Pub Date : 2023-11-01DOI: 10.3847/1538-4357/ad00b5
Meghana Pannikkote, Vaidehi S. Paliya, D. J. Saikia
Abstract The latest entry in the jetted active galactic nuclei (AGN) family is the Fanaroff–Riley type 0 (FR0) radio galaxies. They share several observational characteristics, e.g., nuclear emission and host galaxy morphology, with FR I sources; however, they lack extended, kiloparsec-scale radio structures, which are the defining features of canonical FR I and II sources. Here we report the identification of seven γ -ray-emitting AGN as FR0 radio sources by utilizing the high-quality observations delivered by ongoing multiwavelength wide-field sky surveys, e.g., Very Large Array Sky Survey. The broadband observational properties of these objects are found to be similar to their γ -ray undetected counterparts. In the γ -ray band, FR0 radio galaxies exhibit spectral features similar to more common FR I and II radio galaxies, indicating a common γ -ray production mechanism and the presence of misaligned jets. Although the parsec-scale radio structure of FR0s generally exhibits a wide range, with about half having emission on opposite sides of the core, the γ -ray-detected FR0s tend to have dominant cores with core-jet structures. We conclude that dedicated, high-resolution observations are needed to unravel the origin of relativistic jets in this enigmatic class of faint yet numerous population of compact radio sources.
{"title":"Hunting Gamma-Ray-emitting FR0 Radio Galaxies in Wide-field Sky Surveys","authors":"Meghana Pannikkote, Vaidehi S. Paliya, D. J. Saikia","doi":"10.3847/1538-4357/ad00b5","DOIUrl":"https://doi.org/10.3847/1538-4357/ad00b5","url":null,"abstract":"Abstract The latest entry in the jetted active galactic nuclei (AGN) family is the Fanaroff–Riley type 0 (FR0) radio galaxies. They share several observational characteristics, e.g., nuclear emission and host galaxy morphology, with FR I sources; however, they lack extended, kiloparsec-scale radio structures, which are the defining features of canonical FR I and II sources. Here we report the identification of seven γ -ray-emitting AGN as FR0 radio sources by utilizing the high-quality observations delivered by ongoing multiwavelength wide-field sky surveys, e.g., Very Large Array Sky Survey. The broadband observational properties of these objects are found to be similar to their γ -ray undetected counterparts. In the γ -ray band, FR0 radio galaxies exhibit spectral features similar to more common FR I and II radio galaxies, indicating a common γ -ray production mechanism and the presence of misaligned jets. Although the parsec-scale radio structure of FR0s generally exhibits a wide range, with about half having emission on opposite sides of the core, the γ -ray-detected FR0s tend to have dominant cores with core-jet structures. We conclude that dedicated, high-resolution observations are needed to unravel the origin of relativistic jets in this enigmatic class of faint yet numerous population of compact radio sources.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"31 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135270693","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 : 2023-11-01DOI: 10.3847/1538-4357/ad00b1
Rebecca Diesing
Abstract Identifying the accelerators of Galactic cosmic ray (CR) protons with energies up to a few PeV (10 15 eV) remains a theoretical and observational challenge. Supernova remnants (SNRs) represent strong candidates because they provide sufficient energetics to reproduce the CR flux observed at Earth. However, it remains unclear whether they can accelerate particles to PeV energies, particularly after the very early stages of their evolution. This uncertainty has prompted searches for other source classes and necessitates comprehensive theoretical modeling of the maximum proton energy, Emax , accelerated by an arbitrary shock. While analytic estimates of Emax have been put forward in the literature, they do not fully account for the complex interplay between particle acceleration, magnetic field amplification, and shock evolution. This paper uses a multizone, semianalytic model of particle acceleration based on kinetic simulations to place constraints on Emax for a wide range of astrophysical shocks. In particular, we develop relationships between Emax , shock velocity, size, and ambient medium. We find that SNRs can only accelerate PeV particles under a select set of circumstances, namely, if the shock velocity exceeds ∼10 4 km s −1 and escaping particles drive magnetic field amplification. However, older and slower SNRs may still produce observational signatures of PeV particles due to populations accelerated when the shock was younger. Our results serve as a reference for modelers seeking to quickly produce a self-consistent estimate of the maximum energy accelerated by an arbitrary astrophysical shock. 1 1 Presented as a thesis to the Department of Astronomy and Astrophysics, The University of Chicago, in partial fulfillment of the requirements for a Ph.D. degree.
{"title":"The Maximum Energy of Shock-accelerated Cosmic Rays","authors":"Rebecca Diesing","doi":"10.3847/1538-4357/ad00b1","DOIUrl":"https://doi.org/10.3847/1538-4357/ad00b1","url":null,"abstract":"Abstract Identifying the accelerators of Galactic cosmic ray (CR) protons with energies up to a few PeV (10 15 eV) remains a theoretical and observational challenge. Supernova remnants (SNRs) represent strong candidates because they provide sufficient energetics to reproduce the CR flux observed at Earth. However, it remains unclear whether they can accelerate particles to PeV energies, particularly after the very early stages of their evolution. This uncertainty has prompted searches for other source classes and necessitates comprehensive theoretical modeling of the maximum proton energy, <?CDATA ${E}_{max }$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msub> <mml:mrow> <mml:mi>E</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>max</mml:mi> </mml:mrow> </mml:msub> </mml:math> , accelerated by an arbitrary shock. While analytic estimates of <?CDATA ${E}_{max }$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msub> <mml:mrow> <mml:mi>E</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>max</mml:mi> </mml:mrow> </mml:msub> </mml:math> have been put forward in the literature, they do not fully account for the complex interplay between particle acceleration, magnetic field amplification, and shock evolution. This paper uses a multizone, semianalytic model of particle acceleration based on kinetic simulations to place constraints on <?CDATA ${E}_{max }$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msub> <mml:mrow> <mml:mi>E</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>max</mml:mi> </mml:mrow> </mml:msub> </mml:math> for a wide range of astrophysical shocks. In particular, we develop relationships between <?CDATA ${E}_{max }$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msub> <mml:mrow> <mml:mi>E</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>max</mml:mi> </mml:mrow> </mml:msub> </mml:math> , shock velocity, size, and ambient medium. We find that SNRs can only accelerate PeV particles under a select set of circumstances, namely, if the shock velocity exceeds ∼10 4 km s −1 and escaping particles drive magnetic field amplification. However, older and slower SNRs may still produce observational signatures of PeV particles due to populations accelerated when the shock was younger. Our results serve as a reference for modelers seeking to quickly produce a self-consistent estimate of the maximum energy accelerated by an arbitrary astrophysical shock. 1 1 Presented as a thesis to the Department of Astronomy and Astrophysics, The University of Chicago, in partial fulfillment of the requirements for a Ph.D. degree.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"7 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135510260","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 : 2023-11-01DOI: 10.3847/1538-4357/acf12e
Giuseppe Arrò, Francesco Pucci, Francesco Califano, Maria Elena Innocenti, Giovanni Lapenta
Abstract Magnetic holes (MHs) are coherent structures associated with strong magnetic field depressions in magnetized plasmas. They are observed in many astrophysical environments at a wide range of scales, but their origin is still under debate. In this work, we investigate the formation of subion scale MHs using a fully kinetic 2D simulation of plasma turbulence initialized with parameters typical of the Earth’s magnetosheath. Our analysis shows that the turbulence is capable of generating subion scale MHs from large scale fluctuations via the following mechanism: first, the nonlinear large scale dynamics spontaneously leads to the development of thin and elongated electron velocity shears; these structures then become unstable to the electron Kelvin–Helmholtz instability and break up into small scale electron vortices; the electric current carried by these vortices locally reduces the magnetic field, inducing the formation of subion scale MHs. The MHs thus produced exhibit features consistent with satellite observations and with previous numerical studies. We finally discuss the kinetic properties of the observed subion scale MHs, showing that they are characterized by complex non-Maxwellian electron velocity distributions exhibiting anisotropic and agyrotropic features.
{"title":"Generation of Subion Scale Magnetic Holes from Electron Shear Flow Instabilities in Plasma Turbulence","authors":"Giuseppe Arrò, Francesco Pucci, Francesco Califano, Maria Elena Innocenti, Giovanni Lapenta","doi":"10.3847/1538-4357/acf12e","DOIUrl":"https://doi.org/10.3847/1538-4357/acf12e","url":null,"abstract":"Abstract Magnetic holes (MHs) are coherent structures associated with strong magnetic field depressions in magnetized plasmas. They are observed in many astrophysical environments at a wide range of scales, but their origin is still under debate. In this work, we investigate the formation of subion scale MHs using a fully kinetic 2D simulation of plasma turbulence initialized with parameters typical of the Earth’s magnetosheath. Our analysis shows that the turbulence is capable of generating subion scale MHs from large scale fluctuations via the following mechanism: first, the nonlinear large scale dynamics spontaneously leads to the development of thin and elongated electron velocity shears; these structures then become unstable to the electron Kelvin–Helmholtz instability and break up into small scale electron vortices; the electric current carried by these vortices locally reduces the magnetic field, inducing the formation of subion scale MHs. The MHs thus produced exhibit features consistent with satellite observations and with previous numerical studies. We finally discuss the kinetic properties of the observed subion scale MHs, showing that they are characterized by complex non-Maxwellian electron velocity distributions exhibiting anisotropic and agyrotropic features.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"12 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135510390","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}
Abstract The plateau phase in radio afterglows has been observed in very few gamma-ray bursts (GRBs), and in this paper, 27 radio light curves with plateau phases were acquired from the published literature. We obtain the related parameters of the radio plateau, such as temporal indexes during the plateau phase ( α 1 and α 2 ), break time ( T b,z ), and the corresponding radio flux ( F b ). The two-parameter Dainotti relation between the break time of the plateau and the corresponding break luminosity ( L b,z ) in the radio band is Lb,z∝Tb,z−1.20±0.24 . Including the isotropic energy E γ ,iso and peak energy E p,i , the three-parameter correlations for the radio plateaus are written as Lb,z∝Tb,z−1.01±0.24Eγ,iso0.18±0.09 and Lb,z∝Tb,z−1.18±0.27
射电余辉的平台相位在少数伽玛暴(GRBs)中观测到，本文从已发表的文献中获得了27条具有平台相位的射电光曲线。我们得到了平台期的时间指标(α 1和α 2)、中断时间(tb,z)和相应的无线电通量(F b)等相关参数。平台的破裂时间与相应的无线电波段的破裂光度(lb,z)之间的双参数Dainotti关系为lb,z∝tbz,z−1.20±0.24。包括各向同性能量E γ、iso和峰值能量E p、i在内，射电高原的三参数相关性分别为lb, z∝T b, z−1.01±0.24 E γ，iso 0.18±0.09和lb, z∝T b, z−1.18±0.27 E p,i 0.05±0.28。这种相关性与x射线和光学平台的相关性不太一致，这意味着射电平台可能具有不同的物理机制。穿过观测波段的典型频率可能是导致射电余辉中断的合理假设。我们将GRB经验光度相关性校准为约束宇宙学参数的标准烛光，发现我们的样品可以很好地约束平坦ΛCDM模型，但对非平坦ΛCDM模型不敏感。将grb与其他探测器(如超新星和CMB)相结合，得到平面ΛCDM模型的宇宙学参数约束为Ω m = 0.297±0.006，非平面ΛCDM模型的宇宙学参数约束为Ω m = 0.283±0.008，Ω Λ = 0.711±0.006。
{"title":"Radio Plateaus in Gamma-Ray Burst Afterglows and Their Application in Cosmology","authors":"Xiao Tian, Jia-Lun Li, Shuang-Xi Yi, Yu-Peng Yang, Jian-Ping Hu, Yan-Kun Qu, Fa-Yin Wang","doi":"10.3847/1538-4357/acfed8","DOIUrl":"https://doi.org/10.3847/1538-4357/acfed8","url":null,"abstract":"Abstract The plateau phase in radio afterglows has been observed in very few gamma-ray bursts (GRBs), and in this paper, 27 radio light curves with plateau phases were acquired from the published literature. We obtain the related parameters of the radio plateau, such as temporal indexes during the plateau phase ( α 1 and α 2 ), break time ( T b,z ), and the corresponding radio flux ( F b ). The two-parameter Dainotti relation between the break time of the plateau and the corresponding break luminosity ( L b,z ) in the radio band is <?CDATA ${L}_{{rm{b}},{rm{z}}}propto {T}_{{rm{b}},{rm{z}}}^{-1.20pm 0.24}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant=\"normal\">b</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant=\"normal\">z</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∝</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant=\"normal\">b</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant=\"normal\">z</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.20</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.24</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> . Including the isotropic energy E γ ,iso and peak energy E p,i , the three-parameter correlations for the radio plateaus are written as <?CDATA ${L}_{{rm{b}},{rm{z}}}propto {T}_{{rm{b}},{rm{z}}}^{-1.01pm 0.24}{E}_{gamma ,mathrm{iso}}^{0.18pm 0.09}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant=\"normal\">b</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant=\"normal\">z</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∝</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant=\"normal\">b</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant=\"normal\">z</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.01</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.24</mml:mn> </mml:mrow> </mml:msubsup> <mml:msubsup> <mml:mrow> <mml:mi>E</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>γ</mml:mi> <mml:mo>,</mml:mo> <mml:mi>iso</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0.18</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.09</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> and <?CDATA ${L}_{{rm{b}},{rm{z}}}propto {T}_{{rm{b}},{rm{z}}}^{-1.18pm 0.27}{E}_{{rm{p}},{rm{i}}}^{0.05pm 0.28}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant=\"normal\">b</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant=\"normal\">z</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∝</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant=\"normal\">b</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant=\"normal\">z</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.18</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.27</mml:mn> </mml:mrow> </mml:msubsup> <mml:msubsup> ","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"28 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135764440","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 : 2023-11-01DOI: 10.3847/1538-4357/acfc42
Qing C. Shui, S. Zhang, Shuang N. Zhang, Yu P. Chen, Ling D. Kong, Peng J. Wang, Jing Q. Peng, L. Ji, A. Santangelo, Hong X. Yin, Jin L. Qu, L. Tao, Ming Y. Ge, Y. Huang, L. Zhang, Hong H. Liu, P. Zhang, W. Yu, Z. Chang, J. Li, Wen T. Ye, Pan P. Li, Zhuo L. Yu, Z. Yan
Abstract Although low-frequency quasiperiodic oscillations (LFQPOs) are commonly detected in the X-ray light curves of accreting black hole X-ray binaries, their origin still remains elusive. In this study, we conduct phase-resolved spectroscopy in a broad energy band for LFQPOs in MAXI J1820+070 during its 2018 outburst, utilizing Insight-HXMT observations. By employing the Hilbert–Huang transform method, we extract the intrinsic quasiperiodic oscillation (QPO) variability, and obtain the corresponding instantaneous amplitude, phase, and frequency functions for each data point. With well-defined phases, we construct QPO waveforms and phase-resolved spectra. By comparing the phase-folded waveform with that obtained from the Fourier method, we find that phase folding on the phase of the QPO fundamental frequency leads to a slight reduction in the contribution of the harmonic component. This suggests that the phase difference between QPO harmonics exhibits time variability. Phase-resolved spectral analysis reveals strong concurrent modulations of the spectral index and flux across the bright hard state. The modulation of the spectral index could potentially be explained by both the corona and jet precession models, with the latter requiring efficient acceleration within the jet. Furthermore, significant modulations in the reflection fraction are detected exclusively during the later stages of the bright hard state. These findings provide support for the geometric origin of LFQPOs and offer valuable insights into the evolution of the accretion geometry during the outburst in MAXI J1820+070.
{"title":"A Phase-resolved View of the Low-frequency Quasiperiodic Oscillations from the Black Hole Binary MAXI J1820+070","authors":"Qing C. Shui, S. Zhang, Shuang N. Zhang, Yu P. Chen, Ling D. Kong, Peng J. Wang, Jing Q. Peng, L. Ji, A. Santangelo, Hong X. Yin, Jin L. Qu, L. Tao, Ming Y. Ge, Y. Huang, L. Zhang, Hong H. Liu, P. Zhang, W. Yu, Z. Chang, J. Li, Wen T. Ye, Pan P. Li, Zhuo L. Yu, Z. Yan","doi":"10.3847/1538-4357/acfc42","DOIUrl":"https://doi.org/10.3847/1538-4357/acfc42","url":null,"abstract":"Abstract Although low-frequency quasiperiodic oscillations (LFQPOs) are commonly detected in the X-ray light curves of accreting black hole X-ray binaries, their origin still remains elusive. In this study, we conduct phase-resolved spectroscopy in a broad energy band for LFQPOs in MAXI J1820+070 during its 2018 outburst, utilizing Insight-HXMT observations. By employing the Hilbert–Huang transform method, we extract the intrinsic quasiperiodic oscillation (QPO) variability, and obtain the corresponding instantaneous amplitude, phase, and frequency functions for each data point. With well-defined phases, we construct QPO waveforms and phase-resolved spectra. By comparing the phase-folded waveform with that obtained from the Fourier method, we find that phase folding on the phase of the QPO fundamental frequency leads to a slight reduction in the contribution of the harmonic component. This suggests that the phase difference between QPO harmonics exhibits time variability. Phase-resolved spectral analysis reveals strong concurrent modulations of the spectral index and flux across the bright hard state. The modulation of the spectral index could potentially be explained by both the corona and jet precession models, with the latter requiring efficient acceleration within the jet. Furthermore, significant modulations in the reflection fraction are detected exclusively during the later stages of the bright hard state. These findings provide support for the geometric origin of LFQPOs and offer valuable insights into the evolution of the accretion geometry during the outburst in MAXI J1820+070.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"32 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135372012","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 : 2023-11-01DOI: 10.3847/1538-4357/ad0548
Peter R. Young
Abstract New reference wavelengths for atomic transitions of Mg vii and Si vii in the 272–281 Å wavelength range are derived using measurements from the Extreme-ultraviolet Imaging Spectrometer (EIS) on board the Hinode spacecraft. Mg vii and Si vii are important ions for measuring plasma properties in the solar transition region at around 0.6 MK. The six Si vii wavelengths are 13–21 mÅ and 7–11 mÅ longer than the values in the NIST Atomic Spectra Database (ASD) and the compilations of B. Edlén, respectively. The four Mg vii wavelengths are shorter than the values in the ASD by 8–12 mÅ but show reasonable agreement with the Edlén values. The new wavelengths will lead to more accurate Doppler shift measurements from the EIS instrument and will be valuable for spectral disambiguation modeling for the upcoming Multi-Slit Solar Explorer mission.
{"title":"Updated Reference Wavelengths for Si vii and Mg vii Lines in the 272–281 Å Range","authors":"Peter R. Young","doi":"10.3847/1538-4357/ad0548","DOIUrl":"https://doi.org/10.3847/1538-4357/ad0548","url":null,"abstract":"Abstract New reference wavelengths for atomic transitions of Mg vii and Si vii in the 272–281 Å wavelength range are derived using measurements from the Extreme-ultraviolet Imaging Spectrometer (EIS) on board the Hinode spacecraft. Mg vii and Si vii are important ions for measuring plasma properties in the solar transition region at around 0.6 MK. The six Si vii wavelengths are 13–21 mÅ and 7–11 mÅ longer than the values in the NIST Atomic Spectra Database (ASD) and the compilations of B. Edlén, respectively. The four Mg vii wavelengths are shorter than the values in the ASD by 8–12 mÅ but show reasonable agreement with the Edlén values. The new wavelengths will lead to more accurate Doppler shift measurements from the EIS instrument and will be valuable for spectral disambiguation modeling for the upcoming Multi-Slit Solar Explorer mission.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"31 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135613998","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}
Abstract The kinematics of shocks, ejecta knots, and the compact remnant of a supernova remnant give insights into the nature of the progenitor and the surrounding environment. We report on a measurement of the proper motion of X-ray knots and rims of the magnetar-hosting supernova remnant RCW 103. Chandra data obtained in three epochs, 1999, 2010, and 2016, are used. We find a global deceleration of 12 knots and rims in both northern and southern regions within the last ∼24 yr, even though the age of the remnant is thought to be greater than 2 kyr. Some of them even changed their directions of motion from outward (∼1000 km s −1 ) to inward (∼−2000 km s −1 ). Our findings can be explained by a collision with a high-density medium at both the northern and southern edges of the remnant, although the remnant may still be expanding in the windblown cavity. The proper motion of the associated magnetar 1E 161348−5055 is possibly detected with a velocity of ≈500 km s −1 .
激波、抛射结和超新星遗迹的致密残余物的运动学使我们能够深入了解其祖先和周围环境的性质。我们报告了磁宿主超新星遗迹rcw103的x射线节和边缘的固有运动的测量。钱德拉在1999年、2010年和2016年三个时期获得的数据被使用。我们发现，在过去的~ 24年里，北部和南部地区的全球减速速度为12节和边缘，尽管残余物的年龄被认为大于2凯尔。其中一些甚至改变了它们的运动方向，从向外(~ 1000 km s−1)到向内(~ 2000 km s−1)。我们的发现可以用残骸南北边缘高密度介质的碰撞来解释，尽管残骸可能仍在风吹的空洞中膨胀。伴生磁星1E 161348−5055的固有运动可能以≈500 km s−1的速度被探测到。
{"title":"Global Deceleration and Inward Movements of X-Ray Knots and Rims of RCW 103","authors":"Hiromasa Suzuki, Takaaki Tanaka, Tsuyoshi Inoue, Hiroyuki Uchida, Takuto Narita","doi":"10.3847/1538-4357/ad00ae","DOIUrl":"https://doi.org/10.3847/1538-4357/ad00ae","url":null,"abstract":"Abstract The kinematics of shocks, ejecta knots, and the compact remnant of a supernova remnant give insights into the nature of the progenitor and the surrounding environment. We report on a measurement of the proper motion of X-ray knots and rims of the magnetar-hosting supernova remnant RCW 103. Chandra data obtained in three epochs, 1999, 2010, and 2016, are used. We find a global deceleration of 12 knots and rims in both northern and southern regions within the last ∼24 yr, even though the age of the remnant is thought to be greater than 2 kyr. Some of them even changed their directions of motion from outward (∼1000 km s −1 ) to inward (∼−2000 km s −1 ). Our findings can be explained by a collision with a high-density medium at both the northern and southern edges of the remnant, although the remnant may still be expanding in the windblown cavity. The proper motion of the associated magnetar 1E 161348−5055 is possibly detected with a velocity of ≈500 km s −1 .","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"46 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135566496","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 : 2023-11-01DOI: 10.3847/1538-4357/acf9a3
Ze-Nan Liu, Jin-Jun Geng, Yuan-Pei Yang, Wei-Yang Wang, Zi-Gao Dai
Abstract Fast radio bursts (FRBs) are extragalactic radio transients with extremely high brightness temperature, which strongly suggests the presence of coherent emission mechanisms. In this study, we introduce a novel radiation mechanism for FRBs involving coherent Cherenkov radiation (ChR) emitted by bunched particles that may originate within the magnetosphere of a magnetar. We assume that some relativistic particles are emitted from the polar cap of a magnetar and move along magnetic field lines through a charge-separated magnetic plasma, emitting coherent ChR along their trajectory. The crucial condition for ChR to occur is that the refractive index of the plasma medium, denoted as n r , must satisfy the condition nr2>1 . We conduct comprehensive calculations to determine various characteristics of ChR, including its characteristic frequency, emission power, required parallel electric field, and coherence factor. Notably, our proposed bunched coherent ChR mechanism has the remarkable advantage of generating a narrower-band spectrum. Furthermore, a frequency downward-drifting pattern and ∼100% linearly polarized emission can be predicted within the framework of this emission mechanism.
快速射电暴(FRBs)是一种具有极高亮度温度的河外射电瞬变现象，强烈表明存在相干发射机制。在这项研究中，我们引入了一种新的快速射电暴辐射机制，涉及由可能起源于磁星磁层内的束状粒子发射的相干切伦科夫辐射(ChR)。我们假设一些相对论性粒子从磁星的极帽发射出来，沿着磁力线穿过电荷分离的磁等离子体，沿着它们的轨迹发射出相干的ChR。ChR发生的关键条件是等离子体介质的折射率，记为n r，必须满足条件n r 2 >1。我们进行了综合计算，确定了ChR的各种特性，包括其特征频率、发射功率、所需并联电场和相干系数。值得注意的是，我们提出的聚束相干ChR机制具有产生窄带频谱的显著优势。此外，在这种发射机制的框架内，可以预测频率向下漂移模式和~ 100%线极化发射。
{"title":"Coherent Cherenkov Radiation by Bunches in Fast Radio Bursts","authors":"Ze-Nan Liu, Jin-Jun Geng, Yuan-Pei Yang, Wei-Yang Wang, Zi-Gao Dai","doi":"10.3847/1538-4357/acf9a3","DOIUrl":"https://doi.org/10.3847/1538-4357/acf9a3","url":null,"abstract":"Abstract Fast radio bursts (FRBs) are extragalactic radio transients with extremely high brightness temperature, which strongly suggests the presence of coherent emission mechanisms. In this study, we introduce a novel radiation mechanism for FRBs involving coherent Cherenkov radiation (ChR) emitted by bunched particles that may originate within the magnetosphere of a magnetar. We assume that some relativistic particles are emitted from the polar cap of a magnetar and move along magnetic field lines through a charge-separated magnetic plasma, emitting coherent ChR along their trajectory. The crucial condition for ChR to occur is that the refractive index of the plasma medium, denoted as n r , must satisfy the condition <?CDATA ${n}_{r}^{2}gt 1$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msubsup> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>r</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>></mml:mo> <mml:mn>1</mml:mn> </mml:math> . We conduct comprehensive calculations to determine various characteristics of ChR, including its characteristic frequency, emission power, required parallel electric field, and coherence factor. Notably, our proposed bunched coherent ChR mechanism has the remarkable advantage of generating a narrower-band spectrum. Furthermore, a frequency downward-drifting pattern and ∼100% linearly polarized emission can be predicted within the framework of this emission mechanism.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"137 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135566304","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 : 2023-11-01DOI: 10.3847/1538-4357/acfd30
Jongho Park, Keiichi Asada, Do-Young Byun
Abstract We present a new method of time-dependent instrumental polarization calibration for very long baseline interferometry (VLBI). This method has been implemented in the recently developed polarization calibration pipeline GPCAL. Instrumental polarization, also known as polarimetric leakage, is a direction-dependent effect, and it is not constant across the beam of a telescope. Antenna pointing model accuracy is usually dependent on time, resulting in off-axis polarimetric leakages that can vary with time. The method is designed to correct for the off-axis leakages with large amplitudes that can severely degrade linear polarization images. Using synthetic data generated based on real Very Long Baseline Array (VLBA) data observed at 43 GHz, we evaluate the performance of the method. It was able to reproduce the off-axis leakages assumed in the synthetic data, particularly those with large amplitudes. The method has been applied to two sets of real VLBA data, and the derived off-axis leakages show very similar trends over time for pairs of nearby sources. Furthermore, the amplitudes of the off-axis leakages are strongly correlated with the antenna gain correction factors. The results demonstrate that the method is capable of correcting for the off-axis leakages present in VLBI data. By calibrating time-dependent instrumental polarization, the rms noise levels of the updated linear polarization images have been significantly reduced. The method is expected to substantially enhance the quality of linear polarization images obtained from existing and future VLBI observations.
{"title":"Calibrating VLBI Polarization Data Using GPCAL. II. Time-dependent Calibration","authors":"Jongho Park, Keiichi Asada, Do-Young Byun","doi":"10.3847/1538-4357/acfd30","DOIUrl":"https://doi.org/10.3847/1538-4357/acfd30","url":null,"abstract":"Abstract We present a new method of time-dependent instrumental polarization calibration for very long baseline interferometry (VLBI). This method has been implemented in the recently developed polarization calibration pipeline GPCAL. Instrumental polarization, also known as polarimetric leakage, is a direction-dependent effect, and it is not constant across the beam of a telescope. Antenna pointing model accuracy is usually dependent on time, resulting in off-axis polarimetric leakages that can vary with time. The method is designed to correct for the off-axis leakages with large amplitudes that can severely degrade linear polarization images. Using synthetic data generated based on real Very Long Baseline Array (VLBA) data observed at 43 GHz, we evaluate the performance of the method. It was able to reproduce the off-axis leakages assumed in the synthetic data, particularly those with large amplitudes. The method has been applied to two sets of real VLBA data, and the derived off-axis leakages show very similar trends over time for pairs of nearby sources. Furthermore, the amplitudes of the off-axis leakages are strongly correlated with the antenna gain correction factors. The results demonstrate that the method is capable of correcting for the off-axis leakages present in VLBI data. By calibrating time-dependent instrumental polarization, the rms noise levels of the updated linear polarization images have been significantly reduced. The method is expected to substantially enhance the quality of linear polarization images obtained from existing and future VLBI observations.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"49 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135566705","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 : 2023-11-01DOI: 10.3847/1538-4357/ad003a
Travis J. Thieme, Shih-Ping Lai, Nagayoshi Ohashi, John J. Tobin, Jes K. Jørgensen, Jinshi Sai (Insa Choi), Yusuke Aso, Jonathan P. Williams, Yoshihide Yamato, Yuri Aikawa, Itziar de Gregorio-Monsalvo, Ilseung Han, Woojin Kwon, Chang Won Lee, Jeong-Eun Lee, Zhi-Yun Li, Zhe-Yu Daniel Lin, Leslie W. Looney, Suchitra Narayanan, Nguyen Thi Phuong, Adele L. Plunkett, Alejandro Santamaría-Miranda, Rajeeb Sharma, Shigehisa Takakuwa, Hsi-Wei Yen
Abstract Protostellar disks are an ubiquitous part of the star formation process and the future sites of planet formation. As part of the Early Planet Formation in Embedded Disks large program, we present high angular resolution dust continuum (∼40 mas) and molecular line (∼150 mas) observations of the Class 0 protostar IRAS 15398–3359. The dust continuum is small, compact, and centrally peaked, while more extended dust structures are found in the outflow directions. We perform a 2D Gaussian fitting and find the deconvolved size and 2 σ radius of the dust disk to be 4.5 × 2.8 au and 3.8 au, respectively. We estimate the gas+dust disk mass assuming optically thin continuum emission to be 0.6 M J –1.8 M J , indicating a very low mass disk. The CO isotopologues trace components of the outflows and inner envelope, while SO traces a compact, rotating disk-like component. Using several rotation curve fittings on the position–velocity diagram of the SO emission, the lower limits of the protostellar mass and gas disk radius are 0.022 M ⊙ and 31.2 au, respectively, from our Modified 2 single power-law fitting. A conservative upper limit of the protostellar mass is inferred to be 0.1 M ⊙ . The protostellar mass accretion rate and the specific angular momentum at the protostellar disk edge are found to be in the range of (1.3–6.1) × 10 −6 M ⊙ yr −1 and (1.2–3.8) × 10 −4 km s −1 pc, respectively, with an age estimated between 0.4 × 10 4 yr and 7.5 × 10 4 yr. At this young age with no clear substructures in the disk, planet formation would likely not yet have started. This study highlights the importance of high-resolution observations and systematic fitting procedures when deriving dynamical properties of deeply embedded Class 0 protostars.
原恒星盘是恒星形成过程中无处不在的一部分，也是未来行星形成的地点。作为嵌入式圆盘早期行星形成大型项目的一部分，我们展示了0级原恒星IRAS 15398-3359的高角分辨率尘埃连续体(~ 40 mas)和分子线(~ 150 mas)观测结果。尘埃连续体小而致密，中心呈尖峰状，而在出流方向发现了更多的扩展尘埃结构。我们进行了二维高斯拟合，发现尘埃盘的反卷积尺寸和2 σ半径分别为4.5 × 2.8 au和3.8 au。假设光学薄连续辐射为0.6 M J -1.8 M J，我们估计气体+尘埃盘的质量是非常低的。CO同位素示踪组分为流出液和内包壳，而SO示踪组分为致密的旋转圆盘状组分。通过对SO发射位置-速度图的几个旋转曲线拟合，得到原恒星质量和气体盘半径的下限分别为0.022 M⊙和31.2 au。原恒星质量的保守上限被推断为0.1 M⊙。原恒星质量吸积率和原恒星盘边缘的特定角动量分别在(1.3-6.1)× 10−6 M⊙yr−1和(1.2-3.8)× 10−4 km s−1 pc的范围内，年龄估计在0.4 × 10.4年和7.5 × 10.4年之间。在这个年轻的年龄，盘内没有明确的亚结构，行星的形成可能还没有开始。这项研究强调了高分辨率观测和系统拟合程序在推导深嵌0级原恒星动力学特性时的重要性。
{"title":"Early Planet Formation in Embedded Disks (eDisk). VIII. A Small Protostellar Disk around the Extremely Low Mass and Young Class 0 Protostar IRAS 15398–3359","authors":"Travis J. Thieme, Shih-Ping Lai, Nagayoshi Ohashi, John J. Tobin, Jes K. Jørgensen, Jinshi Sai (Insa Choi), Yusuke Aso, Jonathan P. Williams, Yoshihide Yamato, Yuri Aikawa, Itziar de Gregorio-Monsalvo, Ilseung Han, Woojin Kwon, Chang Won Lee, Jeong-Eun Lee, Zhi-Yun Li, Zhe-Yu Daniel Lin, Leslie W. Looney, Suchitra Narayanan, Nguyen Thi Phuong, Adele L. Plunkett, Alejandro Santamaría-Miranda, Rajeeb Sharma, Shigehisa Takakuwa, Hsi-Wei Yen","doi":"10.3847/1538-4357/ad003a","DOIUrl":"https://doi.org/10.3847/1538-4357/ad003a","url":null,"abstract":"Abstract Protostellar disks are an ubiquitous part of the star formation process and the future sites of planet formation. As part of the Early Planet Formation in Embedded Disks large program, we present high angular resolution dust continuum (∼40 mas) and molecular line (∼150 mas) observations of the Class 0 protostar IRAS 15398–3359. The dust continuum is small, compact, and centrally peaked, while more extended dust structures are found in the outflow directions. We perform a 2D Gaussian fitting and find the deconvolved size and 2 σ radius of the dust disk to be 4.5 × 2.8 au and 3.8 au, respectively. We estimate the gas+dust disk mass assuming optically thin continuum emission to be 0.6 M J –1.8 M J , indicating a very low mass disk. The CO isotopologues trace components of the outflows and inner envelope, while SO traces a compact, rotating disk-like component. Using several rotation curve fittings on the position–velocity diagram of the SO emission, the lower limits of the protostellar mass and gas disk radius are 0.022 M ⊙ and 31.2 au, respectively, from our Modified 2 single power-law fitting. A conservative upper limit of the protostellar mass is inferred to be 0.1 M ⊙ . The protostellar mass accretion rate and the specific angular momentum at the protostellar disk edge are found to be in the range of (1.3–6.1) × 10 −6 M ⊙ yr −1 and (1.2–3.8) × 10 −4 km s −1 pc, respectively, with an age estimated between 0.4 × 10 4 yr and 7.5 × 10 4 yr. At this young age with no clear substructures in the disk, planet formation would likely not yet have started. This study highlights the importance of high-resolution observations and systematic fitting procedures when deriving dynamical properties of deeply embedded Class 0 protostars.","PeriodicalId":50735,"journal":{"name":"Astrophysical Journal","volume":"14 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135714564","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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