Astrophysics and Space Science最新文献

{"title":"Cosmological multifield emulator","authors":"Sambatra Andrianomena,&nbsp;Sultan Hassan,&nbsp;Francisco Villaescusa-Navarro","doi":"10.1007/s10509-025-04440-9","DOIUrl":"10.1007/s10509-025-04440-9","url":null,"abstract":"<div><p>We present the application of deep networks to learn the distribution of multiple large-scale fields, conditioned exclusively on cosmology while marginalizing over astrophysics. Our approach develops a generalized multifield emulator based purely on theoretical predictions from the state-of-the-art hydrodynamic simulations of the CAMELS project, without incorporating instrumental effects which limit the analysis to specifics of a particular large-scale survey design. To this end, we train a generative adversarial network to generate images composed of three different channels that represent gas density (Mgas), neutral hydrogen density (HI), and magnetic field amplitudes (B). We consider an unconstrained model and another scenario where the model is conditioned on the matter density <span>(Omega _{mathrm{m}})</span> and the amplitude of density fluctuations <span>(sigma _{8})</span>. We find that the generated images exhibit great quality which is on a par with that of data, visually. Quantitatively, we find that our model generates maps whose statistical properties, quantified by probability distribution function (PDF) of pixel values and auto-power spectra, agree reasonably well up to the second moment with those of the real maps. The relative deviation between the PDFs is about 25<span>(%)</span> in both moments with larger deviations at the tails. The error between the two auto-power spectra is approximately less than 20<span>(%)</span> on scales larger than <span>(k = 10 h/)</span>Mpc, but becomes larger on smaller scales. Moreover, the mean and standard deviation of the cross-correlations between fields in all maps produced by the emulator are in good agreement with those of the real images, which indicates that our model generates instances whose maps in all three channels describe the same physical region. Furthermore, a CNN regressor, which has been trained to extract <span>(Omega _{mathrm{m}})</span> and <span>(sigma _{8})</span> from CAMELS multifield dataset, recovers the cosmology from the maps generated by our conditional model, achieving coefficient of determination values <span>(R^{2} = 0.96)</span> and 0.83 corresponding to <span>(Omega _{mathrm{m}})</span> and <span>(sigma _{8})</span> respectively. This further demonstrates the great capability of the model to mimic CAMELS data. Our model can be useful for generating data, 1000 multiple images in ∼3 seconds as opposed to a simulation which takes days for one realization, that are required to analyze the information from upcoming multi-wavelength cosmological surveys.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143944173","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":"Performance evaluation of low-cost GNSS receivers for extracting ionospheric TEC","authors":"Jufeng Yang,&nbsp;Shuhui Li,&nbsp;Aochuan Zhang,&nbsp;Shaoqiu Chen,&nbsp;Han Wang","doi":"10.1007/s10509-025-04432-9","DOIUrl":"10.1007/s10509-025-04432-9","url":null,"abstract":"<div><p>This paper aims to compare the performance of the low-cost Global Navigation Satellite System (GNSS) receiver u-blox ZED-F9P and the geodetic receiver JAVAD SIGMA G3T on vertical total electron content (VTEC) estimation, and to evaluate the impacts of different antennas on VTEC estimation. Using the undifferenced and uncombined Precise Point Positioning (PPP) algorithm to process GNSS data on April 15, September 11, and September 12, 2021. Then we compared the accuracy of VTEC and differential code bias (DCB) estimation between the low-cost GNSS receiver and the geodetic receiver. The results showed that VTEC extracted from low-cost GNSS receiver and geodetic receiver are consistent with the Global Ionospheric Model (GIM) products. However, the low-cost GNSS receiver’s VTEC accuracy is slightly lower, with the residual root mean square (RMS) values ranging from 1.07 to 1.72 TECU (Total Electron Content Unit) and the absolute mean bias ranging from −1.48 to −0.85 TECU. Additionally, satellite DCBs from the geodetic receiver were closer to CAS products than those from the low-cost GNSS receiver, with more satellites exhibiting absolute bias less than 1 nanosecond. Moreover, we analyzed the impact of different antennas (SEPCHOKE_B3E6 and JAVAD GrAnt-G3T) on VTEC estimation. For two receivers, VTEC differences between antennas are less than 1 TECU, with RMS of the biases between different antennas less than 0.35 TECU and mean biases do not exceed 0.21 TECU.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143938641","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 the formation mechanisms of double neutron star systems: an analytical perspective","authors":"Ali Taani,&nbsp;Mohammed Abu-Saleem,&nbsp;Mohammad Mardini,&nbsp;Hussam Aljboor,&nbsp;Mohammad Tayem","doi":"10.1007/s10509-025-04433-8","DOIUrl":"10.1007/s10509-025-04433-8","url":null,"abstract":"<div><p>Double Neutron Stars (DNSs) are unique probes to study various aspects of modern astrophysics. Recent discoveries have confirmed direct connections between DNSs and supernova explosions. This provides valuable information about the evolutionary history of these systems, especially regarding whether the second-born Neutron Star (NS) originated from either a Core-Collapse (<span>(CC)</span>) or Electron-Capture Supernovae (<span>(ECSNe)</span>) event. The provided scale diagram illustrates the distribution of different types of DNSs on the basis of their orbital parameters and other factors, including mass loss. As a result, the physical processes in DNSs vary depending on the formation mechanisms of the second-born NS and characteristics of the systems. <span>(ECSNe)</span> processes are typically associated with merging systems (<span>(etimes {P_{orb}}&lt; 0.05)</span>), while <span>(CC)</span> processes are more commonly linked to non-merging systems (<span>(etimes {P_{orb}}&gt; 0.05)</span>). Our results suggest a critical mass threshold of 1.30<span>(M_{odot } pm 0.22M_{odot } )</span> (critical value) for the <span>(ECSNe)</span> process to form an NS, while <span>(CC)</span> processes might occur at higher masses. Examining the orbital parameters of DNSs in a known gravitational potential can enhance our understanding of the theoretical predictions for DNS progenitor characteristics. It turns out that the <span>(ECSNe)</span> process predominantly produces DNS systems with short orbital (<span>(P_{orb} leq 0.25 d)</span>), nearly circular orbits (<span>(esimeq 0.2)</span>), accompanied by minimal kick velocities imparted on the proto-NS and significant mass loss. In contrast, their orbital dynamics in a known gravitational potential plays a crucial role in enhancing our understanding of the SNe geometry and the formation and evolution processes among different NS samples.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143919269","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":"Dark energy dynamics in teleparallel gravity with hyperbolic scale factor","authors":"A. O. Dhore,&nbsp;M. R. Ugale","doi":"10.1007/s10509-025-04431-w","DOIUrl":"10.1007/s10509-025-04431-w","url":null,"abstract":"<div><p>This paper uses the Friedmann–Robertson–Walker (FRW) line element to simulate the development of the universe and explores the cosmological implications of Tsallis Holographic Dark Energy (THDE) in the modified <span>(f(T))</span> teleparallel gravity framework. Teleparallel gravity, in which torsion substitutes curvature as the geometric structure of spacetime, describes the accelerated expansion of the universe in the absence of exotic matter. The work examines key cosmological parameters, such as the Hubble parameter, equation of state (EOS), deceleration parameter, jerk parameter, and <span>(Om)</span> diagnostics, under both interacting and non-interacting conditions by integrating the THDE model, derived from non-additive Tsallis entropy, with <span>(f(T))</span> gravity. To provide a smooth transition from deceleration to acceleration, the study uses a hyperbolic scale factor, <span>(a(t) = left [sinh (alpha t)right ]^{frac{1}{beta }})</span>. It explains how THDE fits into the model of the dynamics of the universe, with a focus on stability analysis using square sound speed and scalar field correspondence. We show that while the non-interacting THDE model remains stable (with <span>(v_{s}^{2}&gt;0)</span>), the interacting model can develop instabilities for larger coupling values. Our analysis, calibrated against 57 Hubble data points, yields best-fit parameters <span>(alpha = {-59.416}_{-0.625}^{+0.625})</span> and <span>(beta = {-1.303}_{-0.022}^{+0.022})</span>, with an <span>(R^{2})</span> value of 0.9321 and a best-fit <span>(H_{0})</span> of 67.8 km/s/Mpc. The study also examines energy conditions, highlighting the role of interaction terms in the development of dark energy (DE) and matter components. Graphical and numerical investigations demonstrate the capacity of the model to reflect empirical data, providing a complete framework for understanding the interactions of DE and teleparallel gravity. This methodology expands the theoretical framework for examining the accelerating expansion of the universe and offers alternate viewpoints on the DE paradigm.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 5","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143908750","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":"Asymmetric cross-correlation functions with delays in Sco X-1: evidence of possible jet triggering","authors":"S. D. Gouse,&nbsp;M. V. R. Abhishek,&nbsp;K. Sriram","doi":"10.1007/s10509-025-04430-x","DOIUrl":"10.1007/s10509-025-04430-x","url":null,"abstract":"<div><p>The formation and origin of jets in Z sources are not understood very well, although a strong X-ray-radio correlation has been noticed. We analyzed seventeen observations of Sco X-1 observed by the Rossi X-ray Timing Explorer (RXTE) where radio jet emissions were detected. In five observations, we report the detection of asymmetric cross-correlation functions (CCF) with delays of a few tens of seconds between soft and hard energy bands light curves in the horizontal branch associated with a flat-topped noise in the power density spectrum (PDS). Interestingly, these five observations were connected to a ballistic-type radio emission. We performed simulations to confirm and robust the cross-correlation coefficients and the observed lags. The CCF was highly symmetric in the remaining twelve observations, exhibiting NBO (Normal Branch Oscillations) or NBO+HBO (Horizontal Branch Oscillations) in the PDS. During these X-ray observations, the radio observations were found to be associated with an ultra-relativistic flow (URF) radio emission. The X-ray spectrum analysis of the two observations that showed core radio emission and abrupt variations in the PDS and CCF revealed that the bbody fractional flux varied by 10–20%, but the spectral parameters did not vary. We suggest that the ballistic jet might have triggered the instability in the inner region of the accretion disk, viz., the boundary layer (BL) plausibly along with the corona, causing the asymmetry with delays observed in the CCFs, and it also explains the absence of any oscillation features in the PDS, leaving behind a flat-topped noise. During symmetric CCF, the accretion flow was steady, hence, NBO / NBO+HBO was persistent. However, connecting the URF either to NBO or HBO is difficult since the majority of PDS exhibit an NBO alone rather than a NBO+HBO. We hypothesize that URF is most likely related to the phenomenon that causes NBO. Overall, we conclude that the asymmetric CCF shows that the inner part of the accretion disk is unstable due to the triggering of a ballistic jet and constrains the inner accretion region’s size to about 20-30 km, which possibly causes the accretion ejection.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143883611","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":"Perihelion precession in non-Newtonian central potentials","authors":"Michele Andreoli","doi":"10.1007/s10509-025-04426-7","DOIUrl":"10.1007/s10509-025-04426-7","url":null,"abstract":"<div><p>High order corrections to the perihelion precession are obtained in non-Newtonian central potentials, via complex analysis techniques. The result is an exact series expansion whose terms, for a perturbation of the form, are calculated in closed form. To validate the method, the series is applied to the specific case of s = 3, and the results are compared with those presented in literature, which are relate to the Schwarzschild metric. As a further test, a numerical simulation was carried out for the case where s = 4. The algebraic calculations and numerical simulations were carried out via software with symbolic capabilities.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871312","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 cosmological effects of a constant jerk parameter in FLRW universe within (f(T)) gravity","authors":"Syed Mudassir Syed Iqbal,&nbsp;G. U. Khapekar","doi":"10.1007/s10509-025-04428-5","DOIUrl":"10.1007/s10509-025-04428-5","url":null,"abstract":"&lt;div&gt;&lt;p&gt;In this paper, we investigate the evolution of the FLRW universe by analyzing the constant jerk parameter &lt;span&gt;(j)&lt;/span&gt; within the framework of &lt;span&gt;(f(T))&lt;/span&gt; gravity. Using a model-independent parametrization approach, we assume &lt;span&gt;(j)&lt;/span&gt; as constant and derive an expression for the Hubble parameter as &lt;/p&gt;&lt;div&gt;&lt;div&gt;&lt;span&gt; $$begin{aligned} H(z)=H_{0}left [xi _{1}left (z+1right )^{frac{3+sqrt{8j+1}}{2}}+ left (1{-xi }_{1}right )left (z+1right )^{frac{3-sqrt{8j+1}}{2}} right ]^{frac{1}{2}} end{aligned}$$ &lt;/span&gt;&lt;/div&gt;&lt;/div&gt;&lt;p&gt; We estimate model parameters via a Chi-square test coupled with Markov Chain Monte Carlo (MCMC) simulations, based on 52 Observational Hubble Data (OHD) points and 1701 Pantheon+SHOES data points. This method yields the best fit values: &lt;span&gt;(xi _{1}={0.39}_{-0.08}^{+0.12})&lt;/span&gt;, &lt;span&gt;(j={0.67}_{-0.19}^{+0.19})&lt;/span&gt;, &lt;span&gt;(H_{0}={66.08}_{-2.78}^{+2.83} ; km/s/Mpc)&lt;/span&gt; for OHD dataset and &lt;span&gt;(xi _{1}={0.37}_{-0.03}^{+0.03})&lt;/span&gt;, &lt;span&gt;(j={0.67}_{-0.38}^{+0.40})&lt;/span&gt;, &lt;span&gt;(H_{0}={72.80}_{-0.29}^{+0.31})&lt;/span&gt; &lt;span&gt;(km/s/Mpc)&lt;/span&gt; for Pantheon+SHOES dataset. The value of &lt;span&gt;(H_{0})&lt;/span&gt; obtained in our analysis closely resembles the value estimated by the Planck Collaboration in 2018, &lt;span&gt;(H_{0}=67.4pm 0.5; km/s/Mpc)&lt;/span&gt;. Our analysis of the deceleration parameter &lt;span&gt;(q)&lt;/span&gt; reveals a transition from an early decelerating phase to a present accelerating expansion, with &lt;span&gt;(q_{0}approx -0.3887)&lt;/span&gt; &lt;span&gt;((OHD))&lt;/span&gt; and &lt;span&gt;(q_{0}approx -0.4139)&lt;/span&gt; &lt;span&gt;((Pantheon+SHOES))&lt;/span&gt;. Additionally, we examine dynamic parameter such as energy density, pressure, and equation of state parameter within the model &lt;span&gt;(fleft (Tright )=T+eta T^{beta })&lt;/span&gt;, where &lt;span&gt;(eta )&lt;/span&gt; and &lt;span&gt;(beta )&lt;/span&gt; are an arbitrary real constant. The equation of state parameter &lt;span&gt;(omega )&lt;/span&gt; in our model demonstrates a smooth transition from the radiation-dominated era to the matter-dominated era and finally to the dark energy era. The present-day values of &lt;span&gt;(omega _{0} approx -0.6196)&lt;/span&gt; &lt;span&gt;((OHD))&lt;/span&gt; and &lt;span&gt;(omega _{0} approx -0.6548)&lt;/span&gt; &lt;span&gt;((Pantheon+SHOES))&lt;/span&gt; suggests that the universe is currently in a quintessence phase, where dark energy behaves as a dynamical component rather than a cosmological constant &lt;span&gt;(omega = -1)&lt;/span&gt;. This behavior indicates that our model is physically acceptable and aligns with the general features of cosmic evolution. Notably, the strong energy condition (SEC) is violated at present &lt;span&gt;(left (z =0right ))&lt;/span&gt; and is projected to remain violated in the future &lt;span&gt;(left (z &lt; 0right ))&lt;/span&gt;, driving the observed accelerated expansion of the universe. Also, this study offers insights into the impact of a constant jerk parameter on cosmic evolution and expansion dynamics within the framework of modified gravity, with a specific focus on the &lt;span&gt;(fleft (Tright ))&lt;/span&gt; gravity ","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865484","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 equilibrium configurations of neutron stars in the optimized (f(R,T)) gravity","authors":"J. T. Quartuccio,&nbsp;P. H. R. S. Moraes,&nbsp;G. N. Zeminiani,&nbsp;M. M. Lapola","doi":"10.1007/s10509-025-04429-4","DOIUrl":"10.1007/s10509-025-04429-4","url":null,"abstract":"<div><p>We construct equilibrium configurations for neutron stars using a specific <span>(f(R,T))</span> functional form, recently derived through gaussian process applied to measurements of the Hubble parameter. By construction, this functional form serves as an alternative explanation for cosmic acceleration, circumventing the cosmological constant problem. Here, we aim to examine its applicability within the stellar regime. In doing so, we seek to contribute to the modified gravity literature by applying the same functional form of a given gravity theory across highly distinct regimes. Our results demonstrate that equilibrium configurations of neutron stars can be obtained within this theory, with the energy density and maximum mass slightly exceeding those predicted by General Relativity. Additionally, we show that the value of some parameters in the <span>(f(R,T))</span> functional form must differ from those obtained in cosmological configurations, suggesting a potential scale-dependence for these parameters. We propose that further studies apply this functional form across different regimes to more thoroughly assess this possible dependence.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143845600","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":"Investigation of optimal transfers to retrograde co-orbital orbits in the Earth-Moon system","authors":"G. A. Caritá,&nbsp;M. H. M. Morais,&nbsp;S. Aljbaae,&nbsp;A. F. B. A. Prado","doi":"10.1007/s10509-025-04427-6","DOIUrl":"10.1007/s10509-025-04427-6","url":null,"abstract":"<div><p>Recent findings on retrograde co-orbital mean-motion resonances in the Earth-Moon system, highlight the potential use of spacecraft in retrograde resonances. Based on these discoveries, this study investigates retrograde co-orbital resonances within the Earth-Moon system, focusing on both optimal and sub-optimal orbital transfers to such configurations. The paper provides a comprehensive analysis of retrograde co-orbital resonances, optimization techniques to evaluate and enhance the performance of bi-impulsive transfers to these configurations. The results reveal the feasibility of low-cost transfers, which could support a range of future missions, including space exploration and satellite deployment. Combining advanced optimization processes, we obtained solutions for orbital transfers for different arrival points in retrograde co-orbitals improving mission efficiency and offering a cost-effective approach to interplanetary exploration.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143840513","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":"Tracing gravitational waves by integrating wavelet, PCA and clustering analysis using pulsar timing array data","authors":"Adityan S,&nbsp;A. Stanley Raj","doi":"10.1007/s10509-025-04425-8","DOIUrl":"10.1007/s10509-025-04425-8","url":null,"abstract":"<div><p>Pulsar Timing Arrays (PTAs) are a powerful tool to trace gravitational waves (GWs) signatures in the nanohertz frequency range by precisely monitoring timing residuals of millisecond pulsars. This study explores advancements in PTA methodologies, emphasizing machine learning (ML) techniques, wavelet analysis, and cross-correlation studies to enhance sensitivity to GW signals. Using data from the Indian Pulsar Timing Array (InPTA), we apply Principal Component Analysis (PCA), clustering algorithms, and wavelet-based time-frequency decomposition to improve the detection of the Stochastic Gravitational Wave Background (SGWB).Our analysis reveals a strong correlation (Pearson r = 0.872) between measured pulsar timing residuals and the Hellings-Downs curve, supporting the presence of an SGWB signal. Wavelet decomposition identifies significant low-frequency power, suggesting persistent timing residual structures consistent with GW signatures. PCA indicates that the first component captures ∼84.3% of the variance, highlighting a dominant common signal among pulsars. Clustering analysis reveals distinct pulsar groups, with some showing enhanced correlated noise features, likely linked to GW-induced fluctuations. Additionally, the estimated GW amplitude and spectral index for individual pulsars further reinforce the presence of a stochastic background. These findings demonstrate the effectiveness of dimensionality reduction and clustering techniques in isolating astrophysical signals, enhancing the reliability of GW detection. Our results provide strong support for the existence of an SGWB and showcase the potential of integrating machine learning with traditional pulsar timing analyses to refine GW detection strategies.</p></div>","PeriodicalId":8644,"journal":{"name":"Astrophysics and Space Science","volume":"370 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143835693","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}