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Physics Astrophysics

astro-ph Watch Astrophysics

Wednesday 23 September

High Energy Astrophysical Phenomena

Origin of the high-energy spectral cutoff in gamma-ray pulsar halos

Qi-Ling Chen, Ming-Ming Kang, Kun Fang et al. (+2 more)

The spectra of gamma-ray pulsar halos exhibit a clear cutoff feature at tens of TeV. This work investigates the origin of the spectral cutoff by interpreting the HAWC data of the Geminga halo. The most straightforward interpretation is that the cutoff reflects the maximum electron acceleration capability of the central PWN. We model this scenario using spherically symmetric diffusive shock acceleration, where the upstream scale of the PWN termination shock limits the maximum energy. We also propose an alternative interpretation of the cutoff: if the electron diffusion coefficient in the surrounding interstellar medium rises rapidly at high energies, a substantial fraction of high-energy gamma-ray flux from the target source can leak outside the analysis region, producing an observed spectral cutoff effect. Both explanations successfully reproduce the spectral cutoff of the Geminga halo. Meanwhile, the two scenarios make distinct predictions on the statistical properties of pulsar halo spectral cutoffs and the X-ray spectral features of the corresponding PWNe, which may be tested through further observations.
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All authors Qi-Ling Chen, Ming-Ming Kang, Kun Fang, Yi-Qing Guo, Chao-Wen Yang

High Energy Astrophysical Phenomena

On the rates of binary star collisions around hypermassive black holes

Megha Sharma, Alexander Heger, Evgeni Grishin et al. (+1 more)

Observations of the Milky Way show that galaxies have binary stars in their centres. Using Monte Carlo simulations, we model the population statistics of encounters of such binaries with galactic central black holes (BHs) of mass 10^5-10^{10} Msun (hypermassive BHs >= 10^8 Msun HMBHs). Whereas main-sequence single stars cannot undergo tidal disruption events around HMBHs, stellar collisions of main-sequence binary stars may produce observable transients. We use the post-Newtonian Einstein-Infeld-Hoffmann (EIH) equations as implemented in the three-body code Multistar. We simulate 100,000 models each for six BH masses and 10 different binary parameter distributions. We find that stellar collisions occur in all models, with collision fractions ranging from ~7% for circular, equal-mass binaries to ~0.2% for the observationally motivated Moe2017 binary distribution. Most collisions occur for prograde, tight binaries at low impact parameters beta = r_t/r_p, where the tidal force of the BH drives up the binary eccentricity during pericentre passage. Collision velocities are close to the binary escape velocity for lower-mass BHs (<= 10^8 Msun), but span a wider range for higher-mass BHs, implying an increasing fraction of stellar mergers. Using empirical loss-cone rates and the local BH mass function, we estimate detectable LSST collision rates of ~8,600 and ~3,000 events per year for our Kroupa mass function, Opik's law, inclined orbit model and our MS17 model, respectively, around 10^6 Msun BHs; ~330 and ~150 events per year around 10^8 Msun BHs; and ~3.5 and ~2.8 events per year around 10^9 Msun BHs. These results suggest that binary stellar collisions around HMBHs represent a potentially observable population of nuclear transients that may contribute to the growing sample of ambiguous nuclear transients detected by wide-field optical surveys.
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All authors Megha Sharma, Alexander Heger, Evgeni Grishin, Daniel J. Price

Earth and Planetary Astrophysics

Kelvin-Helmholtz vortices in the Martian +E hemisphere downstream of crustal magnetic anomalies

Junxi Niu, Tong Dang, Jiuhou Lei et al. (+6 more)

At unmagnetized planetary bodies, the Kelvin-Helmholtz (KH) instability at the solar-wind boundary is a key driver of atmospheric escape, fundamentally shaping long-term climate evolution. This shear-driven plasma mixing is theoretically predicted to be asymmetric, strongly favoring the hemisphere where the solar-wind electric field points toward the planet (-E hemisphere). Here we report the observation of a coherent train of fully developed KH vortices in the traditionally unfavorable +E hemisphere of Mars, using in-situ MAVEN measurements. Contemporaneous upstream constraints from Tianwen-1 confirm a steady interplanetary magnetic field, indicating sustained shear-driven growth rather than a transient boundary response. We find that these vortices developed within an expanded, weak-field boundary layer downstream of strong southern crustal magnetic anomalies. Our analysis suggests that regional boundary structuring can override the large-scale hemispheric preference to facilitate localized KH growth. These findings demonstrate that shear-driven escape pathways can operate in traditionally unfavorable regions, altering our understanding of atmospheric volatile loss at weakly magnetized planets.
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All authors Junxi Niu, Tong Dang, Jiuhou Lei, Binzheng Zhang, Wenya Li, Binbin Tang, Junjie Chen, Sudong Xiao, Tielong Zhang

Astrophysics of Galaxies

Ubiquitous nuclear disks and bars embedded in massive galaxies in the cosmic morning

Jianyuan Luo, Fangzhou Jiang, Jinning Liang et al. (+8 more)

The morphology of the central regions of high-redshift galaxies remains relatively unexplored, while recent case studies suggest that giant disks can emerge without first developing a prominent central spheroid. Here, we investigate the inner structures of a mass-complete sample of 45 massive galaxies at $z=3$ in the TNG50 simulation. Through double-Sérsic profile decomposition, isodensity ellipse fitting, intrinsic three-dimensional shape measurements, and stellar kinematics, we find that these central structures are ubiquitously flattened and rotation-supported with low Sérsic indices ($n \lesssim 1$). This indicates that the central regions are predominantly nuclear disks and bars rather than bulges. Tracking their evolution, we show that these nuclear disks and bars emerge during gas-rich compaction and do not transform into spheroidal and dispersion-dominated systems until $z \lesssim 1$, before which extended stellar disks have already developed. Our results suggest that massive disks can assemble around rotation-supported centers and bulge-deficient massive galaxies may be a common outcome of galaxy evolution.
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All authors Jianyuan Luo, Fangzhou Jiang, Jinning Liang, Boris S. Kalita, Pinsong Zhao, Jinyi Shangguan, Bingcheng Jin, Zeyu Gao, Weichen Wang, Luis C. Ho, Yingjie Peng

Earth and Planetary Astrophysics

Dynamical Behavior and Surface Features of Large Super-Fast Rotator Near-Earth Asteroid (436724) 2011 UW158

Caio Gomes, Andre Amarante, Filipe Monteiro et al. (+7 more)

The sub-kilometer Super-Fast Rotator and Potentially Hazardous Asteroid (436724) 2011 UW158 exhibits an extreme dynamical environment driven by its rotational period of 0.61072 h. Using a 3-D polyhedral shape model, we investigate the surface dynamic stability under both cohesionless and cohesion-modified conditions, while also addressing families of periodic orbits, station-keeping maneuvers, and energy states in this rapidly rotating, irregular-body regime. Our results show that, with the inclusion of cohesion, the effective slopes decrease to ~45{\deg}, permitting the retention of boulders with maximum sizes of ~50 m near the equatorial region. The dominance of the centrifugal term in the effective potential shifts the exterior equilibrium points inward, creating highly unstable geopotential regions where loose regolith is susceptible to ejection, preventing long-term surface retention outside the polar regions. To quantify this instability, we introduce the equivalent instability speed ($v_{\mathrm{ei}}$), extending conventional escape speed analyses to the SFR regime. These results are consistent with significant internal cohesion in 2011 UW158, which enables the body to maintain structural integrity under rotational stresses exceeding the classical spin barrier. Additionally, thermophysical modeling reveals that the super-fast rotation produces a nearly uniform surface temperature distribution. Finally, we apply a spherical harmonics method to compute families of periodic orbits around the asteroid to assess the fuel cost of station-keeping maneuvers at reduced computational cost. Overall, this study characterizes the dynamical environment of 2011 UW158, contributing to the understanding of Super-Fast Rotator asteroids recently identified in LSST survey images.
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All authors Caio Gomes, Andre Amarante, Filipe Monteiro, Alessandra Ferreira, Leonardo Braga, Allan Kardec de Almeida Jr., Duncan Lyster, Nicoli Rocha, Gabriel Damilano, Leonardo Barbosa

Astrophysics of Galaxies

Distance Estimation using Globular Clusters and Ultra-Compact Dwarfs

Bas van Heumen, Jonah S. Gannon, Duncan A. Forbes et al. (+2 more)

The tight scaling relation between absolute magnitude and internal velocity dispersion ($\sigma$) for globular clusters (GCs), referred to as the GC velocity dispersion (GCVD) relation, has shown great potential as a distance estimator. However, at the high-luminosity end of the GC luminosity function, GCs mix with ultra-compact dwarfs (UCDs). As GCs appear to smoothly transition into UCDs with dynamical mass, we investigate the possibility of a unified distance estimation relation applicable to both GCs and UCDs. To this end, we exploit the transition between scaling relations with dynamical mass, using the Milky Way and M31 GCs alongside literature UCDs. Additionally, we look at the influence of UCDs, and of GC size, on GCVD-derived distances. Using the GCVD for UCDs gives a systematic distance underestimation of $\sim$33 per cent, but a cut to select UCDs with GC-like sizes can eliminate this bias. The minor systematics on GC size produce systematic offsets smaller than the uncertainty of the GCVD. Using the bilinear relation formed by the GCs and UCDs in the absolute magnitude - log dynamical mass plane for distance estimation yields per-object distance uncertainties of $\sim$30-35 per cent (0.12-0.16 dex). We find that the GC - UCD division occurs at $M_V \simeq -10.8$ mag and $M_{dyn} \simeq 3.1\times10^6$ $M_{\odot}$, consistent with previous findings. Applied to the dwarf galaxy NGC1052-DF2, whose distance is strongly debated, the relation returns 19.1 $\pm$ 4.3 Mpc, consistent with literature values.
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All authors Bas van Heumen, Jonah S. Gannon, Duncan A. Forbes, Jean P. Brodie, Aaron J. Romanowsky

Earth and Planetary Astrophysics

The Dynamical Environment of Kepler-223 Planetary System

Carlos E. Chavez, Adrián Fierro and Ándres Avilés

The Kepler space telescope was a successful mission that used the transit method. Multi-planetary systems are interesting because they are dynamically rich due to the planets' interactions. Kepler's mission was the first to find a system with four planets all in resonance, that is Kepler-223. The Kepler-223 system is of unique dynamical interest as the first exoplanetary system confirmed to host four sub-Neptune planets in a precise 3:4:6:8 resonant chain. Previous dynamical studies have struggled to fully recover the long-term phase protection mechanisms, often finding that higher-order resonant angles circulate rather than librate. In this work, we re-examine the dynamical state of Kepler-223 by performing high-resolution N-body integrations and constructing detailed stability maps in the (a,e) phase space, we demonstrate that the system is locked in a deeper resonant state than previously thought. Crucially, we find that all resonant arguments, exhibit robust libration over secular timescales. Our stability maps reveal that the planets reside in clearly defined stability islands that allow for higher eccentricities than previous estimates. We further compare these numerical islands with analytical resonance widths and find excellent agreement for the inner three planets, while the outermost planet (Kepler-223e) exhibits a stability region wider than first-order analytical theories predict, suggesting complex multi-body stabilization effects at the edge of the chain.
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Solar and Stellar Astrophysics · Cross-listed from nucl-th

Multi-Model Analysis of the Astrophysical $S(E)$ Factor for the $^{9}\mathrm{Be}(p,\alpha)^{6}\mathrm{Li}$ Reaction and Its Impact on Astrophysical Reaction Rates

Xue-Jian Wang, Wei-Ke Nan, Qing Wang et al. (+5 more)

The $^{9}\mathrm{Be}(p,\alpha)^{6}\mathrm{Li}$ reaction is a destruction process for $^{9}\text{Be}$ in stars and the Big Bang. The Trojan Horse Method (THM) is a well-established indirect technique that enables the determination of reaction cross sections within the Gamow energy region while avoiding the uncertainties associated with low-energy extrapolations of the $S(E)$ factor and electron-screening effects. In this work, the bare-nucleus THM data reported by Wen et al. are systematically analyzed using polynomial fitting, a double Breit–Wigner model, and the $R$-matrix formalism. The applicability and physical implications of these theoretical approaches in describing the low-energy $S(E)$ factor of the $^{9}\mathrm{Be}(p,\alpha)^{6}\mathrm{Li}$ reaction are investigated and compared. Since the THM data have been incorporated into the NACRE II reaction-rate compilation, leading to improved accuracy in reaction-rate evaluations, the refined theoretical analysis presented here provides further insight into the underlying reaction dynamics and establishes a more reliable foundation for stellar reaction-rate calculations. The results obtained in this work offer valuable reference for future high-precision experimental investigations and the development of theoretical models in nuclear astrophysics.
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All authors Xue-Jian Wang, Wei-Ke Nan, Qing Wang, Tian-Yu Tao, Qun-Gang Wen, Jian-You Guo, Cheng-Bo Li, Hui-Ming Jia

High Energy Astrophysical Phenomena

Estimating redshift distributions of Fermi blazars with multiple machine-learning models

Kerui Zhu, Jiaming Chen, Yonggang Zheng et al. (+4 more)

Approximately half of the Fermi-LAT-detected blazars lack spectroscopic redshift measurements, which limits population studies and investigations of the cosmological evolution of the gamma-ray blazar population. We aim to develop a multi-model ensemble framework to systematically evaluate the performance of machine-learning models for blazar redshift estimation and to provide predictive redshift probability distributions with quantified uncertainties for all blazars without measured redshifts. We construct an ensemble of 35 machine-learning regression models in the $1/(1+z)$ space. Predictions from individual models are combined to build non-parametric redshift probability density functions (PDFs) for each source, allowing an explicit characterization of predictive uncertainty. The source-level PDFs are subsequently stacked to derive population-level redshift distributions. Across the diverse models within our framework, we find comparable predictive performance, indicating a feature-limited performance plateau. We compile a catalog of predictive redshift distributions for 1,590 blazars without measured redshifts. The stacked PDFs recover the characteristic double-peaked redshift structure of blazars without using source class labels. For blazar candidates of uncertain type, the predicted redshift distribution exhibits a bimodal structure, suggesting a slightly larger contribution from FSRQ-like sources. Our multi-model statistical framework achieves competitive predictive performance while retaining faint sources. We provide predicted redshift distributions with quantified uncertainties for 1,590 blazars without measured redshifts, offering improved support for population and evolutionary studies. More broadly, this approach highlights the practical value of uncertainty-aware multi-model regression ensembling in astronomical data analysis.
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All authors Kerui Zhu, Jiaming Chen, Yonggang Zheng, Ruixin Zhou, Shan Chang, Li Zhang, Niansheng Tang

Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

Quasinormal-mode redshifts of black holes in galactic halos with radial pressures

Che-Yu Chen, Hassan Hassanabadi and Soroush Zare

We investigate the black-hole quasinormal mode redshifts induced by a galactic dark-matter halo with nonvanishing radial pressure. The halo is described by an anisotropic fluid with a generalized density profile and a constant radial equation-of-state parameter $w$. We construct the corresponding static, spherically symmetric spacetime and study the resulting corrections to the unstable light ring and quasinormal-mode spectrum. For dilute halos and $w\neq -1$, the light-ring angular frequency and Lyapunov exponent acquire the same leading-order gravitational redshift, implying a universal shift of the real and imaginary parts of the quasinormal frequencies. The magnitude of this effect depends on both the halo structure and the radial pressure. This universal redshift relation holds not only in the case of $w=0$ that has been discovered in the literature but also in a much wider scenario, supporting its importance in black hole spectroscopy. On the other hand, the case $w=-1$ is qualitatively different: the factor that corresponds to the leading common redshift vanishes, the corrections are further suppressed by the hierarchy between the black-hole and halo scales, and the universal relation is broken, with the dominant contribution controlled by the inner halo profile. Our numerical computations of scalar-field quasinormal mode spectra confirm the analytic eikonal results.
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Solar and Stellar Astrophysics

Orbital and spin periods of the intermediate polar 2PBC J0800.5-4306

Yabing Zhao, Chunhua Zhu, Sufen Guo et al. (+3 more)

2PBC J0800.5$-$4306 (Swift J0800.7$-$4309; optical counterpart Gaia DR3 5533020382479508736) is a hard-X-ray-selected cataclysmic variable whose magnetic subtype had remained uncertain. We analyse TESS photometry from Sectors 88 and 89 and archival XMM-Newton timing data. The TESS data show signals at the orbital frequency $\Omega$, its first harmonic $2\Omega$, the white-dwarf spin frequency $\omega$, and the spin–orbit beat frequency $\omega-\Omega$. We measure $P_{\rm orb}=5.38540^{+0.00027}_{-0.00028}$ h and $P_{\rm spin}=0.7015570^{+0.0000059}_{-0.0000062}$ h. The XMM-Newton EPIC-pn, MOS1, and MOS2 periodograms show broad peaks near the 2525.6-s (0.701557-h) optical spin period. Together with the previously published cataclysmic variable classification and Swift/BAT hard-X-ray detection, these timing results identify 2PBC J0800.5$-$4306 as an intermediate polar. We report the first published measurements of its orbital and white-dwarf spin periods, while SPOC difference-image diagnostics and pixel-level timing tests support that the measured TESS modulations are associated with the Gaia counterpart despite the crowded field.
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All authors Yabing Zhao, Chunhua Zhu, Sufen Guo, Guoliang Lü, Xizhen Lu, Xinyu Liu

High Energy Astrophysical Phenomena

Is accretion flow magnetically arrested in M87?

Yuao Ma, Xinwu Cao, Jia-Wen Li et al. (+2 more)

It is still debating on whether the disc is magnetically arrested in M87. We assume that a weak external magnetic field is dragged inwards by the accretion disc, which is substantially enhanced to drive strong jets near the black hole horizon via Blandford-Znajek mechanism. The jet power of M87 has been well constrained with the observational data, while the accretion rate in the inner region of the accretion flow in M87 is estimated by fitting the multi-waveband continuum spectrum and the data of the Faraday rotation measurement, with which the surface density of the disc is derived. Our calculations show that, in order to produce the observed jet power $P_{\rm jet}=3.2\times 10^{43}~\rm erg~s^{-1}$, an external field with several hundred $\mu \rm G$ at the outer edge of the disc is required to be amplified in the disc to hundreds G at the BH horizon, and the accretion flow in M87 must be magnetically arrested. A standard and normal evolution (SANE) disc is allowed in M87, only if the jet power is significantly lower than $\sim 1.75 \times 10^{43} \rm erg~ s^{-1}$,
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All authors Yuao Ma, Xinwu Cao, Jia-Wen Li, Jianchao Feng, Qingwen Wu

High Energy Astrophysical Phenomena

A multi-telescope fit to the FRB population, allowing for FRB repetition

Jordan L. Hoffmann, Clancy W. James, Jason X. Prochaska et al. (+3 more)

Fast radio bursts (FRBs) are millisecond-duration radio pulses with extragalactic origins. A majority of FRBs have only had a single pulse detected from them; however, an increasing number have been identified as repeaters. Here we present a full redshift – dispersion measure ($z$-DM) analysis including a simple power-law model of repetition rates. We assume all FRBs are drawn from the same intrinsic population and fit these FRB population parameters using data from ASKAP, Murriyang (Parkes), DSA, FAST, MeerKAT and CHIME catalogue 1. We do not utilise data from CHIME catalogue 2 yet, as we cannot robustly identify all repeaters in the sample. We constrain the minimum repetition rate above $10^{39}$ erg to $R_{\mathrm{min}}=-4.23^{+1.10}_{-1.74}$ d$^{-1}$, the maximum repetition rate to $R_{\mathrm{max}} \gtrsim 1$ d$^{-1}$ and the repetition rate index to $R_{\gamma}=-2.20^{+0.12}_{-0.22}$. These parameters do not show significant correlation with any other FRB parameters. Our values are an improvement on existing results and are self-consistent with the DM distribution of CHIME and observed ratios of repeaters to non-repeaters across the sky. We also provide updated estimates of the FRB energy function and host galaxy parameters.
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All authors Jordan L. Hoffmann, Clancy W. James, Jason X. Prochaska, Ines Pastor-Marazuela, Kritti Sharma, Liam Connor

Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

Correcting for Evidence Uncertainty in the Templated Background Search for the Stochastic Gravitational-Wave Background

Xiao-Xiao Kou, Argyro Sasli, Muhammed Saleem et al. (+1 more)

We report a new source of systematic bias in the Bayesian Templated Background Search (TBS) for the astrophysical stochastic gravitational-wave background. This bias arises from the statistical uncertainty in nested sampling evidence estimates at the segment level and persists even when the likelihood model accurately characterizes the data. Using an analytically tractable model and a frequency-domain mock data analysis with an astrophysically motivated binary black hole population, we show that this uncertainty coherently inflates the inferred duty cycle by up to an order of magnitude when millions of segments are accumulated. We propose a simple and efficient correction and demonstrate its effectiveness across all tested configurations. We also find that a search prior restricted to high optimal signal-to-noise ratio (SNR) misattributes intermediate-strength signals, while extending the prior to support weaker signals amplifies the evidence uncertainty. Both the correction and careful search prior design are essential for robust inference as TBS analyses scale to upcoming observing runs.
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All authors Xiao-Xiao Kou, Argyro Sasli, Muhammed Saleem, Vuk Mandic

Tuesday 22 September

Instrumentation and Methods for Astrophysics

South Pole-Aitken basin sample Return and eXploration (SPARX) Science Definition Team Report

Lauren M. Jozwiak, James T. Keane, Robert Citron et al. (+18 more)

Sample return from South Pole-Aitken Basin (SPA) on the Moon has been recognized as the highest priority lunar science mission for well over two decades, appearing as a recommended New Frontiers class mission in the two previous Planetary Science Decadal Survey documents (2003-2012 New Frontiers, 2013-2022 Visions and Voyages), and as a prioritized mission for the Lunar Discovery and Exploration Program (LDEP) in the 2023-2032 Origins, Worlds, and Life Decadal Survey. The South Pole-Aitken basin presents the ideal target destination to test nearly 60 years of lunar science hypotheses owing to a unique combination of its size, antiquity, and location on the lunar farside. Convened by NASA in response to OWL Decadal Survey recommendations, the SPARX report provides analysis on prioritized science objectives, measurement requirements, implementation architectures, and a design reference mission for a South Pole-Aitken basin sample return mission. The mission profiles presented in this report leverage key advancements in remote surface exploration technology, the U.S. commercial space industry, and the programmatic focus on sustained human presence and exploration at the lunar south polar region. The science objectives and measurements presented in this report outline a mission that would transform lunar science, would address multiple high-level Decadal science questions at the only place in the Solar System where they can be credibly addressed, would pioneer a new paradigm for planetary surface exploration in the 21st century, would leverage the burgeoning space economy to pursue ground-breaking science on a more cost-efficient basis, and would unite robotic exploration with human exploration in a model for a future sustained lunar enterprise.
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All authors Lauren M. Jozwiak, James T. Keane, Robert Citron, Natalie Curran, Steve Elardo, Caleb Fassett, Abigail Fraeman, Saira Hamid, Lena Heffern, Peter James, Daniel Moriarty, Kevin Righter, Jennifer Whitten, Hunter Vannier, Zoe Wilbur, Tomokatsu Morota, Hiroshi Nagaoka, Caroline-Emmanuelle Morisset, Patrick Hill, James Carpenter, Francesca MacDonald

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Axions and the RR Lyrae Period-Luminosity Relation

Jeremy Sakstein and Djuna Croon

We investigate the impact of axions on the period-luminosity relation (PLR) of RR Lyrae stars. During the red giant branch phase, emission through the electron coupling cools the core, increasing its mass at ignition. The larger core produces more luminous horizontal-branch stars, systematically shifting the zero point of the RR Lyrae PLR toward brighter magnitudes. We model the RR Lyrae population of the globular cluster M3 using stellar evolution and pulsation calculations tailored to its age and composition, and compare the resulting synthetic $K_s$-band PLR with observations. For $\alpha_{26}\equiv 10^{26}g_{ae}^2/4\pi=0.5$, the axion-induced shift in the predicted PLR is comparable to the current uncertainty in the absolute M3 zero-point calibration.
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Cosmology and Nongalactic Astrophysics

Shape Degeneracies: the likely culprit for the differences between lens mass models of galaxy clusters

Liliya L.R. Williams, Derek C. Perera, Jori Liesenborgs et al. (+3 more)

Sky-projected mass distributions of galaxy clusters are widely used to constrain particle properties of dark matter, to magnify in flux and angular extent high redshift background galaxies, and to construct their luminosity function down to faint absolute magnitudes that are otherwise hard or impossible to reach. Obtaining accurate and precise mass maps of clusters is therefore of central importance for these studies. Yet, a visual inspection of any two mass maps of the same cluster shows that the shapes of their isodensity contours are often dissimilar in detail on <30kpc scales, and there is no simple relation connecting the two. These differences are due to systematic uncertainties in reconstructions, which are in turn due to lensing degeneracies. However, commonly known degeneracies, like the mass sheet degeneracy or the source position transformation cannot account for most of these differences, implying that more generalized shape degeneracies are responsible. In this paper we study shape degeneracies using an analytical approach. We conclude with three main takeaways: (i) Shape degeneracies are the likely cause of differences in the mass maps of cluster lenses recovered by different techniques. (ii) Shape degeneracies are significantly suppressed in regions of the lens plane that have tight groupings of lensed images. (iii) In clusters where image numbers are high, such as MACS J0416, their effect on time delays between images from the same source are generally small, of order 1%, but can reach ~10% for some multiply imaged background sources, affecting the determination of H_0.
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All authors Liliya L.R. Williams, Derek C. Perera, Jori Liesenborgs, Ashish K. Meena, Marceau Limousin, Leon R. Ecker

Instrumentation and Methods for Astrophysics

Increasing Sensitivity to Trailed Solar System Objects in Archival JWST NIRCam Imaging with Group Differencing

Anthony Girmenia and Stanimir Metchev

The JWST archive contains thousands of NIRCam exposures distributed across the sky. Small solar system bodies (SSSBs) are present in many of these fields, but are often trailed and more difficult to detect. The standard pipeline produces a single image by fitting a slope to a sequence of $N$ cumulative “up-the-ramp" groups of the detector. Thus, each JWST image comprises a time series of cumulative reads. We demonstrate that transforming the ramp into a series of group difference images reduces the per-image trail length of moving sources, producing an $(N-1)$-group photometrically calibrated time series from an $N$-group integration. This enables higher-cadence trajectory-based searches using as few as a single JWST exposure. A generalized least-squares fit of the group difference images along the trajectory of a moving source recovers the source flux at higher SNR when compared to the ramp fit, with the improvement scaling with the reduction in trailing. We validate our procedure on 13 moving objects detected in archival JWST NIRCam images. To estimate our sensitivity increase, we perform an injection/recovery simulation on the JWST imagery. Trailed moving objects recovered via group differencing show higher SNRs, improving completeness to moving sources compared to standard calibrations. For typical integration lengths of $N=4$ or $6$ for archival JWST/NIRCam exposures in the ecliptic, group differencing yields sensitivity gains between $\sim 1.1$–$1.4$ mag, based on simulation results. This method significantly increases the sensitivity of archival JWST surveys to trailed SSSBs.
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Solar and Stellar Astrophysics · Cross-listed from cs.CV

Super-Resolution of Solar Magnetograms via Adaptive Stratified Ensemble Learning with Uncertainty Estimation

Sina Norouzi Kandalan, Haodi Jiang, Jason T. L. Wang et al. (+1 more)

Single-image super-resolution of Sun's photospheric magnetograms enables consistent analysis across heterogeneous space-based instruments and supports long-term studies of solar magnetic field evolution. We address the super-resolution task from SOHO/MDI (low-resolution) to SDO/HMI (high-resolution) line-of-sight (LOS) magnetograms using a modified RRDBNet architecture initialized by ESRGAN pretrained weights. Through systematic per-image diagnostic analysis, we identify image complexity as the dominant predictor of reconstruction errors. To exploit this finding, we introduce an adaptive stratified specialist ensemble (SSE) of three specialist networks with uncertainty estimation, where each specialist network is trained by images from three different complexity strata using a weighted random sampling strategy. During inference, a lightweight router based on input image statistics assigns each test image to the appropriate specialist network. Our experimental results demonstrate the good performance of the proposed ensemble and its superiority over closely related methods.
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All authors Sina Norouzi Kandalan, Haodi Jiang, Jason T. L. Wang, Qin Li

Astrophysics of Galaxies

Search for High-Ionization Nebular Emission (SHINE). I. A Systematically Selected [Ne V] Sample at z > 3 with JWST/NIRSpec PRISM

Shobita Satyapal, Sara Doan, Daniel Schaerer et al. (+8 more)

We conduct the first systematic Search for High-Ionization Nebular Emission (SHINE) using [Ne V]$\lambda3426$ in JWST/NIRSpec PRISM spectroscopy at $z>3$. From more than 9,000 galaxies, we identify 25 [Ne V] emitters spanning $z=3.059$-$9.444$ and $\log_{10}(L_{\rm [Ne\,V]}/erg\,s^{-1})=40.70$-$42.86$. Their [Ne V] luminosities overlap with those of local [Ne V]-selected active galactic nuclei (AGNs) and exceed those of local metal-poor [Ne V] emitters, although such low-luminosity systems would fall below our sensitivity. The population is diverse, spanning compact and extended morphologies and a broad range of continuum properties and stellar masses, including very low-mass hosts. It includes sources with broad Balmer emission as well as others whose higher-resolution spectra do not require a broad component. The [Ne V] emitters overlap only partly with conventional AGN diagnostics: most do not satisfy conservative high-redshift AGN criteria based on strong rest-optical narrow-line ratios, and only a minority have adopted broad-line classifications. [Ne V] upper limits for independently selected broad-line AGNs and little red dots are too shallow to establish a population-wide [Ne V] deficit. Six sources have secure Chandra counterparts, showing that X-ray weakness is not universal among luminous [Ne V] emitters. Strong [Ne V]/[Ne III] emission is associated with redder ultraviolet slopes and stronger Balmer breaks, but not with UV luminosity, possibly linking strong high-ionization emission to recent changes in star formation. The observed incidence of luminous [Ne V] emission shows no significant evolution over $z>3$, despite an increasing robust [Ne III] detection fraction. The high [Ne V] luminosities and hard line ratios favor black-hole accretion as the dominant power source, establishing [Ne V] emission as a complementary probe of early black-hole growth.
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All authors Shobita Satyapal, Sara Doan, Daniel Schaerer, Rui Marques-Chaves, Anurag Sawarkar, William Matzko, Camilo Vazquez, C. Daoutis, D. Korber, I. Morel, Mengyuan Xia

High Energy Astrophysical Phenomena

EP260119a: A High-Redshift Gamma-Ray Quiet Fast X-ray Transient Probing a Potentially Hidden Population of Relativistic Explosions

Camila Angulo-Valdez, Asuka Kuwata, Edilberto Aguilar-Ruiz et al. (+41 more)

Gamma-ray quiet fast X-ray transients (FXTs) provide a new approach for studying relativistic explosions that evade traditional gamma-ray triggers. In this work, we present multi-wavelength observations and analysis of EP260119a, a high-$z$ FXT detected by Einstein Probe/WXT and followed up with COLIBRÍ, the Liverpool Telescope, and other facilities. Spectroscopy yields a redshift of $z = 5.47$, making EP260119a the most distant FXT detected by Einstein Probe to date. Despite its luminous X-ray and optical emission, no prompt gamma-ray counterpart was detected by SVOM/ECLAIRs, SVOM/GRM, Swift/BAT, or Konus/Wind, despite contemporaneous coverage. The broadband afterglow is well described by synchrotron emission from a uniform relativistic jet propagating into a shallowly stratified external medium close to the constant-density limit, indicating a standard relativistic explosion despite the absence of detectable gamma rays. Occupying the extreme high-$z$ end of the growing Einstein Probe FXT sample, EP260119a supports the possibility that soft X-ray surveys are uncovering relativistic transients that remain undetected by current gamma-ray instruments. Our results indicate that some explosions in the early Universe escape conventional gamma-ray surveys and demonstrate the value of combining sensitive soft X-ray discovery with rapid optical follow-up to obtain a more complete view of the high-$z$ transient population.
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All authors Camila Angulo-Valdez, Asuka Kuwata, Edilberto Aguilar-Ruiz, Rosa L. Becerra, Ramandeep Gill, Miguel Angel Aloy, Antonio de Ugarte Postigo, Alan M. Watson, Chen-Wei Wang, Diego López-Cámara, Daniel A. Perley, Aleksandra Bochenek, Simone Dichiara, Enrique Moreno Méndez, Nathaniel R. Butler, Benjamin Schneider, Jean-Luc Atteia, Stéphane Basa, William H. Lee, Dalya Akl, Sarah Antier, Alexis Coleiro, James DeLaunay, Damien Dornic, Jean-Grégoire Ducoin, Francis Fortin, Dmitry Frederiks, Leonardo García-García, Noémie Globus, Olivier Godet, Jamie Kennea, Gianluca Lombardi, Alexandra L. Lysenko, Francesco Magnani, Tyler Parsotan, Margarita Pereyra, Anna Ridnaia, Samuele Ronchini, Fredd Sánchez-Álvarez, Dmitry Svinkin, Anastasia Tsvetkova, Mikhail Ulanov, Peter Veres, Hui Yang

Astrophysics of Galaxies

Sequential Star-Formation and the Near-Infrared Stellar Populations within N159

Nolan Habel, E. Sabbi, Peter Zeidler et al. (+19 more)

We present the first results from a JWST/NIRCam study of the star-forming region N159, one of the richest H II complexes in the Large Magellanic Cloud. This region stretches over $\sim$130 pc, and exemplifies large-scale sequential star formation. We present photometric results of $>$300,000 point sources combining data from ten near-infrared JWST filters spanning 1-4.7 microns. We detect sources as faint as $\sim$27 magnitudes at F115W, corresponding to stellar masses reaching below $\sim$0.1 $M_{\odot}$. By constructing several color-magnitude and color-color diagrams, we separate young stars from main-sequence and older stars within N159, finding evidence for stellar populations younger than 0.5 Myr. Of the young population, we identify accreting, pre-main sequence stars from their Paschen-$\alpha$ (Pa$\alpha$) excess and a population of sources bearing strong infrared (IR) excess, representing candidate young stellar objects (YSOs). Within this population, we identify a subpopulation of sources with H$_2$O ice absorption. The IR-excess-bearing YSO candidates correlate spatially with dust filaments and molecular gas demonstrating their embedded state. The distribution of stellar and candidate YSO populations across N159 reveal more evolved star-forming populations in the N159E region and newer star formation in the N159W region, supporting the sequential star formation scenario for this region.
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All authors Nolan Habel, E. Sabbi, Peter Zeidler, Tuila Ziliotto, Laurie Chu Margaret Meixner, Guido De Marchi, O. C. Jones, Alec S. Hirschauer, Beena Meena, Jeroen Jaspers, Laura Lenkic, Remy Indebetouw, Karl D. Gordon, Burcu Gunay, Suzanne Madden, James Muzerolle Page, Omnarayani Nayak, Antonella Nota, Theo Oneill, Massimo Robberto, Tony Wong, Petia Yanchulova Mercia-Jones

Astrophysics of Galaxies

A High Resolution View of Three Massive Young Stellar Objects in the Magellanic Clouds

Yu Cheng, Kei I. Tanaka, Takashi Shimonishi et al. (+4 more)

The Magellanic Clouds provide an excellent laboratory to study massive star formation beyond typical Galactic environments. Using ALMA band 7 long-baseline observations, we present the highest resolution (approximately 0.03", $1500{\rm\:au}$) view to date of three massive young stellar objects (MYSOs) in the Magellanic Clouds, i.e., Lh03 and Lh09 in the LMC, and S07 in the SMC. The 0.87 mm continuum, with a sensitivity of $\sim30\:\mu$Jy beam$^{-1}$, reveals varying levels of fragmentation, from a single compact source (S07), a few (Lh03), to a cluster of compact sources (Lh09). In Lh09, we identified 17 core candidates with lowest measured mass of 2.6 Msun, and their de-projected separations peak around 6000~au. All three targets exhibit high velocity CO(3–2) outflows, including detection of a collimated bipolar jet driven by a core in Lh09. Spectral lines from HCO$^+$, SO, and SO$_2$ are detected in all sources. We observe velocity gradients that likely trace rotating toroids (Lh03) or more complex motions (Lh09, S07). Taken together, these phenomena observed on $\sim1500$~au scales are qualitatively similar to those seen in Galactic MYSOs, suggesting a degree of universality in the basic processes of massive star formation across different environments. Nevertheless, the substantial source-to-source diversity in continuum morphology and dense-gas kinematics motivates larger high-resolution surveys to determine how these properties vary with source characteristics and environment.
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All authors Yu Cheng, Kei I. Tanaka, Takashi Shimonishi, Yichen Zhang, Suinan Zhang, Kenji Furuya, Asako Sato

Astrophysics of Galaxies

New Optical and Mid-Infrared RR Lyrae Period-Luminosity-Metallicity Relations for Precision Distances and Metallicity Distributions in the Magellanic Clouds

Clara E. Martínez-Vázquez, Joseph P. Mullen, Massimo Marengo et al. (+11 more)

RR Lyrae (RRL) stars, thanks to the existence of their period-luminosity relations, have been widely used as primary standard candles within the Milky Way and the Local Group of galaxies. We present in this work the latest empirical RRL period-luminosity-metallicity (PLZ) and period-Wesenheit-metallicity (PWZ) relations combining optical ($V, I$) and mid-infrared data ($W1$) using OGLE and WISE photometry, anchored to Gaia DR3 parallaxes. We calibrate these relations with the largest, most complete, and homogeneous catalog of Galactic halo field RRL spectroscopic metallicities. These new PLZ/PWZ relations provide distance measurements in remarkable agreement with those derived from eclipsing binaries in the Large and Small Magellanic Clouds (MC): $(m-M)_{0, LMC} = 18.47 \pm 0.07 (stat) \pm 0.05 (sys)$ mag and $(m-M)_{0, SMC} = 18.87 \pm 0.09 (stat) \pm 0.06 (sys)$ mag (within 1% and 10% of eclipsing binary distances, respectively). We have also re-calibrated photometric metallicity relations to derive individual [Fe/H] abundances of LMC and SMC RRL stars. This allowed us to investigate the metallicity gradient of the MCs and discover two distinct populations of fundamental mode RRL stars in the LMC (only one is instead found in the SMC). Our newly derived mid-infrared period-luminosity relations are poised to become an essential tool to derive precise distances of older stellar populations in the Local Group of galaxies, and can easily be adapted to observations obtained in JWST NIRCam photometric bands.
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All authors Clara E. Martínez-Vázquez, Joseph P. Mullen, Massimo Marengo, Giuseppe Bono, Vittorio F. Braga, Santi Cassisi, Brian Chaboyer, Massimo Dall'Ora, Valentina D'Orazi, Michele Fabrizio, Giuliana Fiorentino, Matteo Monelli, Peter B. Stetson, Frédéric Thévenin

Astrophysics of Galaxies

The galactic HI-to-halo mass relation from isolated galaxies to cosmological hydrodynamic simulations

Marie Korsaga, Jonathan Freundlich, Benoit Famaey et al. (+15 more)

The relation between HI and dark matter (DM) halo masses provides key insights into gas accretion and the regulation of galaxy formation. In a previous study based on SPARC and LITTLE THINGS samples, we showed that the ratio between HI mass and DM halo mass remains approximately constant with stellar mass for nearby disc galaxies ($\log(M_{HI}/M_{200})=-1.90$ with a $1\sigma$ scatter of 0.37 dex). In this work, we extend that analysis by incorporating galaxies from the Analysis of the interstellar Medium in Isolated GAlaxies (AMIGA) sample and from the Gassendi HAlpha survey of SPirals (GHASP). The AMIGA sample provides the most rigorously selected sample of isolated galaxies in the local Universe, well-suited for testing whether the relation found in the previous samples holds in interaction-free galaxies. We construct mass models from high-resolution rotation curves and infrared photometry, and derive DM halo parameters. We confirm the proportionality between HI and DM halo masses and find a nearly constant HI-mass-to-halo-mass ratio of $\log(M_{HI}/M_{200})=-1.90$ over nearly five orders of magnitude in stellar mass ($7\leq\log(M_{\star}/M_\odot)\leq 11.5$), with a $1\sigma$ scatter of 0.36 dex. The AMIGA and GHASP samples are statistically consistent with the relation previously found for the SPARC and LITTLE THINGS samples, indicating that it is robust across galaxies spanning a broad range of isolation levels. In contrast, cosmological hydrodynamic simulations such as SIMBA, IllustrisTNG, and NIHAO predict a dependence on stellar mass, with a break at the high stellar mass end for disc galaxies ($M_{\star}>10^{10}M_{\odot}$). Our results thus further demonstrate that the HI-mass-to-halo-mass ratio is remarkably self-similar across rotationally-supported disc galaxies, hinting at mass-independent self-regulation mechanisms that are not yet understood in current theoretical models.
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All authors Marie Korsaga, Jonathan Freundlich, Benoit Famaey, Lourdes Verdes-Montenegro, Amidou Sorgho, Federico Baraggioni, Andrea V. Maccio, Katarina Kraljic, Laurent Chemin, Peter Kamphuis, Philippe Amram, Benoit Epinat, Roger Ianjamasimanana, Martin Bureau, Pandora Dominiak, Brenda Namumba, Julian Garrido, Susana Sanchez-Exposito

Astrophysics of Galaxies

CECILIA: Multi-line Constraints on Excess Nebular Emission from Low-Ionization Gas at Cosmic Noon

Caroline von Raesfeld, Allison L. Strom, Audrey Clarendon et al. (+7 more)

Spectroscopy from JWST has offered unique insights into elemental abundance patterns at Cosmic Noon (z~2-3), most notably a growing census of sub-solar S/O. These new measurements, coupled with new observations of [O I]{\lambda}6302 at z>1, motivate an updated study of neutral and low-ionization emission within Cosmic Noon galaxies. In this letter, we present a new analysis of [O I]{\lambda}6302 and [S II]{\lambda}{\lambda}6718,33 in 19 galaxies observed using ultra-deep JWST/NIRSpec spectroscopy as part of the CECILIA survey. We find that it is necessary to consider sub-solar abundance patterns in sulfur at high-z when analyzing galaxies on the S2-BPT, and that this correction reveals the potential of additional emission sources in CECILIA galaxies. Using the photoionization model emulator Cue, we find that ~48% of observed [S II] and ~55% of observed [O I] emission in CECILIA galaxies cannot be reproduced by conventional HII region models. We find no clear evidence for turbulence or shocks driving this excess emission when comparing to existing models. Our findings imply that this excess emission may originate in diffuse ionized gas outside of H II regions, though its nature may be different than that of low-z DIG. Further, we find that including emission from gas outside of star-forming regions can incur a small bias up to 0.1 dex in 12+log(S/H).
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All authors Caroline von Raesfeld, Allison L. Strom, Audrey Clarendon, Noah S.J. Rogers, Yijia Li, Nathalie A. Korhonen Cuestas, Gwen C. Rudie, Ryan F. Trainor, Menelaos Raptis, Zhuyun Zhuang

High Energy Astrophysical Phenomena

Disk truncation triggers relativistic jet launching of a highly accreting supermassive black hole

Hirofumi Noda, Kazuhiro Hada, Hiroto Maruyama et al. (+10 more)

Relativistic jets are among the most energetic phenomena in the Universe and influence galaxy evolution through energetic feedback, yet the physical connection between accretion flows and jet launching remains unresolved. Jet production is widely attributed to the Blandford-Znajek mechanism, which extracts black hole rotational energy via large-scale magnetic fields sustained by an accretion flow. Although this mechanism is observationally well supported for hot, geometrically-thick accretion flows, highly accreting environments with strong jets present a paradox, as they are typically dominated by cold, geometrically-thin disks incapable of sustaining large-scale magnetic fields. Here, we report coordinated X-ray microcalorimeter spectroscopy achieved by X-ray Imaging and Spectroscopy Mission (XRISM) and millimeter/radio interferometric observations by Global Millimeter VLBI Array (GMVA), Very Long Baseline Array (VLBA), and East Asian VLBI Network (EAVN) on the broad-line radio galaxy 3C120. High-resolution X-ray spectroscopy reveals a relativistically-broadened Fe-K$\alpha$ line, indicating that the cold, geometrically-thin disk is truncated at $\sim 20~R_{\rm g}$ ($R_{\rm g}$ is the gravitational radius), with the inner region replaced by a hot, geometrically-thick flow. Concurrently, radio imaging indicates that jet profile extrapolation toward the black hole horizon yields a radius comparable to or even narrower than the disk truncation radius. These results demonstrate that, even at high accretion rates, jet launching is linked to a hot inner flow, possibly via the Blandford-Znajek process, providing evidence for a universal disk-jet connection via geometric transition.
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All authors Hirofumi Noda, Kazuhiro Hada, Hiroto Maruyama, Taishu Kayanoki, Kenji Toma, Taiki Kawamuro, Yoshiyuki Inoue, Tomohisa Kawashima, Soyeon Yeo, Ilje Cho, Keiichi Asada, Yasushi Fukazawa, Yoshihiro Ueda

Instrumentation and Methods for Astrophysics · Cross-listed from physics.ed-ph

A Simple Miniaturized Stellar Interferometer: Measuring the Angular Diameter of Venus with a Masked Telescope

Eric J. Friedman and Michelle Goman

We describe a simple, visually compelling demonstration/laboratory of astronomical interferometry using a standard planetary telescope and a thin piece of opaque plastic punched with two small holes. By observing the disappearance of interference fringes as the hole spacing is increased, students can directly estimate the angular diameter of Venus. The demonstration is a tabletop analogue of the landmark 1921 Michelson-Pease measurement of Betelgeuse and scales naturally from that measurement: where Michelson and Pease required a 6.1 m baseline to resolve a disk 47 mas (milli-arcsecond) across, a 15 mm baseline suffices for Venus, when it is approximately 10-15$''$ (arc seconds). The lab works reliably in ordinary atmospheric seeing conditions, and a side-by-side comparison of Venus (or Jupiter) with a bright star such as Sirius provides an immediate visual demonstration of the difference between extended and point sources. It works equally well as a laboratory at a variety of difficulty levels. Furthermore, it does not require advanced knowledge or skills with optical telescopes. While the underlying ideas are well known, we are unaware of any source that presents them in an accessible, unified form.
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High Energy Astrophysical Phenomena

In-Situ Star Formation in a Thick Disk: A Model for Metal Enrichment of Mrk 573

Hannalore J. Gerling-Dunsmore, Mitchell C. Begelman, Jared A. Goldberg et al. (+2 more)

Recent observations of the nearby Seyfert galaxy Mrk 573 found that the galactic nucleus and bicone regions surrounding the jet are significantly metal-enriched. In this paper, we develop a simple model for the observed metal enrichment, assuming a population of stars in the $10 - 30 \, M_{\odot}$ range formed in-situ in the accretion disk. We assume the stars form according to a Salpeter initial mass function and generate the typical metal yields expected of field stars of the same mass. We find that in the thick disk ($H/r \sim 0.1$) case, a Salpeter population of stars can easily explain the observed metal enrichment and provide limits on the formation model; we also argue that a thin disk ($H/r \lesssim 0.01$) is incompatible with the observed metal enrichment. In our model, AGN metallicity scales most strongly with disk thickness, implying a potentially powerful observable diagnostic.
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All authors Hannalore J. Gerling-Dunsmore, Mitchell C. Begelman, Jared A. Goldberg, Taeho Ryu, Dominika Ł. Król

Solar and Stellar Astrophysics

A Multiband Catalog of Infrared-Excess Sources in the Vela-Carina Region: VVVX, DECaPS, and GLIMPSE

R. M. Torres, R. K. Saito, V. Fermiano et al. (+4 more)

Multiwavelength surveys of the Galactic midplane enable the identification of infrared-excess sources, signatures of circumstellar material, though high extinction and crowding hinder detection. We construct a homogeneous catalog of infrared-excess candidates in a $\sim$7.0 deg$^2$ field of the Vela-Carina region, characterizing their excess emission via spectral energy distribution (SED) analysis. We combine optical photometry from DECaPS, near-infrared photometry from VVVX, and mid-infrared photometry from Spitzer/GLIMPSE using hierarchical positional cross-matching. Candidates are selected via photometric quality and MIR color diagnostics, and their SEDs are analyzed with VOSA using theoretical atmosphere model grids. Photogeometric distances are adopted, while Gaia DR3 and NEOWISE variability provide complementary diagnostics. From the matched 249,719-source VVVX-GLIMPSE-DECaPS catalog, we identify 1,512 MIR-excess objects, of which 191 have complete 12-band photometry with S/N > 10, enabling detailed SED analysis. Photogeometric distances are statistically consistent with geometric distances for nearly the entire sample. SED analysis independently supports the MIR-excess nature of most sources, indicating emission beyond stellar photospheres. About 15% of sources are flagged variable by Gaia, while NEOWISE light curves reveal MIR variability of a few tenths of a magnitude. Comparisons with published YSO and variability-selected catalogs show limited overlap, particularly with variability-selected samples, indicating that MIR-excess selection complements other approaches to identifying candidate YSOs in the Vela-Carina region. The resulting catalog provides a well-defined MIR-excess sample with homogeneous multiband photometry, SED characterization, distances, and variability diagnostics, forming a foundation for future spectroscopic and time-domain studies.
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All authors R. M. Torres, R. K. Saito, V. Fermiano, P. Esteves, B. W. Borges, D. Quispe, D. Minniti