Earth and Planetary Astrophysics
The GAPS programme at TNG LXXXII. The first atmospheric investigation of the gas giant WASP-13b at high resolution with GIARPS
D. Sicilia, M. Basilicata, G. Guilluy et al. (+17 more)
Low-density transiting gas giant
exoplanets are key
benchmarks for atmospheric studies. Despite their large-scale heights, many of them remain poorly characterised. We present the first atmospheric investigation at high-resolution of the inflated (R$_\mathrm{p}$$\sim$1.4 R$_{\mathrm{J}}$), hot Jupiter (T$\sim$1500$ \mathrm{K}$) WASP-13 b aiming at constraining its atmospheric composition and refine its orbital geometry. We analysed four transits observed with GIARPS at the TNG. Updated stellar and planetary parameters were re-derived from the most precise literature values, and a new Rossiter-McLaughlin analysis was performed to measure the projected
spin-orbit angle ($\lambda$) and stellar rotational velocity ($v\sin{i_\star}$). Atmospheric signals were searched using high-resolution spectroscopy, both with cross-correlation and single-line analyses, targeting key atomic and molecular species (e.g. \ion{He}{I}, H$\alpha$, \ion{Na}{I}, H$_2$O, CO). We find a well-aligned orbit ($\lambda$ = 2.7$\pm$1.1$^\circ$) and $v\sin{i_\star}$ = 4.5$\pm$0.1 km s$^{-1}$, improving upon previous constraints. No significant atmospheric absorption is detected in either VIS or NIR data. Injection-and-recovery tests exclude an isothermal atmosphere with
metallicity [M/H]$\lesssim$10$\times$[M/H]$_\odot$ and simultaneously a grey cloud top pressure P$_{\rm cloud}\gtrsim10$ mbar, under the assumption of chemical
equilibrium. WASP-13 b appears to belong to the class of low-density hot Jupiters with weak or featureless transmission spectra, most likely shaped by the presence of high-altitude clouds. Although a highly metal-enriched atmosphere cannot be fully excluded, current evidence disfavours this scenario. Further observations with next-generation facilities will be essential to characterise the atmospheric properties of this challenging target.
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All authors D. Sicilia, M. Basilicata, G. Guilluy, G. Scandariato, F. Borsa, C. Di Maio, M. Brogi, A. Chiavassa, L. Fossati, F. Amadori, P. Giacobbe, A. S. Bonomo, A. Sozzetti, L. Mancini, G. Andreuzzi, S. Colombo, V. Fardella, A. Ghedina, G. Mantovan, G. Piccinini
Earth and Planetary Astrophysics
Dust-driven vertical shear instability in an isothermal shearing box: I. Turbulence and gas dynamics without dust feedback
Jip Matthijsse, Hossam Aly, Sijme-Jan Paardekooper et al. (+1 more)
The classical vertical shear instability (VSI) is a baroclinic instability that arises from height-dependent azimuthal velocities and is a leading candidate for driving anisotropic
turbulence in discs with extended vertical modes. The classical VSI requires fast cooling times and radial temperature gradients, which are absent in an isothermal stratified (barotropic) setup. We investigate the dust-driven vertical shear instability in an isothermal, stratified shearing box, where the VSI is generated by drag forces acting on the gas due to dust rather than radial thermal stratification. We construct two-fluid (gas+dust) vertically stratified
equilibria including dust
diffusion and use these profiles to initialise 2D (radial-vertical) hydrodynamical simulations with FARGO3D. To separate dust-driven vertical shear instability (DVSI) from drag instabilities, we employ a dust-analogue model in which dust-induced drag on the gas is prescribed as a time-invariant and height-dependent acceleration, such that the underlying spatial distribution of the dust is assumed to be constant. The DVSI grows from regions of strongest vertical shear away from the midplane, exciting predominantly radially short, vertically extended disturbances (large k_x/k_z) and producing banded structures in the perturbed azimuthal and vertical velocities during the linear phase. In the nonlinear regime, the instability saturates via a Kelvin-Helmholtz-like parasitic instability that breaks the coherent vertical-shear modes into smaller-scale eddies, which balance the growth of the vertically extended modes, driving sustained vertical stirring. Dust-driven vertical shear can drive anisotropic
turbulence and vertical mixing in an isothermal model without invoking global thermal gradients and could play an important role in the stratified streaming instability.
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All authors Jip Matthijsse, Hossam Aly, Sijme-Jan Paardekooper, Richard P. Nelson
Earth and Planetary Astrophysics
The Fast & Fourier: Using neural operators to speed up radiative modeling of protoplanetary disks
Lukas Welzel and Melissa K. McClure
Edge-on protoplanetary disks provide a spatially resolved view of the vertical distribution of icy planetary building blocks, but inferring their relative abundances requires radiative-transfer (RT) modeling with multiple anisotropic scattering. Each model costs $10^{1}$-$10^{3}$ CPU hours, which precludes principled
Bayesian inference and homogeneous, population-scale analyses. We develop and validate a fast and reusable surrogate for
Bayesian inference with ice-bearing edge-on disk models. We train a
Fourier Neural Operator on a grid of RADMC-3D spectra. The network maps disk parameters and analytic physical input fields to the spectrum, using mixed-resolution spectra. We use the surrogate in an explicit-likelihood nested sampler and validate it on held-out simulations and synthetic recovery tests with TARP coverage. Finally, we use it to retrieve the disk structure and ice abundances of ESO-H$\alpha$ 569 from its spectral energy distribution. The surrogate reproduces the RADMC-3D spectra with a median error of 4.84%. We recover synthetic parameters without detectable bias and with nominal coverage. For ESO-H$\alpha$ 569, the posterior favors a massive ($M_{\rm gas}=0.028^{+0.015}_{-0.011}\,M_\odot$), nearly edge-on ($i=79.8^{+5.2}_{-2.4}$ deg) disk consistent with the image-plus-SED model of Wolff et al. (2017). Its ice abundances and cavity size remain weakly constrained by broadband data alone. The marginal spectrum-evaluation speed-up is $\sim10^{9}$-$10^{10}$. Neural-operator emulation makes full posterior inference feasible within the adopted model and training prior. Key posterior points should still be checked with high-fidelity RT models. By drastically cutting evaluation time, this approach enables for the first time homogeneous population studies of ices in disks, which new JWST surveys can capitalize on to map the range of compositions within planetary nurseries.
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Earth and Planetary Astrophysics
"Mega-Earths" are likely an artifact of stellar activity
Casey L. Brinkman and Nicolas Cowan
Empirical relations and
planet formation simulations suggest an upper mass limit for rocky
planets of $\sim$10M$_{\oplus}$, as cores above this will almost certainly undergo runaway gas
accretion. Nevertheless, a small number of
planets appear to have densities consistent with rocky Earth-like compositions above this threshold, indicating that unusual formation and evolutionary scenarios are capable of producing extremely massive rocky
planets called "Mega-Earths." However, all of these
planets orbit active
stars with log$R'_{HK}$ $>$-4.75. We find a <1$\%$ probability that all literature ultra-massive rocky
planets would coincidentally orbit such active
stars, and find no astrophysical reason to expect Mega-Earths to preferentially form around active
stars. We therefore conclude that Mega-Earths are artifacts of stellar activity, and we question the reliability of Gaussian Processes to enable mass measurements for rocky
planets around active
stars.
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Cosmology and Nongalactic Astrophysics
Narrowing down the Hubble constant value by exploiting the extended surface brightness of the supernova Refsdal host galaxy
S. Schuldt, C. Grillo, S. H. Suyu et al. (+7 more)
We present the first inference of the Hubble constant and matter density parameter from a strongly lensed
supernova by exploiting the mass model of a
galaxy cluster enhanced by an extended surface brightness reconstruction. Building upon the recent mass model of the
galaxy cluster MACS J1149.5+2223, relying on the identified image positions only, we include the surface brightness distribution of the SN Refsdal host, to infer some cosmological parameter values within a flat LCDM framework. We consider two cosmological parameterizations, with either H0 and {\Omega}m or H0 alone treated as free parameters, acknowledging the milder dependency on {\Omega}m when incorporating additional constraints from the SN host. We explore four different mass-model realizations to assess some of the systematic uncertainties associated with the constraint weighting and source reconstruction. Although known as one of the main possible systematic effects, including influences from the external convergence, we deliberately keep the cluster total mass parametrization fixed to that of the previously published point-like mass model to enable a fair comparison. This reveals that incorporating 77,000 HST pixels reduces the uncertainty on the inferred value of the Hubble constant by a factor of 2.0, while all model realizations remain mutually consistent. Our final measurements are $H_0 = 65.0^{+2.0}_{-1.8}$ km/s/Mpc and $\Omega_m = 0.30^{+0.08}_{-0.09}, in agreement with previous results. This corresponds to a substantially improved precision, reaching a remarkable 3.0% uncertainty on the value of H0 given our cluster total mass parameterization. The contributions of the uncertainties on the lens total mass and on the measured time delays to the final H0 error are now comparable, indicating that future improvements in cluster-scale time-delay cosmography will increasingly depend on (abridged version).
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All authors S. Schuldt, C. Grillo, S. H. Suyu, A. Acebron, L. Bazzanini, P. Bergamini, G. Di Rosa, A. Halkola, A. Mercurio, P. Rosati
Astrophysics of Galaxies
When dust growth takes over: the origin of dust in post-reionization galaxies
Omima Osman, Gabriella De Lucia, Andreas. L. Faisst et al. (+3 more)
The post-reionization epoch ($z\sim4$-6) marks a critical phase in
galaxy evolution, during which
galaxies rapidly assemble their stellar mass, enrich their interstellar medium, and build up substantial dust reservoirs. The physical processes responsible for such rapid dust enrichment remain uncertain. We investigate the dust enrichment history of the ALPINE-CRISTAL-JWST (ACJ) sample using the semi-analytic
galaxy formation model
GAlaxy Evolution and Assembly (GAEA), which follows
galaxy assembly, chemical enrichment, and dust
evolution. We select model
galaxies matching the observed stellar masses,
star formation rates, and
metallicities of the ACJ sample, compare their dust properties with observed scaling relations, and trace their enrichment histories and environments. The model reproduces the observed dust mass-stellar mass relation and the dust-to-stellar mass, dust-to-gas, and dust-to-metal ratios as functions of stellar mass and
metallicity. Reproducing these constraints requires efficient dust growth in the interstellar medium; stellar dust production alone cannot account for the observed dust reservoirs, even under the most optimistic assumptions. The combination of stellar mass,
star formation rate, and
metallicity provides a good predictor of
galaxy dust content. Our model suggests rapid dust build-up consistent with the previously noted rapid metal enrichment, with evidence for a transition around $z\sim8$-9 below which dust growth becomes the dominant dust formation channel. Finally, ACJ-like
galaxies preferentially reside in locally overdense environments, suggesting that environment may have contributed to their accelerated
evolution. Taken together, these results support rapid and coupled stellar, metal, and dust build-up in ACJ
galaxies during the post-reionization era.
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All authors Omima Osman, Gabriella De Lucia, Andreas. L. Faisst, Lizhi Xie, Fabio Fontanot, Michaela Hirschmann
Cosmology and Nongalactic Astrophysics
The road to $H_0$, $\Omega_m$, and $w$ with a global neutrino-telescope network
Pavel Zhelnin, Gonzalo Herrera, Nicholas Kamp et al. (+1 more)
The newly measured correlation between the
neutrino and X-ray luminosities of Seyfert
galaxies has yielded the first
neutrino-based measurement of the Hubble constant. Building on this result, we forecast the reach of a global
neutrino-
telescope network by 2030, utilizing full-sky IceCube exposures combined with KM3NeT-ARCA and Baikal-GVD. We find that this 2030 configuration sharpens the
neutrino-measured Hubble constant from today's $H_0 = 66^{+44}_{-37}$ to $H_0 =66^{+15}_{-13}$ km s$^{-1}$ Mpc$^{-1}$. Additionally, we project that the disk-corona slope of the
neutrino X-ray luminosity relation ($L_\nu\propto L_X^\beta$) will reach $\beta=0.72\pm0.04$, enabling a $\geq \!5\sigma$ exclusion of the calorimetric value $\beta=1$. Finally, we show that, if a high-
redshift population of
neutrino sources, such as JWST's "little red dots," is identified and obeys the same luminosity relation, we can obtain a new independent measurement of the matter density $\Omega_m$ and the dark energy equation-of-state parameter $w$.
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All authors Pavel Zhelnin, Gonzalo Herrera, Nicholas Kamp, Carlos A. Argüelles
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Seeing in the Dark: Gravitational Waves from Resonant Production of Dark Photon Dark Matter
Yanou Cui, Pankaj Saha and Evangelos I. Sfakianakis
Ultralight dark
photons (DPs) are well-motivated dark matter candidates. A promising yet underexplored mechanism for their relic abundance is parametric resonance in the Abelian-
Higgs model that generates the DP mass. We advance previous analytical studies through dedicated 3D
lattice simulations that capture important nonlinear effects, including backreaction and relic partitioning between the dark
Higgs and DPs. We further predict the associated
stochastic gravitational-wave (GW) signal, which can be within reach of a broad range of detectors, opening a new avenue to probe ultralight DP dark matter.
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Earth and Planetary Astrophysics
The accretionally heated atmospheres of protoplanets and brown dwarfs
Nick Choksi, Peter Gao, Jerry Xuan et al. (+2 more)
The ranks of accreting
planets and brown dwarfs are growing. To help interpret their spectra, we study how
accretion affects a
planet's atmosphere. The atmosphere is irradiated from above by whatever nonthermal radiation from the
accretion shock does not directly escape into space. This accretional heating drives a temperature inversion. Even relatively slow
accretion, corresponding to mass doubling times longer than system ages, can raise temperatures by many hundreds of Kelvin at ambient pressures of order millibars. The heated atmosphere radiates an optical/infrared excess. For environments that are not too dusty, the excess concentrates in molecular lines that trace the heated layer. Thus an accretionally heated atmosphere may be distinguished by its muted absorption bands. Irradiation from the
accretion shock also changes the chemical composition of the atmosphere, further altering spectra. Atmospheric
retrievals promise to map out the deposition of accretional energy, helping to decide between ”hot” and ”cold” start modes of
planet formation.
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All authors Nick Choksi, Peter Gao, Jerry Xuan, William Balmer, James Mang
Astrophysics of Galaxies
A Single Line-Emitter Identified in an Unbiased Search with JWST/NIRSpec: Multi-Object Coronagraphy for Slitless Spectroscopy
Mason S. Huberty, Claudia Scarlata, Matthew J. Hayes et al. (+13 more)
We report the detection of a previously unknown object with a single emission line within the Hubble Ultra Deep Field, using a new JWST NIRSpec technique called Multi-Object Coronagraphy for Slitless Spectroscopy (MOCSS) with the G140M/F100LP observing mode. The MOCSS technique involves opening almost all the shutters on the NIRSpec microshutter array, while simultaneously closing the shutters that lie on top of known low
redshift objects, facilitating a wide field slitless spectroscopic search without contamination from bright objects. This observational technique has enabled the detection of a strong emission line in four different dither positions and in two position angles, and thus cannot be artificial. This line is detected at 1.60 $\rm \mu m$ with a line flux of $[2.5\pm 0.3]\times10^{-18} \rm erg\ s^{-1} cm^{-2}$ and a FWHM of $13.2\pm2.0$Å, and does not correspond to any known source with some of the deepest HST and JWST imaging in existence. Based upon the absence of imaging detection, we place a lower limit on the observed frame equivalent width (EW) of 7620Å on this object, which strongly limits the number of possible lines that this line can be. Given the wavelength, an EW limit that is near the ceiling of expectation, and the lack of other lines in the bandpass, this line cannot be easily explained by [OII] at $z=3.29$, [OIII] at $z=2.20$, H$\alpha$ at $z=1.44$, and Ly$\alpha$ at $z=12.16$. We discuss possible AGN and transient phenomena that could explain the finding.
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All authors Mason S. Huberty, Claudia Scarlata, Matthew J. Hayes, Alaina Henry, Danielle A. Berg, Vieri Cammelli, Richard Ellis, Anne E. Jaskot, Yu-Heng Lin, Vihang Mehta, Matilde Mingozzi, Pierluigi Monaco, Alberto Saldana-Lopez, Aayush Saxena, Jonathan C. Tan, Alice Young
Cosmology and Nongalactic Astrophysics
A Burst of Reionization in the Dark Ages
Neal Weiner, Soubhik Kumar, Wenzer Qin et al. (+3 more)
Primordial overdensities at small scales can be significantly larger than those observed at large scales. As a result, they can collapse much earlier, at
redshifts $z \sim 100$. In these collapsed
halos,
stars and black holes can form, where they can then contribute to an early reionization of the universe. If this epoch is temporary, the free electrons will recombine yielding a low level of ionization leading into
cosmic dawn. This contributes to the optical depth of the universe, and adds more weakly to low-$\ell$ polarization signals of ionization compared to later sources. We study the effects of a
redshift-localized source of reionization $\Delta \tau_{burst}$ in the context of a broad suite of cosmological data to constrain this scenario, finding a preference of approximately $\sim 2-2.5\sigma$ for a new contribution. Regardless of Planck reprocessing used (PR3 - SRoll2+plik or PR4 - LoLLiPoP+CamSpec/HiLLiPoP), the results are consistent, favoring a new contribution $\Delta \tau_{burst} \sim 0.012$ ($0.001 < \Delta \tau_{burst} < 0.022$ at 95%) and a similar total optical depth $\tau \sim 0.073$. The precise era of reionization is somewhat discrepant depending on the higher-$\ell$ reprocessing used, with HiLLiPoP favoring $z\sim 45$, CamSpec $z\sim 100$ and plik $z\sim 165$. If such a source is present at $40\lesssim z\lesssim150$, LiteBIRD should be able to detect it, while Simons Observatory should also constrain it.
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All authors Neal Weiner, Soubhik Kumar, Wenzer Qin, Zilu Zhou, Yacine Ali-Haïmoud, Hector Afonso G. Cruz
High Energy Astrophysical Phenomena
Disk Structure May Determine AGN Variability and Explain the Accretion Disk Size Problem: No Broad Line Region Required
Amy Secunda, Yan-Fei Jiang and Jenny E. Greene
Variability is a crucial probe of active galactic
nuclei (AGN) disks, but the impact of the structure and internal physics of the disk on this variability is poorly understood. We perform 3D multi-frequency radiation magnetohydrodynamic simulations of the $1300-5940~\rm{\AA}$ emitting region of an AGN disk. This turbulent disk simulation happens to stochastically have different disk thickness above and below the midplane. Light curves emitted from the thin top of the disk are broadly consistent with traditional variability models, where the X-ray irradiation emitted from the corona is the main driver of variability in UV-optical light curves. Conversely, the UV-optical light curves emitted from the thicker bottom of the disk are not strongly correlated with the X-ray light curve and have disk continuum reverberation mapping lags that are $3-5\times$ longer than the light travel time. While these features are inconsistent with traditional variability models, they are in good agreement with numerous recent observations. Our simulations allow us to interpret these recent observations with a new model for AGN disks, where the thicker disk leads to greater X-ray absorption, less X-ray reprocessing at larger disk radii, and a stronger signal from intrinsic variability driven by fluctuations in the AGN disk. In our simulations, we can measure the inflow timescale of these fluctuations as a long lag between light curves emitted from different disk radii. Understanding how disk structure impacts AGN variability and reverberation mapping can allow us to predict the thickness of AGN disks using UV-optical AGN light curves.
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High Energy Astrophysical Phenomena
Discovery of Hidden Extragalactic Pulsars in the Parkes Archival Data
Rahul Sengar, Laila Vleeschower, Matthew Bailes et al. (+3 more)
Just over 1% of the known
radio pulsar population resides in the Large and Small Magellanic Clouds (MCs), the satellite
galaxies that are 50-62 kpc distant from the Milky Way. These
pulsars are important for constraining the peak of the
pulsar luminosity function, and may give insights into
neutron star populations formed from
stars of different
metallicities than the Milky Way. Using search techniques that have proven highly effective at discovering a large number of
pulsars in archival data by folding candidates near the noise floor at high harmonic folds, we reprocessed the original Parkes Multibeam MC surveys and discovered six
pulsars. Five of these
pulsars are located in the Large Magellanic Cloud (LMC), including one with a
spin period of 3.8s, making it the slowest
pulsar known in the MCs. The remaining
pulsar was detected toward the Small Magellanic Cloud (SMC), and is associated with the Milky Way foreground. Four of the newly discovered
pulsars exhibit scintillation, with one showing clear nulling and others showing possible nulling behavior. These discoveries bring the total number of
radio pulsars known in the LMC to 49. A luminosity function and duty cycle analysis of all current MC
pulsars shows that they are consistent with Galactic canonical
pulsars. Population synthesis simulations suggest that deeper surveys would reveal many more
pulsars in the MCs, including up to handful of millisecond
pulsars, based on the adopted upper limits for their parent populations. Finally, this reprocessing demonstrates the continued importance of reanalyzing archival data, both to improve the completeness of
pulsar surveys and detect scientifically valuable objects.
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All authors Rahul Sengar, Laila Vleeschower, Matthew Bailes, Fronefield Crawford, Duncan R. Lorimer, Joshua P. Ridley
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
A scalar-extended ${\rm U(1)_{L_{\mu}-L_{\tau}}}$ explanation of the LUX-ZEPLIN 248 keV excess
Dipankar Pradhan and Abhik Sarkar
The recently observed dark matter (DM) nuclear recoil event at an energy of $248 \pm 23\,(\text{stat.}) \pm 23\,(\text{syst.})\,\text{keV}$ at the LUX-ZEPLIN (LZ) experiment, favoring an inelastic scattering interpretation, has motivated various beyond the Standard Model (BSM) scenarios aimed at explaining the observed excess. In particular, this provides an opportunity to probe models that naturally accommodate inelastic DM scattering. In this work, we explore one such possibility by extending the $\rm U(1)_{L_{\mu}-L_{\tau}}$ model with two complex scalar fields, $\Phi$ and $S$, carrying charges $-1$ and $+2$, respectively, under the $\rm U(1)_{L_{\mu}-L_{\tau}}$ gauge
symmetry. These charge assignments allow a trilinear interaction between the two scalar fields, which is crucial for generating the DM mass splitting. Following the spontaneous breaking of the $\rm U(1)_{L_{\mu}-L_{\tau}}$
symmetry, with $S$ acquiring a
vacuum expectation value and generating a mass for the BSM gauge
boson $Z_{\mu\tau}$, the real and imaginary components of $\Phi$ acquire a mass splitting. This naturally gives rise to an inelastic DM scattering scenario that can accommodate the LZ excess. We perform a likelihood-based assessment of the sensitivity of the model parameters to the observed event while consistently accounting for other relevant phenomenological constraints. Finally, we discuss the prospects for probing the viable parameter space at future experiments.
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High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Listening to the Horizon: Probing Near-Horizon Reflectivity with GW250114
R. Prasad, Subhodeep Sarkar and Sudipta Sarkar
Testing the horizon properties of astrophysical black holes is a central goal of gravitational-wave astronomy. The recently identified Direct Wave (DW), a
prompt non-quasinormal component of GW250114, provides a new probe of near-horizon physics. While it remains unclear whether the DW itself carries horizon information, we show that it enables a novel null test of horizon reflectivity. If the remnant is an exotic compact object (ECO) with a partially reflecting surface, inward plunge radiation is reflected and leaks back through the gravitational potential barrier, producing a delayed DW echo whose amplitude is set by the surface reflectivity ($|\mathcal{R}_s|$). We construct the corresponding echo template, normalized by the observed DW, and search for it in quasinormal-mode-filtered data. We find no evidence for an echo ($\ln\mathcal{B}=-2.9$) and obtain the 90% credible bound $|\mathcal{R}_s|<0.06$, corresponding to a reflected energy fraction below $0.4\%$, for surfaces from $0.1\, M_f$ to a Planck length from the would-be horizon. Our method thus turns the
prompt ringdown signal into a direct test of horizon reflectivity.
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Cosmology and Nongalactic Astrophysics
Cosmic topology. Part IId. Eigenmodes and correlation matrices of lens spaces
Mikel Martin Barandiaran, Catherine Petretti, Stefano Anselmi et al. (+16 more)
The global
topology of the Universe is a longstanding open question. In this work, we examine the statistical signatures of a positively curved universe with a Friedmann–Lemaitre–Robertson–Walker metric and the
topology of a lens space $L(p,q)$. Since these
manifolds are generally statistically anisotropic and inhomogeneous, their
cosmic microwave background (CMB) covariance
matrices contain non-zero off-diagonal entries that depend on observer location. We compute these full harmonic-space covariance
matrices for scalar perturbations for arbitrary lens spaces and observer position. Using the Kullback–Leibler divergence, we assess the distinguishability of these spaces from a simply connected three-sphere with the same
curvature. The results show that topological signatures can still be significant in a
cosmic-variance-limited regime even when the length, $d_{\rm NC}$, of the shortest loop around the Universe through the observer exceeds the diameter, $d_{\rm LSS}$, of the last-scattering surface by up to $10\%$. This distinguishability depends on the
curvature, the lens space and the observer position mainly through the ratio $d_{\rm NC}/d_{\rm LSS}$, which is set not only by the
curvature radius but also by $p$, $q$ and the observer location. Therefore, for any value of the spatial
curvature, however small, there are lens spaces and observer positions for which $0.985\,d_{\rm LSS}<d_{\rm NC}<1.1\,d_{\rm LSS}$. Such observers would find no matched circles in the CMB large enough to have been detected to date, yet the
topology would remain potentially discoverable through its statistical signatures.
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All authors Mikel Martin Barandiaran, Catherine Petretti, Stefano Anselmi, Deyan P. Mihaylov, Anna Negro, Glenn D. Starkman, Andrius Tamosiunas, Yashar Akrami, George Alestas, Javier Carrón Duque, Craig J. Copi, Fernando Cornet-Gomez, Linn Htat Lu, Andrew H. Jaffe, Arthur Kosowsky, José Javier Ortega Gómez, Ricardo G. Rodrigues, Amirhossein Samandar, Cynthia Trendafilova
Astrophysics of Galaxies
ACORN I. Massive Black Hole Seeding and Tidal Disruption Events from Star Clusters in Cosmological Simulations
Yihao Zhou, Tiziana Di Matteo, Claire E. Williams et al. (+6 more)
JWST has revealed massive
star clusters at $z\gtrsim 6$, which provide promising environments for massive black hole (MBH) seed formation. We introduce a new MBH seeding model for cosmological simulations, physically motivated by the runaway collisions in
star clusters. Subgrid
star clusters are generated according to the local ISM and evolved through stellar
evolution and two-body relaxation. The masses of MBH seeds formed through runaway collisions are determined by the properties of their host clusters, including the effects of
metallicity-dependent stellar winds. We further follow tidal disruption events (TDEs) with the evolving clusters, which can be enhanced in MBH binaries, and account for gravitational-wave (GW) recoil following MBH mergers. We implement this model in a constrained simulation of a 5$\sigma$ overdense region, where seeds of $10^{3}-10^{5.6}\,M_\odot$ form in clusters with $10^{4}\leq m_{\rm SC}\leq 10^{8}\,M_\odot$. Because both the seed abundance and mass are directly connected to the local environment, we have a more physical $M_{\rm BH}\!-\!M_{\rm galaxy}$ scaling for low-mass
galaxies ($M_{\rm galaxy}\sim10^{6-9}\,M_\odot$), a regime poorly described by previous seeding models. Multiple MBHs are naturally allowed to form in-situ within individual
halos, producing a spatially clustered population. This increases the MBH merger rate by $\sim100$ relative to other seeding models, significantly enhancing the expected LISA event rate. TDEs can dominate the growth of $10^{3-4}\,M_\odot$ MBHs and produce luminous
flares of $L_{\rm peak}\sim 10^{42-43}\,{\rm erg\,s^{-1}}$, increasing the observability of low-mass seeds. This seeding prescription accelerates early MBH growth at $z\gtrsim 8$, while subsequent self-regulated gas
accretion drives the central MBH toward similar masses $\sim10^{8.6}\, M_\odot$ by $z=6$ across different seeding models.
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All authors Yihao Zhou, Tiziana Di Matteo, Claire E. Williams, Aklant Kumar Bhowmick, Marta Reina-Campos, Carl L. Rodriguez, Elena González Prieto, Laura Blecha, Rupert Croft
Astrophysics of Galaxies
Inflow-driven galaxy evolution - II: A hierarchy in the scaling relations of star-forming galaxies
Kai Wang, Carlton Baugh, Sownak Bose et al. (+7 more)
The
star-forming main sequence (SFMS; $M_\star$–sSFR), the gas-to-stellar mass relation ($M_\star$–$M_{\rm gas}/M_\star$), and the mass–
metallicity relation (MZR; $M_\star$–$Z_{\rm gas}$) are three core scaling relations for
star-forming
galaxies, and together they encode the information about the baryon cycle that operates during
galaxy evolution. We investigate how these relations emerge by modelling the gas flows that regulate the baryon cycle, using both an ideal and a cosmological gas flow model, and identify a hierarchy among the three relations, with one further parameter entering the scatter budget at each step. In our model, the SFMS and its scatter are set primarily by the formation time of the host
halo, with a weak dependence on the
star formation efficiency and the mass-loading factor. The gas-to-stellar mass relation follows from the ratio of the sSFR to the
star formation efficiency, and inherits the scatter of both. The MZR in turn follows from the gas-to-stellar mass relation together with the mass-loading factor, their relative contributions depending on the
galaxy evolutionary state between the inflow-driven regime and
equilibrium. This hierarchy naturally introduces further correlations among the three relations, such as the fundamental plane of
star formation ($M_\star$–$M_{\rm gas}$–SFR), the fundamental
metallicity relation ($M_\star$–SFR–$Z_{\rm gas}$) and its gaseous counterpart ($M_\star$–$M_{\rm gas}$–$Z_{\rm gas}$), and the correlations of each relation with
galaxy size, which traces the
star formation efficiency through the
star formation law. Together, the three core scaling relations and the higher-dimensional correlations among them follow from a single framework, providing a foundation for linking the observables of
star-forming
galaxies to the underlying baryon cycle.
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All authors Kai Wang, Carlton Baugh, Sownak Bose, Shaun Cole, Carlos S. Frenk, Cedric Lacey, Julio F. Navarro, Kyle A. Oman, Amélie Saintonge, Tom Theuns
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
A Pairwise Surrogate for Gravitational-Wave Spectra from Highly Relativistic Vacuum Bubble Collisions
Malte Buschmann and Toby Opferkuch
Gravitational waves from
vacuum first-order phase transitions probe the nonlinear dynamics of relativistic bubble collisions. Predicting their spectrum requires resolving Lorentz-contracted scalar bubble walls throughout a volume containing many bubbles, making the large-boost regime prohibitively expensive for direct
lattice simulations. We develop a simulation-based pairwise surrogate that separates the microscopic collision dynamics from the geometry of the multi-bubble transition. This utilizes
symmetry-reduced $(1+1)$-dimensional scalar-field simulations to build a library of two-bubble gravitational-wave spectra, including the nonlinear post-collision
evolution. These spectra are combined with
geometric weights that account for screening by other bubbles. We test the two-bubble spectra and the reconstructed spectra of three- and many-bubble systems against full $(3+1)$-dimensional
lattice simulations. Not only can the surrogate be orders of magnitude cheaper computationally, but it also provides access to highly relativistic collisions beyond the practical reach of direct many-bubble simulations. This provides a route to studying how the spectral amplitude and shape depend on the collision boost and scalar potential.
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High Energy Astrophysical Phenomena
Funnel Leakage of the Wien Fireball in the Early Nebula after a Binary Neutron Star Merger
Shao-Ze Li, Yun-Wei Yu, He Gao et al. (+2 more)
A newborn
neutron star (NS) that survives after a binary NS merger can inject its rotational energy into the surrounding ejecta while the ejecta are still optically thick. The injected energy is redistributed by the pair cascade, and the nebula becomes a radiation-dominated
plasma composed of
photons and e^+- pairs. Compton scattering then governs the energy exchange while the
photon number is conserved in scattering. This nebula is evolved with a one-zone model that includes pair creation, annihilation,
photon injection,
diffusion, and in particular the leakage through the jet-induced polar funnel. For typical parameters, we find that the Compton parameter y is much larger than unity at early times. The nebula therefore remains in saturated Comptonization for 100 s to a few thousand seconds, depending on the
magnetic field strength of the post-merger NS. The radiation field takes a Wien spectrum with a Compton
equilibrium temperature. The nebula is then a so-called Wien fireball. The Compton temperature decreases from tens of keV to a few keV at early times. As long as the ejecta are optically thick, the funnel leakage is comparable to or exceeds the adiabatic loss. The funnel emission is quasi-thermal, and its isotropic-equivalent luminosity is much higher than the
spin-down luminosity. We suggest that the quasi-thermal components observed in the extended emission of short gamma-ray bursts could come from the funnel leakage of the nebula fireball.
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All authors Shao-Ze Li, Yun-Wei Yu, He Gao, Peng-Cheng Yang, Yu Qu
High Energy Astrophysical Phenomena
A morphological search for stable year-scale modulation in gamma-ray blazars
Adithiya Dinesh, Alberto Domínguez, Alba Rico et al. (+3 more)
Year-scale quasi-periodic oscillations (QPOs) in blazar gamma-ray light curves have been proposed as signatures of supermassive binary black holes and precessing jets. Red noise can mimic periodicity, and detection alone does not establish persistence or period stability. We develop and calibrate a morphological framework to characterize year-scale modulation and constrain the incidence of stable modulation in blazars. We analyze 120 Fermi-LAT light curves spanning 18.1 yr. Singular spectrum analysis selects the oscillatory mode and period, while weighted wavelet Z-transform ridge tracking measures persistence, period drift, and cycle-to-cycle
volatility. Flux randomization, 10,000 red-noise simulations, and about 20,000 injections calibrate the classification. Of 97 quality-selected sources, two show persistent, coherent modulation consistent with a stationary period (Rank I: PG 1553+113 and B2 1215+30), six show coherent modulation whose stationarity cannot be established (Rank II), and 89 form Rank III. Neither Rank I nor Rank II significantly exceeds red-noise expectations. Stationary 1-3 yr injections reach Rank I in 63-97% of trials at signal-to-noise ratio (SNR) = 1, depending on period, and 100% at SNR = 2; 92% of drifting injections reach Rank II. These results limit stable, approximately sinusoidal 1-3 yr modulation to at most 7% of the sample at SNR >= 1 and 5% at SNR >= 2 (95% confidence). PG 1553+113 has the lowest false-alarm probability, 4.7% after trials. Stable year-scale modulation is uncommon, and no source is established as periodic. The framework distinguishes persistent, stationary modulation from coherent variability whose period may evolve or fluctuate, but not the physical mechanism. PG 1553+113 and B2 1215+30 are candidates for monitoring and continuous gravitational-wave searches, although their stability does not establish a binary origin.
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All authors Adithiya Dinesh, Alberto Domínguez, Alba Rico, Pablo Peñil, Marco Ajello, Sara Buson
High Energy Astrophysical Phenomena · Cross-listed from quant-ph
Quantum Co-Design of Inhomogeneous Many-Body Neutrino Fast Flavor Transformation
Zoha Laraib, Sherwood Richers, Alessandro Baroni et al. (+2 more)
Dense-
neutrino flavor
evolution is a
quantum many-body problem whose fully correlated treatment becomes rapidly more expensive with increasing particle number and spatial structure. We develop a QCNO
quantum simulation code that maps a inhomogeneous forward-scattering
neutrino Hamiltonian with advection and finite-range interactions to TEBD2 product-formula
quantum circuits, and connects ideal many-body simulation, backend-aware execution, and fault-tolerant resource estimation within the same physical model. We reproduce the exact many-body
evolution of the suppressed mean-field-like transverse fast flavor instability through $N=30$ and show that even a single open-boundary interaction generates Rënyi
entanglement and non-stabilizer magic, although noisy backends still produce polarization RMSEs of order $0.1$–$0.3$. The restricted active interaction graph of this problem allows us to estimate the
circuit depth and $T$ gate cost through $N=50$ for both NISQ and fault-tolerant approaches. The measured TEBD2 error in our fiducial ideal simulation of order $10^{-3}$ motivates a synthesis tolerance $\varepsilon_{\rm syn}\sim10^{-7}$, corresponding to about $70$ $T$ gates per $R_Z$ rotation. The generated
circuit contains $1.4\times10^4$ $T$ gates per
qubit for open boundaries (twice that for closed boundaries), requiring an application-level logical-$T$ error target of order $10^{-7}$ for early fault-tolerant architectures.
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All authors Zoha Laraib, Sherwood Richers, Alessandro Baroni, Kathleen Hamilton, In-Saeng Suh
Solar and Stellar Astrophysics
Rotation period of the O giant xi Persei: Coexistence of cyclic and periodic variability. A weakly magnetic candidate star
H.F. Henrichs, N.P. Sudnik and A. David-Uraz
OB
stars exhibit line profile variability, often associated with rotation; notably, in their UV wind-sensitive lines where discrete absorption components tend to recur cyclically. We searched for periodicity in spectral regions of the O7.5III(n)((f))
star xi Persei formed very close to the
star. The NIV 1718 A line was identified as the most uncontaminated spectral with a large and homogeneous available
dataset is available: 307 IUE spectra over 12 years and 11 STIS spectra taken 21 years later. We also studied 322 time-resolved HeII 4686 A spectra and MOST, BRITE, and TESS space photometry, covering a time span of 13 years. We also reconsidered X-ray studies with Chandra. A CLEAN analysis and subsequent weighted least-squares fit of the flux in this region resulted in a unique period of 2.040514(20) d, attributed to rotation. The phase of maximum flux in the NIV, SiIV, Ha, and HeII line profiles coincide with the results of X-ray variability studies. This period was also found in the photometric data. Given the coherent periodic behaviour probing the region of the wind nearest the stellar surface, we propose that xi Per has an as-yet undetected weak global surface
magnetic field. The sinusoidal behaviour suggested that only one
magnetic pole is visible, implying an inclination of i approximately 51 deg, and therefore, 39 deg for the
magnetic obliquity. We present a conceptual framework within which weak wind confinement by a global
magnetic field can create a small magnetospheric disc, while allowing for the formation of more classic corotating interaction regions at higher
magnetic latitudes. The periodic variations are then understood to result from the changing projected area of the magnetospheric disc as a function of rotational phase, both along the line of sight and off the stellar limb.
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Astrophysics of Galaxies
JWST CAPERS: Spectroscopic evaluation of very high redshift galaxy candidates
Callum T. Donnan, Mark Dickinson, Lorenzo Napolitano et al. (+21 more)
JWST/NIRCam imaging has enabled efficient selection of a large number of
galaxy candidates at very high
redshifts. Accurate and robust selection is crucial for statistical analyses, such as measurement of the ultraviolet luminosity function (UV LF). A variety of selection methods and criteria have been proposed in the literature. We evaluate the selection methodology of
galaxy candidates at $z\geq8.5$ using 183 candidates with secure spectroscopic
redshifts obtained from the CAPERS JWST/NIRSpec PRISM program. The success of high-$z$ confirmation is strongly correlated with the photometric signal-to-noise ratio (SNR) in the detection filter, the strength of the Lyman-$\alpha$ break, and the $\Delta \chi^2$ between the best-fitting low-
redshift and high-
redshift spectral energy distribution model. However, the most efficient selection method is the use of a UV LF prior on the inferred $p(z)$ of a source, raising the success rate from $\simeq 35\%$ to $\simeq 77\%$ while achieving greater completeness than conservative SNR and $\Delta \chi^2$ cuts. Out of the 183 candidates we spectroscopically confirm 48 sources at $z\geq8.5$ via detections of emission lines and/or the Lyman-$\alpha$ break (particularly important for those with no emission line detection). We report the highest-
redshift source in CAPERS as UDS-111893 at $z_{\mathrm{spec}}=12.98$, with no sources confirmed at $z>13$. This work provides spectroscopic quantification of JWST/NIRCam photometric selection at $z\geq8.5$, and demonstrates the effectiveness of a UV LF prior for high-
redshift photometric selection.
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All authors Callum T. Donnan, Mark Dickinson, Lorenzo Napolitano, Pablo Arrabal Haro, Anthony J. Taylor, Hollis B. Akins, Ryan Begley, Davide Bevacqua, Adam C. Carnall, Marco Castellano, Fergus Cullen, James S. Dunlop, Steven L. Finkelstein, Carter Flayhart, Mauro Giavalisco, Michaela Hirschmann, Ray A. Lucas, Derek J. McLeod, Ross J. McLure, Casey Papovich, Laura Pentericci, Borja Pérez-Díaz, Thomas M. Stanton, L. Y. Aaron Yung
Instrumentation and Methods for Astrophysics
Data Representation Matters: Optimizing Machine Learning for X-ray Source Classification by Leveraging Spatio-Spectral Information
Maggie Lieu, Ivan Valtchanov, Marguerite Pierre et al. (+4 more)
Distinguishing between faint extended X-ray sources is a fundamental yet challenging task in X-ray surveys. This paper presents a
benchmark comparison of convolutional neural network models for classifying simulated XMM-Newton observations of AGN and
galaxy clusters, focusing on the impact of data representation and interpretability of that data. We evaluate 1D, 2D, 2D+1D, and 3D CNNs trained on distinct data representations derived from simulated XMM-Newton observations of AGN and clusters: 1D (spectral), 2D (imaging) and 3D (event cube) data. We further apply 3D-GradCAM to interpret the learned features and assess the physical basis for the model's decision making to move beyond black-box classification. Our results demonstrate that increased spectral resolution enhances classifier performance using 1D and 2D information provides a strong baseline, the integration of both domains yields significant diagnostic gains. We find that a 3D CNN architecture applied directly to spatio-spectral event cubes provides the most robust performance, with superior consistency across cross-validation folds. Interpretability analysis reveals that the 3D model autonomously learns to distinguish the diffuse thermal emission of the intracluster medium from the localized, non-thermal power-law signatures of AGN. It exploits multi-dimensional correlations that are lost in lower-dimensional projections. While the performance gain over combined 2D and 1D baselines is marginal, the 3D approach demonstrates an ability to perform implicit background characterisation. By operating directly on total
photon counts within event cubes, this method bypasses the need for manual background subtraction and modelling, offering a consistent, streamlined, end-to-end pipeline for automated classification of X-ray sources in large-scale catalogues.
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All authors Maggie Lieu, Ivan Valtchanov, Marguerite Pierre, Esin Gulbahar, Elias Koulouridis, Iván Muñoz Rodríguez, Lucio Chiappetti
Instrumentation and Methods for Astrophysics
Opening the Black Box: What Neural Networks Learn from Pulsar Timing Array Data
James Alvey, Andrea Mitridate, Mauro Pieroni et al. (+1 more)
In recent years, simulation-based inference (SBI) methods have been proposed to address several data-analysis challenges faced by existing and planned gravitational-wave experiments. For example, SBI classification has recently been shown to significantly improve the prospects for detecting anisotropies in
pulsar timing array (PTA) data. In this work, we use a simple toy model of a PTA to provide a more pedagogical explanation of how, and under which circumstances, SBI-based detection can improve on classical detection statistics for gravitational-wave background anisotropies.
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All authors James Alvey, Andrea Mitridate, Mauro Pieroni, Joseph D. Romano
Instrumentation and Methods for Astrophysics · Cross-listed from physics.ins-det
Cavity Characterization for the Princeton Axion Search
Nate Otto, Jianyang Fu, Joelle-Marie Begin et al. (+4 more)
The Princeton
Axion Search (PXS) targets the mass window $0.8\text{--}2.1~\mu\text{eV}$ (corresponding to frequencies $200\text{--}500~\text{MHz}$) at DFSZ sensitivity. The experiment, a haloscope, will use a cylindrical copper-plated aluminum cavity of $700~\text{mm}$ diameter and $1022~\text{mm}$ height, immersed in a $5~\text{T}$ solenoidal
magnetic field. A $152~\text{mm}$ diameter tuning rod spanning the height of the cavity rotates to tune the primary mode resonance from $390\text{--}480~\text{MHz}$, the frequency range for initial operations. We deduce the electric and
magnetic field mode patterns using a combination of dielectric and metallic bead perturbations on the empty cavity. The measured mode frequencies and the $\text{TM}_{010}$ field profile, as a function of tuning rod position, are in excellent agreement with simulations. We describe the effect of fabrication and assembly imperfections, including the bowing of end plates and tilt of the tuning rod. The welded seams and end-cap joints are demonstrated to not significantly degrade $Q$. We combine measurement and simulation to assess an uncertainty on form factor across the full tuning range. Our results validate PXS's cavity architecture and inform future searches for sub-$\mu\text{eV}$
axions, in which large-volume high-$Q$ structures are required to reach QCD sensitivity.
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All authors Nate Otto, Jianyang Fu, Joelle-Marie Begin, Saptarshi Chaudhuri, Roman Kolevatov, Lyman Page, Joe Wiedemann
Earth and Planetary Astrophysics
Longitudinal distribution of Io's dayside atmospheric density
R. S. Giles, J. R. Spencer, T. K. Greathouse et al. (+3 more)
Since 2001, we have used the TEXES high resolution mid-infrared spectrograph at NASA's Infrared
Telescope Facility to study the density of Io's SO$_{2}$-dominated atmosphere. The spectra cover several SO$_{2}$ absorption lines near 530 cm$^{-1}$ and are used to retrieve the equatorial SO$_{2}$ column density. In addition to covering a long time period, our 191 independent observations also cover the full range of Io central longitudes, allowing us to study the longitudinal variability of Io's dayside atmosphere in more depth than has previously been possible. By improving our modeling of longitudinal variability and using a seasonal model to apply a temporal normalization to the retrieved SO$_{2}$ densities, we produce two complete longitudinal distributions of Io's equatorial SO$_{2}$ column abundances, one representing perihelion and one representing aphelion. Both show the same hemispheric asymmetry that has been observed in previous studies, with the highest densities near 200W and the lowest densities near 305W. We find that the contrast between the maximum and minimum densities is a factor of ~27 at aphelion and a factor of ~16 at perihelion. Both longitudinal distributions are asymmetric, with a sharper drop-off on Io's trailing hemisphere than on the leading. We compare these longitudinal distributions to the distributions expected if the spatial variability were primarily driven by volcanic activity, SO$_{2}$-ice inhomogeneity or the effects of eclipses. We conclude that the effect of eclipses is important, but insufficient to explain the shape of the observed longitudinal variability, and frost distribution is likely to also be important.
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All authors R. S. Giles, J. R. Spencer, T. K. Greathouse, C. C. C. Tsang, E. Lellouch, M. A. López-Valverde
Earth and Planetary Astrophysics
Gen-EBM: an energy balance model for terrestrial planets. Climate multistability from snowball to post-runaway greenhouse climates
Siddharth Bhatnagar, Emeline Bolmont, Maura Brunetti et al. (+6 more)
Climate multistability and tipping points are fundamental properties of planetary climates that depend sensitively on
climate feedbacks. We introduce the Geneva Energy Balance Model (Gen-EBM), a new 1-D latitudinal EBM for rapid exploration of terrestrial
planet climates, and use it to investigate how planetary rotation, eccentricity, and thermal inertia shape
climate attractors and multistability. Gen-EBM is implemented in Rust and builds on previous
exoplanet EBMs by incorporating a temperature-dependent outgoing longwave radiation prescription spanning Earth-like, runaway-onset, and post-runaway greenhouse regimes. We construct bifurcation diagrams from ensembles of simulations and explore the effects of rotation rate, orbital eccentricity under the mean-flux approximation, and surface thermal inertia. Including post-runaway greenhouse states substantially enlarges the parameter space over which multiple
climate states coexist. Within our model framework, slow rotators approach the spatially homogeneous limit and maintain broader temperate stability ranges, whereas fast rotators develop strong equator-to-pole temperature gradients that narrow the temperate branch. Under the mean-flux approximation, increasing eccentricity enhances
climate variability and can alter the attractor structure itself. The critical eccentricity at which temperate climates disappear depends strongly on thermal inertia, with ocean-rich
planets remaining stable to larger eccentricities than land-dominated
planets. Gen-EBM therefore broadens rapid parameter-space exploration to climates spanning temperate, runaway-onset, and post-runaway regimes. Its computational efficiency and flexibility make it a valuable bridge between simple
climate models and 3-D general circulation models.
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All authors Siddharth Bhatnagar, Emeline Bolmont, Maura Brunetti, Jérôme Kasparian, Tim Kallioinen, Marine Leyvraz, Guillaume Chaverot, Yonatan Birhanu Haile, Dóra Takács
Cosmology and Nongalactic Astrophysics
An analytical model for non-local stochastic field-level galaxy bias on the sphere
Maximilian von Wietersheim-Kramsta, Nicolas Tessore, Benjamin Joachimi et al. (+3 more)
We present the `Bias of Overdensities in Large-scale Tracers on the Sphere' (BOLTS) model, a novel analytic
galaxy bias model for projected fields on the sphere that incorporates stochasticity and non-locality already at linear order while enforcing physicality and statistical isotropy. Rather than as a deterministic transfer function, we model
galaxy bias as a statistically isotropic random field, allowing stochasticity to enter through fluctuations in the bias itself. The construction yields an explicit decomposition into a linear, non-local
stochastic and deterministic components in harmonic space. We fit the model parameters to the projected power spectra measured in large-volume hydrodynamical simulations (FLAMINGO), enabling sampling of
galaxy populations from simulated matter fields while conditioning on
galaxy properties such as
halo mass or
redshift. By construction, the model reproduces the two-point statistics down to the simulation resolution, and without being calibrated on it, BOLTS recovers the equilateral bispectrum within the sample variance of the simulation down to comoving scales of $\mathcal{O}(10 \, \mathrm{Mpc})$ for
halo masses $ M_{\rm{h}} > 10^{11.5}\,\rm{M}_{\odot} $ over
redshifts $0 < z < 3$. Relative to local bias prescriptions, it more accurately captures amplitude-phase correlations and mode coupling in the measured wavelet phase harmonics wherever the stochasticity of the tracers exceeds their discreteness, including low
redshifts and lower
halo masses $M_{\rm{h}} = 10^{11.5}\,\rm{M}_{\odot}$ where non-linearities become important. This model enables efficient field-level forward modelling for simulation-based inference and model comparison with large
datasets from forthcoming
galaxy surveys including Euclid, Rubin LSST, and Roman, while improving the accuracy of
galaxy bias modelling with respect to standard linear deterministic models.
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All authors Maximilian von Wietersheim-Kramsta, Nicolas Tessore, Benjamin Joachimi, Qianjun Hang, Niall Jeffrey, Joop Schaye