Astronomische Nachrichten最新文献

{"title":"Inflation in a Non-Commutative Riemannian-Foliated Quantum Gravity Domain","authors":"Fridolin Weber,&nbsp;Peter O. Hess,&nbsp;José de Freitas Pacheco,&nbsp;Marcelo Marzola,&nbsp;Dimiter Hadjimichef,&nbsp;Benno Bodmann,&nbsp;Geovane Naysinger,&nbsp;Rodrigo Fraga,&nbsp;João G. G. Gimenez,&nbsp;Moisés Razeira,&nbsp;César A. Zen Vasconcellos","doi":"10.1002/asna.20240152","DOIUrl":"https://doi.org/10.1002/asna.20240152","url":null,"abstract":"<div>\u0000 \u0000 <p>We explore the implications of Branch-Cut Quantum Gravity (BCQG), a novel framework leveraging non-commutative geometry within a symplectic phase-space, on the accelerated expansion of the universe. Non-commutativity, introduced through a deformation of the Poisson algebra and enhanced by a symplectic metric, provides a robust mechanism for addressing key challenges in cosmology, such as the youngness paradox and the fine-tuning of initial conditions in standard inflationary models. By embedding quantum dual-field dynamics within a Riemannian-foliated spacetime, BCQG naturally integrates short- and long-range spacetime effects into a unified formalism. This approach offers an alternative to standard inflationary models by predicting cosmic acceleration through geometric restructuring rather than finely-tuned initial states. In contrast to models like ΛCDM or String Theory, BCQG introduces unique corrections to cosmic scale factors and predicts a novel transition between contraction and expansion phases via topological branch-cuts, circumventing the singularity problem. Moreover, BCQG's non-commutative formulation provides testable predictions, such as modifications in cosmic microwave background (CMB) anisotropies and large-scale structure evolution. We discuss the mathematical foundation, observational implications, and future avenues for validating BCQG through astrophysical data, positioning it as a promising theoretical alternative for understanding the universe's accelerated growth.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 7-8","pages":""},"PeriodicalIF":1.0,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145135439","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}

{"title":"Exploring Absolute Retract in Regular Hayward Black Holes and Their Implications for Astrophysics","authors":"Mohammad Abu-Saleem,&nbsp;Ali Taani","doi":"10.1002/asna.20240148","DOIUrl":"https://doi.org/10.1002/asna.20240148","url":null,"abstract":"<div>\u0000 \u0000 <p>In this article, we study and describe the topology of the spherically symmetric and regular (with no singularity in its event horizon) black hole, which is called Hayward black hole. We use the symmetric metric for this object, associated with the Euler-Lagrangian equation, to derive various types of geodesic equations and components of a subspace geodesic. Under certain conditions, this approach allows us to deduce three types of absolute retractions representing the particle's motion along different axes within a 3-D subspace. These retractions could potentially describe the region of the event horizon of Hayward black holes. We show that the radial geodesics describe motion directly toward the black hole's center, while tangential geodesics illustrate paths without angular displacement. Spacetime curvature near the event horizon emphasizes the intense gravitational effects and distortions caused by the black hole's mass. Particle motion in subspace <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mspace></mspace>\u0000 <msub>\u0000 <mi>ℋ</mi>\u0000 <mn>3</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation>$$ kern0.5em {mathrm{mathscr{H}}}_3 $$</annotation>\u0000 </semantics></math> represents constrained tangential dynamics, providing insights into localized spacetime. In addition, the study of the Hayward black hole (topology and geometry) is valuable for our understanding of general relativity, exploring the quantum field of gravity implications, and contribute to the fields of mathematical physics and astrophysics.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 3-4","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144206467","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}

{"title":"Unveiling the Magnetized Nature of X-Ray Binaries: Cyclotron Line Insights Title","authors":"Mohammad Tayem,&nbsp;Mohammad Abu-Saleem,&nbsp;Ali Taani","doi":"10.1002/asna.20240147","DOIUrl":"https://doi.org/10.1002/asna.20240147","url":null,"abstract":"<div>\u0000 \u0000 <p>Studying the variations of measured cyclotron lines plays a crucial role in gaining insights into the physical processes of accretion in magnetized neutron stars. Our research focuses on the formation and distribution of magnetic fields in various high-mass x-ray binaries (HMXBs). Comparing these sources reveals valuable information about their origin and evolutionary history. It is worth noting that the presence of varying cyclotron lines can be attributed to the influence of accretion dynamics, which provides valuable information about the characteristics of the magnetic field. In addition, by visualizing data, we employ the Kernel Density Estimation method, to provide a robust framework for understanding the distribution of magnetic fields. We observed clear patterns of clustering in the energy range of (10–35) keV, which corresponds to magnetic fields of around <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mrow>\u0000 <mn>2</mn>\u0000 <mtext>–</mtext>\u0000 <mn>4</mn>\u0000 </mrow>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <mo>×</mo>\u0000 <mn>1</mn>\u0000 <msup>\u0000 <mn>0</mn>\u0000 <mn>12</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$$ left(2hbox{--} 4right)times 1{0}^{12} $$</annotation>\u0000 </semantics></math> G. This clustering indicates a shared magnetic field characteristics across these systems, suggesting a possible common origin or similar environmental and accretion condi tions. Finally, our research investigates the behavior of cyclotron lines in HMXBs, illuminating the accretion process and magnetic field properties to better understand their role as indicators of dynamical evolution.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 3-4","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144206630","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}

{"title":"The Meaning of Quasi-Simultaneous X-Rays and Gamma-Ray Observations of RS Oph in Outburst","authors":"Marina Orio,&nbsp;Ke Fang,&nbsp;Jay Gallagher,&nbsp;Gerardo Juan M. Luna,&nbsp;Joanna Mikolajewska","doi":"10.1002/asna.20240140","DOIUrl":"https://doi.org/10.1002/asna.20240140","url":null,"abstract":"<p>Shocks in novae outbursts are ubiquitous, but in symbiotic novae, they are particularly powerful, probably because of the surrounding red giant wind. The recurrent nova RS Oph is the best example of this phenomenon. The presence of shocked plasma in outburst was inferred from optical spectra, and it was confirmed by X-ray observations since 1985. Since 2010, the gamma-ray observatory Fermi has proven that novae in general are the site of particle acceleration, producing copious gamma-ray flux in the few-GeV range. In the last outburst of the symbiotic RS Oph in 2021, gamma-rays were not only detected with Fermi in the GeV range but also detected in the TeV range of the Cherenkov telescopes, for about 3 weeks. Diesing et al. in 2023 showed that there must have been at least two distinct episodes of shocks, likely of hadronic nature, both generating particle acceleration. We present new NuSTAR data and re-discuss XMM-Newton high-resolution grating spectra and NICER data that we recently published. We concluded that the primary shock causing the particle acceleration observed in the range of TeV gamma-rays with the Cherenkov telescopes was the same phenomenon observed and studied with the x-ray observatories. However, the shocked plasma from which the particles were accelerated causing the gamma-ray flux observed after 1 day with Fermi was—at least initially—unobservable. We suggest that this first episode of shock occurred when the nova ejecta collided with a dense outflow close to the atmosphere of the red giant, with such a high absorbing column that x-rays were absorbed.</p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20240140","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143114534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Issue Information: Astron. Nachr. 09/2024","authors":"","doi":"10.1002/asna.20249008","DOIUrl":"https://doi.org/10.1002/asna.20249008","url":null,"abstract":"","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"345 9-10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20249008","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143186909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Cover Picture: Astron. Nachr. 9/2024","authors":"Balázs Pál,&nbsp;László Dobos","doi":"10.1002/asna.20249017","DOIUrl":"https://doi.org/10.1002/asna.20249017","url":null,"abstract":"<p>Denoising a medium resolution stellar spectrum with neural networks. <i>Top</i>: Example of a noiseless simulated stellar spectrum (blue) transformed to an “observation” by adding a realistic noise component (gray) such that the effective S/N≈19. <i>Middle</i>: Comparison of the original noiseless simulated spectrum (blue) and the reconstructed spectrum (dashed orange) using a trained denoising autoencoder. The two lines overlap almost entirely, indicating the high accuracy of the machine learning method. <i>Bottom</i>: Relative error calculated as the fraction of pixel-wise residual noise and the original noiseless flux. The mean and maximum of the relative error are 0.175% and 1.806%, respectively. Formore details see the related paper by Pál and Dobos, published in this issue e240049. \u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure></p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"345 9-10","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20249017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143186908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Phase Structure of Holographic Superconductors With Spontaneous Scalarization","authors":"Hong Guo,&nbsp;Wei-Liang Qian,&nbsp;Bean Wang","doi":"10.1002/asna.20240145","DOIUrl":"https://doi.org/10.1002/asna.20240145","url":null,"abstract":"<div>\u0000 \u0000 <p>Within the holographic framework, we investigate the Einstein-scalar-Gauss-Bonnet theory coupled with a Maxwell field in an asymptotically anti-de Sitter (AdS) spacetime. Our findings reveal that holographic superconductor solutions exist when the Gauss-Bonnet coupling constant is below the critical value <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>λ</mi>\u0000 <mi>c</mi>\u0000 </msub>\u0000 <mo>≈</mo>\u0000 <mn>0.6339</mn>\u0000 </mrow>\u0000 <annotation>$$ {lambda}_capprox 0.6339 $$</annotation>\u0000 </semantics></math>, while spontaneous scalarization solutions emerge for <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>λ</mi>\u0000 <mo>&gt;</mo>\u0000 <msub>\u0000 <mi>λ</mi>\u0000 <mi>c</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation>$$ lambda &gt;{lambda}_c $$</annotation>\u0000 </semantics></math>. This raises the question whether the hairy black holes triggered by different mechanisms are smoothly joined by a phase transition or whether these are actually identical solutions. To examine this transition in greater detail, we constructed a phase diagram in terms of temperature and chemical potential. By explicitly evaluating the Gibbs free energy and its derivatives, we demonstrate that a smooth yet first-order phase transition occurs between the two hairy solutions. In particular, a thermodynamic process can be devised in which a superconducting black hole transitions into a scalarized black hole by raising or lowering the temperature.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 3-4","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144206622","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}

{"title":"Consistent Crust-Core Interpolation and Its Effect on Non-radial Neutron Star Oscillations","authors":"Martín O. Canullán-Pascual,&nbsp;Mauro Mariani,&nbsp;Ignacio F. Ranea-Sandoval,&nbsp;Milva G. Orsaria,&nbsp;Fridolin Weber","doi":"10.1002/asna.20240150","DOIUrl":"https://doi.org/10.1002/asna.20240150","url":null,"abstract":"<div>\u0000 \u0000 <p>To model the structure of neutron stars (NSs) theoretically, it is common to consider layers with different density regimes. Matching the equation of state (EoS) for the crust and core and obtaining a suitable description of these extreme conditions are crucial for understanding the properties of these compact objects. In this work, we construct 10 different NS EoSs incorporating three distinct crust models, which are connected to the core using a thermodynamically and causally consistent formalism. For cold NSs, we propose a linear relationship between pressure and energy density in a narrow region between the crust and core, effectively establishing an interpolation function in the pressure-baryonic chemical potential plane. We then compare this EoS matching method with the classical approach, which neglects causal and thermodynamic consistency. We solve the Tolman–Oppenheimer–Volkoff equation to obtain the mass-radius relationship and compare our results with observational constraints on NSs. Furthermore, we investigate the influence of the new matching formalism on non-radial oscillation frequencies and damping times. Our findings suggest that the method used to <i>glue</i> the crust and core EoS impacts NS observables, such as the radius, oscillation frequencies, and damping times of non-radial modes, which may be crucial for interpreting future gravitational wave observations from neutron star mergers or isolated pulsars. The effects are particularly noticeable for low-mass NSs, regardless of the specific EoS model chosen. In particular, we find that the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>p</mi>\u0000 <mn>1</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation>$$ {p}_1 $$</annotation>\u0000 </semantics></math> oscillation mode exhibits significant differences in frequencies among alternative matching methods, whereas the fundamental <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>f</mi>\u0000 </mrow>\u0000 <annotation>$$ f $$</annotation>\u0000 </semantics></math>-mode remains unaffected by changes in crust models or interpolation schemes.</p>\u0000 </div>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 3-4","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144206623","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}

{"title":"Revisiting Variable Stars Near Globular Clusters South of −29° Declination","authors":"Andrew C. Layden,&nbsp;Julia Evangelista,&nbsp;Sakshi Gupta,&nbsp;Mithilesh Mittameda,&nbsp;Eva Mulloy,&nbsp;Sohan I. Muslim,&nbsp;Tiyinoluwa Olushola-Alao,&nbsp;Akul Rishi","doi":"10.1002/asna.20240135","DOIUrl":"https://doi.org/10.1002/asna.20240135","url":null,"abstract":"<p>We review an often-cited but seldom-accessed catalogue by Fourcade and Laborde (1966) of 785 variable stars near 47 southern Galactic globular clusters, and recover the locations of 85 stars that were not incorporated into subsequent variable star catalogues and hence have become “lost” to the literature. We match the positions of these stars with those of modern variable star databases (Gaia, ASAS-SN, and VSX) and find 96% appear in at least one of these catalogues. We used proper motions and radial velocities from the Gaia Third Data Release to assess cluster membership, finding that most are field stars, but up to five may be members of NGC 5927 and one of NGC 6624.</p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 2","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20240135","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143489842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Searching the Non-Accreting White Dwarf Population in eROSITA Data","authors":"S. Friedrich,&nbsp;C. Maitra,&nbsp;K. Dennerl,&nbsp;A. Schwope,&nbsp;K. Werner,&nbsp;B. Stelzer","doi":"10.1002/asna.20240139","DOIUrl":"https://doi.org/10.1002/asna.20240139","url":null,"abstract":"<p>eROSITA is the soft X-ray instrument aboard the Spectrum Roentgen Gamma (SRG) satellite that is most sensitive in the energy range between 0.2 and 2.3 keV. Between December 2019 and December 2021, eROSITA completed four all-sky surveys, producing all-sky X-ray source lists and sky maps of unprecedented depth. In the energy range between 0.2 keV and 1 keV, we detected about 38,000 sources with a hardness ratio below −0.94, covering a small sample of known white dwarfs found with eROSITA in the dataset to which the German eROSITA consortium has rights (half sky). Two hundred and sixty four of these soft sources have a probability of more than 90% to be a white dwarf. This is more than the 175 white dwarfs ROSAT found in the whole sky. Here we present the results of a pilot study to increase the sensitivity of eROSITA for soft sources by extending the detection threshold down to 0.1 keV. First tests with dedicated sky regions are promising.</p>","PeriodicalId":55442,"journal":{"name":"Astronomische Nachrichten","volume":"346 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asna.20240139","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143113520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}