Pub Date : 2024-03-11DOI: 10.3390/galaxies12020010
A. Tolamatti, Krishna Kumar Singh, Kuldeep Kumar Yadav
We report on the properties of central engines in the γ-ray blazars located at high redshifts beyond z > 0.4, where the extra-galactic background light (EBL) starts affecting their γ-ray spectra. The physical engine that provides power to the blazars of very high bolometric luminosity is assumed to be a highly collimated jet of matter moving relativistically away from the supermassive black hole (SMBH), located in the central region of the host galaxy, in a direction aligned toward the Earth. Due to their peculiar geometry and special physical conditions, blazars at redshifts beyond z > 0.4 are bright enough to be detected in the γ-ray energy band. In this work, we investigate the physical properties of high-z γ-ray blazars detected by the Large Area Telescope (LAT) on board the Fermi satellite. We also study the properties of their emission regions and the central engines and discuss cosmological and astrophysical implications.
我们报告了位于 z > 0.4 以上高红移位置的 γ 射线类炽星的中心引擎的特性，银河系外背景光（EBL）开始影响它们的 γ 射线光谱。为极高测光度的类星体提供能量的物理引擎被假定为一个高度准直的物质射流，它从位于宿主星系中心区域的超大质量黑洞（SMBH）向地球方向作相对论运动。由于其奇特的几何形状和特殊的物理条件，红移超过 z > 0.4 的类星体亮度足以在 γ 射线能段中被探测到。在这项工作中，我们研究了费米卫星上的大面积望远镜（LAT）探测到的高 z γ 射线闪烁星的物理特性。我们还研究了它们的发射区和中心引擎的性质，并讨论了它们对宇宙学和天体物理学的影响。
{"title":"Central Engine and Spectral Energy Distribution Properties of High Redshift Gamma Ray Blazars","authors":"A. Tolamatti, Krishna Kumar Singh, Kuldeep Kumar Yadav","doi":"10.3390/galaxies12020010","DOIUrl":"https://doi.org/10.3390/galaxies12020010","url":null,"abstract":"We report on the properties of central engines in the γ-ray blazars located at high redshifts beyond z > 0.4, where the extra-galactic background light (EBL) starts affecting their γ-ray spectra. The physical engine that provides power to the blazars of very high bolometric luminosity is assumed to be a highly collimated jet of matter moving relativistically away from the supermassive black hole (SMBH), located in the central region of the host galaxy, in a direction aligned toward the Earth. Due to their peculiar geometry and special physical conditions, blazars at redshifts beyond z > 0.4 are bright enough to be detected in the γ-ray energy band. In this work, we investigate the physical properties of high-z γ-ray blazars detected by the Large Area Telescope (LAT) on board the Fermi satellite. We also study the properties of their emission regions and the central engines and discuss cosmological and astrophysical implications.","PeriodicalId":37570,"journal":{"name":"Galaxies","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140253114","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 : 2024-03-04DOI: 10.3390/galaxies12020013
K. Tsuji, Tomohiro Ishikawa, Kurumi Umemura, Yuki Kawasaki, S. Iwaguchi, Ryuma Shimizu, Masaki Ando, Seiji Kawamura
DECIGO is a a future Japanese project for the detection of gravitational waves in space. To conduct various scientific missions, including the verification of cosmic inflation through the detection of primordial gravitational waves as the main objective, DECIGO is designed to have high sensitivity in the frequency band from 0.1 to 10 Hz, with arms of length 1000 km. Furthermore, the use of the Fabry-Perotcavity in these arms has been established for the DECIGO project. In this paper, we scrutinize the significance of the Fabry-Perot cavity for promoting this project, with a focus on the possibility of observing gravitational waves from cosmic inflation and binary compact star systems as indicators. The results show that using the Fabry-Perot cavity is extremely beneficial for detecting them, and it is anticipated to enable the opening of a new window in gravitational wave astronomy.
{"title":"Significance of Fabry-Perot Cavities for Space Gravitational Wave Antenna DECIGO","authors":"K. Tsuji, Tomohiro Ishikawa, Kurumi Umemura, Yuki Kawasaki, S. Iwaguchi, Ryuma Shimizu, Masaki Ando, Seiji Kawamura","doi":"10.3390/galaxies12020013","DOIUrl":"https://doi.org/10.3390/galaxies12020013","url":null,"abstract":"DECIGO is a a future Japanese project for the detection of gravitational waves in space. To conduct various scientific missions, including the verification of cosmic inflation through the detection of primordial gravitational waves as the main objective, DECIGO is designed to have high sensitivity in the frequency band from 0.1 to 10 Hz, with arms of length 1000 km. Furthermore, the use of the Fabry-Perotcavity in these arms has been established for the DECIGO project. In this paper, we scrutinize the significance of the Fabry-Perot cavity for promoting this project, with a focus on the possibility of observing gravitational waves from cosmic inflation and binary compact star systems as indicators. The results show that using the Fabry-Perot cavity is extremely beneficial for detecting them, and it is anticipated to enable the opening of a new window in gravitational wave astronomy.","PeriodicalId":37570,"journal":{"name":"Galaxies","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140265621","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: 10.3390/galaxies12010008
Bettina Koz'ak, Sándor Frey, Krisztina 'Eva Gab'anyi
Narrow-line Seyfert 1 (NLS1) galaxies are a peculiar subclass of active galactic nuclei (AGN). Among them, TXS 1206+549 belongs to a small group of radio-loud and γ-ray-emitting NLS1 galaxies. We focus on the radio properties of this galaxy by analysing archival, high-resolution, very long baseline interferometry (VLBI) imaging observations taken at 8 GHz frequency in six epochs between 1994 and 2018. Using the milliarcsecond-scale radio structure, we can resolve a core and a jet component whose angular separation increases by (0.055±0.006) mas yr−1. This corresponds to an apparent superluminal jet component motion of (3.5±0.4)c. From the core brightness temperature and the jet component proper motion, we determine the characteristic Doppler-boosting factor, the bulk Lorentz factor, and the jet viewing angle. We find no compelling evidence for a very closely aligned blazar-type jet. The parameters for TXS 1206+549 resemble those of radio-loud quasar jets with a moderate Lorentz factor (Γ≈4) and ϑ≈24∘ inclination to the line of sight.
{"title":"Superluminal Motion and Jet Parameters in the Gamma-ray-Emitting Narrow-Line Seyfert 1 Galaxy TXS 1206+549","authors":"Bettina Koz'ak, Sándor Frey, Krisztina 'Eva Gab'anyi","doi":"10.3390/galaxies12010008","DOIUrl":"https://doi.org/10.3390/galaxies12010008","url":null,"abstract":"Narrow-line Seyfert 1 (NLS1) galaxies are a peculiar subclass of active galactic nuclei (AGN). Among them, TXS 1206+549 belongs to a small group of radio-loud and γ-ray-emitting NLS1 galaxies. We focus on the radio properties of this galaxy by analysing archival, high-resolution, very long baseline interferometry (VLBI) imaging observations taken at 8 GHz frequency in six epochs between 1994 and 2018. Using the milliarcsecond-scale radio structure, we can resolve a core and a jet component whose angular separation increases by (0.055±0.006) mas yr−1. This corresponds to an apparent superluminal jet component motion of (3.5±0.4)c. From the core brightness temperature and the jet component proper motion, we determine the characteristic Doppler-boosting factor, the bulk Lorentz factor, and the jet viewing angle. We find no compelling evidence for a very closely aligned blazar-type jet. The parameters for TXS 1206+549 resemble those of radio-loud quasar jets with a moderate Lorentz factor (Γ≈4) and ϑ≈24∘ inclination to the line of sight.","PeriodicalId":37570,"journal":{"name":"Galaxies","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140454508","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 : 2024-02-08DOI: 10.3390/galaxies12010006
Roberto Taverna , Roberto Turolla
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.
{"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}
Pub Date : 2024-02-08DOI: 10.3390/galaxies12010006
Roberto Taverna , Roberto Turolla
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.
{"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}
Pub Date : 2024-02-07DOI: 10.3390/galaxies12010005
Enrico Rinaldi, N. Fraija, M. Dainotti
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.
利用真实的伽玛射线暴数据，首次应用了最先进的半解析伽玛射线暴（GRB）余辉模型与同步加速器自康普顿（SSC）发射进行参数推断。我们以著名的 GRB 190114C 为案例进行了分析。GRB 190114C 的特点是持续时间长、光度高，许多地面和轨道望远镜都观测到了它，其电磁波长范围很广，从射电到 GeV 伽马射线。我们使用了两种先进的推断算法：一种名为 UltraNest 的嵌套采样算法和一种 MCMC 算法 emcee。根据标准余辉模型，推理结果和最佳拟合值得出了一个初始的大体洛伦兹因子（粗略估计为Γ=526），这与费米-LAT仪器识别的GRB中经常出现的值相一致。与文献中其他研究的最佳拟合值类似，推导出的微物理参数、环流密度和动力学效率值与对 GRB 190114C 进行多波长观测建模后发现的值一致。我们的研究表明，来自前震区的 SSC 只能描述几 GeV 以上的高能光子。
{"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}
Pub Date : 2024-02-07DOI: 10.3390/galaxies12010005
Enrico Rinaldi, N. Fraija, M. Dainotti
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.
利用真实的伽玛射线暴数据，首次应用了最先进的半解析伽玛射线暴（GRB）余辉模型与同步加速器自康普顿（SSC）发射进行参数推断。我们以著名的 GRB 190114C 为案例进行了分析。GRB 190114C 的特点是持续时间长、光度高，许多地面和轨道望远镜都观测到了它，其电磁波长范围很广，从射电到 GeV 伽马射线。我们使用了两种先进的算法进行推断：一种是名为 UltraNest 的嵌套采样算法，另一种是 MCMC 算法 emcee。根据标准余辉模型，推理结果和最佳拟合值得出了一个初始的大体洛伦兹因子（粗略估计为Γ=526），这与费米-LAT仪器识别的GRB中经常出现的值相一致。与文献中其他研究的最佳拟合值类似，推导出的微物理参数、环流密度和动力学效率值与对 GRB 190114C 进行多波长观测建模后发现的值一致。我们的研究表明，来自前震区的 SSC 只能描述几 GeV 以上的高能光子。
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Pub Date : 2024-02-06DOI: 10.3390/galaxies12010007
Pavel Abolmasov, Anton Biryukov, Sergei B. Popov
In this paper we review the basics of magneto-rotational properties of neutron stars focusing on spin-up/spin-down behavior at different evolutionary stages. The main goal is to provide equations for the spin frequency changes in various regimes (radio pulsar, propeller, accretor, etc.). Since presently the spin behavior of neutron stars at all stages remains a subject of many uncertainties, we review different suggestions made over the years in the literature.
{"title":"Spin Evolution of Neutron Stars","authors":"Pavel Abolmasov, Anton Biryukov, Sergei B. Popov","doi":"10.3390/galaxies12010007","DOIUrl":"https://doi.org/10.3390/galaxies12010007","url":null,"abstract":"In this paper we review the basics of magneto-rotational properties of neutron stars focusing on spin-up/spin-down behavior at different evolutionary stages. The main goal is to provide equations for the spin frequency changes in various regimes (radio pulsar, propeller, accretor, etc.). Since presently the spin behavior of neutron stars at all stages remains a subject of many uncertainties, we review different suggestions made over the years in the literature.","PeriodicalId":37570,"journal":{"name":"Galaxies","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139799096","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 : 2024-02-06DOI: 10.3390/galaxies12010007
Pavel Abolmasov, Anton Biryukov, Sergei B. Popov
In this paper we review the basics of magneto-rotational properties of neutron stars focusing on spin-up/spin-down behavior at different evolutionary stages. The main goal is to provide equations for the spin frequency changes in various regimes (radio pulsar, propeller, accretor, etc.). Since presently the spin behavior of neutron stars at all stages remains a subject of many uncertainties, we review different suggestions made over the years in the literature.
{"title":"Spin Evolution of Neutron Stars","authors":"Pavel Abolmasov, Anton Biryukov, Sergei B. Popov","doi":"10.3390/galaxies12010007","DOIUrl":"https://doi.org/10.3390/galaxies12010007","url":null,"abstract":"In this paper we review the basics of magneto-rotational properties of neutron stars focusing on spin-up/spin-down behavior at different evolutionary stages. The main goal is to provide equations for the spin frequency changes in various regimes (radio pulsar, propeller, accretor, etc.). Since presently the spin behavior of neutron stars at all stages remains a subject of many uncertainties, we review different suggestions made over the years in the literature.","PeriodicalId":37570,"journal":{"name":"Galaxies","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139858982","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 : 2024-01-22DOI: 10.3390/galaxies12010004
M. Dainotti, G. Bargiacchi, A. Lenart, S. Capozziello
Although the Λ Cold Dark Matter model is the most accredited cosmological model, information at high redshifts (z) between type Ia supernovae (z=2.26) and the Cosmic Microwave Background (z=1100) is crucial to validate this model further. To this end, we have discovered a sample of 1132 quasars up to z=7.54 exhibiting a reduced intrinsic dispersion of the relation between ultraviolet and X-ray fluxes, δF=0.22 vs. δF=0.29 (24% less), than the original sample. This gold sample, once we correct the luminosities for selection biases and redshift evolution, enables us to determine the matter density parameter ΩM with a precision of 0.09. Unprecedentedly, this quasar sample is the only one that, as a standalone cosmological probe, yields such tight constraints on ΩM while being drawn from the same parent population of the initial sample.
{"title":"The Scavenger Hunt for Quasar Samples to Be Used as Cosmological Tools","authors":"M. Dainotti, G. Bargiacchi, A. Lenart, S. Capozziello","doi":"10.3390/galaxies12010004","DOIUrl":"https://doi.org/10.3390/galaxies12010004","url":null,"abstract":"Although the Λ Cold Dark Matter model is the most accredited cosmological model, information at high redshifts (z) between type Ia supernovae (z=2.26) and the Cosmic Microwave Background (z=1100) is crucial to validate this model further. To this end, we have discovered a sample of 1132 quasars up to z=7.54 exhibiting a reduced intrinsic dispersion of the relation between ultraviolet and X-ray fluxes, δF=0.22 vs. δF=0.29 (24% less), than the original sample. This gold sample, once we correct the luminosities for selection biases and redshift evolution, enables us to determine the matter density parameter ΩM with a precision of 0.09. Unprecedentedly, this quasar sample is the only one that, as a standalone cosmological probe, yields such tight constraints on ΩM while being drawn from the same parent population of the initial sample.","PeriodicalId":37570,"journal":{"name":"Galaxies","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139609449","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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