Cosmology and Nongalactic Astrophysics
KGB-evolution: a relativistic $N$-body code for kinetic gravity braiding models
Ahmad Nouri-Zonoz, Farbod Hassani, Emilio Bellini et al. (+1 more)
We present KGB-
evolution, a relativistic $N$-body simulation code that extends the $k$-
evolution code by incorporating an effective field theory parameterization of kinetic
gravity braiding, while also including the $k$-essence model as a limiting case. As a first step, we implement the linearized dark energy stress-energy tensor and scalar field equations, providing the groundwork for a future full Horndeski theory extension. We validate KGB-
evolution by comparing its power spectra against linear predictions from hi$\_$class, finding excellent agreement on large scales at low
redshifts and over all scales at high
redshifts. We demonstrate that nonlinear growth of matter and metric perturbations on small scales drives the linearized dark energy field into a nonlinear clustering regime, which in turn feeds back on the growth of
cosmic structure. In contrast to the $k$-essence limit, a nonzero braiding considerably amplifies this backreaction, producing a significantly stronger alteration of structure formation in the kinetic
gravity braiding model.
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All authors Ahmad Nouri-Zonoz, Farbod Hassani, Emilio Bellini, Martin Kunz
Earth and Planetary Astrophysics
On the Exoplanet Yield of Gaia Astrometry
Caleb Lammers and Joshua N. Winn
We re-examine the expected yield of
Gaia astrometric
planet detections using updated models for
giant-
planet occurrence, the local
stellar population, and
Gaia's demonstrated astrometric precision. Our analysis combines a semi-analytic model that clarifies key scaling relations with more realistic Monte Carlo simulations. We predict $7{,}500 \pm 2{,}100$
planet discoveries in the 5-year
dataset (DR4) and $120{,}000 \pm 22{,}000$ over the full 10-year mission (DR5), with the dominant error arising from uncertainties in
giant-
planet occurrence. We evaluate the sensitivity of these forecasts to the detection threshold and the desired precision for measurements of
planet masses and orbital parameters. Roughly $1{,}900 \pm 540$
planets in DR4 and $38{,}000 \pm 7{,}300$
planets in DR5 should have masses and orbital periods determined to better than $20$%. Most detections will be super-Jupiters ($3$ - $13 M_{\rm J}$) on $2$ - $5$AU orbits around GKM-type
stars ($0.4$ - $1.3 M_\odot$) within $500$ pc. Unresolved binary
stars will lead to spurious
planet detections, but we estimate that genuine
planets will outnumber them by a factor of $5$ or more. An exception is
planets around M-
dwarfs with $a < 1$AU, for which the false-positive rate is expected to be about $50$%. To support community preparation for upcoming data releases, we provide mock catalogs of
Gaia exoplanets and
planet-impostor binaries.
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High Energy Astrophysical Phenomena
Intermittency in Collisionless Large-Amplitude Turbulence
Ryan Golant, Luca Comisso, Philipp Kempski et al. (+1 more)
Large-amplitude
turbulence – characterized by a fluctuating
magnetic field component, $\delta B$, that is stronger than the mean component, $B_0$ – is generically intermittent, populated with intense localized structures such as sharp field-line bends and rapid field reversals. Recent MHD simulations suggest that these structures play an important role in particle transport and acceleration; however, MHD is inapplicable in most of our Universe, where the
plasma is so hot or diffuse that Coulomb collisions are negligible. Therefore, in this paper, we analyze the intermittent properties of collisionless large-amplitude
turbulence in electron-positron
plasmas via fully kinetic 3D simulations, exploring a wide range of $\delta B / B_0$ and scale separations between the
turbulence driving scale, $L$, and kinetic scales, $c/\omega_{\rm p}$. The steady-state collisionless
turbulence in our simulations broadly resembles that of MHD, but the development of pressure anisotropy steepens the scaling between
magnetic field strength, $B$, and scalar field-line
curvature, $K_\parallel$ – yielding $B \propto K_\parallel^{-3/4}$ – and consequently modifies the power-law slope of the probability density function of $K_\parallel$; this slope hardens from $K_\parallel^{-2.5}$ to $K_\parallel^{-2.0}$ as $\delta B / B_0$ increases from 4 to 140. Pressure anisotropy also triggers mirror and firehose instabilities, with the volume-filling fractions of these fluctuations increasing with $\delta B / B_0$; for our largest $\delta B / B_0$, $20\%$ of the volume is mirror-unstable and $6\%$ is firehose-unstable. Both the
curvature and the Larmor-scale fluctuations in collisionless large-amplitude
turbulence are expected to significantly influence
cosmic ray transport and acceleration in the interstellar medium of our
Galaxy and the intracluster medium of
galaxy clusters.
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All authors Ryan Golant, Luca Comisso, Philipp Kempski, Lorenzo Sironi
Cosmology and Nongalactic Astrophysics
unimpeded: A Public Grid of Nested Sampling Chains for Cosmological Model Comparison and Tension Analysis
Dily Duan Yi Ong and Will Handley
Bayesian inference is central to modern cosmology, yet comprehensive model comparison and tension quantification remain computationally prohibitive for many researchers. To address this, we release $\texttt{unimpeded}$, a publicly available Python library and data repository providing pre-computed nested sampling and MCMC chains. We apply this resource to conduct a systematic analysis across a grid of eight cosmological models, including $\Lambda$CDM and seven extensions, and 39
datasets, including individual probes and their pairwise combinations. Our model comparison reveals that whilst individual
datasets show varied preferences for model extensions, the base $\Lambda$CDM model is most frequently preferred in combined analyses, with the general trend suggesting that evidence for new physics is diluted when probes are combined. Using five complementary statistics, we quantify tensions, finding the most significant to be between DES and Planck ($\sigma=3.57\pm0.10$) and SH0ES and Planck ($\sigma=3.27\pm0.10$) within $\Omega_k\Lambda$CDM. We characterise the $S_8$ tension as high-dimensional ($d_G=4.87\pm0.79$) and partially resolvable in certain extended models, whereas the Hubble tension is low-dimensional and persists across the model space. Caution should be exercised when combining
datasets in tension. The $\texttt{unimpeded}$ data products, hosted on Zenodo, provide a powerful resource for reproducible cosmological analysis and underscore the robustness of the $\Lambda$CDM model against this comprehensive
benchmark compilation.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
On the Bondi accretion of a self-interacting complex scalar field
Dražen Glavan, Alexander Vikman and Tom Zlosnik
Scalar fields with a global U(1)
symmetry often appear in cosmology and astrophysics. We study the spherically-symmetric, stationary
accretion of such a classical field onto a Schwarzschild black hole in the test-field approximation. Thus, we consider the relativistic Bondi
accretion beyond a simplified perfect-fluid setup. We focus on the complex scalar field with canonical kinetic term and with a generic quartic potential which either preserves the U(1)
symmetry or exhibits spontaneous
symmetry breaking. It is well known that in the lowest order in gradient expansion the dynamics of such a scalar field is well approximated by a perfect superfluid; we demonstrate that going beyond this approximation systematically reduces the
accretion rate with respect to the perfect fluid case. Hence, black holes can provide a way to distinguish a perfect fluid from its ultraviolet completion in form of the complex scalar field.
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Solar and Stellar Astrophysics
Dynamical Masses of Young Stellar Multiple Systems with the VLBA (DYNAMO-VLBA)
Jazmin Ordonez-Toro, Sergio A. Dzib and Laurent Loinard
Very Long Baseline Interferometry (VLBI) provides high angular resolution images and has been used for
stellar astrometry for decades. The DYNAMO-VLBA project utilizes the Very Long Baseline Array (VLBA) to study tight binary and multiple pre-main sequence
stars, whose components have detectable
radio emission and typical separations on the order of milli-arcseconds. Such systems cannot be resolved by
Gaia, making VLBI an essential tool for the study of their orbital parameters and, eventually, the determination of their mass. Here, we report VLBA dynamical mass measurements of the individual
stars in the S1 system in Ophiuchus and EC\,95 in Serpens. S1 is the most luminous and massive
stellar member of the nearby Ophiuchus
star-forming region. We find that the primary component, S1A, has a mass of $4.11 \pm 0.10\,M_{\odot}$. This is significantly less than the value of $\sim6\,M_{\odot}$ expected from theoretical models given the location of S1A on the HR diagram. The secondary, S1B, has a mass of $0.831 \pm 0.014\,M_{\odot}$ and is most likely a T Tauri
star. In the Serpens triple system EC\,95, we measure the masses of EC\,95A and EC\,95B, finding $2.15\pm0.10$ M$_\odot$ and $2.00\pm0.12$ M$_\odot$, respectively. In this case, the measured masses agree with the location of the
stars in the HR diagram for very young 2 $M_\odot$
stars. For the first time, we also estimated the mass of tertiary, EC\,95C, to be 0.26 $^{+0.53}_{-0.46}$ M$_\odot$.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Effective matter sectors from modified entropies
Ankit Anand, Sahil Devdutt, Kimet Jusufi et al. (+1 more)
We present a general formalism linking modified
entropy functions directly to a modified spacetime metric and, subsequently, to an effective matter sector of entropic origin. In particular, within the framework of general relativity, starting from the first law of black-hole thermodynamics we establish an explicit correspondence between the
entropy derivative and the metric function, which naturally leads to an emergent stress-energy tensor representing an anisotropic effective fluid. This backreaction effect of horizon
entropy may resolve possible inconsistencies recently identified in black hole physics with modified
entropies. As specific examples, we apply this procedure to a wide class of modified
entropies, such as Barrow, Tsallis-Cirto, Renyi, Kaniadakis, logarithmic, power-law, loop-
quantum-
gravity, and exponential modifications, and we derive the associated effective matter sectors, analyzing their physical properties and energy conditions.
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All authors Ankit Anand, Sahil Devdutt, Kimet Jusufi, Emmanuel N. Saridakis
Cosmology and Nongalactic Astrophysics
Addressing the DESI DR2 Phantom-Crossing Anomaly and Enhanced $H_0$ Tension with Reconstructed Scalar-Tensor Gravity
Dimitrios Efstratiou, Evangelos Achilleas Paraskevas and Leandros Perivolaropoulos
Recent cosmological data, including DESI DR2, highlight significant tensions within the $\Lambda$CDM paradigm. When analyzed in the context of General Relativity (GR), the latest DESI data favor a dynamical dark energy (DDE) equation of state, $w(z)$, that crosses the phantom divide line $w=-1$. However, this framework prefers a lower Hubble constant, $H_0$, than Planck 2018, thereby worsening the tension with local measurements. This phantom crossing is a key feature that cannot be achieved by minimally coupled scalar fields (quintessence) within GR. This suggests the need for a new degree of freedom that can simultaneously: (A) increase the best-fit value of $H_0$ in the context of the DESI DR2 data, and (B) allow the crossing of the $w=-1$ line within a new theoretical approach. We argue that both of these goals may be achieved in the context of Modified
Gravity (MG), and in particular, Scalar-Tensor (ST) theories, where phantom crossing is a natural and viable feature. We demonstrate these facts by analyzing a joint
dataset including DESI DR2, Pantheon+, CMB, and growth-rate (RSD) data in the context of simple parametrizations for the effective gravitational constant, $\mu_G(z) \equiv G_{eff}/G_N$, and the DDE equation of state, $w(z)$. This MG framework significantly alleviates the tension, leading to a higher inferred value of $H_0 = 70.6 \pm 1.4 \, \text{km s}^{-1} \text{Mpc}^{-1}$. We also present a systematic, data-driven reconstruction of the required underlying ST Lagrangian and provide simple, generic analytical expressions for both the non-minimal coupling $F(\Phi) = 1+\xi\Phi^{2}e^{n\Phi}$ and the scalar potential $U(\Phi) = U_{0}+ae^{b\Phi^{2}}$, which well-describe the reconstructed functions.
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Solar and Stellar Astrophysics
Peculiarities in the infrared emission of PAH-C$_{60}$ adducts
R. Barzaga, B. Kerkeni, D. A. García-Hernández et al. (+7 more)
The coexistence of PAHs and the C$_{60}$ fullerene in different astrophysical environments can give rise to the formation of new complex species denoted as PAH-C$_{60}$ adducts, which may contribute to the infrared (IR) emission observed. These PAH-C$_{60}$ adducts have been previously reported experimentally due to the high reactivity between PAHs and C$_{60}$. From the astrophysical point of view, however, they have not been considered in detail yet. Here we have performed a combined experimental and theoretical study in order to characterize the IR spectra of PAH-C$_{60}$ adducts, including multiple adducts. By using new advanced experimental techniques, we have been able to synthesize some specific PAH-C$_{60}$ adduct isomers, and measured their IR spectra. These experimental data are used to correct their harmonic scaled spectra, as obtained from
quantum-chemistry calculations performed at the DFT level under the B3LYP-GD3/6-31+G(d) approach. This way, we simulate the IR ($\sim$3$-$25 $\mu$m) spectra of multiple PAH-C$_{60}$ adducts, composed by a different number of PAH units: mostly one or two units. In addition, the chemical kinetics data available in the literature are used to tentatively estimate the possible order of magnitude of the abundances of these PAH-C$_{60}$ adducts using the available observational data. Essentially, our results reveal a possible strong modification of the IR spectra when astronomically estimated abundances are considered. Several spectral peculiarities are observed, such as a broad $\sim$3.4-3.6 $\mu$m feature, and important modifications in the 6-10 and 12-16 $\mu$m spectral regions together with contributions to the C$_{60}$ features at 7.0 and 18.9 $\mu$m. Interestingly, these PAH-C$_{60}$ adducts lack aliphatic CH bonds, but they display IR features around 3.4 $\mu$m, challenging previous interpretations of this astronomical feature.
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All authors R. Barzaga, B. Kerkeni, D. A. García-Hernández, X. Ribas, T. Pelachs, M. Manteiga, A. Manchado, M. A. Gómez-Muñoz, T. Huertas-Roldán, G. Ouerfelli
Solar and Stellar Astrophysics
The Pre-Outburst Properties of the FU Ori Object HBC 722
Gregory J. Herczeg and Bo Reipurth
FU Ori outbursts are thought to play an important role in
stellar assembly and the
evolution of protoplanetary disks. However, the progenitor young
stellar objects are largely uncharacterized. We obtained a low-resolution optical spectrum of HBC 722 before its FU Ori outburst as part of a survey of young
stellar objects in the North America Nebula. The spectrum yields a spectral type of M3.3$\pm$0.4, which when combined with archival photometry allows us to measure the
stellar and
accretion properties of a young
star prior to its FU Ori outburst. The pre-outburst
accretion rate of $7\times10^{-9}$ M$_\odot$ yr$^{-1}$ is high for a protoplanetary disk around an M3-M3.5
star, though about 15,000 times weaker than the
accretion rate during the outburst. The pre-outburst variability, inferred from archival B-band photometry, is about a factor 5 with a standard deviation of 0.16 dex and is consistent with variable
accretion onto young low-mass
stars. The
stellar radius is larger than the radius of accreting young
stars of similar spectral type by a factor of two. The extinction to HBC 722 is $\sim 1.45\pm0.3$~mag, lower than the 2.5–3.7~mag extinction values measured during the outburst. The u-band photometry plays an especially important role in constraining the veiling at longer wavelengths and therefore also the extinction and photospheric luminosity.
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Solar and Stellar Astrophysics
Automatic detection of CMEs using synthetically-trained Mask R-CNN
Francisco A. Iglesias, Diego G. Lloveras, Florencia L. Cisterna et al. (+6 more)
Coronal mass ejections (CMEs) are a major driver of space weather. To assess CME geoeffectiveness, among other scientific goals, it is necessary to reliably identify and characterize their morphology and kinematics in coronagraph images. Current methods of CME identification are either subjected to human biases or perform a poor identification due to deficiencies in the automatic detection. In this approach, we have trained the deep convolutional neural model Mask R-CNN to automatically segment the outer envelope of one or multiple CMEs present in a single difference coronagraph image. The empirical training
dataset is composed of 10^5 synthetic coronagraph images with known pixel-level CME
segmentation masks. It is obtained by combining quiet coronagraph observations, with synthetic white-light CMEs produced using the GCS
geometric model and ray-tracing technique. We found that our model-based trained Mask R-CNN infers
segmentation masks that are smooth and topologically connected. While the inferred masks are not representative of the detailed outer envelope of complex CMEs, the neural model can better differentiate a CME from other radially moving background/foreground features, segment multiple simultaneous CMEs that are close to each other, and work with images from different instruments. This is accomplished without relying on kinematic information, i.e. only the included in the single input difference image. We obtain a median IoU=0.98 for 1.6*10^4 synthetic validation images, and IoU=0.77 when compared with two independent manual
segmentations of 115 observations acquired by the COR2-A, COR2-B and LASCO C2 coronagraphs. The methodology presented in this work can be used with other CME models to produce more realistic synthetic brightness images while preserving desired morphological features, and obtain more robust and/or tailored
segmentations.
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All authors Francisco A. Iglesias, Diego G. Lloveras, Florencia L. Cisterna, Hebe Cremades, Mariano Sanchez Toledo, Fernando M. López, Yasmin Machuca, Franco Manini, Andrés Asensio Ramos
Cosmology and Nongalactic Astrophysics
Parameterizing Noise Covariance in Maximum-Likelihood Component Separation
Goureesankar Sathyanathan, Josquin Errard and Soumen Basak
We introduce a noise-aware extension to the parametric maximum-likelihood framework for component separation by modeling correlated $1/f^\alpha$ noise as a harmonic-space power law. This approach addresses a key limitation of existing implementations, for which a mismodelling of the statistical properties of the noise can lead to biases in the characterization of the spectral laws, and consequently biases in the recovered CMB maps. We propose a novel framework based on a modified ridge likelihood embedded in an ensemble-average pipeline and derive an analytic bias correction to control noise-induced foreground residuals. We discuss the practical applications of this approach in the absence of true noise information, leading to the choice of white noise as a realistic assumption. As a proof of concept, we apply this methodology to a set of simplified, idealized simulations inspired by the specifications of the proposed ECHO (CMB-Bh$\overline{a}$rat) mission, which features multi-frequency, large-format focal planes. We forecast the $95 \%$ upper limit on the tensor-to-scalar ratio, $r_{95}$, under a suite of realistic noise scenarios. Our results show that for an optimistic full sky observation, ECHO can achieve $r_{95}\leq 10^{-4}$ even in the presence of significant correlated noise, demonstrating the mission's capability to probe
primordial gravitational waves with unprecedented sensitivity. Without degrading the statistical performance of the traditional component separation, this methodology offers a robust path toward next-generation B-mode searches and informs instrument design by quantifying the impact of noise correlations on cosmological parameter recovery.
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Solar and Stellar Astrophysics
2D unified atmosphere and wind simulations for a grid of O-type stars
Nicolas Moens, Dwaipayan Debnath, Olivier Verhamme et al. (+4 more)
The atmospheres of massive O-type
stars (O
stars) are dynamic, turbulent environments resulting from radiatively driven instabilities over the iron bump, located slightly beneath the
stellar surface. Here, complex radiation hydrodynamic processes affect the structure of the atmosphere as well as the formation of spectral lines. In quantitative spectroscopic analysis, the effects of these processes are often parametrized with ad hoc techniques and values. This work is aimed at exploring how variation of basic atmospheric parameters affects the dynamics within the subsurface turbulent zone. We also explore how this
turbulence relates to absorption lines formed in the photosphere for a broad range of O
stars at
solar metallically. The work in this paper centers around a grid of 2D, radiation-hydrodynamic O-
star atmosphere and wind simulations, where the turbulent region is an emergent property of the simulation. For each of the 36 models in the grid, we derived the turbulent properties and correlated them to an estimate of turbulent line broadening imposed by the models' velocity fields. Our work suggests that the subphotospheric turbulent velocity in O-
stars scales approximately with the square of the Eddington arameter, $\Gamma_{\rm e}$. We also find a linear correlation between subphotospheric turbulent velocity and the line broadening of several synthetic photospheric absorption lines. Radiation carries more energy than advection throughout the atmosphere for all models in the grid; however, for O-type supergiants, the latter can account for up to 30 % of the total flux at the peak of the iron bump.
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All authors Nicolas Moens, Dwaipayan Debnath, Olivier Verhamme, Frank Backs, Cassandra Van der Sijpt, Jon O. Sundqvist, Andreas A.C. Sander
High Energy Astrophysical Phenomena
Environmental effects in stellar mass gravitational wave sources II: Enhanced detectability of phase shifts in eccentric sub-populations
Lorenz Zwick, Kai Hendriks, Pankaj Saini et al. (+4 more)
We demonstrate that the properties of eccentric gravitational wave (GW) signals enhance the detectability of GW phase shifts caused by environmental effects (EEs): The signal-to-noise ratio (SNR) of EEs can be boosted by up to $\ell_{\rm max}^{1 - n}$ with respect to corresponding circular signals, where $\ell_{\rm max}$ is the highest modeled eccentric GW harmonic and $n$ is the frequency scaling of the GW dephasing prescription associated to the EE. We investigate the impact on a population level, adopting plausible eccentricity distributions for binary sources observed by LIGO/Virgo/Kagra (A+ and A\# sensitivities), as well as
Cosmic Explorer (CE) and the Einstein
Telescope (ET). For sources in the high eccentricity tail of a distribution ($e \gtrsim 0.2$ at 10 Hz), phase shifts can systematically be up to $\ell_{\rm max}^{1 - n}$ times smaller than in a corresponding circular signal and still be detectable. For typical EEs, such as Roemer delays and gas drag, this effect amounts to SNR enhancements that range from $10^2$ up to $10^5$. For CE and ET, our analysis shows that EEs will be an ubiquitous feature in the eccentric tail of merging binaries, regardless of the specific details of the formation channel. Additionally, we find that the joint analysis of eccentricity and phase shift is already plausible in current catalogs if a fraction of binaries merge in AGN migration traps.
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All authors Lorenz Zwick, Kai Hendriks, Pankaj Saini, János Takátsy, Connar Rowan, Johan Samsing, Jakob Stegmann
Astrophysics of Galaxies
The ALMA-ATOMS-QUARKS survey: Resolving a chemically rich massive protostellar outflow
Jia-Hang Zou, Tie Liu, Fengwei Xu et al. (+19 more)
We present a comprehensive study on the physical and chemical structures of a chemically rich bipolar
outflow in a high-mass
star forming region IRAS 16272$-$4837 (SDC335), utilizing high-resolution spectral line data at 1.3 mm and 3 mm dual-bands from the ALMA ATOMS and
QUARKS surveys. The high-velocity jet is enveloped by a lower-velocity
outflow cavity, containing bright
knots that show enhanced molecular intensities and elevated excitation temperatures. Along the
outflow, we have identified 35 transitions from 22 molecular species. By analyzing the spatial distribution and kinematics of these molecular lines, we find that the molecular inventory in the
outflow is regulated by three processes: (i) direct entrainment from the natal molecular core by the
outflow; (ii) shock-induced release of molecules or atoms from
dust grains; and (iii) thermal desorption and gas-phase reactions driven by shock heating. These results confirm that
outflows are not only dynamical structures but also active chemical factories, where entrainment, shocks, and thermal processing jointly enrich the molecular content. Our findings confirmed that
outflow chemistry has multi-origin nature, and provide critical insights into chemical
evolution during high-mass
star formation.
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All authors Jia-Hang Zou, Tie Liu, Fengwei Xu, Xindi Tang, Dezhao Meng, Yankun Zhang, Aiyuan Yang, Tapas Baug, Chang Won Lee, L. Viktor Toth, Ariful Hoque, Sami Dib, Pablo Garcia, Hong-Li Liu, Prasanta Gorai, Swagat R. Das, Guido Garay, Patricio Sanhueza, Li Chen, Di Li, Jihye Hwang, Dongting Yang
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Equivalence of scalar-tensor theories and scale-dependent gravity
Philipp Neckam, Christian Käding, Benjamin Koch et al. (+4 more)
We present a novel equivalence between scale-dependent
gravity and scalar-tensor theories that have only a single scalar field with a canonical kinetic term in the Einstein frame and a conformal coupling to the metric tensor. In particular, we show that the set of well-behaved scale-dependent
gravity theories can be fully embedded into scalar-tensor theories in a unique way. Conversely, there are multiple ways to write a scalar-tensor theory as a scale-dependent theory. This equivalence is established both on the level of the actions and on the level of field equations. We find that, in the context of this equivalence, the scale-setting relation $k(x)$ is naturally promoted to a dynamical field, which is made manifest by including a corresponding kinetic term in the scale-dependent action. In addition, we demonstrate that the new equivalence fits well into the framework of existing equivalences involving the aforementioned theories and $f(R)$-
gravity. Finally, we apply the equivalence relations to explicit examples from both scale-dependent
gravity and scalar-tensor theories.
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All authors Philipp Neckam, Christian Käding, Benjamin Koch, Cristobal Laporte, Mario Pitschmann, Ali Riahinia, Angel Rincon
Cosmology and Nongalactic Astrophysics
Study the nature of dynamical dark energy by measuring the CMB polarization rotation angle
Hua Zhai, Si-Yu Li, Yang Liu et al. (+6 more)
Recent results from the Dark Energy Spectroscopic Instrument (DESI) support the dynamical dark energy. Intriguingly, the data favor a transition of the dark energy equation of state across $w=-1$, a hallmark of the Quintom scenario. In this paper, we consider a different approach to the dynamical nature of dark energy by investigating its interaction with ordinary matters, specifically the Chern-Simons (CS) interaction with
photons. In cosmology, this interaction rotates the polarized plane of the
cosmic microwave background (CMB)
photons, which induces non-zero polarized TB and EB power spectra. We forecast this measurement with the Ali CMB Polarization
Telescope (AliCPT) experiment. We take the best-fit value of the isotropic rotation angle from Planck data as our fiducial input. We project that 11 module-year (modyr) of observations will yield an improved detection sensitivity with a significance $\sim 5\sigma$, given a calibration precision of $0.1^\circ$ in the polarization angle. We also forecast AliCPT's sensitivity to the amplitude of a scale invariant spectrum of the anisotropic polarization rotation field. With $50$~modyr of observations, the large-aperture configuration is expected to reach $\sigma_{A_{\mathrm{CB}}}\sim10^{-2}$, offering a sixfold improvement over the small-aperture design and enabling competitive tests of spatial fluctuations in the dark energy field.
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All authors Hua Zhai, Si-Yu Li, Yang Liu, Yiwei Zhong, Hong Li, Yaqiong Li, Congzhan Liu, Mingzhe Li, Xinmin Zhang
Astrophysics of Galaxies
The AGORA High-resolution Galaxy Simulations Comparison Project. X: Formation and Evolution of Galaxies at the High-redshift Frontier
Hyeonyong Kim, Ji-hoon Kim, Minyong Jung et al. (+22 more)
Recent observations from JWST have revealed unexpectedly luminous
galaxies, exhibiting
stellar masses and luminosities significantly higher than predicted by theoretical models at
Cosmic Dawn. In this study, we present a suite of cosmological zoom-in simulations targeting high-
redshift ($z \geq 10$)
galaxies with dark matter
halo masses in the range $10^{10} - 10^{11}\ {\rm M}_{\odot}$ at $z=10$, using state-of-the-art
galaxy formation simulation codes (Enzo, Ramses, Changa, Gadget-3, Gadget-4, and Gizmo). This study aims to evaluate the convergence of the participating codes and their reproducibility of high-
redshift galaxies with the
galaxy formation model calibrated at relatively low
redshift, without additional physics for high-
redshift environments. The subgrid physics follows the AGORA CosmoRun framework, with adjustments to resolution and initial conditions to emulate similar physical environments in the early universe. The participating codes show consistent results for key
galaxy properties (e.g.,
stellar mass), but also reveal notable differences (e.g.,
metallicity), indicating that
galaxy properties at high
redshifts are highly sensitive to the feedback implementation of the simulation. Massive
halos (${\rm M}_{\rm halo}\geq5\times10^{10}\,{\rm M}_{\odot}$ at $z=10$) succeed in reproducing observed
stellar masses,
metallicities, and UV luminosities at $10\leq z\leq12$ without requiring additional subgrid physics, but tend to underpredict those properties at higher
redshift. We also find that varying the
dust-to-metal ratio modestly affects UV luminosity of simulated
galaxies, whereas the absence of
dust significantly enhances it. In future work, higher-resolution simulations will be conducted to better understand the formation and
evolution of
galaxies at
Cosmic Dawn.
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All authors Hyeonyong Kim, Ji-hoon Kim, Minyong Jung, Santi Roca-Fàbrega, Daniel Ceverino, Pablo Granizo, Kentaro Nagamine, Joel R. Primack, Héctor Velázquez, Kirk S. S. Barrow, Robert Feldmann, Keita Fukushima, Lucio Mayer, Boon Kiat Oh, Johnny W. Powell, Tom Abel, Oscar Agertz, Chaerin Jeong, Alessandro Lupi, Yuri Oku, Thomas R. Quinn, Yves Revaz, Ramón Rodríguez-Cardoso, Ikkoh Shimizu, Romain Teyssier
High Energy Astrophysical Phenomena
The TeV emission of 3C273: inverse Compton radiation from shear-accelerated high-energy electrons in the large-scale jet?
F. Tavecchio
The VERITAS Collaboration recently reported the detection of very-high-energy (VHE) gamma-ray emission from the prototypical
radio quasar 3C273. The temporal and the spectral properties of this component do not appear compatible with the extrapolation of the beamed blazar-like emission of the inner, pc-scale jet. We explore the possibility that the VHE component is produced in the jet at kpc scale through the inverse Compton emission of a population of ultra-high energy electrons (with Lorentz factor $\gamma\sim 10^8$). In the model these electrons are accelerated through the shear acceleration mechanism, and they also account for the still puzzling X-ray emission of
knots detected by Chandra in the large-scale jets of several powerful
quasars (including 3C273). In our scenario the VHE component can be interpreted as the integrated emission from the two brightest
knots of the 3C273 jet. We speculate that the decay of the emission on the timescale of $\sim 3$ years could be accounted for by the scenario if the VHE radiation is produced in some compact regions in the downstream flow of a recollimation shock.
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Instrumentation and Methods for Astrophysics
Cutana: A High-Performance Tool for Astronomical Image Cutout Generation at Petabyte Scale
Pablo Gómez, Laslo Erik Ruhberg, Kristin Anett Remmelgas et al. (+1 more)
The Euclid Quick Data Release 1 (Q1) encompasses 30 million sources across 63.1 square degrees, marking the beginning of petabyte-scale data delivery through Data Release 1 (DR1) and subsequent releases. Systematic exploitation of such
datasets requires extracting millions of source-specific cutouts, yet standard tools like Astropy's Cutout2D process sources individually, creating bottlenecks for large catalogues. We introduce Cutana, a
memory-efficient software tool optimised for batch processing in both local and cloud-native environments. Cutana employs vectorised NumPy operations to extract cutout batches simultaneously from FITS tiles, implements automated
memory-aware scheduling, and supports both Zarr and FITS output formats with multiple common normalisation schemes (asinh, log, zscale). Cutana outperforms Astropy in all tested Q1 subset scenarios achieving near linear scaling and processing thousands of cutouts per second. On just four worker threads, Cutana can process all of Q1 in under four hours. The tool includes an ipywidget interface for parameter configuration and real-time monitoring. Integration with ESA Datalabs is underway for the Euclid DR1 release, with open-source release pending ESA open-source licensing processes.
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All authors Pablo Gómez, Laslo Erik Ruhberg, Kristin Anett Remmelgas, David O'Ryan
Earth and Planetary Astrophysics
Dust Collisions in Protoplanetary Disks: Atomic Simulations of the Surface Free Energy
L. S. Morrissey, D. S. Ebel, L. E. J. Eriksson et al. (+4 more)
Coagulation of
dust particles in protoplanetary disks is the first step on the journey to the formation of
planets. The surface free energy (SFE) of the
dust particles determines the effectiveness of particles sticking to each other after collision, as well as the critical collision velocity above which fragmentation will occur. Studies of SFE have focused on the simplest silicate, silica, usually at standard temperature and pressure. However, protoplanetary
dust grains have a wide variety of mineralogical compositions, temperatures, and a low-pressure environment lacking in water vapor. We perform molecular dynamics simulations using a ReaxFF-type potential of the SFE of silica, albite, and anorthite at temperatures ranging from 30 to 700 K in a true
vacuum. We find that the SFE drops by tens of percent with increasing temperature or shifting to more complex silicate compositions. More dramatically, we find that the values of the SFE in a
vacuum are two orders of magnitude higher than those usually measured in terrestrial laboratories. Our results confirm previous work that suggests that hydroxylation by monolayers of water produces this reduction in SFE in experiments. The coagulation of
dust grains thus appears to depend critically on the cleanliness of their surfaces, as well as their temperature and composition.
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All authors L. S. Morrissey, D. S. Ebel, L. E. J. Eriksson, A. Georgiou, Z. Huang, M.M. Mac Low, T. Pfeil
Earth and Planetary Astrophysics
How the gradient of $M_{\rm d}$ versus UV field strength yields insights into the ages of protoplanetary disc populations
Gavin A. L. Coleman and Sierk E. van Terwisga
FUV radiation from massive
stars launch photoevaporative winds from the outer regions of protoplanetary discs around other
stars, removing gas and
dust. Observations have identified a relation between the median
dust disc mass and the external UV field strength. Here we use disc evolutionary models to explore how this relation evolves over time, and with respect to other
stellar and disc properties. We find that the slope for the relationship $\lambda_{\rm UV}$ flattens over time as populations age, possibly explaining the differences seen between the L1641-N and L1641-S clusters in Orion A. We determine that $\lambda_{\rm UV}$ depends on the
stellar mass where more massive
stars exhibit steeper gradients than their lesser counterparts, in agreement with the differences seen between Herbig and T Tauri
stars. Additionally, the strength of the mechanism for angular momentum transport, either viscosity or MHD disc winds, is found to significantly affect $\lambda_{\rm UV}$ with stronger $\alpha$ values reducing $\lambda_{\rm UV}$ due to more material accreting on to the central
stars in weaker UV environments. Estimates of $\lambda_{\rm UV}$ from observations of L1641 place preliminary constraints on $\alpha$ to be between $10^{-3.5}$–$10^{-2.5}$, consistent with literature estimates. Further observations in different regions and better classifications of
stellar masses will allow us to place stringent constraints on disc
evolution properties, improving our understanding of how protoplanetary discs evolve.
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Cosmology and Nongalactic Astrophysics
Artificial Precision Polarization Array: Sensitivity for the axion-like dark matter with clock satellites
Hanyu Jiang, Baoyu Xu and Yun-Long Zhang
The approaches to searching for
axion-like signals based on
pulsars include observations with
pulsar timing arrays (PTAs) and
pulsar polarization arrays (PPAs). However, these methods are limited by observational uncertainties arising from multiple unknown and periodic physical effects, which substantially complicate subsequent data analysis. To mitigate these issues and improve data fidelity, we propose the Artificial
Pulsar Polarization Arrays (APPA): a satellite network comprising multiple pulsed signal transmitters and a dedicated receiver satellite. To constrain the
axion-
photon coupling parameter $g_{a\gamma}$, we generate simulated observations using Monte Carlo methods and investigate the sensitivity of APPA using two complementary approaches: Likelihood analysis and frequentist analysis. Simulations indicate that for the
axion mass range of $10^{-22}-10^{-18}$ eV, APPA yields a tighter upper limit on $g_{a\gamma}$ (at the 95% C.L.) than conventional ground-based observations, while also achieving superior detection sensitivity. Moreover, a larger spatial distribution scale of the satellite network corresponds to a greater advantage in detecting
axions with lighter masses.
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Earth and Planetary Astrophysics
Transiting Exoplanets from Sharjah Astronomical Observatory (SAO-M47): The Exoplanet HAT-P-25b Using L and V Filters
Mohammad F. Talafha, Mashhoor A. Al-Wardat, Ammar E. M. Abdulla et al. (+1 more)
In this study, we conduct a comparative analysis of observations carried out on the
exoplanet HAT-P-25 b at the Sharjah Astronomical Observatory (SAO). We have employed two distinct filters, namely, the Luminoso (L) and Visual (V) filters. Our research aims to discern any variations in transit depth or
exoplanet size resulting from the use of these different filters. The primary focus of this study is to determine the
exoplanet's size relative to its host
star using the transit method. The application of different filters was expected to introduce subtle variations in size, influenced by factors such as the
exoplanet's atmosphere. Notably, our findings reveal that the
exoplanet's size appears larger when observed through the L filter compared to the V filter. Throughout the analytical process, we employed the TRASCA model to determine the transit depth for each epoch. Fixed parameters, including the orbital period of the
exoplanet (P, measured in days) and the transit duration (measured in minutes), were utilized in these calculations. Our results indicate that the transit depths observed with the L filter were greater than those with the V filter, measuring 0.0238 magnitudes and 0.0200 magnitudes, respectively. These values deviate from the reference result of 0.0204 magnitudes.
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All authors Mohammad F. Talafha, Mashhoor A. Al-Wardat, Ammar E. M. Abdulla, Hamid M. Al-Naimiy
Instrumentation and Methods for Astrophysics · Cross-listed from physics.ins-det
Mitigating effects of nonlinearities in homodyne quadrature interferometers
Johannes Lehmann, Artem Basalaev, Jonathan J. Carter et al. (+12 more)
Homodyne Quadrature interferometers (HoQI) are an interferometric displacement sensing scheme proven to have excellent noise performance, making them a strong candidate for sensing and control schemes in gravitational wave detector seismic isolation. Like many interferometric schemes, HoQIs are prone to nonlinear effects when measuring displacements. These nonlinearities, if left unsuppressed, would substantially limit the use cases of HoQIs. This paper first shows a means of measuring and quantifying nonlinearities using a working HoQI and a mechanical resonator. We then demonstrate a method for real-time correction of these nonlinearities and several approaches for accurately calibrating the correction technique. By correcting in real time, we remove one of the biggest obstacles to including HoQIs in upgrades to future gravitational wave detectors. Finally, we discuss how to post correct data from HoQIs, suppressing even further the nonlinearity-induced errors, broadening the appeal of such sensors to other applications where measurement data can be reconstructed after the fact. We demonstrate all of this on a working HoQI system and show the measured suppression of nonlinear effects from each of these methods. Our work makes HoQIs a more broadly applicable tool for displacement sensing.
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All authors Johannes Lehmann, Artem Basalaev, Jonathan J. Carter, Matteo Carlassara, Harald Lück, Gabriella Chiarini, Pritam Sarkar, Firoz Khan, Satoru Takano, Sara Al-Kershi, Sina M. Koehlenbeck, Pascal Birckigt, Sarah L. Kranzhoff, Juliane von Wrangel, David S. Wu
Earth and Planetary Astrophysics
Spectroscopic analysis of hydrogen and silicon in bright fireballs: New insights into meteoroid composition
V. Vojáček, J. Borovička and P. Spurný
We present a study of the high-temperature spectral component in meteor fireballs, with a particular focus on neutral hydrogen at 656.28 nm and ionised silicon doublet at 634.71 nm and 637.14 nm. By analysing spectra from the European Fireball Network (EN) that exhibit H$\alpha$ and Si~II emissions, we investigated the relationship between H and Si abundances across different meteoroid types. The
plasma temperature of the high-temperature component remains independent of meteor velocity. This allows us to directly compare relative intensities of volatile hydrogen with less volatile silicon in bodies with different velocities. Our results confirmed that the H/Si value remains largely independent of meteor velocity. We show a positive correlation with photometric mass for cometary meteoroids, suggesting that larger bodies better preserve their volatile content, namely hydrogen. This correlation persists across the meteor showers, showing a physical process related to volatile preservation rather than specific parent body composition. Our data suggest that the abundance of hydrogen in large cometary meteoroids is not only higher than in CI chondrites, but is also comparable to or higher than the measured abundances in small particles of
dust from Halley's comet, depending on the assumed
plasma conditions. This work brought new constraints on the distribution and preservation of volatile elements in
Solar System bodies and new insights into the potential delivery mechanisms of water to Earth. The prevalence of hydrogen in larger cometary meteoroids supports models where comets could be significant contributors to Earth's volatile inventory.
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Earth and Planetary Astrophysics
Magnetohydrodynamic simulation assessment of a potential near-ultraviolet early ingress in WASP-189b
Y. Duann, S.-H. Lai, H. J. Hoeijmakers et al. (+8 more)
Ultra-hot Jupiters (UHJs) in close orbits around early-type
stars provide natural laboratories for studying atmospheric escape and
star-
planet interactions under extreme irradiation and wind conditions. The near-ultraviolet (NUV) regime is particularly sensitive to extended upper atmospheric and magnetospheric structures. We investigate whether
star-
planet interactions in the WASP-189 system could plausibly account for the early ingress feature suggested by NUV transit fitting models. We analyzed three NUV transits of WASP-189b observed as part of the Colorado Ultraviolet Transit Experiment (CUTE), which employs a 6U CubeSat dedicated to
exoplanet spectroscopy. To explore whether the observed transit asymmetry could plausibly arise from a magnetospheric bow shock (MBS), we performed magnetohydrodynamic (MHD) simulations using representative
stellar wind velocities and planetary atmospheric densities. During Visit 3, we identified an approximately 31.5-minute phase offset that is consistent with an early ingress. Our MHD simulations indicate that with a wind speed of 573 km s-1 and an upper atmospheric density of about 4.6e-11 kg m-3, a higher-density zone due to compression can form ahead of the
planet within five planetary radii where the fast-mode Mach number falls below ~0.56, even without a MBS. Shock cooling and crossing time estimates suggest that such a pileup could produce detectable NUV absorption. Our results indicate that while MBS formation is feasible for WASP-189b, low
stellar-wind speeds favor NUV-detectable
magnetic pileups over classical bow shocks and enhance the potential detectability of early-ingress signatures.
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All authors Y. Duann, S.-H. Lai, H. J. Hoeijmakers, A. Johansen, C.-L. Lin, L.-C. Huang, Y.-Y. Chang, A. G. Sreejith, K. France, L. C. Chang, W.-H. Ip
Astrophysics of Galaxies
The Apache Point Observatory extra-Galactic Evolution Experiment (APOeGEE): Chemical Abundance Trends for Seven Dwarf Spheroidal Galaxies in the APOGEE Survey
Matthew Shetrone, Rachael L. Beaton, Christian R. Hayes et al. (+10 more)
In addition to comprehensive surveys of the Milky Way bulge, disk, and
halo, the Apache Point
Galactic Evolution Experiment (APOGEE) project observed seven
dwarf spheroidal satellites (dSphs) of the Milky Way: Carina, Sextans, Sculptor, Draco, Ursa Minor, Bootes 1, and Fornax. APOGEE radial velocities,
stellar parameters, and
Gaia EDR3 proper motions are used to identify member
stars in the vicinity of each
dwarf. To properly analyze the abundance patterns of these
galaxies, a novel procedure was developed to determine the measurable upper limits of the APOGEE chemical abundances as a function of the effective temperature and the spectral signal-to-noise ratio. In general, the APOGEE abundance patterns of these
galaxies (limited to [Fe/H] $>$ -2.5) agree with those found in high-resolution optical studies after abundance offsets are applied. Most of the
galaxies studied have abundance patterns that are distinctly different from the majority of
stars found in the MW
halo, suggesting that these
galaxies contributed little to the MW
halo above [Fe/H] $>$ -2.0. From these abundance patterns, we find that these dSphs tend to follow two types of chemical
evolution paths: episodic and continuous
star formation, a result that is consistent with previous photometric studies of their
star formation histories. We explore whether mass and/or environment have an impact on whether a
galaxy has an episodic or continuous
star formation history, finding evidence that, in addition to the
galaxy's mass, proximity to a larger
galaxy and the cessation of
star formation may drive the overall shape of the chemical
evolution.
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All authors Matthew Shetrone, Rachael L. Beaton, Christian R. Hayes, Sten Hasselquist, Joshua D. Simon, Jon A. Holtzman, Katia Cunha, Steven R. Majewski, Jennifer Sobeck, Ricardo Schiavon, Thomas Masseron, Verne V. Smith, David L. Nidever
Solar and Stellar Astrophysics
A phenomenological model of magnetic flux tubes in strong fields induced by axion-origin photons
Vitaliy Rusov and Tatiana Zelentsova
We propose a phenomenological model in which empty flux tubes in strong
magnetic fields are associated with both the conversion of
axions to
photons of
axion origin to generate coronal heating, and the simultaneous preservation of the Parker-Biermann cooling effect by converting high-energy
photons from the radiative zone to
axions from the convective zone through the O-loop tachocline, is the source of the rise of the
magnetic flux tube from the tachocline to the photosphere in the form of sunspots. The model is characterized by two free parameters, justified by existing theoretical and observational constraints, the
axion mass m_a ~3.2*10^{-2} eV, and asymmetric dark matter (ADM) with a particle mass m_ADM ~5 GeV gravitationally captured by the Sun. In this scenario, temporal modulations of the
axion density are caused by anticorrelated 11-year modulations of ADM gravitationally captured by the Sun. We also obtained theoretical estimates of the velocities and times in empty
magnetic tubes in strong fields rising from the tachocline to the surface of the photosphere in the form of sunspots. This ensured complete agreement with known experimentally measured velocities and times using local helioseismological time-distance inversions along the ray trajectories of acoustic waves. This allows us to study not only the subsurface structure and dynamics of active regions, but also the depths of the empty
magnetic flux tube, extending up to 200,000 km from the tachocline to the photosphere. The proposed model links the phenomenology of
axions with the
magnetic structures of the Sun and provides testable consequences for astrophysical and
solar observations.
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Solar and Stellar Astrophysics
Massive stars exploding in a He-rich circumstellar medium XII. SN 2024acyl: A fast, linearly declining Type Ibn supernova with early flash-ionisation features
Y.-Z. Cai, A. Pastorello, K. Maeda et al. (+63 more)
We present a photometric and spectroscopic analysis of the Type Ibn
supernova (SN) 2024acyl. It rises to an absolute magnitude peak of about -17.58 mag in 10.6 days, and displays a rapid linear post-peak light-curve decline in all bands, similar to most SNe Ibn. The optical pseudobolometric light curve peaks at $(3.5\pm0.8) \times 10^{42}$ erg s$^{-1}$, with a total radiated energy of $(5.0\pm0.4) \times 10^{48}$ erg. The spectra are dominated by a blue continuum at early stages, with narrow P Cygni He I lines and flash-ionisation emission lines of C III, N III, and He II. The P Cygni He I features gradually evolve and become emission-dominated in late-time spectra. Our multi-band light-curve modelling yields estimates of the ejecta mass of $M_{\rm ej} = 0.49^{+0.11}_{-0.09}$ M$_\odot$ with a kinetic energy of $E_{\rm k} = 0.06^{+0.01}_{-0.01} \times 10^{51}$ erg, and a $^{56}$Ni mass of $M_{\rm Ni} = 0.018$ M$_\odot$. The inferred CSM properties are characterised by a mass of $M_{\rm CSM} = 0.51^{+0.05}_{-0.04}$ M$_\odot$, an inner radius of $R_0 = 17.8^{+3.6}_{-3.0}$ AU, and a density of $\rho_{\rm CSM} =(8.3_{-1.2}^{+2.7})\times10^{-12}$ g cm$^{-3}$. The multi-epoch spectra are well reproduced by the CMFGEN/he4p0 model, corresponding to a He-ZAMS mass of 4 M$_\odot$ (H-ZAMS mass 18.11 M$_\odot$, pre-SN mass 3.16 M$_\odot$). These findings are consistent with a scenario of an SN powered by ejecta-CSM interaction, originating from a low-mass helium
star that evolved within an interacting binary system where the CSM with some residual hydrogen may originate from the mass-transfer process. In addition, a channel of core-collapse explosion of a late-type Wolf-Rayet
star with H, or an Ofpe/WN9
star with fallback
accretion, cannot be entirely ruled out.
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All authors Y.-Z. Cai, A. Pastorello, K. Maeda, J.-W. Zhao, Z.-Y. Wang, Z.-H. Peng, A. Reguitti, L. Tartaglia, A. V. Filippenko, Y. Pan, G. Valerin, B. Kumar, Z. Wang, M. Fraser, J. P. Anderson, S. Benetti, S. Bose, T. G. Brink, E. Cappellaro, T.-W. Chen, X.-L. Chen, N. Elias-Rosa, A. Esamdin, A. Gal-Yam, M. González-Bañuelos, M. Gromadzki, C. P. Gutiérrez, A. Iskandar, C. Inserra, T. Kangas, E. Kankare, T. Kravtsov, H. Kuncarayakti, L.-P. Li, C.-X. Liu, X.-K. Liu, P. Lundqvist, K. Matilainen, S. Mattila, S. Moran, T. E. Müller-Bravo, T. Nagao, T. Petrushevska, G. Pignata, I. Salmaso, S. J. Smartt, J. Sollerman, M. D. Stritzinger, S. Srivastav, L.-T. Wang, S.-Y. Yan, Y. Yang, Y.-P. Yang, W. Zheng, X.-Z. Zou, L.-Y. Chen, X.-L. Du, Q.-L. Fang, A. Fiore, F. Ragosta, S. Zha, J.-J. Zhang, X.-W. Liu, J.-M. Bai, B. Wang, X.-F. Wang