Pub Date : 2024-02-29DOI: 10.3847/1538-4357/ad22df
L. Yu, S. Y. Huang, H. Fu, Z. Yuan, K. Jiang, Q. Xiong, R. Lin
Space plasmas are turbulent and maintain different types of critical points or flow nulls. Electron vortex, as one type of flow null structure, is crucial in the energy cascade in turbulent plasmas. However, due to the limited time resolution of the spacecraft observations, one can never analyze the three-dimensional properties of the electron vortex. In the present study, with the advancement of the FOTE-V method and the unprecedented high-resolution measurements from four Magnetospheric Multiscale spacecraft, we successfully identify the electron vortex and then reconstruct its three-dimensional topology of the surrounding electron flow field. The results of the reconstruction show that the configuration of the electron vortex is elliptical. Comparison between the observation and reconstruction scales of the vortex indicates the reliable reconstruction of the flow velocity. Our study sheds light on the understanding of the topology and property of the electron vortex and its relationship with kinetic-scale magnetic holes.
{"title":"Reconstruction of Electron Vortex in Space Plasmas","authors":"L. Yu, S. Y. Huang, H. Fu, Z. Yuan, K. Jiang, Q. Xiong, R. Lin","doi":"10.3847/1538-4357/ad22df","DOIUrl":"https://doi.org/10.3847/1538-4357/ad22df","url":null,"abstract":"\u0000 Space plasmas are turbulent and maintain different types of critical points or flow nulls. Electron vortex, as one type of flow null structure, is crucial in the energy cascade in turbulent plasmas. However, due to the limited time resolution of the spacecraft observations, one can never analyze the three-dimensional properties of the electron vortex. In the present study, with the advancement of the FOTE-V method and the unprecedented high-resolution measurements from four Magnetospheric Multiscale spacecraft, we successfully identify the electron vortex and then reconstruct its three-dimensional topology of the surrounding electron flow field. The results of the reconstruction show that the configuration of the electron vortex is elliptical. Comparison between the observation and reconstruction scales of the vortex indicates the reliable reconstruction of the flow velocity. Our study sheds light on the understanding of the topology and property of the electron vortex and its relationship with kinetic-scale magnetic holes.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140415415","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 : 2024-02-29DOI: 10.3847/1538-4357/ad1835
B-G Andersson, J. Karoly, P. Bastien, A. Soam, S. Coudé, M. Tahani, Michael S. Gordon, Sydney Fox-Middleton
We present SCUBA-2/POL-2 850 μm polarimetric observations of the circumstellar envelope (CSE) of the carbon-rich asymptotic giant branch (AGB) star IRC+10216. Both far-IR (FIR) and optical polarization data indicate grains aligned with their long axis in the radial direction relative to the central star. The 850 μm polarization does not show this simple structure. The 850 μm data are indicative, albeit not conclusive, of a magnetic dipole geometry. Assuming such a simple dipole geometry, the resulting 850 μm polarization geometry is consistent with both Zeeman observations and small-scale structure in the CSE. While there is significant spectral-line polarization contained within the SCUBA-2 850 μm passband for the source, it is unlikely that our broadband polarization results are dominated by line polarization. To explain the required grain alignment, grain mineralogy effects, due to either fossil silicate grains from the earlier oxygen-rich AGB phase of the star or due to the incorporation of ferromagnetic inclusions in the largest grains, may play a role. We argue that the most likely explanation is due to a new alignment mechanism wherein a charged grain, moving relative to the magnetic field, precesses around the induced electric field and therefore aligns with the magnetic field. This mechanism is particularly attractive as the optical, FIR, and submillimeter-wave polarization of the carbon dust can then be explained in a consistent way, differing simply due to the charge state of the grains.
{"title":"Submillimeter-wavelength Polarimetry of IRC+10216","authors":"B-G Andersson, J. Karoly, P. Bastien, A. Soam, S. Coudé, M. Tahani, Michael S. Gordon, Sydney Fox-Middleton","doi":"10.3847/1538-4357/ad1835","DOIUrl":"https://doi.org/10.3847/1538-4357/ad1835","url":null,"abstract":"\u0000 We present SCUBA-2/POL-2 850 μm polarimetric observations of the circumstellar envelope (CSE) of the carbon-rich asymptotic giant branch (AGB) star IRC+10216. Both far-IR (FIR) and optical polarization data indicate grains aligned with their long axis in the radial direction relative to the central star. The 850 μm polarization does not show this simple structure. The 850 μm data are indicative, albeit not conclusive, of a magnetic dipole geometry. Assuming such a simple dipole geometry, the resulting 850 μm polarization geometry is consistent with both Zeeman observations and small-scale structure in the CSE. While there is significant spectral-line polarization contained within the SCUBA-2 850 μm passband for the source, it is unlikely that our broadband polarization results are dominated by line polarization. To explain the required grain alignment, grain mineralogy effects, due to either fossil silicate grains from the earlier oxygen-rich AGB phase of the star or due to the incorporation of ferromagnetic inclusions in the largest grains, may play a role. We argue that the most likely explanation is due to a new alignment mechanism wherein a charged grain, moving relative to the magnetic field, precesses around the induced electric field and therefore aligns with the magnetic field. This mechanism is particularly attractive as the optical, FIR, and submillimeter-wave polarization of the carbon dust can then be explained in a consistent way, differing simply due to the charge state of the grains.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"22 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140411886","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 : 2024-02-21DOI: 10.3847/1538-4357/ad2a4e
Xin He, Pei-pei Zhang, Qiang Yuan, Yi-qing Guo
Cosmic rays (CRs) travel throughout the Galaxy, leaving traces from radio to ultra-high-energy γ-rays due to interactions with the interstellar gas, radiation field, and magnetic field. Therefore, it is necessary to utilize multiwavelength investigations on the Galactic diffuse emission to shed light on the physics of CR production and propagation. In this work, we present a spatially dependent propagation scenario, taking account of a local source contribution, while making allowances for an additional CR component freshly accelerated near their sources. In this picture, after reproducing the particle measurements at the solar system, we calculated the intensity and compared the spectral energy distribution to observations from Fermi-LAT and LHAASO-KM2A in the γ-ray band, and from WMAP and Planck among other radio surveys at lower energies. Multiband data considered in conjunction, the former comparison exhibits sufficiently good consistency in favor of our model, while the latter calls for improvement in data subtraction and processing. From this standpoint, there remains potential for advanced observations at energies from milli-eVs to MeVs toward the Galactic plane, in order to evaluate our model further and more comprehensively in the future.
{"title":"Galactic Diffuse Emission from Radio to Ultra-high-energy γ-Rays in Light of Up-to-date Cosmic-Ray Measurements","authors":"Xin He, Pei-pei Zhang, Qiang Yuan, Yi-qing Guo","doi":"10.3847/1538-4357/ad2a4e","DOIUrl":"https://doi.org/10.3847/1538-4357/ad2a4e","url":null,"abstract":"\u0000 Cosmic rays (CRs) travel throughout the Galaxy, leaving traces from radio to ultra-high-energy γ-rays due to interactions with the interstellar gas, radiation field, and magnetic field. Therefore, it is necessary to utilize multiwavelength investigations on the Galactic diffuse emission to shed light on the physics of CR production and propagation. In this work, we present a spatially dependent propagation scenario, taking account of a local source contribution, while making allowances for an additional CR component freshly accelerated near their sources. In this picture, after reproducing the particle measurements at the solar system, we calculated the intensity and compared the spectral energy distribution to observations from Fermi-LAT and LHAASO-KM2A in the γ-ray band, and from WMAP and Planck among other radio surveys at lower energies. Multiband data considered in conjunction, the former comparison exhibits sufficiently good consistency in favor of our model, while the latter calls for improvement in data subtraction and processing. From this standpoint, there remains potential for advanced observations at energies from milli-eVs to MeVs toward the Galactic plane, in order to evaluate our model further and more comprehensively in the future.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"18 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140445207","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 : 2024-02-21DOI: 10.3847/1538-4357/ad1404
T. Morishita, M. Stiavelli, R. Chary, M. Trenti, P. Bergamini, M. Chiaberge, N. Leethochawalit, G. Roberts-Borsani, Xuejian Shen, T. Treu
We present a comprehensive search and analysis of high-redshift galaxies in a suite of nine public JWST extragalactic fields taken in Cycle 1, covering a total effective search area of ∼ 358 arcmin 2 . Through conservative (8σ) photometric selection, we identify 341 galaxies at 5 < z < 14, with 109 having spectroscopic redshift measurements from the literature, including recent JWST NIRSpec observations. Our regression analysis reveals that the rest-frame UV size–stellar mass relation follows R eff ∝ M * 0.19 ± 0.03 , similar to that of star-forming galaxies at z ∼ 3, but scaled down in size by ∼0.7 dex. We find a much slower rate for the average size evolution over the redshift range, R eff ∝ (1 + z)−0.4±0.2, than that derived in the literature. A fraction (∼13%) of our sample galaxies are marginally resolved even in the NIRCam imaging (≲100 pc), located at ≳1.5σ below the derived size–mass slope. These compact sources exhibit a high star formation surface density ΣSFR > 10 M ⊙ yr−1 kpc−2, a range in which only <0.01% of the local star-forming galaxy sample is found. For those with available NIRSpec data, no evidence of ongoing supermassive black hole accretion is observed. A potential explanation for the observed high [O iii]-to-Hβ ratios could be high shock velocities, likely originating within intense star-forming regions characterized by high ΣSFR. Lastly, we find that the rest-frame UV and optical sizes of our sample are comparable. Our results are consistent with these early galaxies building up their structures inside out and being yet to exhibit the strong color gradient seen at lower redshift.
我们对第一周期拍摄的九个公开的 JWST 河外星系场中的高红移星系进行了全面搜索和分析，覆盖的有效搜索区域总计 ∼ 358 弧分 2。通过保守的（8σ）测光选择，我们识别出了 341 个 5 < z < 14 的星系，其中 109 个有文献中的光谱红移测量值，包括最近的 JWST NIRSpec 观测数据。我们的回归分析表明，静帧紫外尺寸-恒星质量关系为 R eff ∝ M * 0.19 ± 0.03，与 z ∼ 3 的恒星形成星系相似，但尺寸缩小了 ∼ 0.7 dex。我们发现，在红移范围内，平均大小的演变速度 R eff ∝ (1 + z)-0.4±0.2 比文献中推导的速度慢得多。在我们的样本星系中，有一部分（13%）即使在 NIRCam 成像中（≲100 pc）也能被微弱地分辨出来，它们位于推导出的大小-质量斜率以下的≳1.5σ处。这些小巧的星源表现出很高的恒星形成表面密度ΣSFR > 10 M ⊙ yr-1 kpc-2，在本地恒星形成星系样本中，只有小于0.01%的恒星形成表面密度在这个范围内。对于那些有NIRSpec数据的星系，没有观测到超大质量黑洞持续吸积的证据。观测到的高[O iii]-to-Hβ比值的一个潜在解释可能是高冲击速度，它很可能源自以高ΣSFR为特征的强烈恒星形成区。最后，我们发现样本的静帧紫外和光学尺寸相当。我们的研究结果与这些早期星系由内而外形成的结构是一致的，它们还没有表现出在较低红移下看到的强烈颜色梯度。
{"title":"Enhanced Subkiloparsec-scale Star Formation: Results from a JWST Size Analysis of 341 Galaxies at 5 < z < 14","authors":"T. Morishita, M. Stiavelli, R. Chary, M. Trenti, P. Bergamini, M. Chiaberge, N. Leethochawalit, G. Roberts-Borsani, Xuejian Shen, T. Treu","doi":"10.3847/1538-4357/ad1404","DOIUrl":"https://doi.org/10.3847/1538-4357/ad1404","url":null,"abstract":"\u0000 We present a comprehensive search and analysis of high-redshift galaxies in a suite of nine public JWST extragalactic fields taken in Cycle 1, covering a total effective search area of \u0000 \u0000\u0000\u0000 \u0000 ∼\u0000 358\u0000 \u0000 \u0000 \u0000 arcmin\u0000 \u0000 \u0000 2\u0000 \u0000 \u0000 \u0000 \u0000 . Through conservative (8σ) photometric selection, we identify 341 galaxies at 5 < z < 14, with 109 having spectroscopic redshift measurements from the literature, including recent JWST NIRSpec observations. Our regression analysis reveals that the rest-frame UV size–stellar mass relation follows \u0000 \u0000\u0000\u0000 \u0000 \u0000 \u0000 R\u0000 \u0000 \u0000 eff\u0000 \u0000 \u0000 ∝\u0000 \u0000 \u0000 M\u0000 \u0000 \u0000 *\u0000 \u0000 \u0000 0.19\u0000 ±\u0000 0.03\u0000 \u0000 \u0000 \u0000 \u0000 , similar to that of star-forming galaxies at z ∼ 3, but scaled down in size by ∼0.7 dex. We find a much slower rate for the average size evolution over the redshift range, R\u0000 eff ∝ (1 + z)−0.4±0.2, than that derived in the literature. A fraction (∼13%) of our sample galaxies are marginally resolved even in the NIRCam imaging (≲100 pc), located at ≳1.5σ below the derived size–mass slope. These compact sources exhibit a high star formation surface density ΣSFR > 10 M\u0000 ⊙ yr−1 kpc−2, a range in which only <0.01% of the local star-forming galaxy sample is found. For those with available NIRSpec data, no evidence of ongoing supermassive black hole accretion is observed. A potential explanation for the observed high [O iii]-to-Hβ ratios could be high shock velocities, likely originating within intense star-forming regions characterized by high ΣSFR. Lastly, we find that the rest-frame UV and optical sizes of our sample are comparable. Our results are consistent with these early galaxies building up their structures inside out and being yet to exhibit the strong color gradient seen at lower redshift.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"27 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140443955","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 : 2024-02-20DOI: 10.3847/1538-4357/ad2346
Haifeng 海峰 Yang 杨, M. Fern'andez-L'opez, Zhi-Yun Li, I. Stephens, L. Looney, Zheyu Lin, Rachel E. Harrison
We investigate the crescent-shaped dust trap in the transition disk Oph IRS 48 using well-resolved (sub)millimeter polarimetric observations at ALMA Band 7 (870 μm). The dust polarization map reveals patterns consistent with dust-scattering-induced polarization. There is a relative displacement between the polarized flux and the total flux, which holds the key to understanding the dust scale heights in this system. We model the polarization observations, focusing on the effects of dust scale heights. We find that the interplay between the inclination-induced polarization and the polarization arising from radiation anisotropy in the crescent determines the observed polarization; the anisotropy is controlled by the dust optical depth along the midplane, which is, in turn, determined by the dust scale height in the vertical direction. We find that the dust grains can be neither completely settled nor well mixed with the gas. The completely settled case produces little radial displacement between the total and polarized flux, while the well-mixed case produces an azimuthal pattern in the outer (radial) edge of the crescent that is not observed. Our best model has a gas-to-dust scale height ratio of 2 and can reproduce both the radial displacement and the azimuthal displacement between the total and polarized flux. We infer an effective turbulence α parameter of approximately 0.0001–0.005. The scattering-induced polarization provides insight into a turbulent vortex with a moderate level of dust settling in the IRS 48 system, which is hard to achieve otherwise.
{"title":"Turbulent Vortex with Moderate Dust Settling Probed by Scattering-induced Polarization in the IRS 48 System","authors":"Haifeng 海峰 Yang 杨, M. Fern'andez-L'opez, Zhi-Yun Li, I. Stephens, L. Looney, Zheyu Lin, Rachel E. Harrison","doi":"10.3847/1538-4357/ad2346","DOIUrl":"https://doi.org/10.3847/1538-4357/ad2346","url":null,"abstract":"\u0000 We investigate the crescent-shaped dust trap in the transition disk Oph IRS 48 using well-resolved (sub)millimeter polarimetric observations at ALMA Band 7 (870 μm). The dust polarization map reveals patterns consistent with dust-scattering-induced polarization. There is a relative displacement between the polarized flux and the total flux, which holds the key to understanding the dust scale heights in this system. We model the polarization observations, focusing on the effects of dust scale heights. We find that the interplay between the inclination-induced polarization and the polarization arising from radiation anisotropy in the crescent determines the observed polarization; the anisotropy is controlled by the dust optical depth along the midplane, which is, in turn, determined by the dust scale height in the vertical direction. We find that the dust grains can be neither completely settled nor well mixed with the gas. The completely settled case produces little radial displacement between the total and polarized flux, while the well-mixed case produces an azimuthal pattern in the outer (radial) edge of the crescent that is not observed. Our best model has a gas-to-dust scale height ratio of 2 and can reproduce both the radial displacement and the azimuthal displacement between the total and polarized flux. We infer an effective turbulence α parameter of approximately 0.0001–0.005. The scattering-induced polarization provides insight into a turbulent vortex with a moderate level of dust settling in the IRS 48 system, which is hard to achieve otherwise.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"42 21","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140448983","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 : 2024-02-16DOI: 10.3847/1538-4357/ad23e5
Jia-Yan Yang, Hechao Chen, Junchao Hong, Bo Yang, Y. Bi
Similar to the cases of anemone jets, two-sided loop solar jets can also be produced by either flux emergence from the solar interior or small-scale filament eruptions. Using high-quality data from the Solar Dynamics Observatory, we have analyzed a two-sided loop solar jet triggered by the eruption of a small filament. The jet occurred in a pre-existing big filament channel. The detailed processes involved in the eruption of the small filament, the interaction between the erupted filament and the big filament channel, and the launch of the two-sided loop jet are presented. The observations further revealed notable asymmetry between the two branches of the jet spire: the northeastern branch is narrow and short, while the southern branch is wide and long and accompanied by discernible untwisting motions. We explored the unique appearance of the jet by employing the method of local potential field extrapolation to calculate the coronal magnetic field configuration around the jet. The photospheric magnetic flux below the small filament underwent cancellation for approximately 7 hr before the filament eruption, and the negative flux near the southern footpoint of the filament decreased by about 56% during this interval. Therefore, we propose that the primary photospheric driver of the filament eruption and the associated two-sided loop jet in this event is flux cancellation rather than flux emergence.
{"title":"Two-sided Loop Solar Jet Driven by the Eruption of a Small Filament in a Big Filament Channel","authors":"Jia-Yan Yang, Hechao Chen, Junchao Hong, Bo Yang, Y. Bi","doi":"10.3847/1538-4357/ad23e5","DOIUrl":"https://doi.org/10.3847/1538-4357/ad23e5","url":null,"abstract":"\u0000 Similar to the cases of anemone jets, two-sided loop solar jets can also be produced by either flux emergence from the solar interior or small-scale filament eruptions. Using high-quality data from the Solar Dynamics Observatory, we have analyzed a two-sided loop solar jet triggered by the eruption of a small filament. The jet occurred in a pre-existing big filament channel. The detailed processes involved in the eruption of the small filament, the interaction between the erupted filament and the big filament channel, and the launch of the two-sided loop jet are presented. The observations further revealed notable asymmetry between the two branches of the jet spire: the northeastern branch is narrow and short, while the southern branch is wide and long and accompanied by discernible untwisting motions. We explored the unique appearance of the jet by employing the method of local potential field extrapolation to calculate the coronal magnetic field configuration around the jet. The photospheric magnetic flux below the small filament underwent cancellation for approximately 7 hr before the filament eruption, and the negative flux near the southern footpoint of the filament decreased by about 56% during this interval. Therefore, we propose that the primary photospheric driver of the filament eruption and the associated two-sided loop jet in this event is flux cancellation rather than flux emergence.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"60 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140455031","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 : 2024-02-13DOI: 10.3847/1538-4357/ad20ea
Ziyuan Yin, Austin Hinkel
As the number of known Galactic structures mounts thanks to the Gaia Space Telescope, it is now pertinent to study methods for disentangling structures occupying the same regions of the Milky Way. Indeed, understanding the precise form of each individual structure and the interactions between structures may aid in understanding their origins and chronology. Moreover, accounting for known structures allows one to probe still finer Galactic structure. In order to demonstrate this, we have developed an odd low-pass filter (OLPF), which removes smaller, odd-parity structures like the vertical waves, and use the filtered data to examine the location of the Galaxy’s midplane. We find that the radial wave identified by Xu et al. continues inward to at least the Sun’s location, with an amplitude that decreases toward the inner, denser parts of the disk, consistent with a simple, qualitative simulation. Additionally, we employ the OLPF results to determine the solar offset, z ⊙, with smaller structures filtered out. We find that z ⊙ = 34.2 ± 0.3 pc.
由于盖亚太空望远镜（Gaia Space Telescope）的出现，已知银河系结构的数量不断增加，因此现在有必要研究如何将银河系同一区域的结构分开。事实上，了解每个结构的精确形式以及结构之间的相互作用有助于了解它们的起源和年代。此外，考虑到已知的结构，我们还可以探测更精细的银河结构。为了证明这一点，我们开发了一种奇数低通滤波器（OLPF），它可以去除像垂直波这样较小的、奇偶性的结构，并利用滤波后的数据来研究银河系中面的位置。我们发现，Xu 等人确定的径向波至少一直向内延伸到太阳的位置，其振幅向星盘内部密度较高的部分减小，这与简单的定性模拟一致。此外，我们还利用 OLPF 结果确定了太阳偏移量 z ⊙，并过滤掉了较小的结构。我们发现 z ⊙ = 34.2 ± 0.3 pc。
{"title":"A Wave-corrected Assessment of the Local Midplane","authors":"Ziyuan Yin, Austin Hinkel","doi":"10.3847/1538-4357/ad20ea","DOIUrl":"https://doi.org/10.3847/1538-4357/ad20ea","url":null,"abstract":"\u0000 As the number of known Galactic structures mounts thanks to the Gaia Space Telescope, it is now pertinent to study methods for disentangling structures occupying the same regions of the Milky Way. Indeed, understanding the precise form of each individual structure and the interactions between structures may aid in understanding their origins and chronology. Moreover, accounting for known structures allows one to probe still finer Galactic structure. In order to demonstrate this, we have developed an odd low-pass filter (OLPF), which removes smaller, odd-parity structures like the vertical waves, and use the filtered data to examine the location of the Galaxy’s midplane. We find that the radial wave identified by Xu et al. continues inward to at least the Sun’s location, with an amplitude that decreases toward the inner, denser parts of the disk, consistent with a simple, qualitative simulation. Additionally, we employ the OLPF results to determine the solar offset, z\u0000 ⊙, with smaller structures filtered out. We find that z\u0000 ⊙ = 34.2 ± 0.3 pc.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"83 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140457445","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 : 2024-02-07DOI: 10.3847/1538-4357/ad26f9
F. Zeuner, T. del Pino Alemán, J. Trujillo Bueno, S. K. Solanki
Solar magnetic fields alter scattering polarization in spectral lines like Sr i at 4607 Å via the Hanle effect, making it a potential diagnostic for small-scale, mixed-polarity photospheric magnetic fields. Recently, observational evidence for scattering polarization in the Sr i 4607 Å line at the solar disk center was found. Here, we investigate the reliability of the reconstruction method that made possible this detection. To this end, we apply it to linear polarization profiles of the Sr i 4607 Å line radiation emerging at the disk center obtained from a detailed 3D radiative transfer calculation in a magneto-hydrodynamic (MHD) simulation snapshot with a small-scale dynamo contribution. The reconstruction method systematically reduces the scattering amplitudes by up to a factor of 2, depending on the noise level. We demonstrate that the decrease can be attributed to two systematic errors: first, the physical constraint that underlies our assumptions regarding the dependence of scattering polarization on the quadrupolar moment of the radiation field; and second, the limitations of our method in accurately determining the sign of the radiation field tensor from the observed intensity image. However, by consistently applying the reconstruction process and after taking into account image-degradation effects due to the temporally variable image quality, such as imposed by seeing, the observed and synthesized polarization signals show remarkable agreement. We thus conclude that the observed scattering polarization at the solar disk center is consistent with that emerging from a MHD model of the solar photosphere with an average magnetic field of 170 G at the visible surface.
太阳磁场通过汉勒效应改变光谱线（如 4607 Å 的 Sr i）的散射极化，使其成为小尺度混合极性光球磁场的潜在诊断工具。最近，在太阳盘中心发现了 Sr i 4607 Å 线散射极化的观测证据。在此，我们研究了使这一探测成为可能的重构方法的可靠性。为此，我们将该方法应用于在磁流体动力（MHD）模拟快照中进行的详细三维辐射传递计算中获得的太阳圆盘中心 Sr i 4607 Å 线辐射的线性偏振剖面，其中包含小尺度动力的贡献。重构方法系统地将散射振幅降低了 2 倍，这取决于噪声水平。我们证明，这种降低可归因于两个系统误差：第一，我们假设散射极化依赖于辐射场的四极矩，而这一假设的基础是物理约束；第二，我们的方法在从观测到的强度图像中准确确定辐射场张量的符号方面存在局限性。然而，通过持续应用重构过程，并考虑到图像质量随时间变化而产生的图像劣化效应（如视线造成的劣化），观测到的偏振信号和合成的偏振信号显示出显著的一致性。因此，我们得出结论，在太阳圆盘中心观测到的散射偏振与太阳光层的 MHD 模型所产生的偏振是一致的，可见表面的平均磁场为 170 G。
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Pub Date : 2024-02-07DOI: 10.3847/1538-4357/ad2357
Zhu-Ling Deng, Xiang-Dong Li, Y. Shao, Kun Xu
The detection of gravitational wave events has stimulated theoretical modeling of the formation and evolution of double compact objects (DCOs). However, even for the most studied isolated binary evolution channel, there exist large uncertainties in the input parameters and treatments of the binary evolution process. So far, double neutron stars (DNSs) are the only DCOs for which direct observations are available through traditional electromagnetic astronomy. In this work, we adopt a population synthesis method to investigate the formation and evolution of Galactic DNSs. We construct 324 models for the formation of Galactic DNSs, taking into account various possible combinations of critical input parameters and processes such as mass transfer efficiency, supernova type, common envelope efficiency, neutron star kick velocity, and pulsar selection effect. We employ Bayesian analysis to evaluate the adopted models by comparing with observations. We also compare the expected DNS merger rate in the galaxy with that inferred from the known Galactic population of pulsar-neutron star systems. Based on these analyses we derive the favorable range of the aforementioned key parameters.
引力波事件的探测激发了对双紧凑天体（DCO）形成和演化的理论建模。然而，即使是研究最多的孤立双星演化通道，在输入参数和双星演化过程的处理方面也存在着很大的不确定性。迄今为止，双中子星（DNS）是唯一可以通过传统电磁天文学直接观测到的双紧凑天体。在这项工作中，我们采用种群合成法来研究银河系双中子星的形成和演化过程。我们构建了 324 个银河 DNS 形成模型，考虑了各种可能的关键输入参数和过程组合，如质量转移效率、超新星类型、共包层效率、中子星踢速和脉冲星选择效应。我们采用贝叶斯分析法，通过与观测数据的比较来评估所采用的模型。我们还将星系中的预期DNS合并率与已知的脉冲星-中子星系统星系群推断的合并率进行了比较。根据这些分析，我们得出了上述关键参数的有利范围。
{"title":"On the Formation of Double Neutron Stars in the Milky Way: Influence of Key Parameters","authors":"Zhu-Ling Deng, Xiang-Dong Li, Y. Shao, Kun Xu","doi":"10.3847/1538-4357/ad2357","DOIUrl":"https://doi.org/10.3847/1538-4357/ad2357","url":null,"abstract":"\u0000 The detection of gravitational wave events has stimulated theoretical modeling of the formation and evolution of double compact objects (DCOs). However, even for the most studied isolated binary evolution channel, there exist large uncertainties in the input parameters and treatments of the binary evolution process. So far, double neutron stars (DNSs) are the only DCOs for which direct observations are available through traditional electromagnetic astronomy. In this work, we adopt a population synthesis method to investigate the formation and evolution of Galactic DNSs. We construct 324 models for the formation of Galactic DNSs, taking into account various possible combinations of critical input parameters and processes such as mass transfer efficiency, supernova type, common envelope efficiency, neutron star kick velocity, and pulsar selection effect. We employ Bayesian analysis to evaluate the adopted models by comparing with observations. We also compare the expected DNS merger rate in the galaxy with that inferred from the known Galactic population of pulsar-neutron star systems. Based on these analyses we derive the favorable range of the aforementioned key parameters.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"19 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140460593","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 : 2024-02-05DOI: 10.3847/1538-4357/ad1bc8
Panomporn Poojon, Aeree Chung, T. Hoang, J. Baek, Hiroyuki Nakanishi, Tomoya Hirota, Chao-Wei Tsai
We present the results of the single-dish observations using the Korean VLBI Network to search for anomalous microwave emission (AME) in nearby galaxies. The targets were selected from ‘Mapping the dense molecular gas in the strongest star-forming galaxies' (MALATANG), a legacy survey project of the James Clerk Maxwell Telescope. The MALATANG galaxies are good representatives of local galaxies with enhanced nuclear activity associated with star formation and/or active galactic nuclei (AGNs), providing IR-bright galaxy samples; thus, they are good candidates for AME hosts. Combining with ancillary data, we investigated the radio–IR spectral energy distribution (SED), while searching for AME signals in five galaxies. The AME in NGC 2903 was well detected at a significant confidence level, whereas that in NGC 2146 and M82 was marginal. NGC 1068 and Arp 299 indicated no significant hints, and we provide upper limits for the AME. The best-fit SED exhibited local peaks of the AME components at higher frequencies and with stronger peak fluxes than those in previous studies. This suggested that AME originates from denser environments such as molecular clouds or photodissociation regions rather than warm neutral/ionized medium as commonly suggested by previous studies. Further, our AME-detected targets were observed to exhibit higher specific star formation rates than the other extragalactic AME hosts. Furthermore, AME favored starburst galaxies among our sample rather than AGN hosts. Consequently, this might imply that AGNs are excessively harsh environments for tiny dust to survive.
{"title":"Detection of Extragalactic Anomalous Microwave Emission in NGC 2903 Using KVN Single-dish Observations","authors":"Panomporn Poojon, Aeree Chung, T. Hoang, J. Baek, Hiroyuki Nakanishi, Tomoya Hirota, Chao-Wei Tsai","doi":"10.3847/1538-4357/ad1bc8","DOIUrl":"https://doi.org/10.3847/1538-4357/ad1bc8","url":null,"abstract":"\u0000 We present the results of the single-dish observations using the Korean VLBI Network to search for anomalous microwave emission (AME) in nearby galaxies. The targets were selected from ‘Mapping the dense molecular gas in the strongest star-forming galaxies' (MALATANG), a legacy survey project of the James Clerk Maxwell Telescope. The MALATANG galaxies are good representatives of local galaxies with enhanced nuclear activity associated with star formation and/or active galactic nuclei (AGNs), providing IR-bright galaxy samples; thus, they are good candidates for AME hosts. Combining with ancillary data, we investigated the radio–IR spectral energy distribution (SED), while searching for AME signals in five galaxies. The AME in NGC 2903 was well detected at a significant confidence level, whereas that in NGC 2146 and M82 was marginal. NGC 1068 and Arp 299 indicated no significant hints, and we provide upper limits for the AME. The best-fit SED exhibited local peaks of the AME components at higher frequencies and with stronger peak fluxes than those in previous studies. This suggested that AME originates from denser environments such as molecular clouds or photodissociation regions rather than warm neutral/ionized medium as commonly suggested by previous studies. Further, our AME-detected targets were observed to exhibit higher specific star formation rates than the other extragalactic AME hosts. Furthermore, AME favored starburst galaxies among our sample rather than AGN hosts. Consequently, this might imply that AGNs are excessively harsh environments for tiny dust to survive.","PeriodicalId":504209,"journal":{"name":"The Astrophysical Journal","volume":"106 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140461726","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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