New Astronomy Reviews最新文献

{"title":"Rational ignorance in the search for extra-terrestrial life","authors":"Edward D. Zanders","doi":"10.1016/j.newar.2023.101675","DOIUrl":"https://doi.org/10.1016/j.newar.2023.101675","url":null,"abstract":"<div><p>The question “are we alone in the universe?” has been asked through the ages and is beginning to be addressed by deploying spacecraft and advanced observatories capable of detecting biological signatures. Apart from the certainty that life exists on the Earth, there is no clear evidence at the time of writing for extra-terrestrial life (also termed <em>exo-life</em>). Although the sheer number of potentially habitable extrasolar planets in our galaxy alone makes a compelling case for widespread exo-life if taken in isolation, the constraints on the emergence of life imposed by chemistry and biology provide a counterbalance to this optimistic view. In the absence of any clear sign of exo-life and therefore our ignorance about whether it exists or not, the only way forward is to apply scientific knowledge in a rational way to discriminate between different scenarios until such a time that real evidence is forthcoming, if at all. This article reviews the main features of current astrobiological research to speculate on the likelihood of each critical transition in the development of living entities, emphasising the involvement of chemistry and informational macromolecules. It concludes that carbon-based compounds may be widespread on and in exoplanets, but the organisation of these prebiotic molecules into cellular structures with anything like the complexity of the primitive organisms on Earth could be very rare or non-existent. However, if such organisms do arise, the path to multicellularity and the functional organisation required for human capabilities may not be so daunting. Some of the key genetic features required for this development may already be present in primitive cells ready to be activated or repurposed.</p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"96 ","pages":"Article 101675"},"PeriodicalIF":6.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49744324","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}

{"title":"Ultraluminous X-ray sources","authors":"Andrew King ,&nbsp;Jean-Pierre Lasota ,&nbsp;Matthew Middleton","doi":"10.1016/j.newar.2022.101672","DOIUrl":"https://doi.org/10.1016/j.newar.2022.101672","url":null,"abstract":"<div><p>The study of ultraluminous X-ray sources (ULXs) has changed dramatically over the last decade. In this review we first describe the most important observations of ULXs in various wavebands, and across multiple scales in space and time. We discuss recent progress and current unanswered questions. We consider the range of current theories of ULX properties in the light of this observational progress. Applying these models to neutron-star ULXs offers particularly stringent tests, as this is the unique case where the mass of the accretor is effectively fixed.</p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"96 ","pages":"Article 101672"},"PeriodicalIF":6.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49763951","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}

{"title":"Review of latest advances on dark matter from the viewpoint of the Occam razor principle","authors":"Eugene Oks","doi":"10.1016/j.newar.2023.101673","DOIUrl":"https://doi.org/10.1016/j.newar.2023.101673","url":null,"abstract":"<div><p>The overwhelming majority of theories on dark matter either introduce exotic, never discovered experimentally subatomic particles or change the physical laws. In this brief review I discuss three theories that do not do this, so that they are preferable from the viewpoint of the Occam razor principle.</p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"96 ","pages":"Article 101673"},"PeriodicalIF":6.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49763959","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}

{"title":"Persistent mysteries of jet engines, formation, propagation, and particle acceleration: Have they been addressed experimentally?","authors":"Eric G. Blackman ,&nbsp;Sergey V. Lebedev","doi":"10.1016/j.newar.2022.101661","DOIUrl":"10.1016/j.newar.2022.101661","url":null,"abstract":"<div><p><span>The physics of astrophysical jets can be divided into three regimes: (i) engine and launch (ii) propagation and </span>collimation<span>, (iii) dissipation and particle acceleration. Since astrophysical jets comprise a huge range of scales and phenomena, practicality dictates that most studies of jets intentionally or inadvertently focus on one of these regimes, and even therein, one body of work may be simply boundary condition for another. We first discuss long standing persistent mysteries that pertain the physics of each of these regimes, independent of the method used to study them. This discussion makes contact with frontiers of plasma astrophysics more generally. While observations theory, and simulations, and have long been the main tools of the trade, what about laboratory experiments? Jet related experiments have offered controlled studies of specific principles, physical processes, and benchmarks for numerical and theoretical calculations. We discuss what has been accomplished on these fronts. Although experiments have indeed helped us to understand certain processes, proof of principle concepts, and benchmarked codes, they have yet to solved an astrophysical jet mystery on their own. A challenge is that experimental tools used for jet-related experiments so far, are typically not machines originally designed for that purpose, or designed with specific astrophysical mysteries in mind. This presents an opportunity for a different way of thinking about the development of future platforms: start with the astrophysical mystery and build an experiment to address it.</span></p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"95 ","pages":"Article 101661"},"PeriodicalIF":6.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88524849","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}

{"title":"Data analysis techniques in light pollution: A survey and taxonomy","authors":"Lala Septem Riza ,&nbsp;Ahmad Izzuddin ,&nbsp;Judhistira Aria Utama ,&nbsp;Khyrina Airin Fariza Abu Samah ,&nbsp;Dhani Herdiwijaya ,&nbsp;Taufiq Hidayat ,&nbsp;Rinto Anugraha ,&nbsp;Emanuel Sungging Mumpuni","doi":"10.1016/j.newar.2022.101663","DOIUrl":"10.1016/j.newar.2022.101663","url":null,"abstract":"<div><p>One of the most pressing issues facing astronomy today is the growing threat of light pollution. Light pollution affects not only astronomical observations but also sustainability in the social and environmental sense. Light pollution has been reported to cause environmental changes by altering the circadian rhythm of organisms such as birds. In this work, we conducted a systematic review of data analyses on light pollution in the literature to assist researchers and those interested in light pollution. The results of the systematic review can be divided into four distinct phases, which are research objective, data collection, data preprocessing, and data analysis. Simple popularity for each phase shows the most popular approaches are measurement as a research objective at 47.46%, ground-based sensors for data collection at 31.91%, image preprocessing at 51.61%, and statistics &amp; machine learning for data analysis at 64.29%. The most popular combination of each phase is a measurement objective with ground-based sensors for data collection without data preprocessing or analysis. This implies that a not insignificant number of studies seek to obtain ground measurements without further analysis of the data. Data analysis as an integral part of the effort for understanding light pollution needs to be used efficiently and effectively by all stakeholders in the pursuit of sustainability.</p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"95 ","pages":"Article 101663"},"PeriodicalIF":6.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77758992","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}

{"title":"Challenges for ΛCDM: An update","authors":"L. Perivolaropoulos,&nbsp;F. Skara","doi":"10.1016/j.newar.2022.101659","DOIUrl":"10.1016/j.newar.2022.101659","url":null,"abstract":"<div><p>A number of challenges to the standard <span><math><mi>Λ</mi></math></span>CDM model have been emerging during the past few years as the accuracy of cosmological observations improves. In this review we discuss in a unified manner many existing signals in cosmological and astrophysical data that appear to be in some tension (<span><math><mrow><mn>2</mn><mi>σ</mi></mrow></math></span> or larger) with the standard <span><math><mi>Λ</mi></math></span><span>CDM model as specified by the Cosmological Principle, General Relativity and the Planck18 parameter values. In addition to the well-studied </span><span><math><mrow><mn>5</mn><mi>σ</mi></mrow></math></span> challenge of <span><math><mi>Λ</mi></math></span>CDM (the Hubble <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> tension) and other well known tensions (the growth tension, and the lensing amplitude <span><math><msub><mrow><mi>A</mi></mrow><mrow><mi>L</mi></mrow></msub></math></span> anomaly), we discuss a wide range of other less discussed less-standard signals which appear at a lower statistical significance level than the <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span><span> tension some of them known as ’curiosities’ in the data) which may also constitute hints towards new physics. For example such signals include cosmic dipoles (the fine structure constant </span><span><math><mi>α</mi></math></span><span><span>, velocity and quasar dipoles), CMB asymmetries, </span>BAO Ly</span><span><math><mi>α</mi></math></span><span><span> tension, age of the Universe issues, the Lithium problem, small scale curiosities like the core–cusp and missing satellite problems, quasars </span>Hubble diagram, oscillating short range gravity signals etc. The goal of this pedagogical review is to collectively present the current status (2022 update) of these signals and their level of significance, with emphasis on the Hubble tension and refer to recent resources where more details can be found for each signal. We also briefly discuss theoretical approaches that can potentially explain some of these signals.</span></p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"95 ","pages":"Article 101659"},"PeriodicalIF":6.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72391134","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}

{"title":"Relativistic models for anisotropic compact stars: A review","authors":"Jitendra Kumar ,&nbsp;Puja Bharti","doi":"10.1016/j.newar.2022.101662","DOIUrl":"10.1016/j.newar.2022.101662","url":null,"abstract":"<div><p><span>The Einstein–Maxwell (or Einstein) system of field equations plays a substantial role in the modeling of compact stars. Although due to its non-linearity getting an exact solution for the system of field equations is a difficult task, the solutions of field equations have a long and rich history. It took a year for Karl Schwarzschild to obtain the first exact solution of Einstein’s field equations since general theory of relativity was published. The number of viable solutions has been growing since then. Many authors have adopted several methods to obtain the solution. Different models have been constructed for a variety of applications. To produce feasible models of compact stars, a considerable amount of effort has been applied in gaining an understanding of the properties of anisotropic matter. Theoretical study indicates that pressure within compact stars with extreme internal density and strong gravity is mostly anisotropic. Anisotropy was found sufficient for the study of compact stars with the dense nuclear matter. It is claimed that it is important to consider the pressure experienced to be anisotropic whenever relativistic fluids are involved. In this review article, we have discussed different ways of generating a </span>static<span> spherically symmetric anisotropic fluid model. The purpose of the article is to present a simple classification scheme for static and spherically symmetric anisotropic fluid solutions. The known solutions are reviewed and compartmentalized as per the proposed scheme so that we can illustrate general ideas about these solutions without being exhaustive.</span></p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"95 ","pages":"Article 101662"},"PeriodicalIF":6.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76793391","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}

{"title":"The IAU working definition of an exoplanet","authors":"A. Lecavelier des Etangs ,&nbsp;Jack J. Lissauer","doi":"10.1016/j.newar.2022.101641","DOIUrl":"10.1016/j.newar.2022.101641","url":null,"abstract":"<div><p><span>In antiquity, all of the enduring celestial bodies<span> that were seen to move relative to the background sky of stars were considered planets. During the Copernican revolution, this definition was altered to objects orbiting around the Sun, removing the Sun and Moon but adding the Earth to the list of known planets. The concept of planet is thus not simply a question of nature, origin, composition, mass or size, but historically a concept related to the motion of one body </span></span><em>around</em> the other, in a hierarchical configuration.</p><p>After discussion within the IAU Commission F2 “Exoplanets and the Solar System”, the criterion of the star-planet mass ratio has been introduced in the definition of the term “exoplanet”, thereby requiring the hierarchical structure seen in our Solar System for an object to be referred to as an exoplanet. Additionally, the planetary mass<span> objects orbiting brown dwarfs, provided they follow the mass ratio criterion, are now considered as exoplanets. Therefore, the current working definition of an exoplanet, as amended in August 2018 by IAU Commission F2 “Exoplanets and the Solar System”, reads as follows:</span></p><p><span><span><em>Objects with true masses below the limiting mass for thermonuclear fusion of </em><em>deuterium</em><em> (currently calculated to be 13 Jupiter masses for objects of solar metallicity) that orbit stars, brown dwarfs or </em></span><em>stellar remnants</em><em> and that have a mass ratio with the central object below the</em></span> <span><math><msub><mrow><mi>L</mi></mrow><mrow><mn>4</mn></mrow></msub></math></span>/<span><math><msub><mrow><mi>L</mi></mrow><mrow><mn>5</mn></mrow></msub></math></span> <em>instability</em> (<span><math><mrow><mi>M</mi><mo>/</mo><msub><mrow><mi>M</mi></mrow><mrow><mi>central</mi></mrow></msub><mo>&lt;</mo><mn>2</mn><mo>/</mo><mrow><mo>(</mo><mn>25</mn><mo>+</mo><msqrt><mrow><mn>621</mn></mrow></msqrt><mo>)</mo></mrow><mo>≈</mo><mn>1</mn><mo>/</mo><mn>25</mn></mrow></math></span>) <em>are “planets”, no matter how they formed.</em></p><p><em>The minimum mass/size required for an extrasolar object to be considered a planet should be the same as that used in our Solar System, which is a mass sufficient both for self-gravity to overcome rigid body forces and for clearing the neighborhood around the object’s orbit.</em></p><p>Here we discuss the history and the rationale behind this definition.</p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"94 ","pages":"Article 101641"},"PeriodicalIF":6.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76586794","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}

{"title":"Black holes at cosmic dawn in the redshifted 21cm signal of HI","authors":"I.F. Mirabel ,&nbsp;L.F. Rodríguez","doi":"10.1016/j.newar.2022.101642","DOIUrl":"10.1016/j.newar.2022.101642","url":null,"abstract":"<div><p>The first stars (Pop III stars) and Black Holes (BHs) formed in galaxies at Cosmic Dawn (CD) have not been observed and remain poorly constrained. Theoretical models predict that indirect insights of those Pop III stars and BHs could be imprinted as an absorption signal in the 21cm line of the atomic hydrogen (HI) in the cold Intergalactic Medium (IGM), against the Cosmic Microwave Background (CMB), when the Universe was less than 200 million years old. The first tentative observation of an HI absorption in the 21cm line at redshifts z &gt; 15 by the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) has stimulated a great deal of research. To explain the additional large amplitude of that absorption signal a plethora of models based on exotic physics and on astrophysical sources have been proposed. Among the latter are models that propose the existence of an additional synchrotron Cosmic Radio Background (CRB) from BH-jet sources of comparable intensity to that of the CMB that boosts the HI absorption signal at CD. The discovery of radio loud supermassive black holes (SMBHs) of ~10⁹ M_⊙ in high-z quasars of up to z ~7.5 suggests the existence of a CRB component from growing BHs at z &gt; 15, of unknown intensity.</p><p>To match the onset of the EDGES signal a CRB of comparable intensity to that of the CMB would be required. With no judgment on whether the EDGES signal is of cosmic origin or not, here we provide approximate calculations to analyze highly redshifted HI absorption signals taking that of EDGES as an example to explore what could be learned on BHs at CD. Assuming a BH mass to radio luminosity ratio as observed in radio-loud Supermassive BHs (SMBHs) of ∼10⁹ M_⊙ in quasars at redshifts z = 6 – 7, by simple calculations we find that rapidly growing radio luminous BHs of Intermediate Mass (IMBHs) , in their way to become SMBHs, are the only type of astrophysical radio sources of a CRB that can explain the onset of the EDGES absorption at z = 18 – 20. At those redshifts the EDGES signal would imply that the global mass density of IMBHs must be dominant over that of stars, more than 70% of the maximum of Stellar Mass Density (SMD) expected at those high redshifts. This suggests that those IMBHs are formed before, and growing faster than the bulk of stars, with no need of a large mass contribution from stellar-mass BH remnants of typical Pop III stars. The highly redshifted signals from these IMBHs at cosmic dawn may be detected at long radio wavelengths with the next generation of ultrasensitive interferometers such as the Square Kilometer Array (SKA), in the infrared with the James Webb Space Telescope (JWST), and in the X-rays with future space missions.</p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"94 ","pages":"Article 101642"},"PeriodicalIF":6.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1387647322000021/pdfft?md5=f320818fe7143b82da599dcaeb650e1c&pid=1-s2.0-S1387647322000021-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78324150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The INTEGRAL view on black hole X-ray binaries","authors":"S.E. Motta ,&nbsp;J. Rodriguez ,&nbsp;E. Jourdain ,&nbsp;M. Del Santo ,&nbsp;G. Belanger ,&nbsp;F. Cangemi ,&nbsp;V. Grinberg ,&nbsp;J.J.E. Kajava ,&nbsp;E. Kuulkers ,&nbsp;J. Malzac ,&nbsp;K. Pottschmidt ,&nbsp;J.P. Roques ,&nbsp;C. Sánchez-Fernández ,&nbsp;J. Wilms","doi":"10.1016/j.newar.2021.101618","DOIUrl":"https://doi.org/10.1016/j.newar.2021.101618","url":null,"abstract":"<div><p><span><em>INTEGRAL</em></span> is an ESA mission in fundamental astrophysics that was launched in October 2002. It has been in orbit for over 18 years, during which it has been observing the high-energy sky with a set of instruments specifically designed to probe the emission from hard X-ray and soft <span><math><mi>γ</mi></math></span>-ray sources. This paper is devoted to the subject of black hole binaries, which are among the most important sources that populate the high-energy sky. We present a review of the scientific literature based on <em>INTEGRAL</em> data, which has significantly advanced our knowledge in the field of relativistic astrophysics. We briefly summarise the state-of-the-art of the study of black hole binaries, with a particular focus on the topics closer to the <em>INTEGRAL</em> science. We then give an overview of the results obtained by <em>INTEGRAL</em> and by other observatories on a number of sources of importance in the field. Finally, we review the main results obtained over the past 18 years on all the black hole binaries that <em>INTEGRAL</em> has observed. We conclude with a summary of the main contributions of <em>INTEGRAL</em> to the field, and on the future perspectives.</p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"93 ","pages":"Article 101618"},"PeriodicalIF":6.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.newar.2021.101618","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72276448","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}