < 14 using archival JWST/NIRSpec PRISM spectra obtained from major JWST Guaranteed Time Observations (GTO), Early Release Science (ERS), and General Observers (GO) programs, including JADES, CEERS, and UNCOVER. Among these galaxies, we identify a remarkable galaxy at z = 9.25, dubbed extremely blue galaxy 1 (EBG-1), with a significantly blue UV slope β = −2.99 ± 0.15, unlike the rest of the galaxies that exhibit red continua or ambiguous blue continua hindered by large uncertainties. We confirm that the β value negligibly changes by the data reduction and fitting wavelength ranges for UV emission/absorption line masking. The extreme blue slope, β = −3.0, rules out significant contributions from dust extinction or AGN activity. Comparing with stellar and nebular emission models, we find that such a blue UV slope cannot be reproduced solely by stellar models even with very young, metal-poor, or top-heavy contiguous star formation associated with strong nebular continua making the UV slopes red, but with a high ionizing photon escape fraction, , for a weak nebular continuum. While the Hβ emission line is not detected, likely due to the limited sensitivity of the spectrum, we find moderately weak [O iii]λλ4959,5007 emission lines for the given star formation rate (3 M⊙ yr−1) and stellar mass (108.0M⊙) that are about 3 times weaker than the average emission lines, again suggestive of the high ionizing photon escape fraction, or more. EBG-1 would provide crucial insights into stellar and nebular continuum emission in high-redshift galaxies, serving as an example of the ionizing photon escaping site at the epoch of reionization.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"38 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144630150","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}

引用次数: 0

ALMA-JELLY. I. High Resolution CO(2–1) Observations of Ongoing Ram Pressure Stripping in NGC 4858 Reveal Asymmetrical Gas Tail Formation and Fallback ALMA-JELLY。1 . ngc4858中持续压力剥离的高分辨率CO（2-1）观测揭示了不对称气尾的形成和回退

The Astrophysical Journal Pub Date : 2025-07-14 DOI: 10.3847/1538-4357/adde47

Harrison J. Souchereau, Jeffrey D. P. Kenney, Pavel Jáchym, Ming Sun, William J. Cramer, Masafumi Yagi, Alessandro Boselli, Elias Brinks, Francoise Combes, Luca Cortese, Boris Deshev, Matteo Fossati, Romana Grossová, Rongxin Luo, Jan Palouš and Tom C. Scott

{"title":"ALMA-JELLY. I. High Resolution CO(2–1) Observations of Ongoing Ram Pressure Stripping in NGC 4858 Reveal Asymmetrical Gas Tail Formation and Fallback","authors":"Harrison J. Souchereau, Jeffrey D. P. Kenney, Pavel Jáchym, Ming Sun, William J. Cramer, Masafumi Yagi, Alessandro Boselli, Elias Brinks, Francoise Combes, Luca Cortese, Boris Deshev, Matteo Fossati, Romana Grossová, Rongxin Luo, Jan Palouš and Tom C. Scott","doi":"10.3847/1538-4357/adde47","DOIUrl":"https://doi.org/10.3847/1538-4357/adde47","url":null,"abstract":"We present new CO(2–1) observations (resolution ∼1″ = 460 pc) of the Coma cluster jellyfish galaxy NGC 4858 obtained from the ALMA-JELLY large program. Analyzing this data alongside complimentary Subaru Hα and Hubble Space Telescope (F600LP / F350LP) observations, we find numerous structural and kinematic features indicative of the effects from strong, inclined ram pressure, including an asymmetric inner gas tail. We estimate a highly inclined disk-wind angle of . By subtracting a simple circular velocity model, we find (1): gas clumps that are being accelerated by ram pressure, and (2): signatures of gas clumps that had been previously pushed out of the disk but are now falling inward. We also discuss head-tail morphologies in star complexes within the stellar disk that appear to be ram pressure stripping (RPS)-influenced. Lastly, we compare this galaxy to state-of-the-art galaxy “wind tunnel” simulations. We find that this galaxy is one of the best nearby examples of strong and inclined ram pressure gas stripping, and of gas that is perturbed by ram pressure but not fully stripped and falls back. We emphasize the importance of torques due to ram pressure in highly inclined interactions, which help drive gas inward on the side rotating against the wind, contributing to the formation of asymmetric inner RPS tails.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144630154","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}

引用次数: 0

Major Mergers Mean Major Offset: Drivers of Intrinsic Scatter in the M GCS–M h Scaling Relation for Massive Elliptical Galaxies 大合并平均大偏移：大质量椭圆星系M - GCS-M - h尺度关系中本征散射的驱动因素

The Astrophysical Journal Pub Date : 2025-07-14 DOI: 10.3847/1538-4357/ade05e

Veronika Dornan and William E. Harris

{"title":"Major Mergers Mean Major Offset: Drivers of Intrinsic Scatter in the M GCS–M h Scaling Relation for Massive Elliptical Galaxies","authors":"Veronika Dornan and William E. Harris","doi":"10.3847/1538-4357/ade05e","DOIUrl":"https://doi.org/10.3847/1538-4357/ade05e","url":null,"abstract":"In this work, we determine the total globular cluster (GC) counts and globular cluster system (GCS) total mass estimates for 27 extremely massive elliptical galaxies. The GC 2D spatial distributions of these galaxies were created from photometry of Hubble Space Telescope images using DOLPHOT in the near-IR wavelength range. The projected radial density profiles of these GCSs were determined using a Voronoi-tessellation-based technique introduced in our previous paper. We then plot these galaxies on the GCS–halo mass relation alongside previously studied galaxies in the literature. The relation now extends across seven decades of halo mass. We find that the 1:1 slope of this relation holds out to the highest-mass galaxies, although extremely massive BCG galaxies are shifted to higher GCS masses than their lower-mass galaxy counterparts. We find a negative correlation with massive galaxies’ offset from the GCS–halo mass relation and the steepness of their GCS density profiles, and that this is being driven by the red GC populations. We suggest that the biggest influence in intrinsic scatter in the GCS–halo mass relation for massive galaxies is through a few major mergers resulting in accretion of massive satellites with old, red GC populations, rather than many accretions of small satellites with younger, blue GC populations.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144630332","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}

引用次数: 0

The Hourglass Simulation: A Catalog for the Roman High-latitude Time-domain Core Community Survey 沙漏模拟：罗马高纬度时域核心社区调查目录

The Astrophysical Journal Pub Date : 2025-07-14 DOI: 10.3847/1538-4357/ade1d6

B. M. Rose, M. Vincenzi, R. Hounsell, H. Qu, L. Aldoroty, D. Scolnic, R. Kessler, P. Macias, D. Brout, M. Acevedo, R. C. Chen, S. Gomez, E. Peterson, D. Rubin, M. Sako and the Roman Supernova Project Infrastructure Team

{"title":"The Hourglass Simulation: A Catalog for the Roman High-latitude Time-domain Core Community Survey","authors":"B. M. Rose, M. Vincenzi, R. Hounsell, H. Qu, L. Aldoroty, D. Scolnic, R. Kessler, P. Macias, D. Brout, M. Acevedo, R. C. Chen, S. Gomez, E. Peterson, D. Rubin, M. Sako and the Roman Supernova Project Infrastructure Team","doi":"10.3847/1538-4357/ade1d6","DOIUrl":"https://doi.org/10.3847/1538-4357/ade1d6","url":null,"abstract":"We present a simulation of the time-domain catalog for the Nancy Grace Roman Space Telescope’s High-Latitude Time-Domain Core Community Survey. This simulation, called the Hourglass simulation, uses the most up-to-date spectral energy distribution models and rate measurements for 10 extragalactic time-domain sources. We simulate these models through the design reference Roman Space Telescope survey: four filters per tier, a five-day cadence, over 2 yr, a wide tier of 19 deg2, and a deep tier of 4.2 deg2, with ∼20% of those areas also covered with prism observations. We find that a science-independent Roman time-domain catalog, assuming a signal-to-noise ratio at a max of >5, would have approximately 21,000 Type Ia supernovae, 40,000 core-collapse supernovae, around 70 superluminous supernovae, ∼35 tidal disruption events, three kilonovae, and possibly pair-instability supernovae. In total, Hourglass has over 64,000 transient objects, 11,000,000 photometric observations, and 500,000 spectra. Additionally, Hourglass is a useful data set to train machine learning classification algorithms. We show that SCONE is able to photometrically classify Type Ia supernovae with high precision (∼95%) to a z > 2. Finally, we present the first realistic simulations of non-Type Ia supernovae spectral time series data from Roman’s prism.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144630335","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}

引用次数: 0

Microphysics of Circumgalactic Turbulence Probed by Fast Radio Bursts and Quasars 由快速射电暴和类星体探测的环星系湍流的微观物理学

The Astrophysical Journal Pub Date : 2025-07-14 DOI: 10.3847/1538-4357/ade0bc

Stella Koch Ocker, Mandy C. Chen, S. Peng Oh and Prateek Sharma

{"title":"Microphysics of Circumgalactic Turbulence Probed by Fast Radio Bursts and Quasars","authors":"Stella Koch Ocker, Mandy C. Chen, S. Peng Oh and Prateek Sharma","doi":"10.3847/1538-4357/ade0bc","DOIUrl":"https://doi.org/10.3847/1538-4357/ade0bc","url":null,"abstract":"The circumgalactic medium (CGM) is poorly constrained at the subparsec scales relevant to turbulent energy dissipation and regulation of multiphase structure. Fast radio bursts are sensitive to small-scale plasma density fluctuations, which can induce multipath propagation (scattering). The amount of scattering depends on the density fluctuation spectrum, including its amplitude , spectral index β, and dissipation scale li. We use quasar observations of CGM turbulence at ≳pc scales to infer , finding it to be m−20/3 for hot (T > 106 K) gas and m−20/3 for cool (104 ≲ T ≲ 105 K) gas, depending on the gas sound speed and density. These values of are much smaller than those inferred in the interstellar medium at similar physical scales. The resulting scattering delays from the hot CGM are negligible (≪1 μs at 1 GHz), but they are more detectable from the cool gas as either radio pulse broadening or scintillation, depending on the observing frequency and sightline geometry. Joint quasar-FRB observations of individual galaxies can yield lower limits on li, even if the CGM is not a significant scattering site. An initial comparison between quasar and FRB observations (albeit for different systems) suggests li ≳ 750 km in ∼104 K gas in order for the quasar and FRB constraints to be consistent. If a foreground CGM is completely ruled out as a source of scattering along an FRB sightline, then li may be comparable to the smallest cloud sizes (≲pc) inferred from photoionization modeling of quasar absorption lines.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144630334","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}

引用次数: 0

Extracting the Epoch of Reionization Signal with 3D U-Net Neural Networks Using a Data-driven Systematic Effect Model 基于数据驱动系统效应模型的三维U-Net神经网络再电离信号纪元提取

The Astrophysical Journal Pub Date : 2025-07-14 DOI: 10.3847/1538-4357/ade2dc

Li-Yang Gao, Léon V. E. Koopmans, Florent G. Mertens, Satyapan Munshi, Yichao Li, Stefanie A. Brackenhoff, Emilio Ceccotti, J. Kariuki Chege, Anshuman Acharya, Raghunath Ghara, Sambit K. Giri, Ilian T. Iliev, Garrelt Mellema and Xin Zhang

{"title":"Extracting the Epoch of Reionization Signal with 3D U-Net Neural Networks Using a Data-driven Systematic Effect Model","authors":"Li-Yang Gao, Léon V. E. Koopmans, Florent G. Mertens, Satyapan Munshi, Yichao Li, Stefanie A. Brackenhoff, Emilio Ceccotti, J. Kariuki Chege, Anshuman Acharya, Raghunath Ghara, Sambit K. Giri, Ilian T. Iliev, Garrelt Mellema and Xin Zhang","doi":"10.3847/1538-4357/ade2dc","DOIUrl":"https://doi.org/10.3847/1538-4357/ade2dc","url":null,"abstract":"Neutral hydrogen serves as a crucial probe for the Cosmic Dawn and the Epoch of Reionization (EoR). Actual observations of the 21 cm signal often encounter challenges such as thermal noise and various systematic effects. To overcome these challenges, we simulate SKA-Low-depth images in the South Celestial Pole field and process them with a deep learning method. We utilized foreground residuals acquired by LOFAR during actual North Celestial Pole field observations, thermal and excess variances calculated via Gaussian process regression, and 21 cm signals generated with 21cmFAST for signal extraction tests. Our approach to overcome these foreground, thermal noise, and excess variance components employs a 3D U-Net neural network architecture for image analysis. When considering thermal noise corresponding to 1752 hr of integration time, U-Net provides reliable 2D power spectrum predictions, and robustness tests ensure that we get realistic EoR signals. Adding foreground residuals, however, causes inconsistencies below the horizon delay line. Lastly, evaluating both thermal noise and excess variances with observations up to 4380 hr and 13,140 hr ensures reliable power spectrum estimations within the EoR window and across nearly all scales, respectively. The incoherence of excess variances in the frequency direction can greatly affect deep learning to extract 21 cm signals.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":"51 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144630341","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}

引用次数: 0