Galaxies最新文献_第3页

Central Engine and Spectral Energy Distribution Properties of High Redshift Gamma Ray Blazars 高红移伽马射线闪电星的中心引擎和光谱能量分布特性

IF 2.5

Galaxies Pub Date : 2024-03-11 DOI: 10.3390/galaxies12020010

A. Tolamatti, Krishna Kumar Singh, Kuldeep Kumar Yadav

引用次数: 0

Significance of Fabry-Perot Cavities for Space Gravitational Wave Antenna DECIGO 法布里-珀罗空腔对空间引力波天线 DECIGO 的意义

IF 2.5

Galaxies Pub Date : 2024-03-04 DOI: 10.3390/galaxies12020013

K. Tsuji, Tomohiro Ishikawa, Kurumi Umemura, Yuki Kawasaki, S. Iwaguchi, Ryuma Shimizu, Masaki Ando, Seiji Kawamura

引用次数: 0

Superluminal Motion and Jet Parameters in the Gamma-ray-Emitting Narrow-Line Seyfert 1 Galaxy TXS 1206+549 发射伽马射线的窄线塞弗特1星系TXS 1206+549的超光速运动和射流参数

IF 2.5

Galaxies Pub Date : 2024-02-16 DOI: 10.3390/galaxies12010008

Bettina Koz'ak, Sándor Frey, Krisztina 'Eva Gab'anyi

引用次数: 0

X-ray Polarization from Magnetar Sources 来自磁星源的 X 射线极化

IF 2.5

Galaxies Pub Date : 2024-02-08 DOI: 10.3390/galaxies12010006

Roberto Taverna , Roberto Turolla

{"title":"X-ray Polarization from Magnetar Sources","authors":"Roberto Taverna , Roberto Turolla ","doi":"10.3390/galaxies12010006","DOIUrl":"https://doi.org/10.3390/galaxies12010006","url":null,"abstract":"The launch of the IXPE telescope in late 2021 finally made polarization measurements in the 2–8keV band a reality, more than 40 years after the pioneering observations of the OSO-8 satellite. In the first two years of operations, IXPE targeted more than 60 sources, including four magnetars, neutron stars with magnetic fields in the petaGauss range. In this paper we summarize the IXPE main findings and discuss their implications for the physics of ultra-magnetized neutron stars. Polarimetric observations confirmed theoretical predictions, according to which X-ray radiation from magnetar sources is highly polarized, up to ≈80%, the highest value detected so far. This provides an independent confirmation that magnetars are indeed endowed with a super-strong magnetic field and that the twisted magnetosphere scenario is the most likely explanation for their soft X-ray emission. Polarization measurements allowed us to probe the physical conditions of the star’s outermost layers, showing that the cooler surface regions are in a condensed state, with no atmosphere on top. Although no smoking-gun of vacuum QED effects was found, the phase-dependent behavior of the polarization angle strongly hints that vacuum birefringence is indeed at work in magnetar magnetospheres.","PeriodicalId":37570,"journal":{"name":"Galaxies","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139793839","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

X-ray Polarization from Magnetar Sources 来自磁星源的 X 射线极化

IF 2.5

Galaxies Pub Date : 2024-02-08 DOI: 10.3390/galaxies12010006

Roberto Taverna , Roberto Turolla

{"title":"X-ray Polarization from Magnetar Sources","authors":"Roberto Taverna , Roberto Turolla ","doi":"10.3390/galaxies12010006","DOIUrl":"https://doi.org/10.3390/galaxies12010006","url":null,"abstract":"The launch of the IXPE telescope in late 2021 finally made polarization measurements in the 2–8keV band a reality, more than 40 years after the pioneering observations of the OSO-8 satellite. In the first two years of operations, IXPE targeted more than 60 sources, including four magnetars, neutron stars with magnetic fields in the petaGauss range. In this paper we summarize the IXPE main findings and discuss their implications for the physics of ultra-magnetized neutron stars. Polarimetric observations confirmed theoretical predictions, according to which X-ray radiation from magnetar sources is highly polarized, up to ≈80%, the highest value detected so far. This provides an independent confirmation that magnetars are indeed endowed with a super-strong magnetic field and that the twisted magnetosphere scenario is the most likely explanation for their soft X-ray emission. Polarization measurements allowed us to probe the physical conditions of the star’s outermost layers, showing that the cooler surface regions are in a condensed state, with no atmosphere on top. Although no smoking-gun of vacuum QED effects was found, the phase-dependent behavior of the polarization angle strongly hints that vacuum birefringence is indeed at work in magnetar magnetospheres.","PeriodicalId":37570,"journal":{"name":"Galaxies","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139853692","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

Parameter Inference of a State-of-the-Art Physical Afterglow Model for GRB 190114C GRB 190114C 最新物理余辉模型的参数推断

IF 2.5

Galaxies Pub Date : 2024-02-07 DOI: 10.3390/galaxies12010005

Enrico Rinaldi, N. Fraija, M. Dainotti

{"title":"Parameter Inference of a State-of-the-Art Physical Afterglow Model for GRB 190114C","authors":"Enrico Rinaldi, N. Fraija, M. Dainotti","doi":"10.3390/galaxies12010005","DOIUrl":"https://doi.org/10.3390/galaxies12010005","url":null,"abstract":"A state-of-the-art semi-analytic gamma-ray burst (GRB) afterglow model with synchrotron self-Compton (SSC) emission has been applied for the first time for parameter inference using real GRB data. We analyzed the famous GRB 190114C as a case study. GRB 190114C, characterized by its long duration and high luminosity, was observed by many ground-based and orbiting telescopes spanning a wide range of electromagnetic wavelengths, from radio to GeV gamma rays. We used two advanced algorithms for inference: a nested sampling algorithm called UltraNest and an MCMC algorithm emcee. Evoking the standard afterglow model, the inference result and the best-fit values lead to an initial bulk Lorentz factor (a rough estimate of Γ=526), which aligns with the values often seen in GRBs identified by the Fermi-LAT instrument. Similarly to the best-fit values of other studies in the literature, the derived values of microphysical parameters, the circumburst density, and the kinetic efficiency are consistent with those found after modeling the multi-wavelength observations in GRB 190114C. We show that the SSC from the forward-shock region can only describe the highest-energy photons above a few GeVs.","PeriodicalId":37570,"journal":{"name":"Galaxies","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139856192","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

Parameter Inference of a State-of-the-Art Physical Afterglow Model for GRB 190114C GRB 190114C 最新物理余辉模型的参数推断

IF 2.5

Galaxies Pub Date : 2024-02-07 DOI: 10.3390/galaxies12010005

Enrico Rinaldi, N. Fraija, M. Dainotti

{"title":"Parameter Inference of a State-of-the-Art Physical Afterglow Model for GRB 190114C","authors":"Enrico Rinaldi, N. Fraija, M. Dainotti","doi":"10.3390/galaxies12010005","DOIUrl":"https://doi.org/10.3390/galaxies12010005","url":null,"abstract":"A state-of-the-art semi-analytic gamma-ray burst (GRB) afterglow model with synchrotron self-Compton (SSC) emission has been applied for the first time for parameter inference using real GRB data. We analyzed the famous GRB 190114C as a case study. GRB 190114C, characterized by its long duration and high luminosity, was observed by many ground-based and orbiting telescopes spanning a wide range of electromagnetic wavelengths, from radio to GeV gamma rays. We used two advanced algorithms for inference: a nested sampling algorithm called UltraNest and an MCMC algorithm emcee. Evoking the standard afterglow model, the inference result and the best-fit values lead to an initial bulk Lorentz factor (a rough estimate of Γ=526), which aligns with the values often seen in GRBs identified by the Fermi-LAT instrument. Similarly to the best-fit values of other studies in the literature, the derived values of microphysical parameters, the circumburst density, and the kinetic efficiency are consistent with those found after modeling the multi-wavelength observations in GRB 190114C. We show that the SSC from the forward-shock region can only describe the highest-energy photons above a few GeVs.","PeriodicalId":37570,"journal":{"name":"Galaxies","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139796135","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

Spin Evolution of Neutron Stars 中子星的自旋演变

IF 2.5

Galaxies Pub Date : 2024-02-06 DOI: 10.3390/galaxies12010007

Pavel Abolmasov, Anton Biryukov, Sergei B. Popov

引用次数: 0

Spin Evolution of Neutron Stars 中子星的自旋演变

IF 2.5

Galaxies Pub Date : 2024-02-06 DOI: 10.3390/galaxies12010007

Pavel Abolmasov, Anton Biryukov, Sergei B. Popov

引用次数: 0

The Scavenger Hunt for Quasar Samples to Be Used as Cosmological Tools 寻找类星体样本作为宇宙学工具的寻宝游戏

IF 2.5

Galaxies Pub Date : 2024-01-22 DOI: 10.3390/galaxies12010004

M. Dainotti, G. Bargiacchi, A. Lenart, S. Capozziello

引用次数: 0