Earth and Planetary Astrophysics
Dust Properties of the Interstellar Object 3I/ATLAS Revealed by Optical and Near-Infrared Polarimetry
Seungwon Choi, Masateru Ishiguro, Jun Takahashi et al. (+17 more)
We present independent polarimetric observations of the interstellar object 3I/ATLAS, including the first near-infrared polarimetric measurements. Using imaging polarimeters, we measured the degree of linear polarization from the visible RC band (0.64 {\mu}m) to the near-infrared KS band (2.25 {\mu}m), and investigated its dependence on
solar phase angle (polarization phase curve; PPC) and wavelength (polarization color curve; PCC). We confirm that the PPC of 3I/ATLAS differs significantly from those of typical
Solar System comets, showing an unusually large polarization amplitude. This PPC shows no significant change in the RC band across perihelion passage, despite the perihelion lying within the water snow line. This indicates that the unusual polarimetric behavior of 3I/ATLAS is unlikely to be driven by transient volatile activity, but instead reflects intrinsic optical properties of refractory
dust particles. The PCC increases with wavelength over 0.6-1.2 {\mu}m and peaks at 1.5-2.0 {\mu}m, suggesting that the dominant scattering units are
dust aggregates composed of submicron-sized monomers, broadly consistent with interstellar
dust and
solar-system cometary aggregates. Taken together, our results indicate that 3I/ATLAS preserves polarimetric properties characteristic of a primitive cometary planetesimal formed in another planetary system, with a refractory
dust composition that differs from that typically observed among
Solar System comets, despite sharing a similar size scale of the aggregate building blocks.
Read the full abstract ▾
All authors Seungwon Choi, Masateru Ishiguro, Jun Takahashi, Tomoki Saito, Yoonsoo P. Bach, Bumhoo Lim, Hiroyuki Naito, Jooyeon Geem, Sunho Jin, Jinguk Seo, Hyeonwoo Ju, Hiroshi Akitaya, Koji S. Kawabata, Mahito Sasada, Kazuya Doi, Hisayuki Kubota, Seiko Takagi, Makoto Watanabe, Tomohiko Sekiguchi, Myungshin Im
Astrophysics of Galaxies
On the Interstellar Extinction Curve toward HD 93222, A Sightline with an Exceedingly Narrow 2175 Angstrom Extinction Bump
Qian Wang, Aigen Li and Xuejuan Yang
The 2175 Angstrom extinction bump, the most prominent spectral feature superimposed on the interstellar extinction curve, is widely seen in the interstellar medium (ISM) of the Milky Way and external
galaxies, both near and far. While its central wavelength is remarkably stable and independent with environment, its width shows considerable variation and environmental dependence. Here we examine the extinction curve for the line of sight toward HD 93222, a young
star located in the Carina nebula. It is found that the 2175 Angstrom bump is extremely sharp, which is among the narrowest ever found in the Milky Way and external
galaxies. We model the derived extinction curve and find that, to explain the extinction characteristics of HD 93222, in addition to the conventional silicate and graphite
dust mixture, an additional population of nano-sized graphitic grains is required.
Read the full abstract ▾
Solar and Stellar Astrophysics
Substellar population of the young massive cluster RCW 36 in Vela
A. R. G. do Brito do Vale, K. Mužić, H. Bouy et al. (+10 more)
The initial mass function (IMF) is a cornerstone of
star formation studies, yet its universality remains debated. We investigate the IMF in the young massive cluster RCW 36, located in the Vela Molecular Ridge and comparable to the Orion Nebula Cluster in
stellar density. Our goal is to build the most complete census of RCW 36 and derive its first IMF and
star-to-brown-
dwarf (BD) ratio. We combine new GLAO observations from HAWK-I/VLT with archival data (2MASS, SOFI/NTT) and
Gaia DR3 kinematics. Photometric accuracy and source extraction were improved using DeNeb, a deep-learning
algorithm that removes complex nebular emission. Membership probabilities were assigned via color-magnitude diagram comparisons with a control field, and
stellar masses were estimated using model isochrones. We find a revised distance of $954\pm40\,$pc and determine the IMF down to $\sim0.03\,M_{\odot}$, described by a broken power law ($dN/dM\propto M^{-\alpha}$) with $\alpha=1.62\pm0.03$ for $0.20$-$20\,M_{\odot}$ and $\alpha=0.46\pm0.14$ for $0.03$-$0.20\,M_{\odot}$. The
star-BD ratio is $2$-$5$, consistent with other
Galactic clusters. Lastly, through a study of the differences in the IMF within and outside $0.2\,$pc and the cumulative mass distributions for low-mass and intermediate to high-mass sources, we also detected signs of possible mass segregation within RCW 36, which should be
primordial. RCW 36 shares many characteristics with other young massive clusters, such as a shallower than Salpeter high-mass slope and the possibility of mass segregation. The flatter lower-mass regime of the IMF is similar to most
Galactic clusters. The
star-BD ratio is also in line with the observed values in other clusters, independent of their inherent properties.
Read the full abstract ▾
All authors A. R. G. do Brito do Vale, K. Mužić, H. Bouy, V. Almendros-Abad, A. Bayo, D. Capela, A. Scholz, A. Bik, G. Suárez, L. Cieza, K. Peña Ramírez, E. Bertin, R. Schödel
Cosmology and Nongalactic Astrophysics
Reconstructing Gamma Ray Burst Energy Relations with Observational H(z) data in Neural Network Framework
Nilanjana Bagchi Aurpa, Abha Dev Habib and Nisha Rani
Gamma-ray bursts (GRBs) offer a powerful probe of the
cosmic expansion history far beyond the
redshift range accessible to Type Ia
supernovae. However, the study of cosmological models using GRBs is hindered by the circularity problem, which arises from assuming a fiducial cosmological model during GRB luminosity distance calibration. In this work, we perform a model-independent calibration of GRB luminosity relations using observational measurements of the Hubble parameter from the A220 and J220 compilations, thereby avoiding explicit cosmological assumptions. We employ an Artificial Neural Network to reconstruct the calibration relation directly from the data. In addition, we implement a
Bayesian Neural Network framework as an alternative approach, enabling a data-driven treatment of both statistical and systematic uncertainties. The calibrated GRB sample is used to constrain the Amati relation, and we systematically compare the outcomes obtained from different calibration techniques and
datasets. We find that the Amati relation slopes derived from the two neural network approaches are consistent with each other and with previous low-
redshift calibrations obtained using model-independent methods. The
Bayesian Neural Network approach provides a more robust framework for propagating uncertainties in the calibration procedure.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Radio timing constraints on the orbital orientation and component masses of PSR J1455$-$3330
D.S. Pillay, V. Venkatraman Krishnan, David J. Champion et al. (+15 more)
PSR J1455$-$3330 is a $\sim$7.98 ms
pulsar in a $\sim$76.17 day nearly circular orbit with a white
dwarf companion. In this work, we combine the available Lovell, Nançay decimetric
Radio Telescope, Green Bank, and MeerKAT
pulsar timing data spanning $\sim$ 30 years to measure the kinematic and relativistic effects of PSR J1455$-$3330 to constrain its 3D orbital geometry and component masses. We detect a relativistic Shapiro delay signal. We measure a significant orthometric amplitude $h_3 = 0.307^{+0.022}_{-0.026}$ $\mu$s and an orthometric ratio $\varsigma = 0.551^{+0.057}_{-0.054}$. We measure the change in projected semi-major axis $\dot{x} = -202.1^{+2.5}_{-2.7} \times10^{-16} \, \rm s\,s^{-1}$ with high significance, parallax, $\varpi$ = 1.11(6) mas, parallax derived distance 0.90(5) kpc, and a precise total proper motion magnitude of 12.432(2) mas yr$^{-1}$. A self-consistent analysis of all kinematic and relativistic effects, assuming general relativity, yields two solutions: (1) a
pulsar mass $M_{\rm p} = 1.39^{+0.38}_{-0.18}\, \rm M_{\odot}$, a companion mass $M_{\rm c} = 0.293^{+0.056}_{-0.026}$ $\rm M_{\odot}$, an orbital inclination, $i = 63(2)^{\circ}$, and longitude of the ascending node, $\Omega = 212(12)^{\circ}$ or (2) a
pulsar mass $M_{\rm p} = 1.53^{+1.10}_{-0.22} \, \rm M_{\odot}$, a companion mass $M_{\rm c} = 0.309^{+0.163}_{-0.026}\, \rm M_{\odot}$, an orbital inclination, $i = 123(4)^{\circ}$, and longitude of the ascending node, $\Omega = 334(12)^{\circ}$. All uncertainties represent the 68.27$\%$ credibility region. These results strongly favour a helium-dominated white
dwarf companion.
Read the full abstract ▾
All authors D.S. Pillay, V. Venkatraman Krishnan, David J. Champion, P. C. C. Freire, M. Kramer, L. Guillemot, M. Bailes, A. Corongiu, M. Geyer, J. Singha, R. M. Shannon, G. Theureau, I. Cognard, M. J. Keith, B. W. Stappers, J. Antoniadis, K. Liu, G. M. Shaifullah
Cosmology and Nongalactic Astrophysics
Revisiting the Great Attractor: The Local Group's streamline trajectory, cosmic velocity and dynamical fate
Richard Stiskalek, Harry Desmond, Stuart McAlpine et al. (+3 more)
We revisit the Great Attractor using the Manticore-Local suite of digital twins of the nearby Universe. The Great Attractor concept has been proposed as an answer to three distinct questions: what sources the Local Group velocity in the
cosmic microwave background frame, where present-day velocity streamlines converge, and where the Local Group is moving to. Addressing the original motivation of the Great Attractor – explaining the Local Group
cosmic velocity – we find that mass within $155~h^{-1}\mathrm{Mpc}$ accounts for only ${\sim}72\%$ of that velocity magnitude with ${\sim}38\,\deg$ directional offset. We show that even in the purely linear regime convergence within this volume is not guaranteed, particularly when also accounting for small-scale contributions to the observer velocity; no single structure, including the proposed Great Attractor, would be expected to dominate the velocity budget. Streamline convergence is smoothing-scale-dependent, transitioning from Virgo at small scales through the Hydra–Centaurus region at intermediate scales to Shapley at large scales; at intermediate smoothing the convergence point lies near Abell 3565 with an asymmetric basin of mass $\log( M / (h^{-1} \mathrm{M}_\odot)) = 16.4 \pm 0.1$ that excludes Norma. To address the third question, we evolve the Manticore-Local realisations to scale factor $a = 10$ in a new Beyond-Present-Time simulation suite and identify the asymptotic future location of the Local Group. We find that the dominant motion is towards Virgo, but even it contributes at most one third of the Local Group velocity. Our results demonstrate that the classical Great Attractor is not a dynamically dominant structure but an artefact of the instantaneous velocity field, and that no single attractor is likely to account for the Local Group motion in the
cosmic rest frame.
Read the full abstract ▾
All authors Richard Stiskalek, Harry Desmond, Stuart McAlpine, Guilhem Lavaux, Jens Jasche, Michael J. Hudson
Solar and Stellar Astrophysics
Thermal-timescale accretion does not always yield critical rotation in mass gainers
Chen Wang, Mike Y.M. Lau, Xiang-Dong Li et al. (+7 more)
Binary
evolution plays a central role in producing rapidly rotating
stars. Previous studies have shown that mass gainers in binaries can reach critical rotation after accreting only modest amounts of material, particularly during thermal-timescale Case B mass transfer, where
tidal spin-down is ineffective due to wide orbits. However, such rapid
accretion often drives the mass gainer out of thermal
equilibrium, and its subsequent
spin evolution during thermal relaxation has not been analysed in depth. In this study, we construct a suite of accreting detailed single-
star models with different
accretion prescriptions, which inflate and
spin up to critical rotation during the
accretion. After the
accretion has ended, the models relax thermally and deflate. We find that the ratio of surface to critical angular velocity decreases to subcritical values during thermal contraction, with the magnitude of this decrease correlating with the degree of thermal disequilibrium at the end of
accretion. This reduction in fractional critical rotation is even stronger when internal angular momentum transport is inefficient. Detailed binary models show the same trend, indicating that the results from our toy single-
star models also apply to real binary
evolution. Our results highlight that binary mass transfer does not always produce critically rotating
stars, but instead may yield a wide range of
spin rates depending on the mass transfer and
accretion history. Our findings offer new insights into the rotational properties of mass gainers in binaries,
stellar merger products, and newly formed massive
stars following
accretion.
Read the full abstract ▾
All authors Chen Wang, Mike Y.M. Lau, Xiang-Dong Li, Norbert Langer, Selma E. de Mink, Ruggero Valli, Stephen Justham, Xiao-Tian Xu, Jakub Klencki, Taeho Ryu
Earth and Planetary Astrophysics
On the estimation of Sulfuric Acid Vapor concentrations below the Venus cloud deck using the Akatsuki Radio Science Experiment
S. Banerjee, R. K. Choudhary, K. R. Tripathi et al. (+2 more)
We report new constraints on the vertical distribution of sulfuric acid vapor in the Venusian atmosphere, derived from a refined analysis of
radio occultation (RO) data. The method estimates the power spectral density (PSD) of the received signal to recover both the signal intensity and the Doppler shift. The received signal power is estimated at 1-sec cadence which enhances the sensitivity and detection of the signal at lower altitudes of Venus, even in regions of high atmospheric opacity. After correcting total attenuation for refractive losses, absorption by known microwave absorbers is removed, leaving a residual signal attributable to sulfuric acid vapor. Two different methods of estimating the absorption due to Sulfur Dioxide have been presented, including one which incorporates in-situ data, which should better constrain the sulfuric acid vapor abundance below the clouds. Retrieved profiles for altitudes of 40 - 50 km reveal an increasing vapor abundance to more than 10 ppm below the clouds, and a sharp decline above 50 km in line with the expected saturation profile. These measurements agree with current models of the Venusian cloud structure and composition, and demonstrate that RO data, when coupled with optimized spectral analysis, can yield quantitative constraints on trace absorbers in optically thick atmospheres.
Read the full abstract ▾
All authors S. Banerjee, R. K. Choudhary, K. R. Tripathi, T. Imamura, H. Ando
Cosmology and Nongalactic Astrophysics
A new magnitude–redshift relation based on Type Ia supernovae
Ósmar Rodríguez and Alejandro Clocchiatti
We present a new empirical relation between the standardized magnitude ($m$) of Type Ia
supernovae (SNe Ia) and
redshift ($z$). Using Pantheon+ and DES-SN5YR, we find a negative linear correlation between $m-5\log(z(1+z))$ and $z$, implying that their magnitude–
redshift relation can be parametrized with just two parameters: an intercept $\mathcal{M}$ and a slope $b$. This relation corresponds to the luminosity distance $d_L(z)=c\,H_0^{-1}z(1+z)10^{bz/5}$ and is valid up to at least $z\simeq1.1$. It outperforms the $\Lambda$CDM and flat $w$CDM models and the (2,1) Padé approximant for $d_L(z)$, and performs comparably to the flat $\Lambda$CDM model and the (2,1) Padé($j_0=1$) model of Hu et al. Furthermore, the relation is stable in the absence of low-$z$ SNe, making it suitable for fitting Hubble diagrams of SNe Ia without the need to add a low-$z$ sample. In deep fields in particular, assuming that the large-scale density is independent of the comoving radial coordinate, $b\propto q_0+1$. We fit the empirical relation to SN data in eight deep-field regions and find that their fitted $\mathcal{M}$ and $b$ parameters are consistent within $1.6\,\sigma$, in agreement with isotropy. The inferred $q_0$ values, ranging from $-0.6$ to $-0.4$, are consistent within $1.5\,\sigma$ and significantly lower than zero, indicating statistically consistent
cosmic acceleration across all eight regions. We apply the empirical relation to the DES-Dovekie and Amalgame SN samples, finding $b$ values consistent with those from DES-SN5YR and Pantheon+. Finally, using the empirical relation in the hemispheric comparison method applied to Pantheon+ up to $z=1.1$, we find no evidence for anisotropies in $\mathcal{M}$ and $b$.
Read the full abstract ▾
Astrophysics of Galaxies
Local Group analogues in a cosmological context – I. Relating velocity structure to the cosmic web
Kai Wang, Peder Norberg, Azadeh Fattahi et al. (+1 more)
Our Local Group, dominated in mass by the Milky Way (MW) and M31, provides a unique laboratory for testing $\Lambda$CDM cosmology on small scales owing to its proximity. However, its connection to the surrounding large-scale environment, which is essential for interpreting its properties, is inadequately understood. In this work, we explore the connection between Local Group analogues (LGAs) and their surrounding large-scale environments using the ABACUSSUMMIT simulation suite, highlighting the key role of the coupling energy of the MW-M31 orbit, $E_{\rm coupling}$. We find that LGAs with high $E_{\rm coupling}$ preferentially reside in denser regions, whereas those with low $E_{\rm coupling}$ tend to occupy low-density environments. Furthermore, LGAs with low $E_{\rm coupling}$ exhibit strong
alignment with
cosmic filaments, manifested as a pronounced polar anisotropy in the distribution of tracer
haloes. By contrast, LGAs with high $E_{\rm coupling}$ show a weaker polar anisotropy but an enhanced azimuthal anisotropy, with large-scale tracer
haloes preferentially lying in the plane spanned by the
halo pair and the orbital
spin vector. Within this framework, our Local Group is characterised by typical $E_{\rm coupling}$ residing in a relatively under-dense environment, yet it remains consistent with the 95% range of analogue systems identified in the simulation.
Read the full abstract ▾
All authors Kai Wang, Peder Norberg, Azadeh Fattahi, Louis E. Strigari
Instrumentation and Methods for Astrophysics
Polychromatic pyramid wavefront sensor with MKID technology for high contrast imaging
Aurélie Magniez, Charlotte Z. Bond, Peter Wizinowich et al. (+2 more)
The high sensitivity of the pyramid wavefront sensor has made it the preferred sensor in high contrast adaptive optics systems. Future higher contrast systems, like the Extremely Large
Telescope's Planetary Camera System, will require higher performance wavefront sensing. A further performance improvement could be achieved with a polychromatic pyramid wavefront sensor by using additional information over a broader wavelength range. The development of such systems is becoming more feasible with the emergence of new detector technologies such as Microwave Kinetic Inductance Detector arrays. These are arrays of
superconductor detectors that give a position, arrival time and measure of the energy for each incident
photon. This paper introduces the polychromatic pyramid wavefront sensor concept by defining the technologies and techniques employed and their requirements. A method is developed to track the optical gains, taking advantage of the additional wavelength information, and used to compensate for optical gains within an optimised reconstructor to minimise noise propagation. An overview of expected performance improvement, using end-to-end simulations, is provided using the Keck II adaptive optics system as a reference design. The polychromatic pyramid wavefront sensor was shown to increase the limiting magnitude by 1 to 2 magnitudes, and the contrast by factors of 1.5 to 4, versus single band pyramid wavefront sensors, by sensing over a wavelength range approximately five to ten times broader (800-1800 nm) compared to Z band (152 nm wide) and H band (300 nm wide). Practical design and implementation issues have also been considered.
Read the full abstract ▾
All authors Aurélie Magniez, Charlotte Z. Bond, Peter Wizinowich, TIm Morris, Kieran O'Brien
Earth and Planetary Astrophysics
Anatomy of Empirical Transit Spectra of Mars based on TGO/NOMAD
Shohei Aoki, Yuka Fujii, Hideo Sagawa et al. (+10 more)
Transit spectroscopy is a powerful tool for probing atmospheric structures of
exoplanets. Accurately accounting for the effects of aerosols is key to reconstructing atmospheric properties from transit spectra, yet this remains a significant challenge. To advance this effort, it is invaluable to examine the spectral features of well-characterized planetary atmospheres. Here, we synthesize empirical transit spectra of Mars across different seasons based on data from the NOMAD's
Solar Occultation channel onboard ExoMars/TGO, which operates at wavelengths of 0.2-0.65 and 2-4 micron. In the generated empirical transit spectra, the atmosphere below 25 km is found to be largely opaque due to the presence of micron-sized
dust and water ice clouds, both of which substantially weaken spectral features. The spectra exhibit CO2 absorption features at 2.7-2.8 micron and signatures of sub-micron-sized mesospheric water ice clouds around 3.1 micron, accompanied by a continuum slope. The amplitudes of these spectral features are found to vary with the Martian seasons, where the
dust storms weaken the CO2 signatures and strengthen the water ice features, which serve as potential indicators of a dusty
planet like Mars. If TRAPPIST-1f possessed a Mars-like atmospheric structure, both CO2 and water ice features would be detectable at a noise level of 3 ppm, a level likely beyond current observational capabilities. Nevertheless, the 3.1 micron feature produced by sub-micron-sized mesospheric water ice clouds offers a novel avenue for characterizing the atmospheres of habitable-zone
exoplanets.
Read the full abstract ▾
All authors Shohei Aoki, Yuka Fujii, Hideo Sagawa, Geronimo L. Villanueva, Ian Thomas, Bojan Ristic, Frank Daerden, Miguel Angel López-Valverde, Manish R. Patel, Jonathon Mason, Yannick Willame, Giancarlo Bellucci, Ann Carine Vandaele
Earth and Planetary Astrophysics
Direct detection of hydrogen reveals a new macroscopic crustal water reservoir on early Mars
Estrid Buhl Naver, Katrine Wulff Nikolajsen, Martin Sæbye Carøe et al. (+13 more)
The next great leap in Martian exploration will be the return of samples to Earth. To ensure the maximum scientific return from studying these samples, the development and utilisation of nondestructive analytical techniques are essential to enable early three-dimensional characterisation of their interiors.
Neutron computed
tomography is a powerful method in this context: it is highly sensitive to hydrogen and complements the more conventional X-ray computed
tomography. Because the distribution and nature of hydrous phases are central to understanding the habitability, the climatic and geological
evolution, and potential biosignatures of Mars, identifying hydrogenbearing phases in Martian crustal rocks is of particular importance. Using the only Martian crustal material available on Earth, the NWA 7034 meteorite and its pairs, we show that combined
neutron and X-ray computed
tomography enables non-destructive sample-wide mapping of hydrogen and reveals the distribution and petrographic contexts of hydrous phases. We identify hydrogen-rich iron oxyhydroxides within ancient igneous clasts, forming a macroscopic mineralogical water reservoir within the meteorite. These alteration assemblages closely resemble those observed in samples collected by the Perseverance rover in Jezero crater, where hydrated iron oxyhydroxides are also present. This similarity suggests that such phases may represent a widespread near-surface water reservoir on early Mars.
Read the full abstract ▾
All authors Estrid Buhl Naver, Katrine Wulff Nikolajsen, Martin Sæbye Carøe, Domenico Battaglia, Jens Frydenvang, Martin Bizzarro, Jakob Sauer Jørgensen, Kim Lefmann, Anders Kaestner, David Christian Mannes, Phil Cook, Henrik Birkedal, Thorbjørn Erik Køppen Christensen, Innokenty Kantor, Henning Friis Poulsen, Luise Theil Kuhn
Astrophysics of Galaxies
Three Models of the Gravitational Potential of the Milky Way
V. V. Bobylev, A. T. Bajkova and A. A. Smirnov
The parameters of an axisymmetric model for the gravitational potential of the
Galaxy have been refined. The basic curve of the
Galaxy's rotation in a distance interval of $R:0-190$ kpc was constructed using the velocities of masers, classical Cepheids, Red Clump
stars, Blue Horizontal Branch
stars,
halo stars, globular clusters, and
dwarf satellite
galaxies of the Milky Way. The rotation curve was selected in such a way that there would be no dominant burst of circular velocities in the central ($R<2$ kpc) region of the
Galaxy. As a result, we constructed two two-component models of the
galactic potential, which include contributions from the disk and the
halo of invisible matter, as well as a three-component model with a small-mass bulge added in advance. These models can be useful in studying the long-term orbital
evolution of
stars and open and globular
star clusters in the central ($R<4$ kpc) region of the
Galaxy. The constructed models were tested for self-consistency by comparing their rotation curves with a set of model curves generated with the Illustris TNG50 software package.
Read the full abstract ▾
Astrophysics of Galaxies
Self-consistent dynamical models with a finite extent – V. Smooth radial truncations and phase-space consistency
Maarten Baes
Many
stellar systems exhibit a finite spatial extent, yet constructing self-consistent spherical models with a prescribed outer boundary is non-trivial because sharp density cutoffs introduce discontinuities that lead to inconsistencies in the associated distribution function. In this paper we show that these difficulties arise from the abruptness of the truncation rather than from the finite extent itself. We introduce a general and infinitely differentiable radial truncation scheme that can be applied to any density profile, and illustrate its behaviour using the Hernquist model. We find that softly truncated models are dynamically consistent provided that the truncation is sufficiently gradual, and we determine the corresponding critical truncation sharpness. Their distribution functions display a characteristic bump-dip feature near the truncation energy that signals the transition between consistent and inconsistent cases. In contrast to sharply truncated models, softly truncated systems can support an extensive family of Osipkov-Merritt orbital structures, including moderately radial ones. Soft truncations therefore offer a general and physically motivated route to constructing finite-extent dynamical models with well-controlled outer-edge behaviour.
Read the full abstract ▾
Instrumentation and Methods for Astrophysics
Evaluating the effectiveness of radio frequency interference removal algorithms for single pulse searches
R. S. Hombal, L. Levin, B. W. Stappers et al. (+10 more)
Radio Frequency Interference (RFI), the presence of artificial and/or terrestrial signals in astronomical data, poses a great challenge to the search for
pulsars and
radio transients, such as Rotating
Radio Transients (RRATs) and Fast
Radio Bursts (FRBs), by obscuring or distorting the signal of interest and resulting in large numbers of erroneous detections. RFI mitigation
algorithms aim to remove this interference and improve the chance of detection of transients, but with the growing number of techniques, selecting the most appropriate method for a given survey can be problematic. The choice of method is particularly important in real-time searches planned for next-generation
telescopes such as those of the SKAO, where there is no possibility to reprocess the data. In this paper, we explore the
algorithm selection problem by injecting pulses into data which simulates several RFI environments. A set of these files is then cleaned using RFI mitigation
algorithms and run through a single pulse search pipeline to analyse the recovery of the injected pulses. We examine the recovery of the injected single pulses with an emphasis on a number of cases spanning a range of pulse brightness, width and dispersion measure. The efficacy and side effects of a few popular RFI excision methods, namely IQRM, SKF, and ZDMF are evaluated.
Read the full abstract ▾
All authors R. S. Hombal, L. Levin, B. W. Stappers, M. Droog, A. Karastergiou, D. Lumbaa, M. B. Mickaliger, A. Naidu, K. M. Rajwade, J. Sepulveda, B. Shaw, S. Singh, T. Prabu
Astrophysics of Galaxies
RotCurves: A PYTHON package for efficient modelling and fitting of galactic rotation curves at high-z
A. Nestor Shachar, A. Sternberg, S. H. Price et al. (+18 more)
Rotation curves are a fundamental tool in the study of
galaxies across
cosmic time, and with the advent of large integral field unit (IFU) kinematic surveys there is an increasing need for efficient and flexible modelling tools. We present RotCurves, a parametric forward-modeling tool designed for rotation curve analysis at high-z, correcting for “beam smearing" by projecting and convolving the beam PSF in the plane of the
galaxy. We
benchmark RotCurves against the established parametric code dysmalpy using synthetic observations. The typical runtime with RotCurves is a few ~10ms, a factor 250 faster than dysmalpy for a single realization. For well-resolved systems (PSF FWHM < Reff), the mock observed rotation and dispersion curves agree to within 5% up to 3Reff, where most of the discrepancies are in the inner disk. whereas in marginally resolved systems (PSF FWHM > 1.5 Reff) discrepancies increase to up to 15%. Using a built-in MCMC fitting procedure, RotCurves recovers well the intrinsic model parameters across a wide range of
galaxy properties and accounting for realistic noise patterns. Systematic biases emerge for the effective radius and for low disk masses (Mdisk < 3x10^9 Msun). We show excellent parameter recovery at high signal-to-noise ratios (S/N > 25), with increasing deviations in parameter recovery at lower S/N. RotCurves is best suited for inclinations of 10 < i < 80. RotCurves is built as an exploratory tool for rapid testing of mass model assumptions, parameter studies and for efficiently processing large samples of observational data from large IFU surveys. The code is publicly available on github.
Read the full abstract ▾
All authors A. Nestor Shachar, A. Sternberg, S. H. Price, N. M. Förster Schreiber, R. Genzel, L. J. Tacconi, H. Übler, C. Barfety, A. Burkert, J. Chen, R. Davies, F. Eisenhauer, J. M. Espejo Salcedo, R. Herrera-Camus, J. B. Jolly, L. L. Lee, T. Naab, S. Pastras, C. Pulsoni, T. T. Shimizu, G. Tozzi
High Energy Astrophysical Phenomena
Not so Swift: 20 years of multiwavelength observations of Mrk 421 and Mrk 501
Gabrielle L. Taylor, Stefan J. Wagner, Alicja Wierzcholska et al. (+1 more)
Aims. The blazars Mrk 421 and Mrk 501 have shown multiwavelength variability on all observed timescales, and have been well studied at high energies on short timescales. We aim to characterise the long-term temporal behaviour of these blazars at synchrotron energies, namely optical, UV, and X-ray, in order to assess current models of these objects and their processes. Methods. Amongst the longest light curves ever studied for these sources, we investigated 20 years of data (2005-2025) from the Swift-UVOT and Swift-XRT
telescopes. We examined spectral models, fractional variabilities, flux distributions, and X-ray
photon index vs flux relations, as well as carrying out in-depth time series analysis using structure functions, Lomb-Scargle periodograms, and discrete correlation functions. Results. Mrk 421 and Mrk 501 both showed intriguing variability in all studied wavelengths; this variability has been found to be energy dependent, as has the trend of lognormality in flux distributions. X-ray
photon indices fluctuated greatly throughout the entire period, showing an overall harder-when-brighter trend. Hints of a quasi-periodicity have been found in the X-ray of Mrk 501 (host frame time scale $\sim390$ days, >3$\sigma$) but not in the UV or X-ray of Mrk 421, or in the UV of Mrk 501. No correlation at any time lag was found between the optical/UV and X-ray bands in either source.
Read the full abstract ▾
All authors Gabrielle L. Taylor, Stefan J. Wagner, Alicja Wierzcholska, Michael Zacharias
Solar and Stellar Astrophysics · Cross-listed from physics.plasm-ph
Velocity-Space Signatures of Energy Transfer for Ion-Acoustic Instabilities
Mahmoud Saad Afify, Kristopher G. Klein, Mihailo M. Martinović et al. (+1 more)
Context. Observations by Parker
Solar Probe (PSP) of electrostatic waves suggest that electrostatic instabilities, including the ion-ion-acoustic instability (IIAI) frequently observed in the inner heliosphere, play an important role in
plasma heating and particle acceleration. Aims. Our aim is to explore the application of single spacecraft diagnostics to the IIAI, in anticipation of application to the current missions operating in the inner heliosphere, e.g. PSP and
Solar Orbiter. Methods. We apply the field-particle correlation (FPC) technique to fully kinetic simulations of IIAI. We characterize the conversion of energy between the electric field and particle species, allowing the differentiation between oscillatory and secular energy transfer to and from the particles and highlighting the role of resonant energy exchange. We then identify the characteristic IIAI signatures for the
proton and electron distributions, and relate them to our previous knowledge of IIAI onset and energy exchange mechanisms. Results. Applying the FPC technique to our simulations run in parameters regime compatible with
solar wind conditions, we have identified IIAI signatures that would enable efficient recognition of IIAI in observations. This task is left for future missions, since the time scale over which IIAI signatures develop is too fast for the sampling rates of current missions.
Read the full abstract ▾
All authors Mahmoud Saad Afify, Kristopher G. Klein, Mihailo M. Martinović, Maria Elena Innocenti
Earth and Planetary Astrophysics
A youthful Titan implied by improved impact simulations
Shigeru Wakita, Brandon C. Johnson, Jason M. Soderblom et al. (+1 more)
The small number of impact craters found on Titan suggests that its surface is relatively young. Previous work estimated its surface age to be between 200 and 1000 Myr. This estimate, however, is based on crater scaling laws for water and sand, which are not representative of the composition of Titan's icy surface. Titan's surface is likely composed of water ice, methane clathrates, or a combination of both. Here, we perform impact simulations for impactors of various sizes that strike an icy target with a 0-15 km thick methane clathrate cap layer. We derive new crater scaling laws based on our numerical results, and find that Titan's surface age is 300-340 Myr, assuming heliocentric impactors and surface clathrates. This age, which represents the crater retention age, indicates a relatively youthful surface, suggesting that active endogenic and/or exogenic processes have recently reshaped Titan's surface.
Read the full abstract ▾
All authors Shigeru Wakita, Brandon C. Johnson, Jason M. Soderblom, Catherine D. Neish
High Energy Astrophysical Phenomena
Constraining the Fraction of LIGO/Virgo/KAGRA Binary Black Hole Merger Events Associated with Active Galactic Nucleus Flares
Liang-Gui Zhu, Lei He, Xian Chen et al. (+1 more)
The formation channels of binary black hole (BBH) mergers detected by the LIGO/Virgo/KAGRA (LVK) network remain uncertain. While BBH mergers occurring inside active
galactic nucleus (AGN) disks may interact with surrounding gas and generate observable optical
flares. We test this scenario by quantifying the spatial and temporal correlation between BBH events in GWTC-4.0 and AGN
flares identified from six years of the Zwicky Transient Facility (ZTF) DR23 data. Using 80 BBH mergers selected for adequate localization,
redshift reach, observing-epoch overlap, and ZTF sky coverage, we construct a likelihood for the
flare-associated fraction, $f_{\rm flare}$, that combines each event's 3D localization with a locally estimated
flare number density derived from a 3D Voronoi tessellation, while explicitly accounting for survey boundaries and incomplete catalog coverage. Adopting a 200-day post-merger time window for potential counterparts, we infer $f_{\rm flare} = 0.07_{-0.05}^{+0.24}$ (90% confidence level). This non-zero maximum-likelihood value is driven primarily by GW190412, for which a single
flare candidate (J143041.67+355703.8) is consistent in both time and spatial position. The candidate's light curve is limited to two data points during its peak, so it remains classified only as a candidate AGN
flare. Excluding GW190412 yields results consistent with no association and an upper limit of $f_{\rm flare} < 0.17$ at 90% confidence level. The intrinsic properties of GW190412 and the characteristics of the candidate host AGN are broadly consistent with theoretical expectations for the AGN-disk formation channel, motivating continued, targeted electromagnetic follow-up of well-localized and highly asymmetric BBH mergers in current and upcoming time-domain surveys.
Read the full abstract ▾
All authors Liang-Gui Zhu, Lei He, Xian Chen, Wen Zhao
High Energy Astrophysical Phenomena
Bifurcated Impact of Neutrino Fast Flavor Conversion on Core-collapse Supernovae Informed by Multi-angle Neutrino Radiation Hydrodynamics
Ryuichiro Akaho, Hiroki Nagakura, Wakana Iwakami et al. (+6 more)
In this Letter, we present a compelling and robust argument for the roles of
neutrino fast
flavor conversion (FFC) in the explosion mechanism of core-collapse
supernova (CCSN), combining the multi-angle FFC subgrid model rooted in
quantum kinetic theory with the multi-dimensional four-species Boltzmann
neutrino radiation hydrodynamics. Employing various progenitor masses and the
nuclear equations of states, we find that the effect of FFC on CCSN explosion is bifurcated depending on the progenitors. For the lowest-mass progenitor, FFC facilitates the shock revival and enhances the explosion energy, whereas for higher-mass progenitors its impact is inhibitory. We identify the mass
accretion rate as the key determinant governing this bifurcation. When the mass
accretion rate is low (high), the contribution of FFC to
neutrino heating becomes positive (negative), because the heating efficiency enhancement via FFC-driven spectral hardening of electron-type
neutrinos dominates over (is outweighed by) the concurrent reduction in
neutrino luminosity. Our results further highlight the limitations of approximate
neutrino transport, and demonstrate that a multi-angle treatment is essential for accurately capturing FFC effects; otherwise, FFCs are missed and even generated spuriously.
Read the full abstract ▾
All authors Ryuichiro Akaho, Hiroki Nagakura, Wakana Iwakami, Shun Furusawa, Akira Harada, Hirotada Okawa, Hideo Matsufuru, Kohsuke Sumiyoshi, Shoichi Yamada
Earth and Planetary Astrophysics
Jupiter-like uniform metal enrichment in a system of multiple giant exoplanets
Jean-Baptiste Ruffio, Jerry W. Xuan, Yayaati Chachan et al. (+15 more)
The
accretion of icy and rocky solids during the formation of a gas
giant planet is poorly constrained and challenging to model. Refractory species, like sulfur, are only present in solids in the protoplanetary disk where
planets form. Measuring their abundance in planetary atmospheres is one of the most direct ways of constraining the extent and mechanism of solid
accretion. Using the unprecedented sensitivity of NASA's James Webb Space
Telescope (JWST), we measure a detailed chemical make-up of three massive gas
giants orbiting the
star HR~8799 including direct detections of H$_2$O, CO, CH$_4$, CO$_2$, H$_2$S, $^{13}$CO, and C$^{18}$O. We find these
planets are uniformly and highly enriched in heavy elements compared to the
star irrespective of their volatile (carbon and oxygen) or refractory (sulfur) nature, which strongly suggests efficient
accretion of solids during their formation. This composition closely resembles that of Jupiter and Saturn and demonstrates that this enrichment also occurs in systems of multiple gas
giant planets orbiting
stars beyond the
Solar System. This discovery hints at a shared origin for the heavy element enrichment of
giant planets across a wider range of
planet masses and orbital separations than previously anticipated.
Read the full abstract ▾
All authors Jean-Baptiste Ruffio, Jerry W. Xuan, Yayaati Chachan, Aurora Kesseli, Eve J. Lee, Charles Beichman, Klaus Hodapp, William O. Balmer, Quinn Konopacky, Marshall D. Perrin, Dimitri Mawet, Heather A. Knutson, Geoffrey Bryden, Thomas P. Greene, Doug Johnstone, Jarron Leisenring, Michael Meyer, Marie Ygouf
Astrophysics of Galaxies
Diverse Origins of Broad H$\alpha$ Lines in Heavily Obscured AGNs Revealed by Multi-epoch Spectroscopy
Shoichiro Mizukoshi, Takeo Minezaki, Subaru Ubukata et al. (+8 more)
According to the classical AGN model, broad emission lines originate from the broad-line region (BLR) and are observable only when the attenuation by the dusty
torus is small. However, we recently found several heavily-obscured ($A_V > 50$ mag) AGNs with broad H$\alpha$ detections: MCG -3-34-64, UGC 5101, and Mrk 268. To investigate the origin of the observed broad line in these AGNs, we performed multi-epoch optical spectroscopic observations to search for flux variability of the broad H$\alpha$ line. For MCG -3-34-64 and UGC 5101, no significant variability was detected, suggesting that the broad line of these AGNs may arise from sources other than the BLR. Spectral fitting analysis suggests possible large contribution of ionized
outflows to the observed broad component of MCG -3-34-64, while both the
outflow and scattering by polar material can explain that of UGC 5101. For Mrk 268, we detected a significant ($4.3\sigma$) flux variation of the broad H$\alpha$ line by using the flux ratio of the H$\alpha$ complex and the [SII]$\lambda\lambda6716$, 6731 doublet, indicating that the broad line originates directly from the BLR. The lack of significant flux variation in the optical continuum implies that the line of sight to the
nucleus of Mrk 268 is mildly obscured. Our results demonstrate that the observed broad H$\alpha$ lines in obscured AGNs likely have multiple origins. Such complexity may introduce additional uncertainties in black hole mass measurements of distant AGNs revealed by e.g., JWST.
Read the full abstract ▾
All authors Shoichiro Mizukoshi, Takeo Minezaki, Subaru Ubukata, Kazuya Matsubayashi, Hiroaki Sameshima, Mitsuru Kokubo, Takashi Horiuchi, Hirofumi Noda, Satoshi Yamada, Bovornpratch Vijarnwannaluk, Chian-Chou Chen
High Energy Astrophysical Phenomena · Cross-listed from nucl-th
Chiral three-nucleon forces for the new local position-space two-nucleon potential in $\textit{ab initio}$ many-body calculations
Rongzhe Hu, Jianguo Li, Siqin Fan et al. (+1 more)
Three-nucleon force (3NF) plays an important role in understanding the structure of finite
nuclei and the saturation properties of infinite
nuclear matter. More specifically, 3NF should be necessary for each two-nucleon force (2NF) to obtain more accurate description of
nuclear systems. 3NF derived from the
chiral effective field theory has been successful in $\textit{ab initio}$ calculations of atomic
nuclei. Most of established
chiral nuclear forces have a nonlocal form in the momentum space. In this work, we construct a companion
chiral 3NF specifically tailored to the new Idaho local position-space 2NF, and calculate binding energies and radii of
nuclei up to $^{132}$Sn. We find that a
chiral 3NF with hybrid local and nonlocal regulators has advantages in improving the
nuclear structure calculations of both binding energies and radii with the new Idaho 2NF. The two low-energy constants of 3NF are constrained by the ground-state energies of $^3$H and $^{16}$O as suggested in a recent work.
Read the full abstract ▾
All authors Rongzhe Hu, Jianguo Li, Siqin Fan, Furong Xu
Solar and Stellar Astrophysics
Unraveling Year-Long Radial Velocity Variations in Red Clump Region – I: Comprehensive analysis of a K0 Giant star, 2 Draconis
Udomlerd Srisuchinwong, Jianzhao Zhou, Huan-Yu Teng et al. (+18 more)
Slow-rotating evolved
stars frequently exhibit radial velocity (RV) variations on annual timescales, complicated by instrumental systematics and aliasing in the one-year regime. Here we investigate the origin of the near-yearly periodicity in 2 Dra, a
star located in the red-clump region, assessing possible causes between
stellar activity, instrumental profile (IP) effects, sampling alias, and planetary companions. We applied two independent approaches: (1) constraining diagnostic signals and performing a correlation analysis ($r$) between period-confined signals, and (2) evaluating phase stability by partitioning Keplerian fits. These methods enabled us to examine the physical connections and phase coherence among
stellar activity indicators, RV measurements, and IP diagnostics. Our analysis suggests a
stellar rotation period of $\simeq270\text{--}320$\,d for 2~Dra. The 340-d RV signal does not appear to originate from
stellar activity in this chromospherically quiet
star ($|r| \lesssim 0.33$), nor from instrumental systematics near the annual period ($|r| \lesssim 0.1$). This conclusion is supported by contrasting phase behavior: the RV and
stellar activity phases remain stable, whereas the IP phases do not. We therefore propose that the 340-d variation likely arises from either small-amplitude intrinsic variability or a tentative gas
giant companion with potential weak activity-induced modulation. The case of 2~Dra provides a framework for distinguishing the origins of $\sim$1-yr RV variations in other evolved
stars.
Read the full abstract ▾
All authors Udomlerd Srisuchinwong, Jianzhao Zhou, Huan-Yu Teng, Guang-Yao Xiao, Bun'ei Sato, Takuya Takarada, Masashi Omiya, Hiroki Harakawa, Eiji Kambe, Hideyuki Izumiura, Michitoshi Yoshida, Yoichi Itoh, Hiroyasu Ando, Eiichiro Kokubo, Marc Hon, Yujuan Liu, Fei Zhao, Wei Wang, Meng Zhai, Shaolan Bi, Gang Zhao
High Energy Astrophysical Phenomena
Observation of the Forbush decrease on 2024 May 10, using the ALPAQUITA air-shower array at the 70-1000 GV rigidity range
M. Anzorena, E. de la Fuente, K. Fujita et al. (+49 more)
The Andes Large area PArticle detector for
Cosmic ray and Astronomy (ALPACA) is a new air-shower array experiment under construction in the Bolivian Andes, and its prototype ALPAQUITA surface array has been operating since 2023 April. In addition to the traditional $\ge$3-hit or $\ge$4-hit coincidences to trigger recording air-shower events, ALPAQUITA records the counting rates of the $\ge$1-hit and $\ge$2-hit events (Any1 and Any2, respectively). We report a successful detection of a Forbush decrease occurred on 2024 May 10 caused by a passage of an interplanetary shock formed ahead of the Interplanetary Coronal Mass Ejection. The amplitude detected in the Any1 rate is 4.26$\pm$0.33% at the median primary
rigidity of 76GV which is consistent with the observations with the worldwide
neutron monitor and
muon detector networks. Under the assumption of a power-law
rigidity spectrum, we renormalized the errors of the observed amplitude ($A_{obs}$) and fitted them as a function of the median primary
rigidity ($R_{m}$) of each detector and observational method. The result $A_{obs} = (10.9\% \pm 0.9\%) \times (R_{m}/10\,GV)^{-0.55 \pm 0.07}$ exhibits a hard nature of this event. Our non-detection in the Any2 rate decrease constrains the amplitude with a 2$\sigma$ upper limit to be 0.95% at 960GV. This marginally suggests an existence of a spectral softening between 100GV and 1000GV as also suggested by the Misato underground
muon detector at 145GV. Although a strong geomagnetic storm was observed during this period, we conclude it does not impact our results. Our novel technique realizes a unique coverage to study the behavior of the Forbush decreases at the highest
rigidity.
Read the full abstract ▾
All authors M. Anzorena, E. de la Fuente, K. Fujita, R. Garcia, Y. Hayashi, K. Hibino, N. Hotta, G. Imaizumi, Y. Katayose, C. Kato, S. Kato, T. Kawashima, K. Kawata, M. Kobayashi, S. Kobayashi, T. Koi, H. Kojima, P. Miranda, S. Mitsuishi, A. Mizuno, K. Munakata, Y. Nakamura, M. Nishizawa, Y. Noguchi, S. Ogio, M. Ohishi, M. Ohnishi, A. Oshima, M. Raljevic, H. Rivera, T. Saito, T. Sako, T. K. Sako, S. Shibata, A. Shiomi, M. Subieta, F. Sugimoto, N. Tajima, W. Takano, Y. Takeyama, M. Takita, N. Tamaki, Y. Tameda, K. Tanaka, R. Ticona, H. Tsuchiya, Y. Tsunesada, S. Udo, G. Yamagishi, Y. Yamanaka, K. Yamazaki, Y. Yokoe
Astrophysics of Galaxies
The contribution of stars, dust, neutral gas and supermassive black holes in galaxies to the cosmic baryon inventory
Jordan C. J. D'Silva, Simon P. Driver, Aaron S. G. Robotham et al. (+5 more)
We compute the
cosmic stellar,
dust and neutral gas mass history at $0<z\lesssim3$ using ProSpect spectral energy distribution modelling of $\approx 800 \, 000$
galaxies in the
Galaxy and Mass Assembly (GAMA) survey and the Deep Extragalactic VIsible Legacy Survey (DEVILS). The
cosmic dust mass history broadly follows the shape of the
cosmic star formation history; though, the decline is slower, suggestive of a slowing rate of
dust growth and destruction as the
star formation declines past its peak at $z\approx 2$. Neutral gas masses were estimated by scaling the
dust masses by the
metallicity-dependent
dust-to-gas ratio. The neutral gas mass density as traced by the
dust is an average of $\approx 0.7$ dex lower than that measured from $21$cm experiments, most likely due to differences in the spatial scales inhabited by
dust and HI. Folding in measurements of the supermassive black hole mass density obtained previously with similar data and methods, we present a self-consistent census of the
baryons confined to
galaxies.
Stars, neutral gas, SMBHs and
dust contained within the optical radii of
galaxies account for $\approx 5$ per cent of the
baryons. Most of the remaining $\approx 95$ per cent of
baryons must be ionised and dispersed throughout the interstellar, circumgalactic and intergalactic media within, around and between
galaxies.
Read the full abstract ▾
All authors Jordan C. J. D'Silva, Simon P. Driver, Aaron S. G. Robotham, Andrew Battisti, Elisabete da Cunha, Luke J. M. Davies, Stephen Eales, Claudia del P. Lagos
Cosmology and Nongalactic Astrophysics
Baryon Acoustic Oscillations from the C IV Forest with DESI DR2
Abby Bault, Andrei Cuceu, Julien Guy et al. (+53 more)
We present a measurement of
Baryon Acoustic Oscillations (BAO) in the cross-correlation of triply ionized carbon C IV absorption with the positions of
quasars (QSO) and Emission Line
Galaxies (ELG). We use
quasars and ELGs from the second data release (DR2) of the Dark Energy Spectroscopic Instrument (DESI) survey. Our data sample consists of 2.5 million
quasars, 3.1 million ELGs, and the C IV absorption is measured along the line of sight of 1.5 million high
redshift quasars with $z > 1.3$. We measure the isotropic BAO signal at 4.2$\sigma$ for the CIV$\times$QSO cross-correlation. This translates into a 3.0% precision measurement of the ratio of the isotropic distance scale, $D_{\rm V}$, and the sound horizon at the drag epoch, $r_{\rm d}$, with $D_{\rm V}/r_{\rm d}(z_{\rm eff} = 1.92) = 30.3 \pm 0.9$. We make the first detection of the BAO feature in the CIV$\times$ELG cross-correlation at a significance of 2.5$\sigma$ and find $D_{\rm V}/r_{\rm d}(z_{\rm eff} = 1.47) = 24.6 \pm 1.0$.
Read the full abstract ▾
All authors Abby Bault, Andrei Cuceu, Julien Guy, J. Aguilar, S. Ahlen, D. Bianchi, A. Brodzeller, D. Brooks, R. Canning, E. Chaussidon, T. Claybaugh, R. de Belsunce, A. de la Macorra, Arjun Dey, P. Doel, S. Ferraro, A. Font-Ribera, J. E. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, C. Gordon, D. Green, G. Gutierrez, C. Hahn, H. K. Herrera-Alcantar, K. Honscheid, M. Ishak, R. Joyce, S. Juneau, D. Kirkby, A. Kremin, C. Lamman, M. Landriau, L. Le Guillou, M. E. Levi, M. Manera, P. Martini, A. Meisner, R. Miquel, J. Moustakas, A. Muñoz-Gutiérrez, S. Nadathur, N. Palanque-Delabrouille, W. J. Percival, Matthew M. Pieri, C. Poppett, F. Prada, I. Pérez-Ràfols, G. Rossi, E. Sanchez, D. Schlegel, H. Seo, J. Silber, D. Sprayberry, G. Tarlé, B. A. Weaver
High Energy Astrophysical Phenomena
Cascade Processes of Strong and Weak MHD Turbulence
Na-Na Gao, Jian-Fu Zhang and Jungyeon Cho
On the framework of relativistic force-free magnetohydrodynamic (MHD)
turbulence, we explore the fundamental properties of strong and weak turbulent cascades using high-resolution numerical simulations in the presence of a uniform background
magnetic field. We find that (1) power spectra and scale-dependent anisotropies both for the strong and weak
turbulence resemble those observed in the non-relativistic MHD
turbulence; (2) intermittency of
magnetic fields in strong
turbulence is stronger than that in the weak one; (3) generated Alfvén modes show similar energy spectra and scale-dependent anisotropies to those of non-relativistic case; (4) generated fast modes present a power spectrum similar to that of Alfvén modes, with a strong (for strong
turbulence) or weak (for weak
turbulence) scale-dependent anisotropy, which are significantly different from non-relativistic
turbulence; and (5) applications of our numerical results to
neutron star magnetospheres show that the strong (or moderately weak) turbulent cascade can explain the X-ray radiation of the Vela
pulsar. Our study is of great significance for understanding energy transfer,
magnetic field
evolution, and particle acceleration mechanisms in extreme astrophysical environments.
Read the full abstract ▾