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Study of Wide-Field-of-View X-ray Observations of the Virgo Cluster Using the Lobster Eye Imager for Astronomy 利用龙虾眼天文成像仪对室女座星团进行宽视场 X 射线观测的研究
IF 2.9 4区 物理与天体物理
Universe Pub Date : 2024-07-17 DOI: 10.3390/universe10070300
Wen-Cheng Feng, Shu-Mei Jia, Hai-Hui Zhao, Heng Yu, Hai-Wu Pan, Cheng-Kui Li, Yu-Lin Cheng, Shan-Shan Weng, Yong Chen, Yuan Liu, Zhi-Xing Ling, Chen Zhang
{"title":"Study of Wide-Field-of-View X-ray Observations of the Virgo Cluster Using the Lobster Eye Imager for Astronomy","authors":"Wen-Cheng Feng, Shu-Mei Jia, Hai-Hui Zhao, Heng Yu, Hai-Wu Pan, Cheng-Kui Li, Yu-Lin Cheng, Shan-Shan Weng, Yong Chen, Yuan Liu, Zhi-Xing Ling, Chen Zhang","doi":"10.3390/universe10070300","DOIUrl":"https://doi.org/10.3390/universe10070300","url":null,"abstract":"The Lobster Eye Imager for Astronomy (LEIA) is the pathfinder of the wide-field X-ray telescope used in the Einstein Probe mission. In this study, we present an image of the Virgo Cluster taken by LEIA in the 0.5–4.5 keV band with an exposure time of ∼17.3 ks in the central region. This extended emission is generally consistent with the results obtained by ROSAT. However, the field is affected by bright point sources due to the instrument’s Point Spread Function (PSF) effect. Through fitting of the LEIA spectrum of the Virgo Cluster, we obtained a temperature of 2.1−0.1+0.3 keV, which is consistent with the XMM-Newton results (∼2.3 keV). Above 1.6 keV, the spectrum is dominated by the X-ray background. In summary, this study validates LEIA’s extended source imaging and spectral resolution capabilities for the first time.","PeriodicalId":48646,"journal":{"name":"Universe","volume":"34 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141721386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
Screened Scalar Fields in the Laboratory and the Solar System 实验室和太阳系中的筛选标量场
IF 2.9 4区 物理与天体物理
Universe Pub Date : 2024-07-15 DOI: 10.3390/universe10070297
Hauke Fischer, Christian Käding, Mario Pitschmann
{"title":"Screened Scalar Fields in the Laboratory and the Solar System","authors":"Hauke Fischer, Christian Käding, Mario Pitschmann","doi":"10.3390/universe10070297","DOIUrl":"https://doi.org/10.3390/universe10070297","url":null,"abstract":"The last few decades have provided abundant evidence for physics beyond the two standard models of particle physics and cosmology. As is now known, the by far largest part of our universe’s matter/energy content lies in the ‘dark’, and consists of dark energy and dark matter. Despite intensive efforts on the experimental as well as the theoretical side, the origins of both are still completely unknown. Screened scalar fields have been hypothesized as potential candidates for dark energy or dark matter. Among these, some of the most prominent models are the chameleon, symmetron, and environment-dependent dilaton. In this article, we present a summary containing the most recent experimental constraints on the parameters of these three models. For this, experimental results have been employed from the qBounce collaboration, neutron interferometry, and Lunar Laser Ranging (LLR), among others. In addition, constraints are forecast for the Casimir and Non-Newtonian force Experiment (Cannex). Combining these results with previous ones, this article collects the most up-to-date constraints on the three considered screened scalar field models.","PeriodicalId":48646,"journal":{"name":"Universe","volume":"52 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141721399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
Thermodynamics of Magnetic Black Holes with Nonlinear Electrodynamics in Extended Phase Space 扩展相空间中具有非线性电动力学的磁性黑洞热力学
IF 2.9 4区 物理与天体物理
Universe Pub Date : 2024-07-13 DOI: 10.3390/universe10070295
Sergey Il’ich Kruglov
{"title":"Thermodynamics of Magnetic Black Holes with Nonlinear Electrodynamics in Extended Phase Space","authors":"Sergey Il’ich Kruglov","doi":"10.3390/universe10070295","DOIUrl":"https://doi.org/10.3390/universe10070295","url":null,"abstract":"We study Einstein’s gravity in AdS space coupled to nonlinear electrodynamics. Thermodynamics in extended phase space of magnetically charged black holes is investigated. We compute the metric and mass functions and their asymptotics, showing that black holes may have one or two horizons. The metric function is regular, f(0)=1, and corrections to the Reissner–Nordström solution are in the order of O(r−3) when the Schwarzschild mass is zero. We prove that the first law of black hole thermodynamics and the generalized Smarr relation hold. The magnetic potential and vacuum polarization conjugated to coupling are computed and depicted. We calculate the Gibbs free energy and the heat capacity showing that first-order and second-order phase transitions take place.","PeriodicalId":48646,"journal":{"name":"Universe","volume":"55 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
Lorentzian Quantum Cosmology from Effective Spin Foams 从有效自旋泡沫看洛伦兹量子宇宙学
IF 2.9 4区 物理与天体物理
Universe Pub Date : 2024-07-13 DOI: 10.3390/universe10070296
Bianca Dittrich, José Padua-Argüelles
{"title":"Lorentzian Quantum Cosmology from Effective Spin Foams","authors":"Bianca Dittrich, José Padua-Argüelles","doi":"10.3390/universe10070296","DOIUrl":"https://doi.org/10.3390/universe10070296","url":null,"abstract":"Effective spin foams provide the most computationally efficient spin foam models yet and are therefore ideally suited for applications, e.g., to quantum cosmology. Here, we provide the first effective spin foam computations of a finite time evolution step in a Lorentzian quantum de Sitter universe. We will consider a setup that computes the no-boundary wave function and a setup describing the transition between two finite scale factors. A key property of spin foams is that they implement discrete spectra for the areas. We therefore study the effects that are induced by the discrete spectra. To perform these computations, we had to identify a technique to deal with highly oscillating and slowly converging or even diverging sums. Here, we illustrate that high-order Shanks transformation works very well and is a promising tool for the evaluation of Lorentzian (gravitational) path integrals and spin foam sums.","PeriodicalId":48646,"journal":{"name":"Universe","volume":"154 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
On the Choice of Variable for Quantization of Conformal GR 关于共形 GR 量子化变量的选择
IF 2.9 4区 物理与天体物理
Universe Pub Date : 2024-07-13 DOI: 10.3390/universe10070294
A. B. Arbuzov, A. A. Nikitenko
{"title":"On the Choice of Variable for Quantization of Conformal GR","authors":"A. B. Arbuzov, A. A. Nikitenko","doi":"10.3390/universe10070294","DOIUrl":"https://doi.org/10.3390/universe10070294","url":null,"abstract":"The possibility of using spin connection components as basic quantization variables of a conformal version of general relativity is studied. The considered model contains gravitational degrees of freedom and a scalar dilaton field. The standard tetrad formalism is applied. Properties of spin connections in this model are analyzed. Secondary quantization of the chosen variables is performed. The gravitational part of the model action turns out to be quadratic with respect to the spin connections. So at the quantum level, the model looks trivial, i.e., without quantum self-interactions. Meanwhile the correspondence to general relativity is preserved at the classical level.","PeriodicalId":48646,"journal":{"name":"Universe","volume":"2010 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
Isospin QCD as a Laboratory for Dense QCD 作为高密度 QCD 实验室的等空间 QCD
IF 2.9 4区 物理与天体物理
Universe Pub Date : 2024-07-12 DOI: 10.3390/universe10070293
Toru Kojo, Daiki Suenaga, Ryuji Chiba
{"title":"Isospin QCD as a Laboratory for Dense QCD","authors":"Toru Kojo, Daiki Suenaga, Ryuji Chiba","doi":"10.3390/universe10070293","DOIUrl":"https://doi.org/10.3390/universe10070293","url":null,"abstract":"QCD with the isospin chemical potential μI is a useful laboratory to delineate the microphysics in dense QCD. To study the quark–hadron continuity, we use a quark–meson model that interpolates hadronic and quark matter physics at microscopic level. The equation of state is dominated by mesons at low density but taken over by quarks at high density. We extend our previous studies with two flavors to the three-flavor case to study the impact of the strangeness, which may be brought by kaons (K+,K0)=(us¯,sd¯) and the UA(1) anomaly. In the normal phase, the excitation energies of kaons are reduced by μI in the same way as hyperons in nuclear matter at the finite baryon chemical potential. Once pions condense, kaon excitation energies increase as μI does. Moreover, strange quarks become more massive through the UA(1) coupling to the condensed pions. Hence, at zero and low temperature, the strange hadrons and quarks are highly suppressed. The previous findings in two-flavor models, sound speed peak, negative trace anomaly, gaps insensitive to μI, persist in our three-flavor model and remain consistent with the lattice results to μI∼ 1 GeV. We discuss the non-perturbative power corrections and quark saturation effects as important ingredients to understand the crossover equations of state measured on the lattice.","PeriodicalId":48646,"journal":{"name":"Universe","volume":"25 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
Stochastic Tunneling in de Sitter Spacetime 德西特时空中的随机隧道效应
IF 2.9 4区 物理与天体物理
Universe Pub Date : 2024-07-11 DOI: 10.3390/universe10070292
Taiga Miyachi, Jiro Soda, Junsei Tokuda
{"title":"Stochastic Tunneling in de Sitter Spacetime","authors":"Taiga Miyachi, Jiro Soda, Junsei Tokuda","doi":"10.3390/universe10070292","DOIUrl":"https://doi.org/10.3390/universe10070292","url":null,"abstract":"Tunneling processes in de Sitter spacetime are studied by using the stochastic approach. We evaluate the Martin–Siggia–Rose–Janssen–de Dominicis (MSRJD) functional integral by using the saddle-point approximation to obtain the tunneling rate. The applicability conditions of this method are clarified using the Schwinger–Keldysh formalism. In the case of a shallow potential barrier, we reproduce the Hawking–Moss (HM) tunneling rate. Remarkably, in contrast to the HM picture, the configuration derived from the MSRJD functional integral satisfies physically natural boundary conditions. We also discuss the case of a steep potential barrier and find an interesting Coleman–de Luccia (CDL) bubblelike configuration. Since the starting point of our analysis is the Schwinger–Keldysh path integral, which can be formulated in a more generic setup and incorporates quantum effects, our formalism sheds light on further studies of tunneling phenomena from a real-time perspective.","PeriodicalId":48646,"journal":{"name":"Universe","volume":"2 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141586208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
Wormhole Restrictions from Quantum Energy Inequalities 从量子能量不等式看虫洞限制
IF 2.9 4区 物理与天体物理
Universe Pub Date : 2024-07-06 DOI: 10.3390/universe10070291
Eleni-Alexandra Kontou
{"title":"Wormhole Restrictions from Quantum Energy Inequalities","authors":"Eleni-Alexandra Kontou","doi":"10.3390/universe10070291","DOIUrl":"https://doi.org/10.3390/universe10070291","url":null,"abstract":"Wormhole solutions, bridges that connect different parts of spacetime, were proposed early in the history of General Relativity. Soon after, it was shown that all wormholes violate classical energy conditions, which are non-negativity constraints on contractions of the stress–energy tensor. Since these conditions are violated by quantum fields, it was believed that wormholes can be constructed in the context of semiclassical gravity. But negative energies in quantum field theory are not without restriction: quantum energy inequalities (QEIs) control renormalized negative energies averaged over a geodesic. Thus, QEIs provide restrictions on the construction of wormholes. This work is a review of the relevant literature, thus focusing on results where QEIs restrict traversable wormholes. Both ‘short’ and ‘long’ (without causality violations) wormhole solutions in the context of semiclassical gravity are examined. A new result is presented on constraints on the Maldacena, Milekhin, and Popov ‘long’ wormhole from the recently derived doubled smeared null energy condition.","PeriodicalId":48646,"journal":{"name":"Universe","volume":"79 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141566973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
Molecular Formation in Low-Metallicity Hot Cores 低金属性热核中的分子形成
IF 2.9 4区 物理与天体物理
Universe Pub Date : 2024-07-04 DOI: 10.3390/universe10070290
Yara Sobhy, Hideko Nomura, Tetsuo Yamamoto, Osama Shalabeia
{"title":"Molecular Formation in Low-Metallicity Hot Cores","authors":"Yara Sobhy, Hideko Nomura, Tetsuo Yamamoto, Osama Shalabeia","doi":"10.3390/universe10070290","DOIUrl":"https://doi.org/10.3390/universe10070290","url":null,"abstract":"The chemical complexity in low-metallicity hot cores has been confirmed by observations. We investigate the effect of varying physical parameters, such as temperature, density and the cosmic ray ionisation rate (CRIR), on the molecular abundance evolution in low-metallicity hot cores using the UMIST gas phase chemical model. CRIR had the strongest effect on molecular abundance. The resultant molecular abundances were divided into three categories with different trends in time evolution. We compared our results with the observations of hot cores in the Large Magellanic Cloud (LMC). Our model fits best with the observations at a time of around 105 years after the evaporation of ice and at the CRIR of 1.36×10−16 s−1. The resultant abundances of the oxygen-bearing complex organic molecules (COMs), such as CH3OH, HCOOCH3 and CH3OCH3, do not fit with observations in the same physical condition and may be located in a different physical environment. Our results suggest that investigating the CRIR value is crucial to predict the molecular evolution in LMC hot cores.","PeriodicalId":48646,"journal":{"name":"Universe","volume":"52 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141553080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
On the Nature of the Radio Calibrator and Gamma-Ray Emitting NLS1 Galaxy 3C 286 and Its Multiwavelength Variability 论射电校准器和伽马射线发射 NLS1 星系 3C 286 的性质及其多波长变异性
IF 2.9 4区 物理与天体物理
Universe Pub Date : 2024-07-02 DOI: 10.3390/universe10070289
S. Komossa, S. Yao, D. Grupe, A. Kraus
{"title":"On the Nature of the Radio Calibrator and Gamma-Ray Emitting NLS1 Galaxy 3C 286 and Its Multiwavelength Variability","authors":"S. Komossa, S. Yao, D. Grupe, A. Kraus","doi":"10.3390/universe10070289","DOIUrl":"https://doi.org/10.3390/universe10070289","url":null,"abstract":"The quasar 3C 286, a well-known calibrator source in radio astronomy, was found to exhibit exceptional multiwavelength properties. Its rich and complex optical emission-line spectrum revealed its narrow-line Seyfert 1 (NLS1) nature. Given its strong radio emission, this makes 3C 286 one of the radio-loudest NLS1 galaxies known to date. 3C 286 is also one of very few known compact steep-spectrum (CSS) sources detected in the gamma-ray regime. Observations in the X-ray regime, rarely carried out so far, revealed evidence for variability, raising the question whether it is driven by the accretion disk or jet. 3C 286 is also well known for its damped Lyman alpha system from an intervening absorber at z = 0.692, triggering a search for the corresponding X-ray absorption along the line-of-sight. Here, we present new observations in the radio, X-ray, optical, and UV bands. The nature of the X-ray variability is addressed. Spectral evidence suggests that it is primarily driven by the accretion disk (not the jet), and the X-ray spectrum is well fit by a powerlaw plus soft excess model. The radio flux density and polarization remain constant at the Effelsberg telescope resolution, reconfirming the use of 3C 286 as radio calibrator. The amount of reddening/absorption along the line-of-sight intrinsic to 3C 286 is rigorously assessed. None is found, validating the derivation of a high Eddington ratio (L/LEdd∼ 1) and of the very high radio-loudness index of 3C 286. Based on the first deep Chandra image of 3C 286, tentative evidence for hard X-ray emission from the SW radio lobe is reported. A large variety of models for the gamma-ray emission of 3C 286 are briefly discussed.","PeriodicalId":48646,"journal":{"name":"Universe","volume":"34 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141501867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
引用次数: 0
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