Astronomy & Astrophysics最新文献

{"title":"Revisiting the SATIRE-S irradiance reconstruction: Heritage of Mt Wilson magnetograms and Ca II K observations","authors":"Theodosios Chatzistergos, Natalie A. Krivova, Sami K. Solanki, Kok Leng Yeo","doi":"10.1051/0004-6361/202554044","DOIUrl":"https://doi.org/10.1051/0004-6361/202554044","url":null,"abstract":"<i>Context.<i/> Accurate information on long-term variations in solar irradiance, important for understanding the solar influence on Earth’s climate, cannot be derived from direct irradiance measurements due to the comparatively short lifetimes of space-borne experiments. Models using measurements of the solar photospheric magnetic field as input can provide an independent assessment of the changes.<i>Aims.<i/> The Spectral And Total Irradiance Reconstruction in the satellite era (SATIRE-S) model does just that. Unfortunately, the magnetogram archives used by SATIRE-S to recover irradiance variations are also relatively short-lived and have short mutual overlapping periods, making it difficult to evaluate their consistency. To overcome this and bridge the various archives more reliably, we include additional input data sets.<i>Methods.<i/> We improve SATIRE-S total solar irradiance (TSI) reconstruction by firstly incorporating magnetograms from the Mt Wilson Observatory as well as unsigned magnetograms reconstructed from Meudon, Rome, and San Fernando Ca II K data, and secondly, by re-analysing all periods of overlaps between the various archives.<i>Results.<i/> Our combined daily irradiance reconstruction from all eight input archives returns an excellent agreement with direct measurements of irradiance, in particular we find a correlation coefficient of 0.98 when compared to TSIS1/TIM (Total and Spectral Solar Irradiance Sensor Total Irradiance Monitor) data. The minimum-to-minimum TSI difference between 1976 and 2019 is −0.2 ± 0.17 Wm<sup>−2<sup/>, while the TSI difference between the 1986 and 2019 minima is statistically insignificant (−0.06 ± 0.13 Wm<sup>−2<sup/>). Our analysis also sheds light on the trend shown by the TSI over the so-called ACRIM gap, disfavouring a hypothesised increasing trend in TSI in that period.<i>Conclusions.<i/> By including more direct and indirect magnetogram time series, we have made the TSI reconstructed by SATIRE-S more robust and accurate. The new series shows a reduced trend of decreasing TSI over the last half century, which agrees well with most composites of measured TSI.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"4 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853333","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":"Planetesimal formation via the streaming instability in simulations of infall-dominated young disks","authors":"L.-A. Hühn, C. P. Dullemond, U. Lebreuilly, R. S. Klessen, A. Maury, G. P. Rosotti, P. Hennebelle, E. Pacetti, L. Testi, S. Molinari","doi":"10.1051/0004-6361/202452689","DOIUrl":"https://doi.org/10.1051/0004-6361/202452689","url":null,"abstract":"Protoplanetary disks naturally emerge during protostellar core collapse. In their early evolutionary stages, infalling material dominates their dynamical evolution. In the context of planet formation, this means that the conditions in young disks are different from the ones in the disks typically considered in which infall has subsided. High inward velocities are caused by the advection of accreted material that is deficient in angular momentum, rather than being set by viscous spreading, and accretion gives rise to strong velocity fluctuations. Therefore, we aim to investigate when it is possible for the first planetesimals to form and for subsequent planet formation to commence. We analyzed the disks obtained in numerical 3D nonideal magnetohydrodynamical simulations, which served as a basis for 1D models representing the conditions during the class 0/I evolutionary stages. We integrated the 1D models with an adapted version of the TwoPopPy code to investigate the formation of the first planetesimals via the streaming instability. In disks with temperatures such that the snow line is located at ~10 AU and in which it is assumed that velocity fluctuations felt by the dust are reduced by a factor of 10 compared to the gas, ~10<sup>−3<sup/> M<sub>⊙<sub/> of planetesimals may be formed already during the first 100 kyr after disk formation, implying the possible early formation of giant planet cores. The cold-finger effect at the snow line is the dominant driver of planetesimal formation, which occurs in episodes and utilizes solids supplied directly from the envelope, leaving the reservoir of disk solids intact. However, if the cold-finger effect is suppressed, early planetesimal formation is limited to cold disks with an efficient dust settling whose dust-to-gas ratio is initially enriched to <i>ε<i/><sub>0<sub/> ≥ 0.03.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"28 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853330","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":"Coronal abundance fractionation linked to chromospheric transverse magnetohydrodynamic waves in a solar active region observed with FISS/GST and EIS/Hinode","authors":"Kyoung-Sun Lee, Jongchul Chae, Hannah Kwak, Kyuhyoun Cho, Kyeore Lee, Juhyung Kang, Eun-Kyung Lim, Donguk Song","doi":"10.1051/0004-6361/202453177","DOIUrl":"https://doi.org/10.1051/0004-6361/202453177","url":null,"abstract":"<i>Context.<i/> The elemental abundance in the solar corona differs from that in the photosphere, with low first ionization potential (FIP) elements showing enhanced abundances, a phenomenon known as the FIP effect. This effect is considered to be driven by ponderomotive forces associated with magnetohydrodynamic (MHD) waves, particularly incompressible transverse waves.<i>Aims.<i/> We aim to investigate the relationship between coronal abundance fractionation and transverse MHD waves in the chromosphere. We focus on analyzing the spatial correlation between the FIP fractionation and these waves, while exploring wave properties to validate the ponderomotive-force-driven fractionation model.<i>Methods.<i/> We analyzed the H<i>α<i/> data from the Fast Imaging Solar Spectrograph of the Goode Solar Telescope to detect chromospheric transverse MHD waves, and Si X (low FIP) and S X (high FIP) spectra from the EUV Imaging Spectrometer on board Hinode to determine the relative abundance in an active region. By extrapolating linear-force-free magnetic fields with Solar Dynamics Observatory/Helioseismic and Magnetic Imager magnetograms, we examine the connection between chromospheric waves and coronal composition. Around 400 wave packets were identified, and their properties, including the period, velocity amplitude, propagation speed, and propagation direction, were studied.<i>Results.<i/> These chromospheric transverse MHD waves, mostly incompressible or weakly compressible, are found near loop footpoints, particularly in the sunspot penumbra and superpenumbral fibrils. The highly fractionated coronal region is associated with areas where these waves were detected within closed magnetic fields. Our examination of the statistics of wave properties revealed that downward-propagating low-frequency waves are particularly prominent, comprising about 43% of the detected waves.<i>Conclusions.<i/> The correlation between abundance fractionation and transverse MHD waves, along with wave properties, supports the hypothesis that FIP fractionation occurs due to the ponderomotive force from transverse MHD waves in the chromosphere. Additionally, the observed characteristics of these chromospheric waves provide valuable observational constraints for understanding the FIP fractionation process.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"24 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853336","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":"Dynamic spectra of solar radio emissions from weak-turbulence simulation","authors":"M. Lazar, L. F. Ziebell, P. H. Yoon, R. A. López, S. Poedts","doi":"10.1051/0004-6361/202553752","DOIUrl":"https://doi.org/10.1051/0004-6361/202553752","url":null,"abstract":"<i>Context.<i/> In recent decades, serious efforts have been made in the analytical and numerical modeling of solar radio bursts generated by the electron beam interacting with the background plasma, including the dynamic spectra with decreasing frequency over time/space. These are type II and type III radio bursts, with the fundamental components at the local plasma frequency (<i>ω<i/><sub><i>p<i/><sub/> = 2<i>πf<i/><sub><i>p<i/><sub/>) and the harmonics (<i>nω<i/><sub><i>p<i/><sub/> = 2<i>πnf<i/><sub><i>p<i/><sub/>). Synthetic spectra built for a number of radio events were able to reproduce the decreasing frequency profiles reasonably well, despite the limitations of the approximate analytical theory.<i>Aims.<i/> We propose new modeling of dynamic radio emission spectra using weak-turbulence (WT) theory. This novel approach also aims at a self-consistent and quantitative evaluation of radio emissions, based on first-principles modeling of electron beam plasma instabilities and nonlinear wave interaction.<i>Methods.<i/> We performed the WT simulation, which has the ability to quantitatively describe the standard plasma emission involving the nonlinear interaction of Langmuir (<i>L<i/>), ion-sound (<i>S<i/>), and transverse electromagnetic (<i>T<i/>) waves. The composite dynamic spectra are constructed for type II- and type III-like events, against the background electron density model that behaves as an inverse square of the distance from the solar source.<i>Results.<i/> The new dynamic spectra are obtained distinctly, with a rapid frequency shift for type III emissions (generated by fast electron beams from coronal sources), as well as a less steep frequency drop for type II spectra (whose sources move away from the Sun along with interplanetary shocks). Upon making a qualitative comparison with typical solar radio emission events, we find that our first-principle-based synthetic dynamic spectra are in good agreement.<i>Conclusions.<i/> The findings of the present study demonstrate that the theoretical approach taken in this paper can be further applied to obtain (i) quantitatively relevant predictions and replications of the observed dynamic spectra of radio bursts, and (ii) more realistic large-scale models of the solar radio source, for example the type II and type III source models computed from the large-scale magnetohydrodynamics (MHD) simulations or even from direct spacecraft observations.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"41 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853276","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":"Switchbacks and their role in the turbulent cascade: Solar Orbiter observations","authors":"D. Perrone, F. Chiappetta, A. Settino, R. De Marco, R. D’Amicis, D. Telloni, R. Bruno, S. Perri","doi":"10.1051/0004-6361/202453094","DOIUrl":"https://doi.org/10.1051/0004-6361/202453094","url":null,"abstract":"<i>Context.<i/> Magnetic switchbacks are large-amplitude magnetic field deflections of Alfvénic nature that are characterized by a high degree of correlation between the velocity and the magnetic field that are routinely detected in the inner heliosphere. Their timescales vary between hundreds of seconds to up to few hours, so that their role within the turbulent transfer of energy from large to small scales in the solar wind is a key question.<i>Aims.<i/> We investigate the contribution of switchbacks to the turbulence cascade in the magnetic and velocity fields. The considered interval was taken within the rarefaction region of the first stream of slow Afvénic wind observed by Solar Orbiter in the inner heliosphere.<i>Methods.<i/> The analysis was based on full-cadence measurements for the magnetic field vector from the fluxgate magnetometer MAG and reprocessed ion data sampled at a resolution of 4 s from the Proton and Alpha particle sensor (PAS) of the Solar Wind Analyser (SWA) suite. Alfvénicity, structure functions, and intermittency were evaluated to investigate the turbulence ands kinetic parameters to study the reaction of the plasma to the switchbacks.<i>Results.<i/> Switchbacks are observed as isolated structures or in well-localized patches that are generated by two (or more) interacting structures that cover a range from magnetohydrodynamic to kinetic scales. In this interval of the slow Afvénic wind, they mainly affect the magnetic cascade in the radial direction (which in this sample is almost parallel to the mean field direction) not only in terms of the energy content across the scales, but also in terms of the inhomogeneity (i.e., intermittency), which play a role in transferring magnetic and kinetic energies across scales. Moreover, switchbacks are characterized by a high anticorrelation between the magnetic and velocity field components, which implies that these structures are regions of a local alignment of <b><i>v<i/><b/> and <b><i>b<i/><b/>. Finally, no equipartition between kinetic and magnetic energy is found, which suggests that the emergence of magnetic structures is already well consolidated at about 0.6 au.<i>Conclusions.<i/> Our results in this interval of slow Afvénic wind suggest that an important role is played by switchbacks in the magnetic and velocity turbulent cascade in the flow direction. Moreover, by confirming and expanding previous features observed for a single case-study, our results support the idea that switchbacks strongly influence the surrounding plasma and play a different role on protons and alpha particles.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"33 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853277","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":"Detection of magnetic fields in superclusters of galaxies","authors":"G. V. Pignataro, S. P. O’Sullivan, A. Bonafede, G. Bernardi, F. Vazza, E. Carretti","doi":"10.1051/0004-6361/202553709","DOIUrl":"https://doi.org/10.1051/0004-6361/202553709","url":null,"abstract":"<i>Context.<i/> The properties of magnetic fields in large-scale structure filaments, far beyond galaxy clusters, are still poorly known. Superclusters of galaxies are laboratories for investigating low-density environments, which are not easily identified given the low signals and large scales involved. The observed Faraday rotation measure (RM) of polarised sources along the line of sight of superclusters allows us to constrain the magnetic field properties in these extended environments.<i>Aims.<i/> The aim of this work is to constrain the magnetic field intensity in low-density environments within the extent of superclusters of galaxies using the Faraday RM of polarised background sources detected at different frequencies.<i>Methods.<i/> We selected three rich and nearby (<i>z<i/> < 0.1) superclusters of galaxies for which polarisation observations were available at both 1.4 GHz and 144 MHz: Corona Borealis, Hercules, and Leo. We compiled a catalogue of 4497 polarised background sources that have RM values either from the literature or derived from unpublished observations at 144 MHz. For each supercluster we created a 3D density cube in order to associate a density estimate with each RM measurement. We computed the median absolute deviation (MAD) variance of the RM values grouped in three density bins that correspond to the supercluster outskirts (0.01 < <i>ρ<i/>/<i>ρ<i/><sub><i>c<i/><sub/> < 1), filaments (1 < <i>ρ<i/>/<i>ρ<i/><sub><i>c<i/><sub/> < 30), and nodes (30 < <i>ρ<i/>/<i>ρ<i/><sub><i>c<i/><sub/> < 1000) regimes to investigate how variations in the RM distribution are linked to the mean density crossed by the polarised emission.<i>Results.<i/> We find an excess Δ<i>σ<i/><sub>MAD<sub/><sup>2<sub>RRM<sub/><sup/> = 2.5 ± 0.5 rad<sup>2<sup/> m<sup>−4<sup/> between the lowest-density regions (outside supercluster boundaries) and the low-density region inside the supercluster. This excess is attributed to the intervening medium of the filaments in the supercluster. We modelled the variance of the RM distribution as being due to a single-scale, randomly oriented magnetic field distribution and therefore as being dependant upon the magnetic field intensity along the line of sight, the magnetic field reversal scale, and the line-of-sight path length. Our observations do not constrain the latter two parameters, but if we marginalise over their respective prior range, we constrain the magnetic field to nG.<i>Conclusions.<i/> Our findings are consistent with several other works that studied filaments of the large-scale structure. The results suggest that the purely adiabatic compression of a primordial magnetic field, which would imply observed magnetic fields of the order of <i>B<i/><sub>||<sub/> ∼ 2 nG, is not the only mechanism playing a role in amplifying the primordial seeds in superclusters of galaxies.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"31 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853335","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":"Investigation of the inverse velocity dispersion in a solar energetic particle event observed by Solar Orbiter","authors":"Zheyi Ding, Robert F. Wimmer-Schweingruber, Alexander Kollhoff, Patrick Kühl, Liu Yang, Lars Berger, Athanasios Kouloumvakos, Nicolas Wijsen, Jingnan Guo, Daniel Pacheco, Yuncong Li, Manuela Temmer, Javier Rodriguez-Pacheco, Robert C. Allen, George C. Ho, Glenn M. Mason, Zigong Xu, Sindhuja Gunaseelan","doi":"10.1051/0004-6361/202553806","DOIUrl":"https://doi.org/10.1051/0004-6361/202553806","url":null,"abstract":"<i>Context.<i/> Solar energetic particle (SEP) events provide crucial insights into particle acceleration and transport mechanisms in the heliosphere. Inverse velocity dispersion (IVD) events, characterized by higher-energy particles that arrive later than lower-energy particles, challenge the classical understanding of SEP events and are increasingly observed by spacecraft, such as Parker Solar Probe and Solar Orbiter. However, the mechanisms underlying IVD events remain poorly understood.<i>Aims.<i/> We investigate the physical processes that cause long-duration IVD events by analyzing the SEP event observed by Solar Orbiter on 2022 June 7. We explore the role of evolving shock connectivity, particle acceleration at interplanetary (IP) shocks, and cross-field transport in shaping the observed particle profiles.<i>Methods.<i/> We used data from the Energetic Particle Detector (EPD) suite on board Solar Orbiter to analyze the characteristics of the IVD, and we modeled the event using the heliospheric energetic particle acceleration and transport (HEPAT) model. The simulations tracked evolutions of shock properties, particle acceleration and transport to assess the influence of shock expansion, shock connectivity, and transport processes on the formation of IVD events.<i>Results.<i/> The IVD event exhibited a distinct and long-duration IVD signature across proton energies from 1 to 20 MeV, and it lasted for approximately 10 hours. Heavy ions exhibited varying nose energies, defined as the energy corresponding to the first-arriving particles. Simulations suggest that evolving shock connectivity and the evolution of the shock play a primary role in the IVD signature. The magnetic connection shifts from the shock flank to the nose over time, which results in a gradual increase in the maximum particle energy along the field line. Furthermore, the model results show that limited cross-field diffusion can influence both the nose energy and the duration of the IVD event.<i>Conclusions.<i/> This study demonstrates that long-duration IVD events are primarily driven by evolving magnetic connectivity along a nonuniform shock that evolves over time, where the connection moves to more efficient acceleration sites as the shock propagates farther from the Sun. Other mechanisms, such as the acceleration time at the shock, may also contribute to the observed IVD features. The interplay of these factors remains an open question that warrants further investigation in other events.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"49 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853332","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":"Uniturbulence and Alfvén wave solar model","authors":"T. Van Doorsselaere, M. V. Sieyra, N. Magyar, M. Goossens, L. Banović","doi":"10.1051/0004-6361/202450630","DOIUrl":"https://doi.org/10.1051/0004-6361/202450630","url":null,"abstract":"<i>Context.<i/> Alfvén wave solar models (AWSOMs) have been very successful in describing the solar atmosphere by incorporating the Alfvén wave driving as extra contributions in the global MHD equations. However, they lack the contributions from other wave modes.<i>Aims.<i/> We aim to write governing equations for the energy evolution equation of kink waves. In a similar manner to AWSOM, we combine the kink-wave-evolution equation with MHD. Our goal is to incorporate the extra heating provided by the uniturbulent damping of the kink waves. We attempt to construct the UAWSOM equations (uniturbulence and Alfvén wave driven solar models).<i>Methods.<i/> We recently described the MHD equations in terms of the <i>Q<i/> variables. These make it possible to follow the evolution of waves in a co-propagating reference frame. We transformed the <i>Q<i/>-variable MHD equations into an energy evolution equation. First we did this generally, and then we focused on the description of kink waves. We model the resulting UAWSOM system of differential equations in a 1D solar atmosphere configuration using a Python code. We also couple this evolution equation to the slowly varying MHD formulation and solve the system in 1D.<i>Results.<i/> We find that the kink-wave-energy evolution equation contains non-linear terms, even in the absence of counter-propagating waves. Thus, we confirm earlier analytical and numerical results. The non-linear damping is expressed solely through equilibrium parameters, rather than an ad hoc perpendicular correlation term (popularly quantified with a length scale <i>L<i/><sub>⊥<sub/>), as in the case of the AWSOM models. We combined the kink evolution equation with the MHD equations to obtain the UAWSOM equations. A proof-of-concept numerical implementation in python shows that the kink-wave driving indeed leads to radial outflow and heating. Thus, UAWSOM may have the necessary ingredients to drive the solar wind and heat the solar corona against losses.<i>Conclusions.<i/> Not only does our current work constitute a pathway to fix shortcomings in heating and wind driving in the popular AWSOM model, it also provides the mathematical formalism to incorporate more wave modes (e.g. the parametric decay instability) for additional driving of the solar wind.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"30 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143841177","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 p < 0.0001 detection of cosmic microwave background cooling in galactic halos and its possible relation to dark matter","authors":"Frode K. Hansen, Diego Garcia Lambas, Heliana E. Luparello, Facundo Toscano, Luis A. Pereyra","doi":"10.1051/0004-6361/202453117","DOIUrl":"https://doi.org/10.1051/0004-6361/202453117","url":null,"abstract":"We confirm, at the 5.7<i>σ<i/> level, previous studies reporting cosmic microwave background (CMB) temperatures being significantly lower around nearby spiral galaxies than expected from the ΛCDM model. Results from our earlier work were disputed in a recent paper, however, that analysis included areas far beyond the galactic halos, while disregarding the neighbourhood of the galaxies where the main signal is seen. Here, we limit the present study to pixels that are well within the galactic halos, focussing on galaxies in dense cosmic filaments and improving the signal-to-noise ratio (S/N), as compared to previous studies. The average CMB temperature in discs around these galaxies is always much lower in Planck data than in any of the 10 000 Planck-like CMB simulations. Even when correcting for the look-elsewhere effect, the detection is still at the 3 − 4<i>σ<i/> level. We further show that the largest scales (<i>ℓ<i/> < 16) of the Planck CMB fluctuations are more correlated with the distribution of nearby galaxies than 99.99% of simulated CMB maps. We argue that the existence of a new CMB foreground cannot be ignored and a physical interaction mechanism should be sought, which could possibly involve dark matter and could also be linked to intergalactic magnetic fields.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"8 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143841174","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 new uncertainty scheme for galaxy distances from flow models","authors":"Konstantin Haubner, Federico Lelli, Enrico Di Teodoro, Francis Duey, Stacy McGaugh, James Schombert","doi":"10.1051/0004-6361/202554164","DOIUrl":"https://doi.org/10.1051/0004-6361/202554164","url":null,"abstract":"The systemic velocity or redshift of galaxies is a convenient tool to calculate their distances in the absence of primary methods, but the uncertainties on these flow distances may be substantial due to galaxy peculiar motions. Here, we derived a simple and easily applicable method to assign uncertainties to flow distances from four different methodologies, namely the Hubble law with both heliocentric and local-sheet velocities, the Cosmicflows-4 model, and the numerical action methods model. Our uncertainty scheme was constructed by comparing these flow distances to accurate, redshift-independent distances of a subsample of ∼2000 galaxies from the Cosmicflows-4 database, using the tip magnitude of the red giant branch, Cepheids, surface brightness fluctuations, supernovae type Ia, masers, and supernovae type II. We provide simple functions and tables to calculate the distance uncertainties for all the flow models considered. This uncertainty scheme is generally applicable except for the region around the Virgo cluster, where we assign increased uncertainties due to larger peculiar motions.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"2018 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143841176","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}