New Astronomy Reviews最新文献

{"title":"Gamma Ray Burst afterglow and prompt-afterglow relations: An overview","authors":"M.G. Dainotti ,&nbsp;R. Del Vecchio","doi":"10.1016/j.newar.2017.04.001","DOIUrl":"10.1016/j.newar.2017.04.001","url":null,"abstract":"<div><p><span>The mechanism responsible for the afterglow<span> emission of Gamma Ray Bursts (GRBs) and its connection to the prompt </span></span><em>γ</em><span>-ray emission is still a debated issue. Relations between intrinsic properties of the prompt or afterglow emission can help to discriminate between plausible theoretical models of GRB production. Here we present an overview of the afterglow and prompt-afterglow two parameter relations, their physical interpretations, their use as redshift estimators and as possible cosmological tools. A similar task has already been correctly achieved for Supernovae (SNe) Ia by using the peak magnitude-stretch relation, known in the literature as the Phillips relation (Phillips 1993). The challenge today is to make GRBs, which are amongst the farthest objects ever observed, standardizable candles as the SNe Ia through well established and robust relations. Thus, the study of relations amongst the observable and physical properties of GRBs is highly relevant together with selection biases in their physical quantities.</span></p><p>Therefore, we describe the state of the art of the existing GRB relations, their possible and debated interpretations in view of the current theoretical models and how relations are corrected for selection biases. We conclude that only after an appropriate evaluation and correction for selection effects can GRB relations be used to discriminate among the theoretical models responsible for the prompt and afterglow emission and to estimate cosmological parameters.</p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"77 ","pages":"Pages 23-61"},"PeriodicalIF":6.0,"publicationDate":"2017-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.newar.2017.04.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87522734","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 carriers of the unidentified infrared emission features: Clues from polycyclic aromatic hydrocarbons with aliphatic sidegroups","authors":"X.J. Yang ,&nbsp;R. Glaser ,&nbsp;Aigen Li ,&nbsp;J.X. Zhong","doi":"10.1016/j.newar.2017.01.001","DOIUrl":"10.1016/j.newar.2017.01.001","url":null,"abstract":"<div><p><span>The unidentified infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, 11.3 and 12.7  µ m are ubiquitously seen in a wide variety of astrophysical regions in the Milky Way and nearby galaxies as well as distant galaxies at redshifts </span><em>z</em><span> ≳ 4. The UIE features are characteristic of the stretching and bending vibrations of aromatic hydrocarbon materials. The 3.3  µ m feature which results from the C–H stretching vibration in aromatic species is often accompanied by a weaker feature at 3.4  µ m. The 3.4  µ m feature is often thought to result from the C–H stretch of aliphatic groups attached to the aromatic systems. The ratio of the observed intensity of the 3.3  µ m aromatic C–H feature (</span><em>I</em>_3.3) to that of the 3.4  µ m aliphatic C–H feature (<em>I</em>_3.4) allows one to estimate the aliphatic fraction (e.g., <em>N</em>_{C, aliph}/<em>N</em>_{C, arom}<span>, the number of C atoms in aliphatic units to that in aromatic rings) of the carriers of the UIE features, provided that the intrinsic oscillator strengths (per chemical bond) of the 3.3  µ m aromatic C–H stretch (</span><em>A</em>_3.3) and the 3.4  µ m aliphatic C–H stretch (<em>A</em>_3.4) are known. In this review we summarize the computational results on <em>A</em>_3.3 and <em>A</em>_3.4<span> and their implications for the aromaticity and aliphaticity of the UIE carriers. We use density functional theory<span> and second-order perturbation theory to derive </span></span><em>A</em>_3.3 and <em>A</em>_3.4<span> from the infrared vibrational spectra of seven polycyclic aromatic hydrocarbon (PAH) molecules with various aliphatic substituents (e.g., methyl-, dimethyl-, ethyl-, propyl-, butyl-PAHs, and PAHs with unsaturated alkyl chains). The mean band strengths of the aromatic (</span><em>A</em>_3.3) and aliphatic (<em>A</em>_3.4) C–H stretches are derived and then employed to estimate the aliphatic fraction of the carriers of the UIE features by comparing the ratio of the intrinsic band strength of the two stretches (<em>A</em>_3.4/<em>A</em>_3.3) with the ratio of the observed intensities (<em>I</em>_3.4/<em>I</em>_3.3). We conclude that the UIE emitters are predominantly aromatic, as revealed by the observationally-derived mean ratio of ⟨<em>I</em>_3.4/<em>I</em>_3.3⟩ ≈ 0.12 and the computationally-derived mean ratio of ⟨<em>A</em>_3.4/<em>A</em>_3.3⟩ ≈ 1.76 which suggest an upper limit of <em>N</em>_{C, aliph}/<em>N</em>_{C, arom} ≈ 0.02 for the aliphatic fraction of the UIE carriers.</p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"77 ","pages":"Pages 1-22"},"PeriodicalIF":6.0,"publicationDate":"2017-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.newar.2017.01.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84282305","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":"High energy polarimetry of prompt GRB emission","authors":"Mark L. McConnell","doi":"10.1016/j.newar.2016.11.001","DOIUrl":"10.1016/j.newar.2016.11.001","url":null,"abstract":"<div><p>[Evidence] of polarized <em>γ</em><span>-ray emission (&gt; 50 keV) from Gamma-Ray Bursts (GRBs) has been accumulated in recent years. Measurements have been reported with levels in the range of 30–80%, typically with limited statistical significance. No clear picture has yet emerged with regards to the polarization properties of GRBs. Taken at face value, the data suggest that most GRBs have a relatively large level of polarization (typically, &gt; 50%), which may suggest synchrotron emission associated with an ordered magnetic field structure within the GRB jet. But these results are far from conclusive. Here, we review the observations that have been made, concentrating especially on the instrumental issues and the lessons that might be learned from these data.</span></p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"76 ","pages":"Pages 1-21"},"PeriodicalIF":6.0,"publicationDate":"2017-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.newar.2016.11.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87984063","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 jet feedback mechanism (JFM) in stars, galaxies and clusters","authors":"Noam Soker","doi":"10.1016/j.newar.2016.08.002","DOIUrl":"10.1016/j.newar.2016.08.002","url":null,"abstract":"<div><p><span><span>I review the influence jets and the bubbles they inflate might have on their ambient gas as they operate through a negative jet feedback mechanism (JFM). I discuss astrophysical systems where jets are observed to influence the ambient gas, in many cases by inflating large, hot, and low-density bubbles, and systems where the operation of the JFM is still a theoretical suggestion. The first group includes </span>cooling flows<span> in galaxies and clusters of galaxies, star-forming galaxies, </span></span>young stellar objects<span>, and bipolar planetary nebulae<span>. The second group includes core collapse supernovae, the common envelope evolution, the grazing envelope evolution, and intermediate luminosity optical transients. The suggestion that the JFM operates in these four types of systems is based on the assumption that jets are much more common than what is inferred from objects where they are directly observed. Common to all eight types of systems reviewed here is the presence of a compact object inside an extended ambient gas. The ambient gas serves as a potential reservoir of mass to be accreted on to the compact object. If the compact object launches jets as it accretes mass, the jets might reduce the accretion rate as they deposit energy to the ambient gas, or even remove the entire ambient gas, hence closing a negative feedback cycle.</span></span></p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"75 ","pages":"Pages 1-23"},"PeriodicalIF":6.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.newar.2016.08.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73582049","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 white dwarf luminosity function","authors":"Enrique García–Berro ,&nbsp;Terry D. Oswalt","doi":"10.1016/j.newar.2016.08.001","DOIUrl":"10.1016/j.newar.2016.08.001","url":null,"abstract":"<div><p><span><span>White dwarfs are the final remnants of low- and intermediate-mass stars. Their evolution is essentially a cooling process that lasts for ∼ 10 Gyr. Their observed properties provide information about the history of the Galaxy, its dark matter content and a host of other interesting astrophysical problems. Examples of these include an independent determination of the past history of the local </span>star formation rate, identification of the objects responsible for the reported </span>microlensing<span><span> events, constraints on the rate of change of the gravitational constant, and upper limits to the mass of </span>weakly interacting massive particles<span>. To carry on these tasks the essential observational tools are the luminosity and mass functions of white dwarfs, whereas the theoretical tools are the evolutionary sequences of white dwarf progenitors, and the corresponding white dwarf cooling sequences. In particular, the observed white dwarf luminosity function<span> is the key manifestation of the white dwarf cooling theory, although other relevant ingredients are needed to compare theory and observations. In this review we summarize the recent attempts to empirically determine the white dwarf luminosity function for the different Galactic populations. We also discuss the biases that may affect its interpretation. Finally, we elaborate on the theoretical ingredients needed to model the white dwarf luminosity function, paying special attention to the remaining uncertainties, and we comment on some applications of the white dwarf cooling theory. Astrophysical problems for which white dwarf stars may provide useful leverage in the near future are also discussed.</span></span></span></p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"72 ","pages":"Pages 1-22"},"PeriodicalIF":6.0,"publicationDate":"2016-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.newar.2016.08.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87220981","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":"Circumstellar debris and pollution at white dwarf stars","authors":"J. Farihi","doi":"10.1016/j.newar.2016.03.001","DOIUrl":"10.1016/j.newar.2016.03.001","url":null,"abstract":"<div><p><span>Circumstellar disks<span> of planetary debris are now known or suspected to closely orbit hundreds of white dwarf stars. To date, both data and theory support disks that are entirely contained within the preceding giant </span></span>stellar radii<span><span>, and hence must have been produced during the white dwarf phase. This picture is strengthened by the signature of material falling onto the pristine </span>stellar surfaces<span>; disks are always detected together with atmospheric heavy elements. The physical link between this debris and the white dwarf host abundances enables unique insight into the bulk chemistry of extrasolar planetary systems via their remnants. This review summarizes the body of evidence supporting dynamically active planetary systems at a large fraction of all white dwarfs, the remnants of first generation, main-sequence planetary systems, and hence provide insight into initial conditions as well as long-term dynamics and evolution.</span></span></p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"71 ","pages":"Pages 9-34"},"PeriodicalIF":6.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.newar.2016.03.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77552384","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 secondary supernova machine: Gravitational compression, stored Coulomb energy, and SNII displays","authors":"Donald D. Clayton,&nbsp;Bradley S. Meyer","doi":"10.1016/j.newar.2016.03.002","DOIUrl":"10.1016/j.newar.2016.03.002","url":null,"abstract":"<div><p>Radioactive power for several delayed optical displays of core-collapse supernovae is commonly described as having been provided by decays of ⁵⁶Ni nuclei. This review analyses the provenance of that energy more deeply: the form in which that energy is stored; what mechanical work causes its storage; what conservation laws demand that it be stored; and why its release is fortuitously delayed for about 10⁶<span><span> s into a greatly expanded supernova envelope. We call the unifying picture of those energy transfers the secondary supernova machine owing to its machine-like properties; namely, mechanical work forces storage of large increases of nuclear Coulomb energy, a positive energy component within new nuclei synthesized by the secondary machine. That positive-energy increase occurs despite the fusion decreasing negative total energy within nuclei. The excess of the Coulomb energy can later be radiated, accounting for the intense </span>radioactivity in supernovae. Detailed familiarity with this machine is the focus of this review. The stored positive-energy component created by the machine will not be reduced until roughly 10</span>⁶ s later by radioactive emissions (EC and <span><math><mrow><mi>β</mi><mo>+</mo></mrow></math></span>) owing to the slowness of weak decays. The delayed energy provided by the secondary supernova machine is a few × 10⁴⁹ erg, much smaller than the one percent of the 10⁵³<span><span> erg collapse that causes the prompt ejection of matter; however, that relatively small stored energy is vital for activation of the late displays. The conceptual basis of the secondary supernova machine provides a new framework for understanding the energy source for late SNII displays. We demonstrate the nuclear dynamics with nuclear network abundance calculations, with a model of sudden compression and reexpansion of the nuclear gas, and with nuclear energy decompositions of a nuclear-mass law. These tools identify excess Coulomb energy, a positive-energy component of the total negative nuclear energy, as the late </span>activation energy. If the value of fundamental charge </span><em>e</em> were smaller, SNII would not be so profoundly radioactive. Excess Coulomb energy has been carried within nuclei radially for roughly 10⁹<span><span> km before being radiated into greatly expanded supernova remnants. The Coulomb force claims heretofore unacknowledged significance for supernova </span>physics.</span></p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"71 ","pages":"Pages 1-8"},"PeriodicalIF":6.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.newar.2016.03.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85561396","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":"A critical review of period analyses and implications for mass exchange in W UMa eclipsing binaries: Paper 3","authors":"R.H. Nelson ,&nbsp;D. Terrell ,&nbsp;E.F. Milone","doi":"10.1016/j.newar.2016.02.001","DOIUrl":"https://doi.org/10.1016/j.newar.2016.02.001","url":null,"abstract":"<div><p><span>This is the third of a series of four papers, the goal of which is to identify the overcontact eclipsing binary star systems for which a solid case can be made for mass exchange. To reach this goal, it is necessary first to identify those systems for which there is a strong case for period change. We have identified 60 candidate systems; in the first two papers (</span><span>Nelson et al., 2014</span>, <span>Nelson et al., 2016</span>) we discussed 40 individual cases; this paper continues with the last 20. For each system, we present a detailed discussion and evaluation concerning the observational and interpretive material presented in the literature. At least one eclipse timing (ET) diagram, commonly referred to as an “O–C diagram”, that includes the latest available data, accompanies each discussion. In paper 4, we will discuss the mechanisms that can cause period change and which of the 60 systems can be reliably concluded to exhibit mass exchange; we will also provide a list of marginal and rejected cases – suitable for future work.</p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"70 ","pages":"Pages 1-26"},"PeriodicalIF":6.0,"publicationDate":"2016-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.newar.2016.02.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136510639","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":"A critical review of period analyses and implications for mass exchange in W UMa eclipsing binaries: Part 2","authors":"R.H. Nelson ,&nbsp;D. Terrell ,&nbsp;E.F. Milone","doi":"10.1016/j.newar.2015.07.001","DOIUrl":"https://doi.org/10.1016/j.newar.2015.07.001","url":null,"abstract":"<div><p>This is the second of a series of four papers, the goal of which is to identify the overcontact eclipsing binary star systems for which a solid case can be made for mass exchange. To reach this goal, it is necessary first to identify those systems for which there is a strong case for period change. We have identified 60 candidate systems; in the first paper (Nelson et al., 2014) we discussed 20 individual cases; this paper continues with the next 20. For each system, we present a detailed discussion and evaluation concerning the observational and interpretive material presented in the literature. An eclipse timing (ET) diagram (or diagrams), commonly referred to as an \"O–C diagram\", that includes the latest available data accompanies each discussion. In paper 4, we will discuss the mechanisms that can effect period change and which of the 60 systems can be reliably concluded to exhibit mass exchange; we will also provide a list of marginal and rejected cases suitable for future work.</p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"69 ","pages":"Pages 1-15"},"PeriodicalIF":6.0,"publicationDate":"2015-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.newar.2015.07.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"137072060","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 modelling of feedback in star formation simulations","authors":"James E. Dale","doi":"10.1016/j.newar.2015.06.001","DOIUrl":"10.1016/j.newar.2015.06.001","url":null,"abstract":"<div><p><span><span>I review the current state of numerical simulations of stellar feedback in the context of </span>star formation<span> at scales ranging from the formation of individual stars to models of galaxy formation<span><span> including cosmic reionisation. I survey the wealth of algorithms developed recently to solve the </span>radiative transfer problem and to simulate </span></span></span>stellar winds<span>, supernovae<span> and protostellar jets. I discuss the results of these simulations with regard to star formation in molecular clouds, the interaction of different feedback mechanisms with each other and with magnetic fields, and in the wider context of galactic- and cosmological-scale simulations.</span></span></p></div>","PeriodicalId":19718,"journal":{"name":"New Astronomy Reviews","volume":"68 ","pages":"Pages 1-33"},"PeriodicalIF":6.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.newar.2015.06.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86902233","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}