High Energy Astrophysical Phenomena
On the astrophysical origin of cosmic rays: Constraining the Ultra-High-Energy Cosmic Ray Horizon through Nearby Galaxy Distributions
F. Dávila-Kurbán, F. Duplancic and D. Garcia Lambas
The origin of ultra-high-energy
cosmic rays (UHECR) remains a central open problem in astroparticle physics. The observed large-scale anisotropy of UHECR arrival directions above several EeV, together with the spectral suppression at the highest energies, suggests extragalactic sources confined to a limited volume of the nearby Universe, though the effective spatial scale of this contribution remains poorly constrained. We aim to constrain the effective propagation horizon of UHECR with energies E >= 8 EeV by studying how well the observed large-scale anisotropy is reproduced by the distribution of nearby
galaxies at different distances, accounting for
Galactic magnetic-field deflections. We construct volume-limited
galaxy samples from the GLADE+ catalogue extending to 10000 km/s (~150 Mpc) and use both dipole comparisons and angular cross-correlation analyses with the Pierre Auger Observatory UHECR flux map (E >= 8 EeV) to characterize the distance dependence of the anisotropy signal, further weighting the
galaxy-UHECR correlations using deflection maps derived from a
Galactic magnetic field model. We find that the angular separation between the
galaxy and UHECR dipoles is minimized for
galaxies within cz < 4000 km/s (< 60 Mpc), where the
galaxy dipole amplitude is also maximal. The
galaxy-UHECR cross-correlation signal is dominated by this nearby population and weakens rapidly at larger distances. Accounting for
Galactic magnetic field deflections enhances the correlation amplitude by more than a factor of two, indicating that
magnetic effects significantly shape the observed anisotropy. Our results indicate that the observed anisotropy of UHECR of 8 EeV and above is primarily driven by sources within ~50-60 Mpc, consistent with expectations from energy losses and
magnetic deflections, retaining a measurable imprint of the nearby extragalactic matter distribution.
Read the full abstract ▾
Earth and Planetary Astrophysics
Onset of dynamo action in planetesimals
Ludovic Huguet, Jonathan E. Mound, Christopher J. Davies et al. (+1 more)
Several meteorites have been found to carry primary remanent magnetizations imparted by fields generated within planetesimal cores during the early
solar system. Thermal
evolution models have shown that thermal convection likely drove the dynamo in the early
evolution of these bodies. In such small cores, the
magnetic Reynolds number is thought to be close to the threshold for dynamo action. However, the critical value of the
magnetic Reynolds number, meaning its value at the onset, is also poorly constrained in dynamo simulations. We perform dynamo simulations to investigate the onset of the dynamo at different Ekman ($E$) and
magnetic Prandtl ($Pm$) numbers, in a quasi-full sphere. Along two empirical paths in this $(E,Pm)$ space, the onset of dynamo action depends on whether the
magnetic field is initially strong or weak. The onset of the dynamo occurs at larger supercriticality (ratio between the Rayleigh number ($Ra$) and its critical value ($Ra_c$)) when moving toward more realistic parameter values. Once extrapolated to planetesimal core conditions, the supercriticality for the onset of the dynamo is about $10^3$ for a strong initial
magnetic field (meaning
magnetic energy is of the same order of magnitude or larger than the kinetic energy). For a weak initial field, the required $Ra/Ra_c$ would be larger. Compared to previous estimates, this revised criterion facilitates dynamo activity, and so extends the lifetime of the
magnetic field compared to previous models and allows the generation of a
magnetic field in smaller planetesimals.
Read the full abstract ▾
All authors Ludovic Huguet, Jonathan E. Mound, Christopher J. Davies, James F.J. Bryson
Astrophysics of Galaxies
SED Fitting of the Globular Clusters in Abell 2744 at z=0.3
Jinoo Kim and William E. Harris
We present a spectral energy distribution (SED) fitting analysis of globular cluster (GC) candidates in Abell 2744, a massive
galaxy cluster at
redshift z = 0.308 with a lookback time of 3.5 Gyr, using deep JWST/NIRCam photometry. By leveraging observations in eight broadband filters (F070W to F444W), we derive constraints on GC masses, ages, and
metallicities of 69 GC candidates, refining previous studies focused on color-magnitude analysis. The inferred GC masses predominantly fall near 10^7 M_sun, consistent with the high-mass end of typical GCs seen in the Local Group and overlapping with UCDs (Ultra-Compact
Dwarfs). Although the best-fit age estimates are unavoidably uncertain, we very tentatively identify two prominent concentrations: one at intermediate ages (4-6.5 Gyr) near [M/H]=-0.25; and a second at older ages 8 - 10 Gyr with both metal-poor ([M/H]=-0.66) and metal-rich ([M/H]=+0.15) components. As expected for broadband SED fitting, we find mass-age and age-
metallicity degeneracies in our result. Monte Carlo error propagation and tests with different SSP model assumptions show that the population-level trends in age and
metallicity are preserved, although individual age estimates must be interpreted with caution. The resulting mass-to-light ratios show wavelength dependence with a mild decline toward longer wavelengths and increase with age, while showing minimal sensitivity to
metallicity. These results demonstrate the power and current limitations of multi-band JWST SED fitting that highlight the potential of future JWST data for detailed characterization of GCs at lookback times of several Gigayears.
Read the full abstract ▾
Earth and Planetary Astrophysics
JWST/MIRI Reveals the Evolution from Molecular to Atomic Disk Winds
Naman S. Bajaj, Ilaria Pascucci, Sylvie Cabrit et al. (+10 more)
The
evolution and dispersal of protoplanetary disks–governed by
accretion, magnetically launched jets and winds, and photoevaporative winds–fundamentally shape planetary systems. Determining how these mass-loss processes co-evolve is crucial for constraining
planet formation pathways. We analyze archival JWST/MIRI/IFU data of 72 inclined (i>40deg) mostly ClassII disks to identify and characterize spatially resolved jets and winds, focusing on [NeII] and H2 lines. Extended emission in H2 S(1), S(3), S(5), S(7) and/or [NeII] is detected toward 66 disks, revealing diverse morphologies. We develop a framework to identify conical H2 winds and high-velocity [NeII] jets perpendicular to the disk, detecting them toward 46 and 40 disks, respectively. All sources with [NeII] jets exhibit a corresponding wind traced in either H2 (85%) or [OI], establishing a connection between jets and winds. The detection fractions of [NeII]-jets and H2-winds correlate positively with mass
accretion rate, with no dependence on disk inclination or
stellar mass. Conversely, marginally resolved low-velocity [NeII] winds are found preferentially toward lower accretors. Among sources with H2 winds, detection of hotter winds traced by S(7) and S(5) declines more rapidly with decreasing
accretion rate than the colder S(1) component. Comparison with high-resolution [OI]6300\textÅ spectroscopy reveals [OI] LVC and extended H2 wind detections preferentially toward moderate-to-high accretors (>~10^{-8.5}~Msun/yr), whereas lower accretors exhibit only [OI] and [NeII] winds. Together, these results indicate that atomic jets and atomic+molecular winds, consistent with an MHD disk-wind origin, dominate during early, actively accreting disk phases, while at lower
accretion rates, jets weaken and winds become predominantly atomic.
Read the full abstract ▾
All authors Naman S. Bajaj, Ilaria Pascucci, Sylvie Cabrit, Suzan Edwards, Gabriele Cugno, Andrew D. Sellek, Joan R. Najita, Ke Zhang, Richard Alexander, Gregory J. Herczeg, Uma Gorti, Sophie C. Clark, Tracy L. Beck
Astrophysics of Galaxies
Outflows in super-Eddington quasars drive clumpy circumgalactic medium and extended H$\alpha$ nebulae at $z \gtrsim 6$
Lucas Tortora, Tiago Costa, Debora Sijacki et al. (+1 more)
The discovery of gargantuan black holes with masses exceeding a billion
solar masses at $z\gtrsim6$ suggests rapid black hole growth and significant energy input into their host
galaxies in the early Universe. With JWST probing previously unseen phases of the interstellar (ISM) and circumgalactic (CGM) medium around $z > 6$
quasars, detailed theoretical studies can now be directly confronted with observations. We use zoom-in simulations of a massive protocluster at $z\sim6$, employing both the fiducial FABLE
galaxy formation model and modifications that allow earlier black hole seeding and mildly super-Eddington
accretion. The central
quasar remains Compton-thick throughout most of its
evolution, with the obscuration arising from the ISM of its compact host
galaxy. The onset of sufficiently strong
quasar feedback drives a 'blow-out' episode, clearing out escape channels for ionizing radiation and leaving the central engine unobscured. This leads to a complete transformation of the CGM, whereby powerful, metal-enriched
outflows produce a population of cold, fast, neutral clumps, significantly increasing the covering fraction of neutral hydrogen in the host
halo. Radiative transfer calculations performed with a new ray-tracing code show that the CGM responds to
quasar activity through the formation of H$\alpha$ nebulae, whose size and luminosity increase with the strength of
quasar feedback and decrease with obscuration level. Enhanced early black hole growth thus fundamentally reshapes the ISM and CGM of $z\sim6$
quasars, leaving clear observable signatures in their obscuration, neutral hydrogen distribution, and extended H$\alpha$ emission.
Read the full abstract ▾
All authors Lucas Tortora, Tiago Costa, Debora Sijacki, Jake S. Bennett
Astrophysics of Galaxies
Megaparsec-Scale Neutral Hydrogen Flows in the Neighborhood of Hickson Compact Group 100
Qingzheng Yu, Taotao Fang, Enrico M. Di Teodoro et al. (+2 more)
The
evolution of
galaxies is strongly influenced by their ability to exchange gas with their surroundings, yet direct observational constraints on these processes remain scarce. Using ultra-deep neutral hydrogen (HI) observations with the Five-hundred-meter Aperture Spherical
Telescope (FAST), we detect a diffuse HI structure extending over $\sim$1 Mpc around the compact
galaxy group HCG 100, with integrated column densities down to $\sim$$8.6\times10^{17}$ cm$^{-2}$. This structure is among the most extended and lowest-density neutral gas systems ever observed in emission. The HI gas forms a coherent envelope connecting the compact group to neighboring
galaxies and shows a large-scale coherent velocity gradient around HCG 100 extending across $\sim$0.6 Mpc. The extended structure contains $\sim$$1.4\times10^{10}$ $M_\odot$ of diffuse neutral gas, implying that up to $\sim$40$-$50% of the HI gas resides outside
galaxies. Such a large diffuse HI structure may arise either from large-scale
tidal debris or gas
accretion from the surrounding
cosmic web. Our results demonstrate that massive reservoirs of diffuse neutral gas can persist on megaparsec scales around
galaxy groups for extended periods, providing a previously unseen component of
baryon cycling in dense environments.
Read the full abstract ▾
All authors Qingzheng Yu, Taotao Fang, Enrico M. Di Teodoro, Cheng Cheng, Cong Kevin Xu
Instrumentation and Methods for Astrophysics
Low-cost, ultra-wideband, differential low-noise amplifier for interferometric radio telescopes
Sophia Da Costa, Albert Wai Kit Lau and Keith Vanderlinde
We present a low-cost, ultra-wideband, dual-polarized differential low-noise amplifier that eliminates the need for a pre-amplification balun. Built entirely from commercial surface-mount components, the design costs approximately 20 US dollars per unit. The amplifier has been characterized through laboratory gain and noise measurements together with feed-coupled hot-cold testing at the Dominion
Radio Astrophysical Observatory. A noise figure close to 0.3 dB is demonstrated across a 10:1 bandwidth when matched to a constant 130 $\Omega$ source, while feed-coupled measurements yield system noise temperatures as low as 25 K when matched to a Vivaldi feed operating over a 300-1500 MHz bandwidth.
Read the full abstract ▾
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Viscosity effects on the shadow of a non-rotating black hole
Sayantani Lahiri, Sergio Gimeno-Soler, Alejandro Cruz-Osorio et al. (+2 more)
We study the effect of shear viscosity in stationary magnetized
accretion tori on synthetic images of non-rotating black hole shadows. Shear viscosity and spacetime-
curvature contributions are introduced perturbatively in the
tori through first and second-order transport coefficients within a second-order causal theory of non-ideal relativistic hydrodynamics. Synthetic black hole shadow images at 230\,GHz are obtained via general relativistic radiative transfer computations assuming thermal synchrotron emission and for a wide range of
plasma magnetization parameters, viewing inclination angles, electron-temperature prescriptions, and viscosity parameters. A comparative pixel-by-pixel analysis using two normalized metrics shows that the largest image differences occur for strongly magnetized
tori. While shear viscosity induces only minor changes in the overall shadow morphology, its combined effects with spacetime
curvature are more evident in localized modifications of the synchrotron emission and pixel-wise flux distribution. These effects become increasingly pronounced at higher inclination angles, with the largest brightness differences between viscous and non-viscous configurations occurring for larger values of the electron-temperature parameter. Overall, our results indicate that shear viscosity and spacetime
curvature leave only modest imprints on black hole shadow images produced by stationary thick disks, with differences remaining at the level of a few $\mu$Jy. Since our analysis is limited to stationary
tori, the effects of shear viscosity might however be more significant in fully dynamical
accretion systems.
Read the full abstract ▾
All authors Sayantani Lahiri, Sergio Gimeno-Soler, Alejandro Cruz-Osorio, José A. Font, Ziri Younsi
Astrophysics of Galaxies
The AGORA High-resolution Galaxy Simulations Comparison Project. IX - Part 2: Effects of a Major Galaxy Merger on the Stellar Morphology of a Milky Way-mass Galaxy Progenitor
Thinh Huu Nguyen, Kirk S. S. Barrow, Minyong Jung et al. (+23 more)
Galaxy mergers, with their high sensitivity to initial conditions, provide a valuable setting for comparative studies of
galaxy simulation codes. Following our first paper focusing on merger-driven
star formation, we present a code comparison examining the morphological transformation impact of a major
galaxy merger at $z \approx 4.5$ on a Milky Way-mass
galaxy progenitor. Our analysis employs nine state-of-the-art codes from the AGORA CosmoRun cosmological zoom-in simulation suite. For this merger, we show that the adopted
stellar feedback type influences the
galaxy's compaction and
stellar disc formation. Codes with purely thermal feedback produce a merger remnant that forms a disc and becomes compact primarily during and after coalescence; codes that include kinetic feedback begin disc formation and compaction around the first periapsis; and codes with strong delayed cooling or superbubble feedback suppress disc formation and produce a more extended remnant. In contrast, the orientation of the remnant disc is code-independent. In all codes, the rotational angular momentum of the remnant disc aligns with the interaction's orbital angular momentum rather than the pre-merger rotational axis, implying that the infalling gas preserves its orbital angular momentum to form a new disc. Comparisons with the Santa Cruz semi-analytic model show reasonable agreement in
stellar mass and half-mass radius, yet the model underpredicts (overpredicts) the dark matter fraction and velocity dispersion for codes exhibiting strong compaction (expansion). The systematic dependence of our remnants' morphology on feedback schemes demonstrates that merger remnant morphology may serve as a powerful probe of
stellar feedback processes.
Read the full abstract ▾
All authors Thinh Huu Nguyen, Kirk S. S. Barrow, Minyong Jung, Ramón Rodríguez-Cardoso, Santi Roca-Fàbrega, Ji-hoon Kim, Joel R. Primack, Kentaro Nagamine, Renyue Cen, Daniel Ceverino, Weiguang Cui, Anna Genina, Hyeonyong Kim, Yuri Oku, Johnny W. Powell, Yves Revaz, Pablo Granizo, Alessandro Lupi, Ikkoh Shimizu, Héctor Velázquez, Tom Abel, Oscar Agertz, Avishai Dekel, Boon Kiat Oh, Thomas R. Quinn, the AGORA Collaboration
Astrophysics of Galaxies
The AGORA High-resolution Galaxy Simulations Comparison Project. IX - Part 1: Effects of a Major Galaxy Merger on Star Formation of a Milky Way-mass Galaxy Progenitor
Thinh Huu Nguyen, Kirk S. S. Barrow, Minyong Jung et al. (+23 more)
Given their highly nonlinear dynamics and sensitivity to initial conditions,
galaxy mergers are a compelling area to conduct a simulation code comparison. We perform a comparative study of a major
galaxy merger at $z \approx 4.5$ in cosmological zoom-in hydrodynamic simulations of a Milky Way-mass
galaxy progenitor. The comparison employs the AGORA CosmoRun suite of nine well-calibrated, state-of-the-art numerical codes, each adopting a different
stellar feedback scheme. We find that the
evolution of the
star formation rate (SFR) during the interaction is strongly shaped by the
stellar feedback type. Using kinetic feedback in the feedback model drives a pronounced merger-induced starburst that starts to subside before coalescence; using thermal feedback without kinetic feedback yields prolonged SFR growth even after coalescence; and using delayed cooling or radiation pressure results in highly fluctuating SFR. Tracking gas particles in particle-based codes reveals that kinetic feedback facilitates gas inflow from the secondary
galaxy onto the primary
galaxy between the first periapsis and apoapsis, thus producing an earlier and more prominent starburst. In contrast, thermal feedback, augmented by superbubble or delayed-cooling feedback, suppresses gas cooling, creates a more extended gas distribution, and hinders strong starbursts during the merger. We also observe an inverse correlation between burst fraction and pre-merger gas fraction that is independent of feedback models. Overall, these results highlight the sensitivity of simulated
galaxy mergers'
star formation response to
stellar feedback prescriptions. This study indicates that
galaxy mergers may serve as a good testbed for
stellar feedback processes in cosmological simulations.
Read the full abstract ▾
All authors Thinh Huu Nguyen, Kirk S. S. Barrow, Minyong Jung, Ramón Rodríguez-Cardoso, Santi Roca-Fàbrega, Ji-hoon Kim, Joel R. Primack, Kentaro Nagamine, Renyue Cen, Daniel Ceverino, Weiguang Cui, Anna Genina, Hyeonyong Kim, Yuri Oku, Johnny W. Powell, Yves Revaz, Pablo Granizo, Alessandro Lupi, Ikkoh Shimizu, Héctor Velázquez, Tom Abel, Oscar Agertz, Avishai Dekel, Boon Kiat Oh, Thomas R. Quinn, the AGORA Collaboration
Cosmology and Nongalactic Astrophysics · Cross-listed from cs.LG
An Introduction to Bayesian and Frequentist Simulation-Based Inference with Machine Learning
Maximilian Dax, Theo Heimel and Gilles Louppe
Simulation-based inference (SBI) with machine learning is an increasingly important tool for solving inverse problems in science and engineering, including parameter inference and the inversion of detector effects. We provide an overview of the
Bayesian and frequentist statistical frameworks, describe how machine-learning-based SBI methods, such as neural posterior estimation and neural likelihood estimation, can be used for parameter estimation within these frameworks, and show that the same methods can also be applied to Empirical Bayes or unfolding tasks. We also discuss how to validate inference results and the limitations of SBI with machine learning.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Formation and scaling of $\mathbb{Z}_N$ strings for global $\mathrm{SU}(N)/\mathbb{Z}_N$ symmetry
Masaki Yamada
We numerically investigate networks of global $\mathbb{Z}_N$ strings with multi-string junctions in a scalar field model whose
vacuum manifold is $\mathrm{PSU}(N)=\mathrm{SU}(N)/\mathbb{Z}_N$. The construction of the model is motivated by the
Higgs vacua of mass-deformed $\mathcal{N}=4$ supersymmetric Yang-Mills theory, commonly known as $\mathcal{N}=1^*$ theory, and provides a tractable effective description of string networks with
baryon-vertex-like junctions. We perform classical
lattice simulations of the formation and
evolution of these networks in a radiation-dominated universe. For $N=2,3,4,5,$ and $8$, we find that the networks approach a scaling regime rather than becoming frustrated. The normalization of the string density grows in proportion to the dimension of the adjoint representation, $N^2-1$, while non-minimal-charge components remain subdominant. These results imply that, at least for $N\lesssim 8$, the amplitude of the gravitational-wave energy density generated by the
cosmic-string network scales as $\Omega_{\rm GW}\propto \mu^2 (N^2-1)^2$, where $\mu$ is the tension of a unit-charge string.
Read the full abstract ▾
Astrophysics of Galaxies
Different paths, same appearance: an intermediate-age red nugget at z~0.13
F. La Barbera, F. Buitrago, I. Ferreras et al. (+1 more)
Massive ultra-compact
galaxies are commonly regarded as nearby relics of the compact quiescent population at z~2-3, and detailed studies have focused so far only on old systems in dense environments. Here we present a spatially resolved analysis of G79071, an ultra-compact (R_e<2kpc), massive (M*~10^{11}MSun) ETG at z~0.13 residing in a low-mass group environment, based on deep VLT/X-Shooter long-slit spectroscopy. We extract
stellar kinematics out to ~4R_e and constrain
stellar population properties and the low-mass end of the
stellar IMF, by combining full spectral fitting, full-index fitting, and index fitting, using different
stellar population models. G79071 shows significant rotation, consistent with a fast-rotator-like kinematic structure, and is dominated by an intermediate-age
stellar population (~3-4Gyr) with a flat age profile and no evidence for a significantly old (>5Gyr) component. The central
metallicity is supersolar and decreases with radius, while most abundance ratios show flat radial trends and are consistent with typical massive, low-
redshift ETGs at similar velocity dispersion. Moreover,
metallicity and [Na/Fe] abundance are significantly enhanced, reflecting a very efficient chemical enrichment process.Our analysis suggests that the IMF remains bottom-heavy out to ~2R_e, implying a mass-excess factor alpha>~2. Jeans anisotropic models with an NFW
halo are consistent with the IMF-based
stellar mass normalization and with compactness-corrected (non-homologous) dynamical mass
estimators, yielding a modest projected dark-matter fraction within one effective radius, f_DM(<R_e)=0.18 \pm 0.07. These results show that at least some massive compact
galaxies with a bottom-heavy IMF can form and persist at lower
redshift and outside high-density environments, providing new constraints on the diversity of formation pathways for massive
galaxies.
Read the full abstract ▾
All authors F. La Barbera, F. Buitrago, I. Ferreras, C. Tortora
High Energy Astrophysical Phenomena
Light Antinuclei Coalescence: Femtoscopic Constraints via Neural-Flow Surrogates
M. Korwieser, L. Fabbietti, B. Hashemi et al. (+4 more)
Precise predictions of
cosmic-ray antinuclei fluxes, a
prime dark matter signature, are limited by the lack of data constraining production rates of antinuclei. We mitigate this bottleneck with a fast, differentiable normalizing-flow surrogate for the femtoscopic source model (CECA), fit to 49 ALICE
proton-
proton correlation functions, and extrapolated via scaling laws to the low-multiplicity domain relevant for
cosmic rays. The surrogate reproduces CECA with sub-percent emulation fidelity, yielding data-constrained source functions that remove the dominant uncertainty in coalescence-based antinuclei production rates. The resulting uncertainties on the coalescence parameters $B_2$ and $B_3$ shrink from factors of 10-100 and ${\sim}$1000 to the few percent and ten-percent level, respectively, with an additional ${\sim}15\%$ wavefunction systematic for $B_{2}$.
Read the full abstract ▾
All authors M. Korwieser, L. Fabbietti, B. Hashemi, L. Heinrich, M. Mahlein, D. L. Mihaylov, C.S. Zeyn
Instrumentation and Methods for Astrophysics
Detecting habitable exoplanet atmospheres with LIFE, the Large Interferometer for Exoplanets
Sarah Rugheimer, Aiden Weatherbee, James Fecanin et al. (+21 more)
A key goal of astronomers with the next generation
telescopes is to detect signs of life in
exoplanet atmospheres. NASA's next flagship is the Habitable Worlds Observatory (HWO). In the context of ESA's Voyage 2050 program, the Senior Committee report prioritises detecting habitable
exoplanet atmospheres in the mid-IR. The most suited mission for this is the Large Interferometer for
Exoplanets (LIFE) which can detect an even wider range of biosignatures than HWO and at lower concentrations. LIFE is a global science collaboration based out of ETH Zürich. With the UK's expertise in building infrared instruments we could play a leading role in realising an ambitious European-led mission. Notably, LIFE is able to detect necessary planetary context like surface temperature and pressure, along with a key discriminator molecule for biosignature false positives, methane, which will be much harder or impossible with HWO. Also, LIFE will be able to investigate many of the nearby rocky
exoplanets known from radial velocity searches that are inaccessible to HWO due to its limited spatial resolution.
Read the full abstract ▾
All authors Sarah Rugheimer, Aiden Weatherbee, James Fecanin, Alistair Glasse, Paul Rimmer, Eleonora Alei, Esther Wang, Marrick Braam, Sascha P. Quanz, Adrian Glauser, Alexander Archibald, Beth Biller, Mark Booth, Tereza Constantinou, Gregory Cooke, Daniel Dicken, Trent Dupuy, Mei Ting Mak, Paul Palmer, Tim Pearce, Vito Squicciarini, Amaury Triaud, Floris van der Tak, Sergey Yurchenko
Solar and Stellar Astrophysics
Echoes of Star Stories: Integrating Indigenous narratives into modern stellar astrophysics
Dionysios Gakis
Indigenous narratives have long preserved observations of celestial phenomena, offering insights that resonate with modern astrophysical research. Deeply embedded in cultural traditions, these stories describe events such as
stellar variability,
supernovae, eclipses, and planetary
alignments. Indigenous communities have also used the
stars for
navigation and calendar systems, reflecting a sophisticated understanding of celestial patterns. These narratives not only complement historical records but offer human-centric perspectives on
stellar life cycles that often parallel modern models. Drawing from traditions from diverse Indigenous communities - including Aboriginal Australians, Pueblo peoples, Inuit, and Polynesians - this paper highlights the profound connections between Indigenous knowledge and
stellar astrophysics. Integrating these traditions acknowledges their value, safeguards their relevance in the Space Age, and fosters mutual learning through cross-cultural collaboration. We explore how such narratives can enrich education, public engagement, and even inspire scientific hypotheses, bridging cultural heritage and modern astrophysics.
Read the full abstract ▾
High Energy Astrophysical Phenomena
XMM-Newton and Swift Unveil Another X-Ray Transient in NGC 4945, XMM J130514.64-493311.27
Ryan W. Pfeifle, Kimberly A. Weaver, Jenna M. Cann et al. (+2 more)
NGC 4945 hosts a Compton-thick, low luminosity AGN and a
nuclear starburst in its core and has been the subject of many previous X-ray investigations of the AGN emission structure,
nuclear starburst properties, and ultraluminous X-ray (ULX) source populations. Indeed, NGC 4945 has proven to be a rich system for ULX and X-ray transients, with at least four X-ray transients being reported over the last 15 years. Here we report the detection of an X-ray transient source, XMM J130514.64-493311.27, in NGC 4945 in the latest and deepest XMM-Newton observation of NGC 4945 to-date. The source lies $\sim5.5'$ south of the
nucleus and was not detected in any previous XMM-Newton or Chandra imaging, but the source was detected by Swift-XRT in 2008, 2019, and in 2022, the latter of which coincides roughly with our new XMM-Newton imaging; we are therefore tracing the most recent outburst of this object with XMM-Newton. The source is soft with $\Gamma\approx3$, and our spectroscopic analysis suggests the source is best characterized by a multicolor disk + power law model or, alternatively, a multicolor disk + thermal
plasma model, with a 0.3-10 keV X-ray luminosity of $\sim2.2-2.3\times10^{38}$. We find no evidence for a counterpart in the optical, near-infrared, ultraviolet, or in the
radio, but we identify a candidate counterpart in NEOWISE mid-IR light curves. We propose that this X-ray source is an X-ray binary within NGC 4945 caught during its most recent active phase.
Read the full abstract ▾
All authors Ryan W. Pfeifle, Kimberly A. Weaver, Jenna M. Cann, Murray Brightman, Miranda McCarthy
Astrophysics of Galaxies
Identifying and Distinguishing Quenching Galaxies with Spatially Resolved Star Formation in the Hubble Frontier Fields
Cameron Lawlor-Forsyth, Michael L. Balogh, Sean L. McGee et al. (+1 more)
We investigate the nature and prevalence of different quenching signatures for 1437
galaxies with $M_{*} \geqslant 10^{8}~\mathrm{M}_{\odot}$ and $\text{SFR} \geqslant 10^{-3}~M_{\odot}~\text{yr}^{-1}$ in the Hubble Frontier Fields through spatially resolved spectral energy distribution fitting with FAST++. We use the morphological metrics previously presented in our series of investigations to quantify the distribution of
star formation, and use a $k$-nearest neighbors
algorithm to classify quenching
galaxies into different quenching pathways, including an inside-out pathway and an outside-in pathway. We find 129
galaxies have morphologies consistent with an inside-out quenching pathway, and 70 are consistent with an outside-in pathway. Inside-out quenching
galaxies are $0.8^{+0.2}_{-0.1}~\text{dex}$ more massive compared to outside-in quenching
galaxies, where both populations are more massive in clusters than the field, by $0.8^{+0.3}_{-0.1}~\text{dex}$. Inside-out quenching
galaxies are found more often in clusters (106/129), compared to outside-in quenching
galaxies (25/70). In clusters, the fraction of inside-out quenching
galaxies strongly increases with mass, representing ${\sim}$30% of the non-quenched
galaxy population at high masses. A milder
evolution is seen in the field. The fraction of outside-in quenching
galaxies is independent of mass, representing ${\lesssim}$10% of the non-quenched population, in both the cluster and field. We find no strong dependence for the fraction of any population with estimated infall time, except massive inside-out quenching
galaxies, which increase in fraction with increasing infall time.
Read the full abstract ▾
All authors Cameron Lawlor-Forsyth, Michael L. Balogh, Sean L. McGee, Gregory H. Rudnick
Cosmology and Nongalactic Astrophysics
Hubble tension: a short review of theoretical explanations
Jia-Qi Wang and Zong-Kuan Guo
The $\Lambda$ cold dark matter model successfully describes a wide range of cosmological observations. However, the persistent discrepancy between the value of the Hubble constant inferred from
cosmic microwave background (CMB) measurements within this model and that obtained from local distance-ladder determinations points to a significant inconsistency. This short review examines theoretical responses across the cosmological inference chain, from the gravitational field equations to the pre-recombination sound horizon and the late-time distance-
redshift relation. It discusses early-time and late-time mechanisms, as well as modified
gravity, as ways to alter the acoustic ruler, distances, structure growth, or gravitational response. Current proposals can reduce the nominal tension, but often at the cost of correlated shifts in CMB spectra, standard-ruler distances,
lensing, structure growth, or calibrator information. Further progress requires unified likelihoods and multi-probe tests linking all key observables under the same model assumptions.
Read the full abstract ▾
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
A story about a tipsy kangaroo: Reversible jump MCMC for model selection in the analysis of gravitational-wave signals from the coalescence of compact objects
Anna Puecher, Tim Dietrich, Hauke Koehn et al. (+4 more)
Bayesian inference is commonly employed in the analysis of gravitational-wave signals not only to estimate the source parameters, but also for model selection. The latter provides insight into the physics of the source and has the potential to inform the direction for future model development. Although model comparison is usually performed by analyzing the data separately with different models and comparing the obtained
Bayesian evidences, an alternative approach consists in sampling directly over the model itself. Here, we present t-roo, a reversible jump Markov chain Monte Carlo sampler capable of performing transdimensional inference on gravitational-wave signals from compact binary coalescences. Employing t-roo, a single analysis provides simultaneously the model odds ratio and the parameter posteriors for the favored models, hence yielding a potentially substantial computational advantage, particularly when comparing many models or analyzing highly informative data. t-roo is built on the sampler eryn and is specifically designed to compare models describing different kinds of sources, i.e., binary black hole, binary
neutron star, or
neutron star-black hole systems, as well as multiple models for the same source class. We validate the sampler on a set of injections, finding agreement with the results obtained with the nested sampler dynesty. We then use t-roo to analyze the real events GW190425 and GW230529, for which the system's parameters alone do not provide conclusive evidence of the presence of a
neutron star component. t-roo can be adapted to any model-comparison scenario, thus providing a valuable tool in particular for next-generation detectors, where analyzing data separately with competing models becomes computationally even more demanding.
Read the full abstract ▾
All authors Anna Puecher, Tim Dietrich, Hauke Koehn, Jonathan Gair, Gregory Ashton, Luca Negri, Anuradha Samajdar
Solar and Stellar Astrophysics
CO second overtone line variability in three carbon-rich early post-AGB stage stars
Kārlis Puķītis
Near-infrared CO molecular lines are suggested to be linked with dynamic processes in post-AGB
stars; however, they have not been investigated at high spectral resolution. CO second overtone line variability in the H-band is presented for the cool carbon-rich post-AGB
stars IRAS 22272+5435, IRAS Z02229+6208, and IRAS 20000+3239. CO features are observed to change intensity, shape, and radial velocity as well as switch between emission and absorption during the pulsation cycle. At all times, the CO line positions are located no more than around 10 km/s away from the systemic velocity. Molecular line variation is qualitatively similar in all three
stars, and it appears that the site of formation is the extended atmosphere. Emission in CO lines tends to be strongest during pulsation phases close to light maximum, and weakest emission or absorption tends to be seen when close to light minimum, resembling the behaviour in CN Red and C$_2$ Swan system lines at shorter wavelengths. The connection of molecular line variability with pulsation of the
star could be related to a shock that traverses the atmosphere once per pulsation cycle.
Read the full abstract ▾
Astrophysics of Galaxies
ALMA CO-CAVITY II. Resolved Scaling Relations in Void Galaxies
S. B. De Daniloff, D. Espada, S. Duarte Puertas et al. (+22 more)
Scaling relations involving
star formation rates (SFRs), molecular gas mass, and
stellar mass are key to understand
galaxy evolution, and have previously been explored at resolved scales. However, they have not been examined with particular emphasis on the large-scale environments (LSEs). In this work, we study the resolved Schmidt-Kennicutt relation (rSK), molecular gas main sequence (rMGMS) and
star-forming main sequence (rSFMS) from a sample of 41 void
galaxies (VGs) residing in the least dense regions of the Universe. Using high-resolution interferometric CO(1-0) data and optical IFU data from the ALMA CO-CAVITY and CAVITY surveys at scales of 2.5" (0.8-2.1 kpc), we study these relations for the full sample as well as for individual
galaxies in voids. We fit the relations, finding a similar parametrisation as that used for
galaxies from all LSEs. However, the rMGMS is the tightest of the three relations ($\sigma_{rMGMS}=0.16$ dex, $\sigma_{rSK}=0.21$ dex, and $\sigma_{rSFMS}=0.24$ dex), unlike in other samples. We find that a large source of deviations in the relations comes from
galaxy-to-
galaxy variations. However, the rMGMS is less affected by these variations. It has been suggested that the rMGMS arises from the concentration of molecular gas within the gravitational potential set by the
stellar content and dark matter. We hypothesise that deviations from the rMGMS trace changes in the gravitational potential occurring on longer time-scales, whereas deviations in the rSK and the rSFMS are driven by more rapid variations in the SFR. This distinction is particularly relevant for our sample of VGs because the 41 ALMA CO-CAVITY VGs are more isolated than
galaxies in other LSEs, and therefore are less affected by events that can significantly alter the gas distribution or trigger SF on short time-scales. In this sense, the rMGMS is likely the most stable of these relations over time.
Read the full abstract ▾
All authors S. B. De Daniloff, D. Espada, S. Duarte Puertas, Y. K. González-Koda, G. Torres-Ríos, S. F. Sánchez, R. García-Benito, S. Verley, I. Pérez, M. Argudo-Fernández, A. Bongiovanni, M. Sánchez-Portal, U. Lisenfeld, M. I. Rodríguez, A. Conrado, A. Jiménez, B. Bidaran, L. Sánchez-Menguiano, T. Ruiz-Lara, A. Zurita, P. Vásquez-Bustos, M. Alcázar-Laynez, P. Villalba-González, E. Florido, R. E. Miura
Instrumentation and Methods for Astrophysics
Atmosphere mitigation in CMB observations using multi-frequency time-domain component separation
Julien Tang, Shamik Ghosh, Jacques Delabrouille et al. (+4 more)
CMB observations from ground-based observatories are limited in sensitivity by the fluctuating emission from the Earth's atmosphere, mostly due to water vapor inhomogeneities. Even in atmospheric windows, this spurious signal remains the dominant source of contamination in the data. Traditional mitigation techniques include low-frequency filtering, or for polarization measurements specifically, pair-differencing or modulation with a rotating half-wave plate. The first method filters out a significant fraction of the target cosmological signal while the second leaves residuals due to imperfections, temperature to polarization leakage, or polarized atmospheric emission. In this work, we present a new data analysis framework, based on estimation of atmosphere emission templates using a multi-frequency focal plane. The core novelty of this setup is to have detectors dedicated to atmosphere monitoring, allowing the removal of atmospheric contamination with time-domain component separation techniques. We introduce a multipole-dependent atmospheric decontamination factor $A^\mathrm{atm}_\ell$ to quantify the relative reduction of the atmospheric contamination angular power spectrum achievable with this approach. Using this criterion, we demonstrate that our component separation pipeline can outperform a classical filter-bin map-making pipeline by a factor of 4000 for $30\le \ell \le 300$.
Read the full abstract ▾
All authors Julien Tang, Shamik Ghosh, Jacques Delabrouille, John C. Groh, Oliver Jeong, Reijo Keskitalo, Theodore Kisner
Instrumentation and Methods for Astrophysics
Modeling Dependence Structures in Astronomical Multi-Band Time Series Data via Multi-Output Gaussian Processes
Samata Das, Lishan Shi, Yasaman Hamayouni et al. (+2 more)
Modern astronomical time-domain surveys routinely collect multi-band light curves that provide complementary information about the physical processes governing source variability. Gaussian processes (GPs) provide a flexible probabilistic framework for modeling irregularly sampled and noisy time-series data. While considerable
attention has been devoted to developing covariance kernels for individual time series, comparatively less
attention has been paid to the statistical representation of dependence among multiple photometric bands. In this work, we present a unified statistical framework for modeling such dependence structures using multi-output GPs. Within this framework, we consider two complementary formulations. The covariance-based formulation specifies dependence directly through
matrix-valued covariance functions and emphasizes the
stochastic properties of the observed light curves, including covariance functions and power spectral densities. In contrast, the latent-process formulation represents the observed light curves as transformations of latent GPs and emphasizes the physical mechanisms generating the observed dependence. To illustrate these formulations, we develop covariance-based and latent-process multi-output damped random walk models and derive their corresponding spectral representations. We further demonstrate the practical implications of dependence-structure modeling through applications to multi-band active
galactic nucleus variability and continuum reverberation mapping. Rather than advocating a universally preferred formulation, this work provides a principled basis for selecting dependence structures according to the scientific objectives and clarifies how this choice influences the statistical characterization and scientific interpretation of
stochastic variability in astronomical sources.
Read the full abstract ▾
All authors Samata Das, Lishan Shi, Yasaman Hamayouni, Hyungsuk Tak, Jong-Hak Woo
Earth and Planetary Astrophysics
Experimental Measurements of Benzene Ice Critical Saturation Ratios on Titan Tholins and Impact on the Microphysical Modeling of Titan's South Polar Benzene Cloud
David Dubois, Erika Barth, Laura T. Iraci et al. (+3 more)
The Cassini Composite Infrared Spectrometer (CIRS) revealed the presence of a benzene (C6H6) ice cloud in Titan's autumn south polar stratosphere, following the northern spring equinox in August 2009. This event increased the mixing ratio of benzene and raised the cloud top altitude. We present here new experimental measurements of the critical saturation (Scrit) of pure C6H6 ice at low temperature (from 13.8 at 138 K to 3.3 at 157 K), representative of Titan's atmospheric temperatures, when deposited onto Titan aerosol analogs (tholins) produced in the NASA Ames
COsmic SImulation Chamber (
COSmIC). Comparisons of Scrit values of benzene vapor deposition obtained on blank substrates versus on Titan tholins reveals the highly favorable role aerosols play as condensation
nuclei. We have included these new Scrit measurements to calculate the nucleation contact parameter from m = 2.6e-4 T + 0.9494 in the Community Aerosol and Radiation Model for Atmospheres (CARMA) to investigate the variation in size and number density of C6H6 cloud particles as a function of altitude in Titan's southern polar atmosphere at 87 S. We discuss how these new temperature-dependent measurements impact the microphysical modeling and result in simulated benzene clouds forming about 20 km lower than seen in previous observations. A possible explanation for this discrepancy is that the cloud system was likely influenced by the co-condensation of more than one volatile gas species.
Read the full abstract ▾
All authors David Dubois, Erika Barth, Laura T. Iraci, Ella Sciamma-O'Brien, Farid Salama, Sandrine Vinatier
High Energy Astrophysical Phenomena
Ultra-High-Energy Particle Production in Binary Mergers Endowed with Magnetic Fields
Carlos H. Coimbra-Araujo, Rita C. Anjos, Jonas P. Pereira et al. (+1 more)
We study the production of ultra-high-energy particles via the Bañados–Silk–West (BSW) mechanism in the pre-merger phase of binary systems detected by LIGO-Virgo-KAGRA. By solving the geodesic equations for charged particles in magnetized Kerr spacetime with fields of $B \sim 10^{12}$–$10^{14}$~G, we demonstrate that collisions near the horizon can achieve center-of-mass energies $E_{\mathrm{cm}} \sim 10^{18}$– $10^{20}$~eV, placing them firmly in the ultra-high-energy
cosmic-ray (UHECR) range. We systematically explore the parameter space of merger remnants, varying black hole mass ($M \sim 20$–$150\,M_\odot$, characteristic of the binary black hole population), dimensionless
spin ($\chi_f \sim 0.7$–$0.9$),
magnetic field strength, and particle angular momenta. Our analysis reveals three distinct acceleration regimes: a
gravity-dominated regime ($B < 10^{12}$~G) with negligible
magnetic enhancement; a transition regime ($10^{12}~\text{G} \lesssim B \lesssim 10^{13}~\text{G}$) where gravitational and
magnetic effects compete; and a
magnetic-dominated regime ($B > 10^{13}$~G) where fields amplify collision energies by nearly an order of magnitude. For the 34 gravitational-wave events with high remnant
spins ($\chi_f > 0.7$), we compute the maximum achievable energies, finding that systems with $\chi_f \gtrsim 0.85$ and $M \gtrsim 100\,M_\odot$ can reach $E_{\mathrm{max}} \sim 10^{20}$~eV. Our results establish magnetized binary mergers, particularly black hole–
neutron star systems and postmerger black hole remnants formed in binary
neutron star coalescences, as promising sources of UHECRs and provide quantitative predictions linking gravitational-wave observables to particle acceleration efficiency.
Read the full abstract ▾
All authors Carlos H. Coimbra-Araujo, Rita C. Anjos, Jonas P. Pereira, Jaziel G. Coelho
High Energy Astrophysical Phenomena
Importance and Science Outcomes from the first XSPECT/XPoSat Workshop
Anuj Nandi, Rwitika Chatterjee, V. P. Shyam Prakash et al. (+49 more)
This paper summarizes the science outcomes of the first Workshop on Data Analysis using observations from the XSPECT payload onboard the XPoSat, which brought together early-career researchers and experts to explore the instrument's scientific capabilities through lectures and hands-on analyses. Participants performed end-to-end data analysis, including calibration, spectral modeling, and timing studies, on seven sources comprising
Neutron Star Low-Mass X-ray Binaries,
pulsars, and Black Hole X-ray Binaries, demonstrating the instrument's scientific potential. The observations, obtained during the first year of XSPECT operations, together with in-house developed software, were provided to the participants, making them the first users outside the instrument team to analyze XSPECT data. For NS-LMXBs, Aql X-1 exhibited a classical Type-I X-ray burst, enabling constraints on the
stellar radius through spectral fitting. Sco X-1, observed across its complete Z-track, revealed systematic spectral
evolution driven by
accretion-rate fluctuations and disk-corona coupling, while Cir X-1 displayed orbital phase-dependent transitions between hard and soft states, reflecting changes in
accretion geometry. Among
accretion-powered
pulsars, GX 301-2 showed a double-peaked, energy-dependent pulse profile and strong iron fluorescence lines due to
stellar wind reprocessing, whereas Vela X-1 exhibited orbital phase-dependent absorption and steady coronal temperatures. Among BH-XRBs, Cyg X-1 transitioned from a hard to soft-intermediate state with increasing disk contribution and spectral softening, while Cyg X-3 remained in the intermediate state with multiple emission lines originating from a clumpy
stellar wind. The workshop outcomes highlight the scientific promise of XSPECT and the importance of collaborative training in maximizing the science from XSPECT and future Indian space astronomy missions.
Read the full abstract ▾
All authors Anuj Nandi, Rwitika Chatterjee, V. P. Shyam Prakash, Ankur Kushwaha, M. C. Ramadevi, Kiran M. Jayasurya, Vivek K. Agrawal, M. Varun, Karan Akbari, Arya Sudhakaran, Daneshwar Bhandari, Vishal Kale, Vishal Jadoliya, Suchismito Chattopadhyay, Sakshi Maurya, Swasthik Visakh S, Debasish Krishnatreya, M Dhamodhar Reddy, Akash Agarwal, Giridharan L., Meghamani Halder, Juris N. J., Athira Mohanan, P. Majumder, Arbind Pradhan, Deblina Lahiri, Abhishek Jhala, Garima Tyagi, Abhisek Tamang, Akshara S B, P Aromal, Sreetama Das Choudhury, Sunirmal Rana, Ajith Balu, Mary Bosco, Jeyaraman Ilangovan, Shivani Chaudhary, Bhranti Rao, Biyas Chowdhury, Joysankar Majumdar, Sanjeeva Rao Prattipati, Subhasish Das, Sandip Naskar, Swapnil Singh, Vaishali S, Koushal Vadodariya, Radhakrishna Vatedka, Anurag Tyagi, Sachin Narang, Prapti Mittal, Madhu K V, Brindavan Mahto
High Energy Astrophysical Phenomena
Rapid Orbital Decay of Supersoft X-Ray Source WX Cen: a Surrounding Circumbinary Disk
Zhi-Qiang Liu, Wei-Min Liu and Wen-Cong Chen
WX Cen is most likely a candidate of compact binary supersoft X-ray sources, which consists of a white
dwarf (WD) and a donor
star that fills the Roche lobe. Recently, this source was detected to be experiencing a rapid orbital decay at a rate of $\dot{P} =-(4.4\pm0.4)\times10^{-7}~ \rm days~\rm{yr}^{-1}$. According to the mass function and optical eclipses, the donor-
star mass can be constrained to be $0.41-0.44$, $0.47-0.50$, and $0.55-0.59~M_\odot$ when the WD mass is $0.7$, $0.9$, and $1.2~M_\odot$, respectively. The observed orbital period derivative cannot be produced by the angular momentum loss due to mass loss during the
accretion of the WD,
magnetic braking (MB) mechanisms, including standard MB, convection and rotation-enhanced MB, and anomalous MB prescriptions. We propose that the rapid orbital decay of WX Cen is caused by the
tidal torque that originates from the resonant interaction between the binary and a surrounding circumbinary (CB) disk. Detailed
stellar evolution models indicate that a WD binary with a $2.5 \times 10^{-7}~M_{\odot}$ CB disk can evolve toward a WX Cen-like system, which has an orbital period derivative of $\dot{P}=-4.0\times10^{-7}~ \rm days~\rm{yr}^{-1}$ and a relatively high mass-transfer rate of $5.3\times10^{-7}~M_\odot\rm yr^{-1}$ that can trigger a stable hydrogen burning process on the surface of the WD.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ex
Solar axion searches with RES-NOVA: projected sensitivity and first prototype limit
D. Alloni, G. Benato, P. Carniti et al. (+49 more)
RES-NOVA is a cryogenic experiment based on PbWO4 scintillating bolometers produced from archaeological lead, originally designed to detect coherent elastic
neutrino-
nucleus scattering (CEvNS) from
galactic core-collapse
supernovae. We show that the same high-density, high-Z absorbers and sub-keV energy resolution make RES-NOVA an appealing probe of
solar axions. We compute the expected signal from the Primakoff, ABC (atomic recombination and de-excitation, Bremsstrahlung, Compton), longitudinal-plasmon (LP), and 57Fe
nuclear-line components of the
solar axion flux, folded through the inverse-Primakoff and axioelectric detection channels in PbWO4, which probe the
axion couplings to
photons (g_a-gamma), electrons (g_ae), and nucleons (g_aN), respectively. We derive projected sensitivities for a 1 ton*y exposure of the RES-NOVA demonstrator in the (g_ae,g_a-gamma), (g_ae,g_aN), and (g_a-gamma,g_aN) planes. The projected reach in g_ae approaches that of XENONnT to within a factor of ~2, despite a background roughly four orders of magnitude higher, thanks to the large target mass, the high-Z enhancement of the axioelectric and inverse-Primakoff cross sections, and the sub-keV energy resolution. Because the inverse-Primakoff constraint on g_a-gamma relies on absorption rather than coherent conversion, it is independent of the
axion mass, unlike bounds from
magnetic helioscopes. We complement these projections with the first
solar-
axion exclusion limit obtained on real data with a 13 g PbWO4 prototype grown from archaeological lead, using a background-model-independent optimum-interval analysis. These results establish RES-NOVA as a promising multi-coupling probe of
solar axions, with simultaneous sensitivity to g_ae, g_a-gamma and g_aN that is complementary to existing helioscope and direct-detection searches.
Read the full abstract ▾
All authors D. Alloni, G. Benato, P. Carniti, M. Cataldo, L. Chen, M. Clemenza, M. Consonni, G. Croci, I. Dafinei, F.A. Danevich, J. De Miguel, C. de Vecchi, D. Di Martino, R. Elleboro, N. Ferreiro Iachellini, F. Ferroni, F. Filippini, V. Fonoll, S. Ghislandi, A. Giachero, M. Giannotti, L. Gironi, P. Gorla, C. Gotti, D.L. Helis, D.V. Kasperovych, V.V. Kobychev, A. Lella, G. Lucente, G. Marcucci, A. Melchiorre, A. Menegolli, S. Nisi, M. Musa, L. Pagnanini, L. Pattavina, G. Pessina, S. Pirro, S. Pozzi, M.C. Prata, A. Puiu, S. Quitadamo, M.P. Riccardi, M. Rossella, R. Rossini, E. Sala, F. Saliu, A. Salvini, V.I. Tretyak, L. Trombetta, D. Trotta, H. Yuan
Earth and Planetary Astrophysics
Magnetohydrodynamical opening of dust traps in protoplanetary disks
Sergey Khaibrakhmanov and Vitaly Akimkin
Observed ring-like structures in protoplanetary disks are often interpreted as local pressure maxima, which induce efficient
dust concentration. We revisit this paradigm, considering the effect of the large-scale
magnetic field stresses on the gas rotation speed. Our simulations show that the
magnetic field can be dynamically strong and cause $1-2$% deviation from the Keplerian rotation at the periphery of a typical turbulent disk with
dust grains of size $> 1\,\mu$m. This effect increases the inward drift speed of large grains characterized by Stokes number of $0.01-0.1$ by up to two times in our simulations. Importantly, such MHD deviation from the Keplerian rotation does not depend on the local gas pressure gradient and leads to drift towards the
star only. The fast drift induced by this effect can cancel out the outward drift caused by the positive pressure gradient at the inner edge of a ring and open up the
dust trap. For the disks with
turbulence parameter $\alpha=10^{-3}$, this effect appears in the rings with a half-width of $10$ au and a density contrast up to $60$% ($200$% for $\alpha=10^{-2}$). Thus, the presence of a large-scale
magnetic field in protoplanetary disks either completely prevents or imposes stricter conditions for
dust accumulation and the onset of the streaming instability in the density rings in protoplanetary disks.
Read the full abstract ▾