High Energy Astrophysical Phenomena · Cross-listed from nucl-th
Trace-anomaly decomposition and universal dark matter scaling in compact stars
Adamu Issifu, Constança Providência and Tobias Frederico
We investigate how dark matter (DM) admixture modifies the conformal properties and phase structure of dense
neutron-
star matter within a self-consistent single-fluid framework, with the global DM fraction $F_\chi=N_\chi/N_B$ fixing the local relation $n_\chi=F_\chi n_B$. We derive an exact decomposition of the total trace anomaly, $\Delta_{\rm tot}$, into microscopic contributions. For
collider-motivated
Higgs-portal
benchmarks, explicit
Higgs, vector-mediator, and contact-interaction contributions are negligible, while heavy nonrelativistic DM has an intrinsic trace anomaly close to the nonrelativistic limit, $\Delta_\chi\simeq1/3$. Consequently, the DM rest-mass energy fraction dominates the DM-induced modification of $\Delta_{\rm tot}$, producing a smooth upward shift of up to $\sim0.1$ for $F_\chi\sim0.2\%$. In the pressureless, comoving heavy-WIMP regime, we further identify a universal dark-sector scaling governed by the mass-loading parameter $\lambda=F_\chi m_\chi/m_N$: numerical calculations with different $(F_\chi,m_\chi)$ pairs at fixed $\lambda$ exhibit overlapping trace-anomaly, sound-speed, and mass–radius responses for a given baryonic equation of state. In hybrid
stars, DM leaves the coexistence pressure and chemical potential essentially unchanged, whereas first-order
hadron–
quark deconfinement produces sharp discontinuities in the squared sound speed $c_s^2$, $\Delta_{\rm tot}$, and $\Delta_{\rm tot}-\Delta_B$. The combined softening substantially reduces the maximum stellar mass, placing $F_\chi\sim0.2\%$ in tension with the observed $2\,M_\odot$
neutron stars. These results show that the trace anomaly and its density
evolution provide a sensitive diagnostic for distinguishing smooth DM-induced modifications of dense matter from genuine first-order deconfinement.
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High Energy Astrophysical Phenomena
The Impact of a Clumpy Ambient Medium on the Dynamics and Synchrotron Emission of AGN Jets
Ivan Almeida, Christian Fendt and Bhargav Vaidya
Relativistic jets from AGN are expected to propagate through an inhomogeneous ISM, but the role of small-scale gas inhomogeneities in shaping their early
evolution remains uncertain. We investigate this problem using 3D special-relativistic magnetohydrodynamic simulations with PLUTO, following a jet with a Lorentz factor of 10 propagating through a pc-scale medium. We compare a homogeneous ambient medium with two clumpy ambient-medium models, motivated by dense gas in the nuclear ISM, in which clouds occupy volume filling factors of $0.1$ and $1$ per cent. We compute synthetic synchrotron maps and spectra from Lagrangian macro-particles that have been accelerated by diffusive shock acceleration. Jet-cloud interactions deflect the flow, enhance shock formation, and produce a more asymmetric cocoon than in the homogeneous ISM case. Altogether, this results in a substantially stronger mass loading: the entrained mass increases from $0.43$ M$_{\odot}$ in the homogeneous run to $5.3$ and $8.8$ M$_{\odot}$ in the clumpy runs. The clumpy ISM also modifies the
turbulence and the material mixing within the jet cocoon. The dynamical differences we find translate into brighter and more irregular synchrotron emission. For the same injected jet, the models with a clumpy medium produce stronger frequency-integrated synchrotron emission than the homogeneous run, with the largest differences in the SED occurring from the sub-mm to the infrared/optical bands. Our results demonstrate that including a small-scale ISM structure provides a more complete description of the early dynamical
evolution of young AGN jets and their radiative properties.
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High Energy Astrophysical Phenomena
Intrinsic versus observation induced spin nonstationarity in pulsar timing
Reginald Christian Bernardo
Whether
spin noise of a
neutron star is stationary is, in two-component models, a question of whether stellar angular momentum is conserved internally or exchanged externally through independent
stochastic torques on the crust and superfluid. The question is posed in the two components' angular velocities, but
radio pulsar timing observes only the crust, through its rotational phase after a deterministic timing model is fitted. We develop a Gaussian process method for testing
spin noise stationarity directly with such phase data. Starting from the exact analytical phase means and covariances of a singular, nonstationary and a minimal, stationary two-component model, we show that the crust phase covariances are semiseparable and construct a likelihood that scales linearly with the number of observations, with the timing model marginalized analytically. We analyze simulated phase data from both models using full-state and crust-only observations, and after differentiation into local
spin frequencies. Integration, timing model removal and differentiation neither create nor destroy the distinction between stationary and nonstationary
spin noise, but determine how much survives in a finite, noisy data set. With both components observed, the models are distinguished decisively and the generating parameters are recovered. With the crust alone, both models describe the observed phase equally well over much of parameter space, and the Bayes factors are of order unity and prior-limited. The minimal model nonetheless ties the hidden superfluid phase to the observed crust phase through a single factor set by the superfluid inertia fraction, so an independent estimate of this fraction, as from glitches, turns it into a falsifiable prediction that a continuous gravitational wave observation of the interior could test.
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Solar and Stellar Astrophysics
Wolf-Rayet formation through L/M-dependent superwinds
Aisling McKeown, Ciarán Furey, Gautham N. Sabhahit et al. (+1 more)
Mass-loss in red supergiants (RSGs) is poorly understood and stellar
evolution models rely on empirical prescriptions. In recent years, new superwind mass-loss ideas, including an $L/M$ dependence have been proposed, unlike traditional RSG wind recipes which are formulated on a $L$ dependence alone. We investigate how contrasting RSG mass-loss prescriptions affect the late-time
evolution of massive
stars from their RSG phase onwards. We used MESA to create a series of stellar
evolution models with masses ranging from $10\,{\rm M}_\odot - 40\,{\rm M}_\odot$, using the RSG \cite{VS23} $L/M$ recipe and traditional mass-loss prescriptions. Independent of the treatment of the stellar envelope, we find for a 25$\,{\rm M}_\odot$
star that the $L/M$ recipe reaches an order of magnitude higher mass-loss rate than traditional recipes due to its inverse mass dependence. As the RSG luminosity is set by the core mass and becomes largely insensitive to the current stellar mass, this creates a positive feedback loop driving runaway envelope stripping. Consequently,
stars with an initial mass $M_{\rm init} \sim \,20\,{\rm M}_\odot$ are able to strip their hydrogen envelope and form classical Wolf-Rayet (WR)
stars. We draw this conclusion not solely on the basis of their HRD location, but also on their predicted emission-line spectrum that we compute with the PoWR stellar atmosphere code.
Stars with $M_{\rm init}<20\,{\rm M}_\odot$ do not fully strip, meaning they expand after core helium burning. In Appendix A we present a generic analytical model showing that the tendency for runaway stripping increases rapidly with the strength of the inverse mass-loss scaling with mass. Our models demonstrate a viable single-
star pathway into the yellow supergiant and WR regimes. The amounts of full and partial stripping have a direct effect on
supernova (SN) progenitors, including partially stripped type IIb SNe.
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All authors Aisling McKeown, Ciarán Furey, Gautham N. Sabhahit, Jorick S. Vink
Solar and Stellar Astrophysics
LACHESIS: Robust stellar parameters through Bayesian model averaging of isochrone grids
Jose I. Vines and Austin T. Ware
Accurate stellar parameters underpin much of astrophysics, from exoplanetary systems to Galactic archaeology. For isolated field
stars, masses and especially ages are usually inferred from stellar
evolution models, yet these inferences depend on the chosen model grid, and the systematic differences between grids can rival the statistical uncertainties of any single pipeline. We present LACHESIS, a Python package that determines stellar masses, radii, and ages from photometry and spectroscopy while explicitly accounting for the systematic uncertainty from the choice of model grid. We interpolate five independent isochrone grids in [Fe/H], log age, and equivalent evolutionary phase conditioned on the data, sample each with nested sampling, and combine the per-grid posteriors by
Bayesian model averaging, weighting each grid by its
Bayesian evidence. We validate LACHESIS against a
benchmark of Kepler asteroseismic dwarfs and subgiants. Masses are recovered with a robust scatter of ~4% and radii to ~2%, with negligible radius bias (<1%) and a small ~3% mass systematic. Age is recovered with a robust scatter of 30% that depends strongly on evolutionary state; the grid-to-grid systematic contributes a ~9% floor, a subdominant but real term that a single-grid fit omits. Model averaging is better calibrated than selecting a single grid: its credible intervals approach nominal coverage once the reference uncertainty is included, and cover near the nominal rate in injection tests even when the generating model lies outside the ensemble. By marginalizing over an ensemble of stellar model grids, LACHESIS folds the choice-of-grid systematic directly into the posterior, so the reported uncertainties no longer reflect only within-grid data noise. This delivers homogeneous, well-characterized masses, radii, and ages for
exoplanet hosts and stellar population studies.
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High Energy Astrophysical Phenomena
Stationarity and angular momentum conservation in pulsar spin noise
Reginald Christian Bernardo
We present an analysis of
pulsar spin noise based on physically-motivated two-component models of
spin wandering. We focus on two models, distinguished by their total angular momentum dynamics: a singular, nonstationary model with a diffusive total angular momentum, and a minimal, stationary model anchored on a conserved total angular momentum. We develop scalable Gaussian process methods and, using mock data, show that the two models are fully testable and distinguishable with full-state observations, i.e., simultaneous independent data on the crust and the superfluid rotational states. This paves a path to testing stationarity in
pulsar spin noise, potentially achievable with joint continuous gravitational wave observations and
radio timing of
pulsars. However, robust inferences and predictions are harder to achieve, and depend on the priors and data quality, when only one component is observationally accessible.
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Instrumentation and Methods for Astrophysics
Radio Interferometric Calibration with the Exponential Map
L. Cabral, M. Fernandez-Corazza, G. Gancio et al. (+1 more)
The
antenna-elements that make up a
radio interferometer form a spatial filter that samples components of the
Fourier transform of a target
radio astronomical source brightness. Along the signal path, there are multiplicative and additive perturbation effects that alter the signal and that should be corrected. The process of mitigating these perturbation effects is called calibration. In this work, we develop a new and fast Maximum Likelihood based
estimator of these perturbation effects using the Exponential Map and Lie groups. To evaluate its performance, we compare it to the Cramér-Rao Lower Bound and, to test the estimation time, we compare it with the Expectation Maximization
algorithm, another fast Maximum Likelihood
estimator. Finally, we apply our
estimator to a real observation of the protoplanetary disk AS 209 made with the Submillimeter Array. We found that our proposed
estimator meets the Cramér-Rao Lower Bound and it was approximately 40 times faster than the Expectation Maximization
algorithm.
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All authors L. Cabral, M. Fernandez-Corazza, G. Gancio, P. Benaglia
High Energy Astrophysical Phenomena
Recycling serendipitous observations of XRISM for dark matter searches
Lidiia Zadorozhna, Denys Malyshev and Oleg Ruchayskiy
Searches for radiative decays of keV-mass dark matter have been limited by energy resolution. We propose a strategy for the XRISM/Resolve low count rate observations, and search the 3.48-3.56 keV band for a decay line from the Milky Way
halo. Despite a lower exposure, our bounds are stronger than those from XRISM observations of
galaxy clusters. We also identify a residual at E = 3.5311 keV with ~3sigma local significance, coincident with the previously reported unidentified feature, and having no plausible atomic or instrumental counterpart. These bounds will continue to tighten as additional pointings become available.
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Instrumentation and Methods for Astrophysics
hyprfine: simulating the 21-cm signal from the Dark Ages through to the Epoch of Reionization on a GPU
Harry T. J. Bevins
hyprfine is an analytic simulation of the sky-averaged 21-cm signal from $z=1100 - 6$ written using JAX and Python for native GPU capabilities. It models the average temperature of the 21-cm signal over
cosmic time as a function of the $\Lambda$-CDM cosmology parameters and the astrophysics of the first
stars and
galaxies. As far as we are aware, the code is the first analytic GPU native simulation of the 21-cm signal. It runs in a fraction of a second, parallelises efficiently across a GPU and is differentiable through the Dark Ages ($z \geq 35$). The code is publicly available at https://www.github.com/htjb/hyprfine.
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High Energy Astrophysical Phenomena
Slingshot on compact binaries in the nuclear region of galaxies as the origin of large offset gamma-ray bursts
Juan C. Rodríguez-Ramírez, Viviane Alfradique, Clécio R. Bom et al. (+1 more)
A growing number of gamma-ray bursts (GRBs) have been observed at large projected offsets from the centres of their putative host
galaxies, sometimes extending to several tens of kiloparsecs. When the GRB is associated with a kilonova, a compact binary with at least one
neutron star is expected to be involved, and the cause of the offset can be attributed to the
neutron star natal kick. In this work, we explore an alternative mechanism: the gravitational scattering of compact binaries populating the nuclear region of the host
galaxy, by an intermediate-mass black hole or secondary supermassive black hole. We specifically consider populations of
neutron star-
neutron star (NS-NS),
neutron star-black hole (NS-BH), and
neutron star-white dwarf (NS-WD) binaries, and analyse the ejection of bound systems from the nuclear region through a gravitational-slingshot effect. We proceed analytically to derive the conditions for binary survival and to parametrise the post-encounter velocity. To quantify the associated merger offsets, we numerically integrate the post-slingshot trajectory of the binary centre-of-mass in host-
galaxy potentials that include the primary SMBH, the stellar component, and the dark-matter
halo, considering both elliptical-like and spiral-like
galaxy profiles. Our parameter sampling shows that NS-NS and NS-WD binaries typically merge farther from the galactic centre than NS-BH systems, with approximately 30-45% of successful ejections merging at three-dimensional distances exceeding 100 kpc; these extreme-offset mergers occur within $\sim$0.1-10 Gyr after ejection. These results motivate the analysed mechanism as a candidate channel for observed extreme-offset transients.
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All authors Juan C. Rodríguez-Ramírez, Viviane Alfradique, Clécio R. Bom, Davi C. Rodrigues
Cosmology and Nongalactic Astrophysics
Cosmological inference from a joint DESI DR1 full-shape power spectrum and bispectrum analysis
Caroline Guandalin, Prakhar Bansal, Pedro Carrilho et al. (+9 more)
The
galaxy bispectrum directly probes the non-linear gravitational
evolution of large-scale structure (LSS) and can break parameter degeneracies that remain in power-spectrum analyses. We present a joint full-shape cosmological analysis of three luminous red
galaxy (LRG)
redshift bins and the
quasar (QSO) sample from the first Data Release (DR1) of the Dark Energy Spectroscopic Instrument (DESI). We model the
redshift-space power spectrum at one loop and the tree-level bispectrum within the Effective Field Theory of LSS. The bispectrum is decomposed in the Tripolar Spherical Harmonics basis, for which the convolution with the survey window function can be formulated as a direct linear transformation of the theoretical multipoles. Our power-spectrum constraints are in good agreement with the official DESI DR1 full-modelling results. We investigate the impact of including the bispectrum in the inference, finding that the monopole substantially improves the constraints on the cold dark matter density and amplitude of matter fluctuations by 9-18% and 8-20%, respectively, in the individual-tracer analyses. The corresponding reductions are 15% and 10% for the combined LRG sample, and 6% and 4% when all tracers are combined. In a restricted test using the first LRG bin, the bispectrum quadrupole changes the marginalised uncertainties by only a few percent. Extending the analysis to $w_0w_a$CDM substantially broadens the cosmological posteriors, while the bispectrum produces only a mild change in the allowed dark-energy parameter region, which remains sensitive to the adopted prior ranges. Our results demonstrate the potential of higher-order clustering statistics to improve cosmological constraints, while providing a framework for incorporating the bispectrum into full-shape analyses of current and future spectroscopic
galaxy surveys.
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All authors Caroline Guandalin, Prakhar Bansal, Pedro Carrilho, Alejandro Aviles, Mike Shengbo Wang, Marcos Pellejero-Ibañez, Aaditya Sarma, Jaide Swanson, Marco Bonici, Florian Beutler, Arnaud de Mattia, Hee-Jong Seo
Astrophysics of Galaxies
Diverse Protoclusters at $z\sim3$ Disclosed by Systematic Spectroscopy
Jun Toshikawa, Kentaro Koretomo, Nobunari Kashikawa et al. (+6 more)
We present the results from follow-up spectroscopy of three protocluster candidates at $z\sim3$, selected as overdense regions of $U$-dropout
galaxies in the wide-field imaging of the Hyper SuprimeCam Subaru Strategic Programme. All three targets exhibit tight clustering in three-dimensional space, i.e. on the sky ($>4\sigma$ overdensity) and in
redshift ($>98.4\%$ confidence), making for clear evidence of genuine protoclusters. Since these three protoclusters are identified by the same
dataset and technique, they represent a good sample to study the diversity of protocluster properties with minimal observational biases. Although the average population across the three protoclusters is consistent with field
galaxies, each protocluster individually exhibits distinguishing properties from each other or from field
galaxies. In one protocluster, member
galaxies stand out by a higher Ly$\alpha$ equivalent width ($EW_0$), and massive members that are still highly
star-forming. In contrast, relatively more suppressed
star formation appears in another protocluster where the Ly$\alpha$ $EW_0$ of member
galaxies is systematically lower. These variations can be attributed to differences in the developmental phase of protoclusters. If the presence of quenching
galaxies indicates a more mature system,
galaxies with stronger Ly$\alpha$ emissions may be more prevalent in the earlier stages of cluster formation. The uniform approach to searching protoclusters on which this study builds enables us to link observed variations at the onset of
cosmic noon to different pathways in the history of cluster formation.
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All authors Jun Toshikawa, Kentaro Koretomo, Nobunari Kashikawa, Stijn Wuyts, Marcin Sawicki, Malcolm N. Bremer, Yoshiaki Ono, Mariko Kubo, Tomoki Saito
Astrophysics of Galaxies
Galaxy Protoclusters as Drivers of Cosmic Reionization: II. Te-Based Metallicities of Lyman-{\alpha} Emitters
C. Moya-Sierralta, C. L. Martin, L. F. Barrientos et al. (+15 more)
Context. Protoclusters at reionization are thought to host a significant fraction of the
cosmic star formation rate density, making them crucial for the timing and
topology of reionization. The gas-phase
metallicity, a key tracer of
galaxy evolutionary stage, can now be measured directly in the early Universe with JWST. Aims. We measure the gas-phase
metallicity of Lyman-$\alpha$ emitters (LAEs) in the LAGER-z7OD1 protocluster at $z\approx6.93$ via the direct ($T_e$-based) method using the [O III]$\lambda$4363 auroral line, and combine it with stellar masses to constrain the mass-
metallicity relation (MZR) in dense environments. Methods. We use JWST/NIRSpec MSA G395H spectroscopy, derive
metallicities with self-consistent analytic prescriptions, and propagate the dust-extinction uncertainty into an asymmetric error budget via Monte Carlo simulations based on the observed Balmer decrements. Stellar masses come from BEAGLE SED fitting of JWST/NIRCam and UltraVISTA photometry. Results. We obtain five secure [O III]$\lambda$4363 detections and one upper limit, with 12+log(O/H) $\approx$ 7.2-8.0. The weighted spectral stack yields 12+log(O/H) = $7.76^{+0.06}_{-0.05}$, ~0.26 dex higher than stacks of LAEs at similar
redshifts from JWST surveys. However, the MZR fit gives a slope $\gamma$ = 0.232 +/- 0.214 and normalization $Z_0$ = 7.888 +/- 0.199, placing our sources below the established MZR of normal
galaxies and recent protocluster baselines at $z\sim5-7$. Conclusions. The higher
metallicity relative to general LAEs suggests accelerated assembly driven by the overdensity, while the offset below the MZR points to a complex interplay between mass build-up and gas
accretion. Since we target actively
star-forming LAEs, we are likely capturing a phase of pristine gas inflow from the intergalactic medium that fuels
star formation but dilutes the interstellar media of these protocluster members.
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All authors C. Moya-Sierralta, C. L. Martin, L. F. Barrientos, L. Infante, J. González-López, W. Hu, A. L. Faisst, Y. Harikane, A. M. Koekemoer, S. Malhotra, M. Ouchi, Z. Peng, J. Rhoads, J. Wang, J. R. Weaver, I. Wold, J. Yang, Z. Zheng
Solar and Stellar Astrophysics
Ensemble pulsational characteristics of eclipsing binaries containing $\beta$ Cep stars observed by the TESS mission
C. I. Eze, G. Handler, M. Vanrespaille et al. (+4 more)
Massive pulsators in eclipsing binaries provide precise, model-independent stellar parameters that, combined with asteroseismic constraints, provide powerful probes of interior properties and angular-momentum transport in massive
stars. This study investigates the pulsational characteristics and their impact on the structure and
evolution of $\beta$ Cep pulsators in eclipsing binaries. We analyse an ensemble of 65 $\beta$ Cep
stars in eclipsing binaries, identify rotationally split modes where possible, and statistically investigate the dependence of pulsational properties on binary orbital parameters. We derive their interior properties using MESA model grids and associated StORM pulsation frequencies, together with an asteroseismic routine that tracks stellar age and rotation across the $\beta$ Cep instability region. Interior rotation rates are derived for 14 systems that exhibit rotational mode splitting. While differential rotation is tentatively inferred for HD 112485, the other systems, except CZ Vel, are consistent with quasi-rigid rotation. The seismic and evolutionary properties of HD 112485 and EK Cru are derived through detailed forward asteroseismic modelling. HD 112485 is one of the least evolved $\beta$ Cep
stars asteroseismically modelled to date, with a core hydrogen mass fraction $X_{c}= 0.501_{-0.013}^{+0.009}$. The two reproduced zonal modes in HD 112485 are the first radial-order dipole pressure mode and the second radial-order quadrupole
gravity mode, while the zonal modes in EK Cru are the second-order quadrupole mixed mode and the third order dipole pressure mode. A multivariate regression shows a negative correlation of the pulsation amplitude with pulsation frequency, and no statistically significant relationship with the orbital period. In addition, no significant relationship is observed between the pulsation frequency and the orbital period in this sample.
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All authors C. I. Eze, G. Handler, M. Vanrespaille, A. Kemp, A. Tkachenko, D. M. Bowman, C. Aerts
Solar and Stellar Astrophysics
Delayed, Line-dependent Reorganization of Pore Oscillations Following a Compact C8.2 Flare Observed by Sunrise III/SUSI
Shahin Jafarzadeh, David B. Jess, Marco Stangalini et al. (+34 more)
Magnetic oscillations permeating the solar atmosphere can be altered by
flares. This could be due to changes in the atmospheric
magnetic waveguide, the thermodynamic stratification, or both. To investigate this, we examine oscillations in a
magnetic pore crossed in part by the ribbon of a C8.2
flare, using observations from the Sunrise Ultraviolet Spectropolarimeter and Imager (SUSI) aboard Sunrise III. We track the core intensities of eight spectral lines between 327-329 nm and show that oscillatory power in the 4.2-7.0 mHz range, measured around 30 minutes after the
flare peak, exceeds the pre-event value in all eight lines by factors of 1.60-8.71. Conversely, in the 7.0-11.5 mHz band, the post-event intensity power is lower - approximately 0.13-0.41 of the original power in seven of the observed lines. Line-center velocity measurements support the lower-frequency enhancement. This delayed, line-dependent shift toward the lower-frequency band is consistent with
flare-induced changes in wave transmission, reflection, or resonant response, although thermodynamic and
magnetic effects cannot yet be separated.
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All authors Shahin Jafarzadeh, David B. Jess, Marco Stangalini, Lyndsay Fletcher, Ryan O. Milligan, Paulo J. A. Simões, Peter H. Keys, Sami K. Solanki, H. N. Smitha, Andreas Lagg, Achim Gandorfer, Alex Feller, Francisco A. Iglesias, Tino L. Riethmüller, Bianca Grauf, Johannes Hoelken, José Carlos del Toro Iniesta, Yukio Katsukawa, Pietro Bernasconi, Thomas Berkefeld, Alberto Álvarez-Herrero, Masahito Kubo, David Orozco Suárez, Michael Carpenter, Alexander Bell, Valentín Martínez Pillet, Francisco Javier Bailén, Julian Blanco Rodríguez, Juan Sebastián Castellanos Durán, Edvarda Harnes, Ryohtaroh T. Ishikawa, Yusuke Kawabata, Takuma Matsumoto, Takayoshi Oba, Azaymi L. Siu-Tapia, Hanna Strecker, Dušan Vukadinović
Astrophysics of Galaxies
Weighing Galaxies Inside-Out: Small-Scale Lensing and the Stellar Mass Problem
Divya Rana, Henk Hoekstra, Konrad Kuijken et al. (+2 more)
Small-scale
galaxy-
galaxy weak
lensing provides an independent way to probe the stellar initial mass function by constraining the matter distribution within
galaxies. We forecast the potential of upcoming Euclid observations using realistic mock catalogues designed for a DESI-like Bright
Galaxy Survey, which is expected to cover approximately $9000\,\mathrm{deg}^2$ of the Euclid wide survey area. We assess the impact of foreground lens light, which introduces significant scale-dependent biases in source detection, photometry, and shape measurements. Subtracting the lens light with Galfit reduces these biases by nearly an order of magnitude at scales down to four times the half-light radius. We model the predicted
lensing signal around central
galaxies with stellar masses between $9.5 \leq \log(M_*/h^{-2}M_\odot) \leq 11.5$ over projected separations of $10$ to $100\,h^{-1}\mathrm{kpc}$. The resulting signal-to-noise ratios reach $\sim 150$ for intermediate-mass
galaxies. Assuming an NFW profile for the dark matter contribution, we constrain the stellar mismatch parameter $\alpha$ to a precision of approximately $8.5$ percent for the full sample and $8.6$ percent for massive
galaxies. These results highlight the potential of small-scale
galaxy–
galaxy weak
lensing as a robust probe of the IMF and the connection between stellar and dark matter in
galaxies using upcoming Euclid data.
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All authors Divya Rana, Henk Hoekstra, Konrad Kuijken, Alessandro Sonnenfeld, Maryam Tajalli
Earth and Planetary Astrophysics
Constraining Particle Stiffness in Asteroid Regolith from Early-Time High-Speed Penetrator Dynamics under Local Granular Variability
Zichen Wang, Yang Yu, Chenyang Huang et al. (+4 more)
Mechanical properties of rubble-pile asteroid regolith remain poorly constrained because contact responses depend on both material properties and local particle configuration. This study examines whether early-time high-speed penetrator dynamics can constrain particle stiffness, represented by the particle Young's modulus E, within a controlled discrete-element model. A bidirectionally coupled EDEM-Adams discrete-element-multibody model is used to screen six parameters: Young's modulus, Poisson's ratio, coefficient of restitution, static friction coefficient, rolling friction coefficient, and adhesion strength. Five Young's-modulus levels are then tested at the same 17 spatial locations in one settled granular bed, giving 85 simulations with location-matched comparisons across modulus levels. Within the 75-90 m s^-1 speed range, varying Young's modulus yields the clearest and most systematic differences in probe deceleration, whereas the other parameters have weaker effects over the tested ranges. Validation by withholding all modulus cases at one location in turn indicates that the early response is more informative for distinguishing broad modulus ranges than adjacent modulus levels. Mesoscale analysis links the response differences to concentrated interface load sharing and spatially extended three-dimensional high-capacity contact paths as Young's modulus increases. The results provide a numerical basis for narrowing the particle Young's-modulus range from high-speed penetration responses despite local granular variability. Quantitative application to real asteroid regolith requires further experimental validation.
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All authors Zichen Wang, Yang Yu, Chenyang Huang, Zhijun Song, Yutian Wu, Xiaojing Zhang, Xuhui Zhang
High Energy Astrophysical Phenomena
Disk-Like Matter Outflow from a Kerr-Type Wormhole: Possible Observational Manifestations and Magnetic Effects
Mikhail Piotrovich, Stanislava Buliga and Tinatin Natsvlishvili
We present a phenomenological study of a hypothetical compact object with a traversable 2 Kerr-type wormhole geometry connecting two asymptotically distinct regions. One mouth of the wormhole is assumed to reside in an active galactic
nucleus (AGN) environment with ongoing
accretion, while the second mouth is located in a comparatively quiescent galactic
nucleus without
accretion activity. In such a configuration, matter accreted near the AGN-side mouth may traverse the wormhole throat and emerge from the opposite mouth. Because the inflowing matter possesses angular momentum, the resulting outflow is expected to be predominantly equatorial, producing a disk-like structure fundamentally different from a conventional
accretion disk around a black hole. Several dynamical regimes are considered depending on the outflow velocity relative to the local escape and orbital velocities. Possible observational manifestations, thermal properties, recombination signatures, and
magnetic field effects are discussed. Special
attention is given to the possibility of jet formation in the absence of a conventional
accretion disk. We explicitly distinguish the weak-field, large-radius Newtonian classification used for the outer flow from the strong-field region near the throat, where the dynamics should be treated in a general-relativistic and magnetohydrodynamic framework. We further discuss the specific energy and angular momentum inherited from the inner edge of the
accretion flow, the possible modification of these quantities by
magnetic stresses and energy-extraction processes, and the effects of an intrinsic dipolar
magnetic field of the wormhole.
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Astrophysics of Galaxies
Constraining the density distribution of the cold Circumgalactic Medium of quasars at z>2 through Lya, HeII and Ha emission
Andrea Travascio, Sebastiano Cantalupo, Titouan Lazeyras et al. (+16 more)
Extended Lya emission is routinely detected around high-
redshift quasars, revealing large reservoirs of cool circumgalactic medium (CGM). Its resonant nature complicates interpretation of gas density, ionization state, and kinematics, making non-resonant tracers such as HeII and Ha essential. Extending previous analytical models, we use CLOUDY photo-ionization simulations to predict HeII/Ha in
quasar-illuminated gas over a broad parameter range, including log-normal density distributions. The ratio constrains density fluctuations, commonly quantified by the clumping factor C. We compare the models with extended Lya, HeII, and Ha observations around
quasars at z~2.1-4.5. At z~2.2, we observed 13
quasars with Keck/KCWI and targeted the systems with the most prominent extended Lya and HeII emission with Keck/MOSFIRE, providing the first statistical
quasar-CGM sample with combined Lya, HeII, and Ha measurements. Within matched apertures out to ~35 pkpc, stacked spectra give Lya/Ha=9.1, HeII/Ha=0.54, and HeII/Lya=0.06. Single-density models require very high CGM densities (n>10 cm^-3) or implausibly soft AGN spectra to reproduce the low HeII/Ha ratio. Broad log-normal density distributions instead reproduce it at lower median densities but require a substantial emissivity-weighted high-density tail, corresponding formally to C~10^3-10^4 in our parameterization. We also analyze 26 VLT/MUSE
quasars at 3.1<z<4.5, where Ha is inaccessible from the ground, finding 14 systems with co-spatial extended Lya and HeII emission. The detected, emission-weighted HeII/Lya component shows no evidence for strong
evolution between z~2.2 and z~3.7, though this does not imply an invariant underlying density PDF. These constraints provide a basis for comparison with theoretical models and hydrodynamical simulations of the physical processes shaping
quasar CGM at high
redshift.
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All authors Andrea Travascio, Sebastiano Cantalupo, Titouan Lazeyras, Naveen A. Reddy, Charles C. Steidel, Yongming Liang, Gabriele Pezzulli, Massimo Gaspari, Matteo Fossati, Michele Fumagalli, Chiara Feruglio, Fabrizio Fiore, Huiyang Mao, Marta Galbiati, Weichen Wang, Nicolas Ledos, Bahram Mobasher, Antonio Pensabene, Giada Quadri
High Energy Astrophysical Phenomena
Detection of kilosecond hard lags in the new pulsating ULX candidate NGC 7456 ULX-1
W. Leone, F. Pintore, C. Pinto et al. (+19 more)
Context. Ultraluminous X-ray sources (ULXs) are thought to be powered, in many cases, by super-Eddington
accretion onto compact objects. While soft X-ray lags have been detected in several ULXs, hard lags remain rare and poorly understood. Aims. We investigate the temporal and energy dependence of X-ray lags in NGC 7456 ULX-1 to constrain their physical origin and probe the super-Eddington
accretion flow. Methods. We analyzed the two deepest XMM-Newton observations, taken in 2018 and 2023. Hard (1-10 keV) and soft (0.3-1 keV) light curves were cross-correlated using adaptive-binning techniques optimized for Poissonian low-count data. We measured lags over consecutive 10 ks intervals and investigated their energy dependence. Spectra were modeled using thermal and Comptonization models. Results. We detect significant hard X-ray lags in both observations, with the hard emission delayed by $\sim 10^3$ s during phases of rapid flux variability. The delays are primarily driven by the lowest-energy
photons. Spectral modeling indicates a Comptonization-dominated flow comprising a cooler, extended outer region and a hotter, compact inner flow embedded in an optically thick wind. We interpret the delays as the combined effect of inward propagation of
accretion-rate fluctuations and
photon diffusion within the dense outflow. Fluctuations first enhance the soft-emitting outer regions and then propagate toward the hotter inner flow, where
photons undergo stronger Comptonization before escaping with a kilosecond delay. The small inferred inner emitting radius disfavors an intermediate-mass black hole accretor. Conclusions. The sign, amplitude, and energy dependence of the delays disfavor standard reverberation. Propagation-driven variability coupled with radiative transfer in optically thick winds appears to play a major role in shaping the timing properties of super-Eddington
accretion flows.
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All authors W. Leone, F. Pintore, C. Pinto, N. O. Pinciroli Vago, A. Sanna, A. Wolter, T. Di Salvo, R. Iaria, A. D'Aì, A. Anitra, R. Soria, P. Esposito, F. Barra, E. Ambrosi, S. Caserta, C. Salvaggio, R. Salvaterra, G. L. Israel, S. Banerjee, M. Marelli, G. Rodriguez-Castillo, L. Burderi
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Graceful Exit to Radiation Domination in the Starobinsky Model: A Dynamical Realization
Bhargabi Saha and Malay K. Nandy
The Starobinsky model provides a successful realization of inflation and serves as a
benchmark for alternative inflationary models. Motivated by its observational success, we investigate the dynamical
evolution of the early Universe within this framework. Incorporating radiation production from scalaron decay, we formulate a coupled system of dynamical equations describing scalaron depletion and radiation buildup while ensuring exact energy conservation in the expanding background. In the Friedmann equation, both scalaron and radiation components gravitate, thereby accounting for the backreaction of the generated radiation. Starting with a radiation-free Universe and initial conditions from the standard slow-roll approximations, exact numerical
evolution shows that inflationary dynamics is predominantly governed by the scalaron. Despite continuous radiation production, the radiation component remains subdominant, and the slow-roll conditions persist throughout inflation, yielding approximately 60 e-folds. Following inflation, the scalaron enters a damped oscillatory phase accompanied by rapid radiation growth. This transition provides a graceful exit from inflation and a smooth entry into reheating. During reheating, radiation grows continuously as the scalaron energy is depleted, with the radiation energy density ultimately becoming substantially larger than the residual scalaron energy density. This indicates the onset of a hot, radiation-dominated phase, satisfying the Kofman-Yi criterion for successful reheating. Our results demonstrate that the coupled scalaron-radiation dynamics provides a self-consistent realization of graceful exit and the transition to radiation domination in the Starobinsky model.
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Astrophysics of Galaxies
Resolving the physics of Quasar Ly$\alpha$ Nebulae (RePhyNe): II. The dense and clumpy CGM of Quasars at $z \sim$ 3.5
Titouan Lazeyras, Sebastiano Cantalupo, Andrea Travascio et al. (+10 more)
The small scale density distribution of the cold circumgalactic medium (CGM) plays a central role in
galaxy evolution, yet it is still poorly understood. We provide new constraints on the cold CGM density distribution by comparing the CGM emission from MUSE observations of
quasar (QSO) nebulae at $z \sim 3.8$ with mock observations generated from the new DaLya simulation suite under the assumption of maximal fluorescence. These are further complemented by mock observations generated from the COLIBRE (m5 and m6 resolutions) and HELLO simulations. We first investigate the distribution of the observed and simulated Ly$\alpha$ surface brightness (SB) values, which directly depend on the cold gas density distribution under our assumption, finding stark differences between observations and upper limits provided by simulations with the exception of the COLIBRE higher-resolution run (m5). The observations generally show a much larger covering fraction of regions with relatively large Ly$\alpha$ SB values and suggest that densities reaching at least 10 cm$^{-3}$ must be present in the CGM of QSOs within a radial distance of 50 to 200 ckpc. To understand the origin of this discrepancy, we study the cold CGM density distribution finding in all cases simulated PDFs consistent with skewed lognormal ones with medians $\sim 10^{-2}$ cm$^{-3}$ and clumping factors between 16 and 102. We compare the broadness of these distributions to the one implied by the observed HeII/Ly$\alpha$ CGM ratio, which is independent on the assumption of maximum fluorescence. Assuming lognormal PDFs with median values similar to the simulations, the observed ratio requires a broader PDF with a clumping factor at least 8 times larger than predicted by simulations. These results suggest that higher resolution and/or additional physical mechanisms are needed to reproduce the observed CGM of QSOs at these
redshifts.
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All authors Titouan Lazeyras, Sebastiano Cantalupo, Andrea Travascio, Nicolas Ledos, Joop Schaye, Gabriele Pezzulli, Federico Baraggioni, Alessandro Lupi, Andrea V. Macciò, Marta Galbiati, Antonio Pensabene, Giada Quadri, Weichen Wang
Solar and Stellar Astrophysics
Solarprop 2.0: Modern charge-sign dependent solar modulation for everyone
Henning Gast
I present a greatly improved version of SOLARPROP, an open source framework for building models of charge-sign dependent solar modulation of
cosmic rays in the heliosphere. The transport equation of charged particles is solved by converting it to a set of
stochastic differential equations (SDEs). The code now includes the full set of SDEs in two spatial dimensions, allowing for
magnetic fields with latitudinal components, and it has been generalized to accommodate models in three spatial dimensions. Due to code parallelization and optimization, a speedup of up to three orders of magnitude with respect to the original version is achieved. Python bindings have been added for ease of use. The code has been validated against the results of several model calculations found in the literature. While excellent agreement is found in many cases, important differences are observed for two model implementations. Possible root causes for the differences have been investigated.
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Astrophysics of Galaxies · Cross-listed from physics.ins-det
State of the Art in Direct Dark Matter Detectors: Technologies, Performance, and Future Directions
Muad Ghaith and Khaled Obaideen
Identifying the particle nature of dark matter remains one of the most significant challenges in modern physics. Direct detection experiments aim to observe rare scattering events between dark matter particles and terrestrial targets, a task that demands extreme background suppression and sensitivity to minute energy depositions. This review critically assesses the current experimental landscape, organizing detector technologies by the fundamental physical trade-offs that define their scientific reach. We contrast the multi-tonne scalability of noble-
liquid Time Projection Chambers (TPCs), which currently define the sensitivity frontier for high-mass Weakly Interacting Massive Particles (WIMPs), with the precision of cryogenic
semiconductors and Charge-Coupled Device (CCD)- based sensors, which dominate the search for low-mass and sub-GeV candidates. Special emphasis is placed on the role of advanced reconstruction pipelines and machine learning (ML) as integral components of detector performance. Finally, we discuss the strategic roadmap for the next decade as experiments approach the
neutrino fog, where coherent elastic
neutrino-
nucleus scattering (CE{\nu}NS) produces an increasingly significant and ultimately irreducible background that can mimic DM-induced nuclear recoils. We argue that future progress will rely not on a single technology but on a complementary global program combining increased target mass, ultra-low energy thresholds, improved background discrimination, and distinct observables - such as directionality and temporal signatures - to maintain robust discovery capability in the presence of
neutrino-induced backgrounds.
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Solar and Stellar Astrophysics
Towards solar many-line inversions
Johannes Hölken
The Sun's atmosphere is significantly influenced by events that often measure only tens of kilometres in the horizontal direction. They happen in both quiet and active regions and are determined by magneto-hydro-dynamic processes. Their origins often lie in the lowest layers of the solar atmosphere. To improve the understanding of chromospheric and coronal heating, the solar dynamo and its activity cycle, or to improve the prediction of space weather events we must therefore enhance our understanding of such small-scale events. In this work I first describe the process of calibrating spectropolarimetric observations with very high spatial resolution and put together the building blocks for the mathematical proof the MOMFBD image reconstruction
algorithm. In the second part I describe the FISS-SP prototype which is designed to fully exploit the resolution power of a 1.6m
telescope. This instrument is built to provide suitable data for image reconstruction of spectropolarimetric data. The resulting data can resolve small-scale features down to the diffraction limit. The simultaneous interpretation of a few lines is still the norm for spatially highly resolved solar spectra. Theoretical works have shown that the simultaneous interpretation of multiple solar lines can greatly improve the robustness against noise. Using observations from FISS-SP I advance the theoretical idea into a practical technique. With this I can retrieve a coherent model of the local solar atmosphere, resolving structures down to a horizontal size of about 49~km. Finally, I use those new techniques to interpret an observation of a solar pore. In this last part I describe and analyse small-scale structures, which could not be spectropolarimetrically resolved before. Typical pore-boundary features - namely, dark striations with bright grains moving into the pore - are identified as convective features.
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Solar and Stellar Astrophysics
Structure of Convective-Reactive Zone in a Supernova Progenitor
M. Mocak, C. Meakin, F. Rizzuti et al. (+5 more)
Convective-reactive events are phases of stellar
evolution where turbulent mixing and nuclear burning directly compete, since their timescales become similar within convection zones. During these events the convection zone structure is shaped by a complex and dynamic interaction of convective transport and nuclear burning of individual chemical elements, with
plasma streams connecting the entrainment regions with the burning layers. Here we analyse a 3D hydrodynamic simulation of an oxygen–neon shell merger in a massive pre-
supernova star. We study the emergent structure using the Reynolds-Averaged Navier-Stokes (RANS) mean-field composition transport equation. We find that the merged convective zone develops a complex,
turbulence-driven mixing structure of multiple nested convective-reactive shells, all contained within the single convection zone. Key controlling factors include not only the mean stratification and mixing, but also emergent collective behaviour of involved nuclear reactions for every chemical isotope. Almost all layers show a quasi-steady balance between burning and mixing. We categorise the various layers, and discuss/contrast with 1D stellar
evolution code treatments, highlighting some implications.
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All authors M. Mocak, C. Meakin, F. Rizzuti, S. W. Campbell, V. Varma, R. Hirschi, C. Georgy, W.D. Arnett
Solar and Stellar Astrophysics
Probing Accretion and Outflow in V1180 Cas through High-Resolution Optical Spectroscopy
Tarak Chand, Saurabh Sharma, Koshvendra Singh et al. (+9 more)
We present an analysis of a high-resolution optical spectrum of V1180 Cas obtained with HIRES at the W. M. Keck Observatory during a bright photometric state of the source. The spectrum is dominated by strong emission lines, including H$\alpha$, the Ca II infrared triplet, He I, and O I, along with numerous Fe I and Fe II transitions and several forbidden lines such as [O I] and [S II], indicating ongoing
accretion and mass-loss activity. A weak Li I $\lambda$6708 absorption feature confirms the youth of the source. Using the Li I absorption and selected Fe I emission lines, we report for the first time a radial velocity of $-16 \pm 3$ km s$^{-1}$ for V1180 Cas. The H$\alpha$ and H$\beta$ profiles exhibit asymmetric structures with blueshifted absorption components, suggesting outflowing material along the line of sight. The He I $\lambda$5876 line displays a narrow component likely associated with post-shock
accretion regions and a broad, slightly blueshifted component probably arising from magnetospheric flows and/or inner disk winds. The [O I] $\lambda$6300 profile is decomposed into low- and high-velocity components, tracing a slow disk wind and a fast jet. Using the forbidden [O I] line, we estimate for the first time a disk inclination angle of $\approx50^\circ$. The derived mass
accretion and jet mass-loss rates imply $\dot{M}_{jet}/\dot{M}_{acc} \sim 0.01$–$0.03$, at the lower end of, but consistent with, the range observed for Class II YSOs. Forbidden-line diagnostics indicate densities $\sim10^{3}$ and $10^{6}$ cm$^{-3}$ with temperatures of $\sim10^{4}$ K, supporting a multi-component outflow scenario. Overall, the results support a picture in which V1180 Cas is an actively accreting, moderately inclined system hosting a multi-component outflow.
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All authors Tarak Chand, Saurabh Sharma, Koshvendra Singh, Joe P. Ninan, Arpan Ghosh, Devendra K. Ojha, Jyotirmoy Dey, Manojit Chakraborty, Kartik Gokhe, Aayushi Verma, Mamta, Ajay Kumar Singh
High Energy Astrophysical Phenomena
25 Years of Mrk 421 with XMM-Newton: Unveiling Structured Jets and Energy-Dependent Escape
Tek P. Adhikari, Gopal Bhatta, Sangeetha Kizhakkekalam et al. (+4 more)
We present a long-term X-ray spectral and timing analysis of the TeV blazar Mrk~421 based on nearly a quarter century of archival XMM-Newton/pn observations obtained between 2000 and 2025. Our sample comprises 76 epochs obtained with the pn instrument in both IMAGING and TIMING modes, allowing us to trace the source's variability and spectral
evolution. Mrk~421 exhibits flux variations by approximately an order of magnitude, with prominent flaring periods interspersed with low-activity states. A clear harder-when-brighter trend is observed, accompanied by scatter in the hardness ratio (HR), suggesting flux alone does not uniquely determine the spectral state. Fractional variability in the hard band ($2-10$ keV) correlates tightly with that in the soft band ($0.3-2$ keV), with a steeper slope indicating pronounced variability at higher energies. The flux distribution is non-Gaussian and lognormal-like, dominated by moderate flux levels with a tail of bright
flares. Spectral analysis shows that power-law model is not sufficient; 59 epochs are best described by a broken power-law (BPL) and 17 by a log-parabola (LP). This fluctuation between BPL and LP models suggests the emission region transitions between a distinct acceleration shockfront and downstream
stochastic turbulence. The spectral break energy of BPL remains predominantly clustered around $2$ keV across all flux states, while the average spectral steepening above the break is mild ($\Delta \Gamma \approx 0.19$), inconsistent with standard one-zone cooling models. Our results support structured jet scenarios or energy-dependent electron escape, providing key constraints on the long-term behavior of relativistic jets in high-synchrotron-peaked blazars.
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All authors Tek P. Adhikari, Gopal Bhatta, Sangeetha Kizhakkekalam, Navaneeth P K, Alex Markowitz, Zhicheng He, Santanu Mondal
Astrophysics of Galaxies
Chemical complexity in feedback from supernova remnants: first detection of PO+ in IC443 and W44
G. Cosentino, F. Priestley, S. Scibelli et al. (+1 more)
Supernova remnant (SNR) may shape the physical and chemical properties of
star formation. By releasing refractory elements into the gas phase, they inject material of pre-biotic relevance into molecular clouds. Such elements may be inherited by planetary systems and become relevant for the emergence of life. We investigate the presence of P-bearing species in molecular clouds impacted by SNR-shocks. P is a crucial biological element, but its presence and reservoir in molecular clouds remain elusive. We present high-sensitivity 3 mm observations obtained with the IRAM 30m, toward the interaction sites between the SNRs W44 and IC443 and their associated molecular clouds. Focusing on PO+(2-1) and PN(2-1), we derive molecular column densities and abundances in local thermodynamic
equilibrium. We investigate the correlation between P-bearing species and the shock tracer Silicon Monoxide (SiO). We detect, for the first time, PO+ toward SNRs, with abundances X(PO+)~8e-12-5e-11, but no significant PN emission. PO+ toward both SNRs is associated with strong SiO emission, showing similar linewidths but velocity offsets, suggesting that PO+ preferentially traces the most compressed and more strongly ionised layers of the shock. By comparing the derived abundances with those reported in literature, we suggest that the PO+ abundance mainly depends on a combination of shock strength and shocked medium density. Our results indicate that P-chemistry in SNR shocks is shifted toward an ion-dominated regime, likely driven by enhanced
cosmic-ray ionisation rates. In this scenario, neutral species such as PN are efficiently destroyed, while ion-molecule reactions favour the production of PO+. This suggests that SNR shocks may play a role in processing P-bearing material and shaping gas-phase P chemistry in molecular clouds, with potential implications for the chemical inventory of
star-forming environments.
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All authors G. Cosentino, F. Priestley, S. Scibelli, F. Fontani
Astrophysics of Galaxies
Do Submillimeter Galaxies Trace Megaparsec Large-scale Structures? – An Overdensity Analysis of 449 Submillimeter Galaxies in COSMOS
Canze Deng, Daizhong Liu, Helmut Dannerbauer et al. (+19 more)
We present an environmental analysis and overdensity catalog for a large sample of submillimeter
galaxies (SMGs) in the COSMOS field in order to understand whether SMGs are signposts of megaparsec-scale overdensity structures. We apply the Poisson Probability Method (PPM) protocluster finder to characterize the significance ($\sigma$) and overdensity value ($\delta$) of any overdense structures surrounding specific 'beacon'
galaxies. These beacons include 449 SMGs from A3COSMOS (including 168 with spectroscopic
redshifts, 52 of which have CO or [CII] 158$\mu$m line detections), as well as a control sample of over 5000 main-sequence
star-forming
galaxies (SFGs) selected from the 40-band photometric-
redshift catalog in COSMOS2025. We successfully reproduce 15 known protoclusters and clusters in COSMOS (including Hyperion large-scale structure, CL J1001+0220 at z~2.5, and AzTEC-3 protocluster at z~5.3), and report 26 new PPM-based high-overdensity ($\delta$ $\geq$ 5), high-significance ($\sigma$ $\geq$ 5), robust candidates. We measure an overdensity fraction of 11.5-71.2% (1.3-61.0%) in the CO/[CII] 52 SMG (full 449 SMG) sample with different criterion categories, confirming that SMGs are signposts of overdensities compared to the control SFG sample. We also notice that the fraction is lower than 100%, indicating that not all SMGs are associated with overdensities. We thus inspect the JWST morphology and argue that the triggering of starburst in SMGs must have non-environmental mechanisms, for instance, merger and violent disk instability. Finally, we further conduct a spatial distribution analysis, finding that the location of SMGs in overdensities has a
redshift evolution, with SMGs being more concentrated in the inner regions of overdensities at higher
redshift.
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All authors Canze Deng, Daizhong Liu, Helmut Dannerbauer, Gianluca Castignani, Rosa Calvi, Lauro Moscardini, Benjamin Magnelli, Sylvia Adscheid, Eva Schinnerer, Hui Li, Rafael Arango-Toro, Caitlin Casey, Jacky S.W. Chan, Andreas Faisst, Maximilien Franco, Zohreh Ghaffari, Santosh Harish, Jeyhan Kartaltepe, Greta Toni, Jorge Zavala, Xin Zeng, Xianzhong Zheng