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Physics Astrophysics Cosmology and Nongalactic Astrophysics

astro-ph.CO Watch Cosmology and Nongalactic Astrophysics

Tuesday 13 October · still arriving

Cosmology and Nongalactic Astrophysics

Constraints on the cosmic reheating history from PTA data

Qi-Lin Yang, Shi-Jie Wang and Nan Li

The cosmic reheating is an important epoch in the very early Universe, and has significant impacts on the primordial black hole (PBH) abundance and the scalar-induced gravitational wave (SIGW) spectrum. The relevant energy scale and the constituents of cosmic medium are encoded in the reheating frequency $f_{\mathrm{reh}}$ and the equation of state parameter $w$. In this work, we perform a full parameter space Bayesian inference, using the NANOGrav 15-yr dataset to constrain the thermal history of reheating. Treating $f_{\mathrm{reh}}$ and $w$ as free parameters, we systematically investigate the Dirac $\delta$, narrow and broad log-normal primordial power spectra. Current pulsar timing array data can effectively constrain the peak frequency of the SIGW spectrum as $f_{\rm p}\sim 10^{-7.6}$–$10^{-7.0}$ Hz, along with $f_{\rm reh}\sim 10^{-9.0}$–$10^{-8.3}$ Hz and $w\sim 0.19$–$0.79$ (the $68\%$ confidence level), when the power spectrum has a relatively narrow width $\Delta \lesssim 1$. A broader power spectrum introduces a smoothing effect that obscures the characteristic frequency knee in the SIGW spectrum, leading to the loss of information about cosmic reheating. Furthermore, for the Dirac $\delta$ and narrow spectra, the PBH masses associated with the SIGWs are anchored at the planetary mass scale around $10^{-6}$–$10^{-4} M_{\odot}$. This establishes a consistent physical framework that naturally bridges the nanohertz gravitational wave background with the dark matter candidates implied by the Optical Gravitational Lensing Experiment microlensing events.
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Cosmology and Nongalactic Astrophysics

Structure and evolution of cosmic voids within DESI DR1

Óscar Monllor-Berbegal, Susana Planelles and Vicent Quilis

Ongoing stage IV galaxy surveys such as DESI or Euclid offer an unprecedented amount of information to study the large-scale structure of the Universe by mapping tens of millions of galaxies. Within the context of cosmic voids, already released and future catalogues will help better understand the void structure and evolution as well as the cosmological model constraints derived from their statistics. With the recent DESI Data Release 1, our aim is to obtain a new void catalogue that allows us to study the properties of cosmic voids at different redshifts, hence providing insight not only on their structure but also on their evolution. We select the DESI BGS and LRG samples for this study. Before the void-finding process, the data goes through a preprocessing pipeline tackling redshift space distortions and reconstructing the mildly non-linear velocity field. After that, the new AVISM void finder is applied to the preprocessed data, obtaining two void catalogues in different redshift bins (0.1 < z < 0.3 and 0.4 < z < 0.8), both within a 1400^3 cMpc^3 cube. We successfully recover N_BGS = 1114 and N_LRG = 216 clean voids with sizes up to ~ 65 cMpc. The void size function, 3D shape variables, density profiles, and linear bias are obtained and analysed. Both the size function and the density profiles obtained are in agreement with previous theoretical studies. The expected mass depletion in void evolution is shown by the evolution of density profiles. We obtain a roughly constant linear bias inside r < Re with mean values of 1.31 +/- 0.02 and 2.14 +/- 0.04 for BGS and LRG, respectively. Both void catalogues are publicly released.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Cosmological Consequences of a Highly Decoupled Right-handed Neutrino

Stephen F. King, Rishav Roshan and Sudipta Show

In the minimal type-I seesaw, one right-handed neutrino (RHN) can decouple from neutrino mass generation. Such a state is usually neglected, yet its feeble couplings make it long-lived, and it can dominate the energy density of the Universe before decaying. We study this in a minimal $U(1)_{B-L}$ model, where the RHNs are produced through $B-L$ gauge interactions, for the cases of a decoupled lightest RHN $N_1$ and a decoupled heaviest RHN $N_3$. The resulting early matter-dominated era dilutes the baryon asymmetry, and for decoupled $N_3$ it also delays the equilibration of the charged-lepton Yukawa interactions, allowing a lighter $N_1$ to generate the asymmetry in the unflavoured regime. Breaking $U(1)_{B-L}$ forms cosmic strings whose gravitational-wave background acquires a spectral break from the early matter-dominated era, with a frequency set by the decoupled RHN mass and the lightest neutrino mass, within reach of future detectors such as SKA, THEIA, LISA, $\mu$ARES, DECIGO and ET.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Signature of GW from the Hidden Sector in light of the Recent LZ Event

Sujit Kumar Sahoo, Narendra Sahu and Vicky Singh Thounaojam

The LZ collaboration has recently reported a single nuclear-recoil event at $E_R=248\pm23_\text{stat}\pm23_\text{sys}$ keV, observed in a 2.84 tonne-year exposure with a local significance of $3.4\sigma$, pointing towards an inelastic dark matter (DM) interpretation. We explain this event within a gauged $U(1)_X$ hidden-sector model, spontaneously broken by a singlet scalar whose vacuum expectation value (VEV) gives rise to: (i) gauge boson mass, (ii) a small Majorana mass for the vector-like singlet fermion, the DM candidate, charged under the new symmetry, which splits the fermion into two pseudo-Dirac states (mass splitting proportional to the scalar VEV) thus resulting in a purely off-diagonal vector current, (iii) the frequency and the amplitude of the GW signal arising from the hidden sector symmetry breaking via first-order phase transition (FOPT). The symmetry-breaking scale thus provides a multi-messenger probe connecting terrestrial direct-detection kinematics at the LZ and early-universe FOPT thermodynamics while obtaining thermal DM relic abundance. We delineate the viable parameter space compatible with the LZ event, correct relic density, and detectable GW signals in the low frequency regimes at future interferometers like $\mu {\rm ARES}$ and THEIA while satisfying existing cosmological, astrophysical, and terrestrial bounds.
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Cosmology and Nongalactic Astrophysics

Validation of harmonic-space likelihood methods for LiteBIRD B-mode polarisation analysis

G. Galloni, P. Campeti, C. Gimeno-Amo et al. (+112 more)

The LiteBIRD satellite mission aims to measure the tensor-to-scalar ratio $r$ with unprecedented sensitivity through observations of the cosmic microwave background (CMB) $B$-mode polarisation. Robust constraints on $r$ require accurate likelihood modelling across a wide range of angular scales. In this work, we validate harmonic-space likelihood methods against pixel-based benchmarks using 20\,000 end-to-end simulations that include CMB, instrumental noise, and Galactic foreground residuals processed through a realistic component-separation pipeline. We compare a debiased pixel-based likelihood, which serves as our benchmark on large scales ($\ell\leq32$), with an offset Hamimeche & Lewis (oHL) likelihood applicable across the full multipole range. We systematically explore the space of analysis settings, identifying the number of simulations used for covariance estimation and the choice of beam window function as the most critical factors. Over the full multipole range considered ($\ell\leq128$), where the benchmark combines the pixel-based likelihood at $\ell\leq32$ with a harmonic one at smaller scales, the 68% upper bound on $r$ from the oHL likelihood is $19$–$29\%$ larger than the benchmark one, depending on the beam window function. This demonstrates its viability as a computationally efficient baseline for LiteBIRD data analysis and cosmological inference from the polarisation $B$-mode field.
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All authors G. Galloni, P. Campeti, C. Gimeno-Amo, A. Carones, A. Rizzieri, Y. Chinone, N. Krachmalnicoff, E. Martínez-González, L. Pagano, D. Adak, E. Allys, A. Anand, K. Aryan, J. Aumont, C. Baccigalupi, A. J. Banday, R. B. Barreiro, N. Bartolo, A. Basyrov, M. Bersanelli, A. Besnard, F. Bouchet, N. Brancadori, T. Brinckmann, F. J. Casas, L. Castelló Gomar, L. Colombo, F. Columbro, A. Coppolecchia, M. Cruz, F. Cuttaia, P. de Bernardis, E. de la Hoz, M. De Lucia, S. Della Torre, C. Demay, P. Diego-Palazuelos, J. J. Díaz García, F. Finelli, C. Franceschet, U. Fuskeland, M. Galloway, K. Ganga, M. Gerbino, T. Ghigna, S. Giardiello, E. Gjerløw, M. Gomes, A. Gruppuso, S. E. Harper, M. Hazumi, S. Henrot-Versillé, L. T. Hergt, E. Hivon, K. Ikuma, H. Ishino, K. Kohri, L. Lamagna, M. Lattanzi, C. Leloup, M. Lembo, F. Levrier, A. I. Lonappan, M. López-Caniego, D. Maino, V. Maranchery, S. Masi, S. Matarrese, S. Micheli, M. Migliaccio, M. Monelli, L. Montier, G. Morgante, M. Morshed, L. Mousset, M. Najafi, T. Namikawa, P. Natoli, I. Obata, A. Occhiuzzi, A. Paiella, D. Paoletti, S. Paradiso, G. Pascual-Cisneros, F. Piacentini, G. Piccirilli, M. Pinchera, G. Polenta, L. Porcelli, M. Reinecke, M. Remazeilles, A. Ritacco, J. A. Rubiño-Martín, M. Ruiz-Granda, Y. Sakurai, L. Salvati, J. Sanghavi, D. Scott, D. Shenoy, M. Shiraishi, G. Signorelli, S. Stellati, R. M. Sullivan, K. Tassis, L. Terenzi, M. Tomasi, H. Tran, L. Vacher, B. van Tent, P. Vielva, S. Vinzl, D. J. Watts, I. K. Wehus, G. Weymann-Despres, for the LiteBIRD Collaboration

Cosmology and Nongalactic Astrophysics

CosmoForge II. An exact treatment of arbitrary linear filters in quadratic maximum-likelihood power spectrum estimation

Giacomo Galloni

Ground-based cosmic microwave background (CMB) experiments filter their time-ordered data to remove $1/f$ noise and ground pickup, which removes or mixes the large angular scales where primordial $B$ modes peak. A common remedy is a pseudo-$C_\ell$ estimator with harmonic $B$-purification and a transfer function measured from simulations. Another applies it after a matrix-based $E/B$ purification of the maps. We extend the quadratic maximum-likelihood (QML) estimator of CosmoForge to filtered maps, treating the filter exactly: a linear filter conjugates the estimator's ingredients without altering its structure. The same holds for the pixel-based likelihood of CosmoForge, which gives the smallest error bar achievable on the same maps. We compare all methods in a simplified setup under several map-level filters through the error bars on bandpowers and on the tensor-to-scalar ratio $r$. QML sits $2$ to $4\%$ above the pixel-likelihood bound on $\sigma (r)$ in every filter state. At low noise, the pure pseudo-$C_\ell$ $\sigma (r)$ is $1.21$ times QML's without filtering, $3.0$ times under a scan filter along stripes of constant declination, and $3.7$ times under one from a toy constant-elevation scan. The matrix-purified pseudo-$C_\ell$ $\sigma (r)$ is at most $1.03$ times QML's except under the constant-elevation filters, where it reaches $1.10$. These factors shrink towards unity at higher noise. The pure pseudo-$C_\ell$ gap comes from apodisation and from harmonic $E/B$ separation; pixel-space separation closes it, except under the constant-elevation filters, which attenuate modes rather than remove them and widen the gap. QML stays within a few per cent of the optimal error bars without the tuning and simulated transfer functions of the pseudo-$C_\ell$ pipelines. Thus, CosmoForge provides a robust framework for power-spectrum estimation and inference on filtered maps. (Abridged)
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Cosmology and Nongalactic Astrophysics

Mapping Dark Matter in Merging Clusters with Weak Lensing for CSST: Morphology and Filament Recovery

Xinyue Chen, Ran Li, Qiao Wang et al. (+6 more)

Weak gravitational lensing offers a direct probe of the projected dark matter distribution in cluster-scale structures and the surrounding cosmic web. We investigate the capability of the China Space Station Telescope (CSST) to recover non-spherical dark matter morphologies using mock reduced-shear maps generated from cosmological N-body simulations. We apply the deep-learning-based MIU2Net mass-reconstruction framework to CSST-like wide- and deep-field source densities, focusing on two representative systems: filament-connected halo pairs and elongated halos. MIU2Net accurately recovers halo centers, elongated mass distributions, and the filamentary structures connecting halo pairs in both survey configurations. Halo centers are localized within about 0.1 h^(-1) Mpc, and elongated-halo shapes and orientations are reliably recovered. Filament paths are stable against shape noise, with mean normalized instability parameters I_F, defined as the mean deviation from the true filament locus in units of R_200, decreasing from 0.041 to 0.037 in the low-redshift bin and from 0.051 to 0.045 in the high-redshift bin from the wide to deep field. The recovered filament shapes remain consistent with the true maps at the percent level. Compared with conventional Kaiser-Squires reconstruction, MIU2Net better preserves low-contrast anisotropic structures while suppressing small-scale noise. These results demonstrate that CSST weak-lensing data, combined with machine-learning-based mass reconstruction, will enable statistical studies of cluster assembly, anisotropic matter accretion, and the connection between massive halos and the filamentary cosmic web.
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All authors Xinyue Chen, Ran Li, Qiao Wang, Hengjie Lin, Liang Gao, Xiangkun Liu, Huanyuan Shan, Ji Yao, Ming Li

Cosmology and Nongalactic Astrophysics · Cross-listed from astro-ph.HE

The Promise of Gravitational-Wave Astronomy

Parameswaran Ajith

We review the promise of upcoming gravitational-wave (GW) observations in addressing some of the important open questions in astrophysics and cosmology. A decade after the first direct detection of GWs, the field is entering a transformative phase driven by progressive detector upgrades and the anticipated advent of space-based and next-generation ground-based observatories. These instruments will not only push the distance horizon of GW observations to cosmological redshifts, but will dramatically extend the accessible frequency band, opening entirely new source classes that lie beyond the reach of current detectors. The source landscape is rich enough that surprises are likely. This review surveys our current understanding across this landscape and offers some perspective on the discoveries that upcoming GW observations are poised to deliver.
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Cosmology and Nongalactic Astrophysics · Cross-listed from astro-ph.GA

Non-equilibrium chemistry and radiation hydrodynamics in metal-poor and metal-rich interstellar gas

Shyam H. Menon, Piyush Sharda, Blakesley Burkhart et al. (+1 more)

We present a flexible implementation of non-equilibrium chemical networks with the $\texttt{KROME}$ framework, coupled to a nonlocal variable Eddington tensor-closed radiation transport scheme ($\texttt{VETTAM}$). Our fiducial network is designed to explicitly capture the formation pathways of important molecular species such as CO, OH, and $\rm H_2O$, intermediaries like $\rm H_3^+$, and the destruction of these species through photon and cosmic-ray dissociation. We validate our scheme through benchmark tests, and demonstrate its success in 1D and 3D problems covering a broad range of metallicities ($0 \leq Z \lesssim \rm Z_{\odot}$) and densities ($n \lesssim 10^{17} \, \rm cm^{-3}$). We confirm earlier works that suggest that OH and $\rm H_2O$ are the key molecular species in dense gas ($n \gtrsim 10^{5} \, \rm cm^{-3}$) for $Z\lesssim 0.01 \rm Z_{\odot}$, dominate the cooling at these densities, and demonstrate that our scheme can reproduce their abundances with similar accuracy as dedicated static photo-dissociation region (PDR) codes. We also find that the dominant fine-structure coolant in dense ($n \gtrsim 10^3 \, \, \rm cm^{-3}$) PDRs transitions from CI to CII to OI at increasingly lower $Z$. Finally, we find that in turbulent media, rapid mixing at PDR interfaces renders the chemical species out of equilibrium, and show that this could potentially alleviate the long-standing problem of (static) PDR models producing excess CI in the diffuse ISM over UV absorption-line measurements. We conclude by presenting and comparing with alternative implementations of reduced but faster chemical networks in our scheme, discussing the problem-dependent performance-accuracy tradeoffs and future prospects.
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All authors Shyam H. Menon, Piyush Sharda, Blakesley Burkhart, Tommaso Grassi

Monday 12 October

Cosmology and Nongalactic Astrophysics

MeV dark matter decay forecasts for the COSI mission

Robin Anthony-Petersen, Orion Ning, Yu Watanabe et al. (+21 more)

The decay of dark matter (DM) is a generic prediction of many particle physics models, producing distinctive monochromatic signatures in environments such as the Galactic halo. Searches for decaying DM in the elusive 'MeV gap' have remained conspicuously under-explored, despite well-motivated models including axion-like particles, sterile neutrinos, and hidden-sector scenarios predicting signatures in this energy range. The upcoming Compton Spectrometer and Imager (COSI) telescope will help bridge this gap. Designed to probe this energy band with high spectral resolution, low background, and wide field of view, COSI is well-suited for DM line searches at the MeV scale. In this work, we make projections for COSI's 2-year sensitivity for DM decay in the Milky Way halo using dedicated all-sky simulations incorporating COSI's predicted instrument response. We conclude that COSI will improve the sensitivity to the DM lifetime by more than an order of magnitude over the DM mass range 0.4 to 10 MeV.
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All authors Robin Anthony-Petersen, Orion Ning, Yu Watanabe, Benjamin R. Safdi, Maíra Dutra, Francesca Calore, Savitri Gallego, William Guan, Christopher M. Karwin, Alexander Kusenko, Israel Martinez-Castellanos, Shigeki Matsumoto, Michela Negro, Uwe Oberlack, Field R. Rogers, Thomas Siegert, Tadayuki Takahashi, Haoyu Xie, Hiroki Yoneda, Andreas Zoglauer, Steven E. Boggs, Dieter H. Hartmann, Carolyn A. Kierans, John A. Tomsick

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Dark Matter Stability from residual flavour symmetries

Giacomo Landini, Simone Marciano and Federico Mescia

We propose a model-independent framework in which Dark Matter stability emerges naturally from residual discrete $\mathbb{Z}_N$ symmetries left unbroken by the spontaneous breaking of continuous flavour symmetries, both Abelian and non-Abelian. No ad hoc stabilizing symmetry is required, as Dark Matter stability is an inherent consequence of the underlying flavour dynamics. As an explicit example, we construct a prototype model based on a $\text{SU}(2)_\text{F} \otimes \text{U}(1)_\text{F}$ Froggatt-Nielsen symmetry, which successfully reproduces the observed charged lepton mass spectrum and the PMNS mixing matrix, while identifying the lightest sterile neutrino as a stable Dark Matter candidate. Furthermore, we study the Dark Matter phenomenology within our model in the freeze-in regime, including production channels mediated by higher-dimensional operators suppressed by the cutoff scale $\Lambda$. Our analysis shows that continuous flavour symmetries can provide a unified, self-consistent framework addressing both the flavour puzzle and the origin, stability, and production of Dark Matter.
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Cosmology and Nongalactic Astrophysics

Interpreting the stacked kinetic SZ signal II: the degeneracy between satellite galaxies and baryonic feedback

Lurdes Ondaro-Mallea, Boryana Hadzhiyska and Raul E. Angulo

The kinetic Sunyaev-Zel'dovich (kSZ) signal stacked around a galaxy sample traces the gas around halos and is a powerful probe of baryonic feedback. Its interpretation, however, depends on the satellite galaxies in the sample. Using the FLAMINGO hydrodynamical simulations and DESI-like samples of luminous red galaxies (LRGs), bright galaxies survey (BGS), and emission-line galaxies (ELGs), we show that satellites and feedback have similar effects: both suppress the small-scale signal. This degeneracy arises because stacking on satellites, which are offset from the centre of their host haloes, mimics the extended gas distribution produced by feedback. Although satellites make up only 20-30% of each sample, they account for 50-80% of the signal because they occupy more massive halos than centrals; thus their imprint on the stacked profiles can be as large as that of feedback. At the precision of current DESI$\times$ACT data, neglecting satellites in the modelling biases the inferred gas fractions low, by up to a factor of two, and overestimates the feedback strength, particularly for the LRG and BGS samples. Remaining agnostic about the satellite population avoids this bias but reduces the constraining power, so robust constraints would require knowing the satellite fraction to better than 10%, for instance from lensing and clustering data of the same galaxy samples. Finally, a further contribution from satellites will become statistically significant with upcoming surveys: satellites trace the anisotropic gas distribution around their host haloes, an effect that contributes 10% of the signal, and will likely require simulation-based models to capture.
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Cosmology and Nongalactic Astrophysics

Beyond the Kullback–Leibler divergence: the likelihood-ratio distribution as a detectability measure

Amirhossein Samandar, Mikel Martin Barandiaran, Linn Htat Lu et al. (+13 more)

The Kullback–Leibler (KL) divergence is the expectation value of the log-likelihood ratio between two specified models, evaluated with respect to one of the two models. It provides an average measure of the distinguishability of the models. We examine its connection to discovery potential and the accuracy of parameter estimates when one model represents a null hypothesis, and the alternative is a family of models characterized by one or more continuous parameters. For data drawn from a multivariate Gaussian distribution, we derive the log-likelihood-ratio distribution and its cumulants under two such hypotheses. We then search over the alternative model's parameter space and use peak prominence, the height of a likelihood-profile peak above its surrounding baseline, as an operational detection statistic. Repeating this search on simulated data drawn from the null model allows us to calibrate the prominence threshold for a specified false-positive rate. We study a toy Gaussian model as well as three cosmological examples involving cosmic topology, the tensor-to-scalar ratio, and dark energy. In all these cases, detectability of a particular model depends not only on KL divergence, but also on the size of the model parameter space, the likelihood-ratio distributions, and the distance of the model from any parameter space boundaries. The relationship between KL divergence, discovery potential, and parameter estimation must therefore be calibrated for each family of models and detection statistic under consideration.
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All authors Amirhossein Samandar, Mikel Martin Barandiaran, Linn Htat Lu, Andrew H. Jaffe, Deyan P. Mihaylov, Glenn D. Starkman, Cynthia Trendafilova, Yashar Akrami, Stefano Anselmi, Javier Carrón Duque, Craig J. Copi, Fernando Cornet-Gomez, Arthur Kosowsky, Anna Negro, Ricardo G. Rodrigues, Andrius Tamosiunas

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Decay-Assisted Leptogenesis during Preheating

Wenbin Zhao

We revisit the non-thermal leptogenesis mechanism during preheating using the quantum Boltzmann equations. This framework allows us to study the production and decay of heavy right-handed neutrinos in a consistent manner. Due to their fermionic nature, right-handed neutrino production can saturate after a few inflaton oscillations when their occupation numbers approach unity. Right-handed neutrino decays can deplete their occupation numbers, allowing more particles to be produced and generating a larger lepton asymmetry. Compared with the case where right-handed neutrinos decay only after production has finished, we find that the final baryon asymmetry can be enhanced by two orders of magnitude.
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Cosmology and Nongalactic Astrophysics

The Cosmic Radio Dipole and Observer Effects in SKA all-sky surveys

D. Bertacca, L. Böhme, B. Bottazzi Baldi et al. (+13 more)

The Square Kilometre Array (SKA) will observe our Universe on the largest scales and so enable the study of fundamental assumptions in cosmology, such as cosmic homogeneity and isotropy. Observations over recent years have reaffirmed an unexpected challenge to the Cosmological Principle first seen in measurements of the cosmic radio dipole. This dipole anisotropy is thought to be caused by our local observer motion, however, it is observed to be about three times larger than predicted, with significances exceeding 5$\sigma$. The SKA is in a unique position to shed light on this anomaly by measuring this and other effects related to our observer motion. To quantify this, we forecast the capability of large-angle HI and continuum surveys of the SKA to constrain the kinematic matter dipole in galaxy number counts, the modulation of the matter power spectrum by a kinematic dipole, and kinematic spectral distortions of diffuse radio emission.
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All authors D. Bertacca, L. Böhme, B. Bottazzi Baldi, C. Burigana, M. Y. Elkhashab, C. L. Hale, S. von Hausegger, H. R. Klöckner, M. Land-Strykowski, G. F. Lewis, V. Mittal, O. T. Oayda, D. J. Schwarz, P. Tiwari, T. Trombetti, J. D. Wagenveld

Cosmology and Nongalactic Astrophysics · Cross-listed from astro-ph.HE

Indirect Dark Matter Detection in the Multi-Messenger Era: Experiments, Systematics, Anomalies, and Prospects for Discovery

Muad Ghaith and Khaled Obaideen

Indirect searches for dark matter (DM) span gamma rays, charged cosmic rays, neutrinos, X-rays, radio emission, the cosmic microwave background (CMB), and the 21~cm signal, but reported constraints and anomalies vary in evidential strength. This critical review synthesizes peer-reviewed literature from January 2000 through October 2026 using a structured search strategy. We assess observations through a framework linking particle interactions and halo source terms to propagation or cosmological energy deposition, instrumental response, background modeling, and statistical inference. Fermi-LAT observations of dwarf spheroidal galaxies provide robust GeV-scale benchmarks for DM annihilation, whereas Galactic-center searches offer higher expected signals but depend more on foregrounds and halo profiles. Charged-cosmic-ray measurements are precise but limited by propagation and source uncertainties, while neutrino searches offer complementary sensitivity through solar capture, directional and flavor information, and high-mass annihilation or decay. Several widely discussed signals, including the 3.5~keV line, 511~keV emission, the Galactic-center GeV excess, charged-particle features, cluster radio excesses, and candidate gamma-ray lines remain inconclusive because of limited independent confirmation, uncertain target scaling, spectral degeneracies, or background-modeling limitations. Cosmological observations provide complementary constraints from CMB energy-injection limits and 21~cm measurements of the intergalactic medium. Artificial intelligence increasingly supports reconstruction and inference but requires rigorous calibration and domain-shift validation. The strongest case for DM discovery would require statistically consistent evidence across independent targets, instruments, or messengers, under common particle-physics parameters, and with well-characterized uncertainties.
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Cosmology and Nongalactic Astrophysics

Self-Interacting Dark Matter: From Particle Physics Theories to Structure Formation Simulations

Martin Rosenlyst, Vinh Tran, Oliver Zier et al. (+7 more)

We present a unified theory-to-simulation framework for self-interacting dark matter (SIDM), combining a self-contained introduction to its particle-physics foundations and representative benchmark models with an explicit, systematic mapping to simulation inputs and validated numerical implementations in the moving-mesh code AREPO-2. We characterize representative elementary and composite dark-sector models through their particle content, symmetries, interactions, production mechanisms, and constraints. We then establish an explicit mapping from their microscopic properties to the inputs required for structure-formation simulations, including modifications to cosmological initial conditions, internal-state mass splittings and populations, reaction networks, velocity- and angle-dependent cross sections, dissipative energy loss, and decay rates and recoil kinematics. Building on the efficient, scalable SIDM infrastructure introduced in our companion work, we implement isotropic and anisotropic self-scattering with constant or velocity-dependent cross sections, multi-state and inelastic reactions, and dissipative scattering, as well as a dedicated DM decay module. We validate the implementations through beam-lattice deflection experiments, thermalization and uniform-box decay tests, isolated-halo gravothermal core-collapse simulations, and cosmological box and zoom-in simulations. The tests reproduce analytical predictions and published inelastic and dissipative benchmarks, with agreement across numerical schemes. The resulting framework provides a common reference for researchers across disciplines and a practical route from microscopic dark-sector theories to nonlinear astrophysical predictions beyond standard isotropic, elastic SIDM.
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All authors Martin Rosenlyst, Vinh Tran, Oliver Zier, Xuejian Shen, Mark Vogelsberger, Thejs Brinckmann, Mads T. Frandsen, Jesús Zavala, Frederik Holt Dihver Christensen, Mikkel Theiss Kristensen

Cosmology and Nongalactic Astrophysics

A census of Dark Energy Survey Year 3 redMaPPer galaxy clusters in a high exposure eROSITA All Sky Survey region

P. A. Giles, A. K. Romer, J. Pilling et al. (+64 more)

We present the cross-match of galaxy clusters detected by redMaPPer using the first three years of Dark Energy Survey (DESY3RM) operations, and the first release of the eROSITA-All Sky Survey (eRASS1) taken by eROSITA on board the Spectrum Roentgen Gamma telescope. We define a sky region ($60^{\circ}<{\rm R.A.}<90^{\circ}$ and $-58^{\circ}<{\rm Dec}<-48^{\circ}$) whereby the mean eRASS1 exposure time of clusters falling within this footprint is $\sim$2.5 times longer than the mean exposure time of the full eRASS1–DESY3RM overlap. Limiting to a redshift range $0.2 < z < 0.65$ and redMaPPer estimated richnesses to $>$50, we obtain a sample of 57 clusters. We match these clusters to the cluster catalogue constructed for the eRASS1, finding 45 clusters with a match and 12 with no match in the catalogue. X-ray properties of the 12 unmatched clusters are estimated via a forced photometry analysis. We investigate the form of the luminosity-richness relation, finding the relation using the full 57 cluster sample is statistically consistent with using only the 45 matched clusters, and will require the deeper data of future eRASS releases (or dedicated X-ray follow-up) to explore further potential differences. Using external data from XMM, ACT and SPT, we find detections of 5 of the 12 unmatched clusters, indicating the presence of virialised gas. Finally, we found the 12 unmatched clusters occupy a higher redshift range and lower richness range (compared to the matched clusters), and find no evidence for an underlying physical reason for the lack of X-ray emission.
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All authors P. A. Giles, A. K. Romer, J. Pilling, R. Wilkinson, D. J. Turner, T. Jeltema, A. Farahi, M. E. Ramos-Ceja, F. Balzer, M. Kluge, S. Grandis, E. Bulbul, M. Hilton, S. Bhargava, E. Aljamal, A. E. Evrard, E. W. Upsdell, P. T. P. Viana, A. Abdulghafour, M. Aguena, S. S. Allam, O. Alves, F. Andrade-Oliveira, D. Bacon, D. Brooks, R. Camilleri, A. Carnero Rosell, J. Carretero, M. Costanzi, L. N. da Costa, J. De Vicente, S. Desai, P. Doel, C. Doux, B. Flaugher, J. Frieman, J. Garc, M. Gatti, D. Gruen, G. Gutierrez, S. R. Hinton, D. L. Hollowood, K. Honscheid, K. Kuehn, O. Lahav, S. Lee, J. L. Marshall, J. Mena-Fernández, F. Menanteau, R. Miquel, R. C. Nichol, R. L. C. Ogando, A. A. Plazas Malagón, S. Samuroff, E. Sanchez, D. Sanchez Cid, M. Smith, M. E. da Silva Pereira, M. Soares-Santos, E. Suchyta, M. E. C. Swanson, C. To, D. L. Tucker, V. Vikram, A. R. Walker, N. Weaverdyck, J. Weller

Cosmology and Nongalactic Astrophysics

The XMM Cluster Survey: Cross-Calibration of eROSITA and XMM using Dark Energy Survey Y3 Galaxy Clusters

J. E. Pilling, D. J. Turner, P. A. Giles et al. (+9 more)

We present the cross-calibration of the eROSITA and XMM telescopes, using galaxy clusters detected by redMaPPer from the first three years of Dark Energy Survey observations (DESY3RM). We use the X-ray: Generate and Analyse (XGA) Python module to measure eROSITA properties, and validate our methodology using a deep pointed eROSITA CAL-PV observation of A3158, and a sample of 119 clusters from the expanded HIgh FLux Galaxy Cluster Sample (eeHiFLUGCS). Next, we construct a sample of DESY3RM clusters matched to XMM observations analysed by the XMM Cluster Survey (XCS), and to clusters in the first release of the eROSITA All-Sky Survey (eRASS1). This produced a sample of 114 DESY3RM clusters with both XMM and eROSITA detections. Our resulting X-ray temperatures determined from eROSITA were compared to eRASS1 catalogue values, showing consistency between the two analyses. Comparisons between XMM and eROSITA temperatures reveal a systematic offset, with XMM temperatures 28$\pm$7% higher on average. Finally, we fit $L_{\rm X,soft}$-$\lambda_{\rm RM}$ and $T_{\rm X}$-$\lambda_{\rm RM}$ scaling relations for both eROSITA and XMM using the same cluster sample, finding minimal differences in the $L_{\rm X,soft}$-$\lambda_{\rm RM}$ relation but a clear normalisation offset in the $T_{\rm X}$-$\lambda_{\rm RM}$ relation, particularly for the highest richness systems. This study will enable future work combining eROSITA and XMM observatories for DESY3RM clusters.
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All authors J. E. Pilling, D. J. Turner, P. A. Giles, A. K. Romer, R. Wilkinson, P. J. Rooney, M. Hilton, S. Bhargava, J. Hall, R. Wang, A. Abdulghafour, B. J. Maughan

Cosmology and Nongalactic Astrophysics · Cross-listed from stat.ML

$\texttt{NFDiag}$: High-dimensional MCMC Convergence Diagnosis with Normalizing Flows

Kutay Nazl{\i} and Elena Sellentin

Accurately assessing the convergence of Monte Carlo Markov Chains is crucial for ensuring their validity in Bayesian inference problems. However, convergence assessment in high dimensions is known to be difficult, due to most convergence diagnostics becoming insensitive beyond a few dozen parameters. Conventional convergence statistics analyze marginal distributions which in high dimensions neglects increasing levels of information from the joint and conditional probability distributions. Thus we propose $\texttt{NFDiag}$, which taps into the information of the full multivariate joint posterior with a normalizing flow (NF). Our convergence diagnostic thereby also analyzes information from conditional distributions. In other words, by working in the full multivariate space, it is sensitive with respect to the geometry of the chain in high dimensions. Our diagnostic utilizes that NFs assume independent and identically distributed (iid) training samples, which is a testable assumption that will be violated by a non-converged or strongly correlated chain. Our diagnostic trains NFs on separate parts of a chain, and then assesses whether these correspond to the same multivariate target distribution. We test our diagnostic in up to 250 dimensions, and demonstrate it is universal and unbiased, and detects problematic chain quality also when Gelman-Rubin $\hat{R}$ and the multivarite effective sample size do not.
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Cosmology and Nongalactic Astrophysics

CosmoAgent: AI Agent for Theoretical Cosmology

Stephon Alexander, Loukas Gouskos, Savvas M. Koushiappas et al. (+2 more)

We present CosmoAgent, an agentic AI framework using large language models (LLMs) to search for dark-energy and modified-gravity models. We define a covariant grammar that allows LLM agents to explore the space of modified-gravity Lagrangians. An in-house computational pipeline derives the equations of motion, solves the background dynamics, and evaluates the likelihood using late-time expansion data, including the DES 5-year type Ia supernova sample and the DESI Data Release 2 BAO measurements. Theories are ranked by the Akaike Information Criterion (AIC) to balance simplicity and likelihood. We benchmarked 8 frontier LLMs from ChatGPT, Claude, Gemini, Kimi, DeepSeek, and Qwen, and all LLMs are able to find theories with a lower nominal AIC than flat $\Lambda$CDM, with a best improvement of $\Delta$AIC = -3.328. Seven recover quadratic quintessence. Exploratory searches also return induced-gravity and scalar-Gauss-Bonnet structures. The modest AIC improvements do not establish an observational preference for these models over flat $\Lambda$CDM. The code is publicly available at wsunamoutlook-prog/AI-Modified-Gravity.
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All authors Stephon Alexander, Loukas Gouskos, Savvas M. Koushiappas, Cooper Niu, Wenrong Sun

Cosmology and Nongalactic Astrophysics

Sensitivity of calibration-free DESI DR2 BAO–supernova constraints to a distance-duality tilt

Stéphane Fay, Mikel Artola and Leandros Perivolaropoulos

Recent measurements from DESI baryon acoustic oscillations (BAO) have reported a moderate preference for dynamical dark energy, challenging the standard $\Lambda$CDM paradigm. Nonetheless, such a trend could reflect a tension between the shape and the offset of the Hubble diagrams predicted by current BAO and Type Ia supernovae (SN) data, which may underpin a possible breakdown of the cosmic distance duality relation (CDDR) linking luminosity distances $D_{\rm L}$ and angular-diameter distances $D_{\rm A}$. We explore this possibility by parametrizing deviations from this relation as $\eta(z) \equiv D_{\rm L} / [{(1+z)}^2 D_{\rm A}] = \alpha{(1+z)}^\varepsilon$, and investigate how the preference for a Chevallier-Polarski-Linder (CPL) dynamical dark energy is modified once $\varepsilon \!\neq\! 0$ is allowed. Using DESI DR2 and uncalibrated SN data (Pantheon$+$, DES-Dovekie, Union3, and Union3.1), we find that allowing $\varepsilon$ to vary freely in both $\Lambda$CDM and CPL reduces the CPL preference with respect to $\Lambda$CDM by a larger amount than the addition of spatial curvature $\Omega_k$; only Union3.1 exhibits comparable reductions. We also find that the preference reduction is robust to alternative $\eta(z)$ parametrizations, and that the $\eta(z)$ constraints remain stable under the removal of BAO tracers or low-redshift cutoffs for Pantheon$+$, whereas the DES-Dovekie preference largely disappears once $z < 0.1$ SN are removed. In a separate calibrated analysis, illustrative Planck sound-horizon and SH0ES absolute-magnitude priors give $\alpha \simeq 0.942 \pm 0.014$, quantifying the normalization mismatch under those assumptions. We also map the CDDR violation onto photon-loss and varying-$G$ scenarios, concluding that the cosmological constraints are much weaker than existing constraints on these physical mechanisms.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Nonequilibrium framework for first-order phase transitions

Jie Liu and Ligong Bian

The first-order phase transition is central to electroweak baryogenesis and gravitational wave generation, yet thermal equilibrium effective potential analyses cannot describe the real-time non-equilibrium dynamics of the phase transition process. We use the Schwinger-Keldysh closed-time-path formalism of real-time finite-temperature field theory to study these effects. For the $\phi^6$ model, we derive the effective action and the corresponding Langevin equation. We further extend the formalism to the two scalar fields case, obtaining the coupled Langevin equations. These results provide a theoretical framework for the bubble nucleation simulation of the non-equilibrium phase transition process, laying the foundation for reliable predictions of baryogenesis and gravitational wave signals.
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Cosmology and Nongalactic Astrophysics

Detectability of 21-cm Power Spectra from the Epoch of Reionization using Modern Radio Telescopes

Ali Bagheri Koochaksaraei, Lily Mobahat, Sara Gholamhosseinian et al. (+1 more)

One of the unsolved questions in astrophysics and cosmology is the development of a robust physical model to explain the thermal history of the intergalactic medium during the epoch of reionization. Various astrophysical models have been proposed, but current models remain only partially constrained by available observations. To clarify this ambiguity, hydrodynamical, semi-numerical, and N-body simulations can help solve this issue. One notable simulation from the epoch of reionization is the 21SSD simulations, which provide high-resolution results for the global 21-cm brightness temperature and the 21-cm power spectrum during the epoch of reionization. The simulation includes 45 models spanning three key astrophysical parameters of X-ray emissivity, Lyman-band emissivity, and the X-ray hard-to-soft emissivity ratio. Distinct values of these parameters result in different models of this simulation. In this work, four active radio observatories, including HERA, MWA, GMRT, and LOFAR have been considered to investigate the sensitivity and thermal noise of the 21-cm power spectrum. Each observatory has a particular sensitivity based on its instrumental characteristics, which helps assess which models lie above the forecast sensitivity thresholds of current instruments.
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All authors Ali Bagheri Koochaksaraei, Lily Mobahat, Sara Gholamhosseinian, Javad T. Firouzjaee

Cosmology and Nongalactic Astrophysics

How much can shape degeneracies affect the Hubble constant measurement?

Ashish K. Meena, Prasenjit Saha, Liliya L. R. Williams et al. (+1 more)

Cluster lens models are constrained almost entirely by observed lensed image positions, leaving a large space of mass perturbations with arbitrary amplitudes such that they reproduce every image exactly. Such degeneracies are known as shape degeneracies (ShaDes). We show that these ShaDes shift the observed time delays, by the difference of the perturbing potential between the two images, without depending on the number of source/lens planes. Bounding their amplitude by preserving the positivity of the convergence, image multiplicity, and parity, in MACS J0138.0$-$2155, they can contribute at least $\simeq7$ days to the delay between the detected images of SN-Encore (i.e., $17.5\%$ of the measured value of $39.8$ days) and $\simeq112$ days (i.e., $2.8$–$3.7\%$ of predicted value of $3,000-4000$ days) to the reappearance intervals predicted for SN-Encore and SN-Requiem. These error bars transfer one-to-one to $H_0$, and remain invisible in comparisons of independent models.
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All authors Ashish K. Meena, Prasenjit Saha, Liliya L. R. Williams, Derek Perera

Sunday 11 October

Cosmology and Nongalactic Astrophysics

Joint Constraints on the Hubble Constant and Cosmic Baryon Density from Localized Fast Radio Bursts and DESI DR2 Baryon Acoustic Oscillations

Ji-Guo Zhang, Tian-Nuo Li, Guo-Hong Du et al. (+3 more)

Fast radio bursts (FRBs) probe free-electron columns along cosmological sightlines through their dispersion measures (DMs), whereas baryon acoustic oscillations (BAO) constrain cosmic expansion geometry through acoustic distance ratios. In this work, we leverage their distinct physical sensitivities to simultaneously determine the Hubble constant ($H_0$) and cosmic baryon density ($\Omega_{\rm b}$) without external cosmic microwave background (CMB) or Big Bang nucleosynthesis (BBN) priors. Combining 120 localized FRBs and DESI DR2 BAO, we obtain $H_0=71.4^{+2.2}_{-2.5}\ {\rm km\ s^{-1}\ Mpc^{-1}}$ and $\Omega_{\rm b}=0.0503^{+0.0025}_{-0.0021}$ in $\Lambda$CDM, corresponding to precisions of $3.3\%$ and $4.6\%$, respectively. The inferred $H_0$ is statistically consistent with both SH0ES and CMB, and $\Omega_{\rm b}$ agrees with the joint constraint from BBN and CMB. Adopting IllustrisTNG-based DM distributions and fixing the diffuse-gas baryon fraction tightens the constraint to $H_0=68.8\pm1.0\ {\rm km\ s^{-1}\ Mpc^{-1}}$, but lowers the central value toward the CMB-inferred value, identifying extragalactic DM modeling as the dominant systematic uncertainty. These results establish FRB-BAO complementarity as a new avenue for simultaneously constraining $H_0$ and $\Omega_{\rm b}$.
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All authors Ji-Guo Zhang, Tian-Nuo Li, Guo-Hong Du, Wan-Peng Sun, Jing-Fei Zhang, Xin Zhang

Saturday 10 October

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Cosmology & Astrophysics of the Dark Dimension with Bulk Majorana Neutrinos

Luis A. Anchordoqui and Cumrun Vafa

Recently, the possibility of having sterile Majorana neutrinos charged under $B-L$ gauge symmetry in the bulk of the dark dimension has been explored. We point out a cosmological restriction on the Majorana mass of bulk neutrinos leading to mass $\gtrsim 100~{\rm GeV}$. This avoids the over-production of Kaluza-Klein neutrino towers in the early universe thus resolving the cosmological neutrino catastrophe of extra dimension scenarios. If the mass of the bulk neutrino is at the lower end of this bound, it can potentially also explain the recently observed Fermi halo excess on gamma rays through the evaporation of long-lived 5d (i.e. dark) black holes through Hawking radiation to bulk neutrinos, which promptly decay into standard model particles.
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Cosmology and Nongalactic Astrophysics

TDCOSMO 2026: new insights on the Hubble tension from strong lensing time delays

TDCOSMO Collaboration, Simon Birrer, Michele Cappellari et al. (+26 more)

We discuss the measurement of the Hubble constant ($H_0$) in flat $\Lambda$ cold dark matter cosmology based on the blind hierarchical analysis of 11 multiply-imaged quasars (hereafter the TDCOSMO-2026 sample) and described in greater detail in a companion paper. In addition to the time delays, we use lens models based on high-resolution imaging from the Hubble Space Telescope (HST) and from the James Webb Space Telescope (JWST), analyzed jointly with axisymmetric dynamical models based on JWST-NIRSpec, VLT-MUSE, and Keck-KCWI spectroscopy. Our primary result $H_0=71.1^{+2.4}_{-2.3}$ km.s$^{-1}$.Mpc$^{-1}$ is based on the TDCOSMO-2026 sample, in combination with $\Omega_{\rm m}$ constraints from the DES-Dovekie supernova (SN) dataset. Our 3% precision accounts for the mass-sheet degeneracy. Importantly, our measurement is independent of the local distance ladder (LDL). Among individual late-universe probes, only the traditional LDL is more precise. We discuss our result in the context of the Hubble tension, the difference between $H_0$ measured in the late universe and the prediction based on early-universe probes such as the cosmic microwave background (CMB). We construct combinations of independent late-universe probes and show that the tension with the Planck CMB prediction is robust to excluding any one of the methods based on Type-Ia Supernovae, Cepheids, or the Tip of the Red Giant Branch. For example, we construct a 'no-SN' $H_0$ measurement, by replacing the DES-Dovekie constraint on $\Omega_{\rm m}$ with that from DESI baryon acoustic oscillations, and then combining TDCOSMO-2026 with independent non-SN late-universe probes. This 'no-SN' late-universe probe is in 3.7$\sigma$ tension with Planck. Even after completely excluding the LDL, the tension with Planck persists at the 2.7$\sigma$ level.
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All authors TDCOSMO Collaboration, Simon Birrer, Michele Cappellari, Frédéric Courbin, Christopher D. Fassnacht, Pierre Fleury, Joshua A. Frieman, Aymeric Galan, Xiang-Yu Huang, Daniel P. Johnson, Sanjana Khanolkar, Shawn Knabel, Hrvoje Krizic, Martin Millon, Takahiro Morishita, Veronica Motta, Pritom Mozumdar, Eric Paic, Hadrien Paugnat, Allan G. Schweinfurth, Anowar J. Shajib, William Sheu, Dominique Sluse, Massimo Stiavelli, Sherry H. Suyu, Tommaso Treu, Felipe Urcelay, Devon M. Williams, Kenneth C. Wong

Cosmology and Nongalactic Astrophysics

Gravitational waves from strong first-order phase transitions in an expanding Universe

Jintao Zou, Zizhuo Zhao, Yongtao Jia et al. (+1 more)

We investigate the gravitational waves generated by first-order phase transitions (PTs) in an expanding Universe. Using a scalar field-fluid coupled model, we perform three-dimensional lattice numerical simulations of slow first-order PTs with strong strength. We observe that the contribution from sound waves to the gravitational wave (GW) signal significantly dominates over that from bubble collisions. The sound wave spectra exhibit two peaks located at the mean bubble separation and the sound-shell width. Rotational modes are generated in the fluid during the bubble collisions, and their magnitude grows with the PT strength. The lifetime of the sound wave source increases with decreasing $\alpha$: for weaker transitions the source can persist for longer than a Hubble time, while for stronger transitions it decays within a Hubble time. When the walls propagate as deflagrations, the GW spectral shape changes drastically, with steeper ultraviolet tails and a shorter-lived sound wave source. We also observe that the magnitude of the normalized GWs is roughly an order of magnitude smaller than obtained in the Minkowski spacetime simulations.
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All authors Jintao Zou, Zizhuo Zhao, Yongtao Jia, Ligong Bian

Cosmology and Nongalactic Astrophysics

TDCOSMO 2026: A 3% measurement of the Hubble constant from strong lensing and stellar kinematics

TDCOSMO Collaboration, Simon Birrer, Michele Cappellari et al. (+26 more)

We present cosmological constraints from 11 strongly lensed quasars with measured time delays (hereafter, the TDCOSMO-2026 sample). In addition to expanding the sample, we improve many aspects of our blind analysis with respect to our 2025 analysis. Among other improvements, spatially resolved kinematics are available for nine systems, including six with JWST-NIRSpec, compared to one in 2025; for three lens models, JWST-NIRCam images now replace HST; axisymmetric dynamical modeling is applied directly to the spatially resolved data, instead of an axisymmetric correction factor applied to spherical models; and the line-of-sight convergence is now based on the Euclid Flagship simulations instead of the Millennium Simulation. Our baseline and primary result is based on the TDCOSMO-2026 sample, in combination with a prior on $\Omega_{\rm m}$ from the DES-Dovekie supernova sample. In the flat $\Lambda$ cold dark matter ($\Lambda$CDM) cosmology, we find $H_0=71.1^{+2.4}_{-2.3}$ km.s$^{-1}$.Mpc$^{-1}$, a 3.3% uncertainty that accounts for the mass-sheet degeneracy. The SLACS and SL2S samples are in excellent agreement with the TDCOSMO-2026 sample, improving the precision on $H_0$ in flat $\Lambda$CDM to 3.0%. Using the DESI-DR2 baryon acoustic oscillations (BAO) likelihood instead of DES-Dovekie yields fully consistent results. We also present constraints in the open $\Lambda$CDM, $w$CDM, $w_0w_a$CDM, and $w_{\phi}$CDM cosmologies; the TDCOSMO $H_0$ inference is robust and consistent across all of them. The combination of the TDCOSMO+SLACS+SL2S likelihood with those from DESI-DR2 and DES-Dovekie disfavors $w=-1$ at the $2.3$-$2.5\sigma$ level in all three dark energy extensions that we tested. We find, e.g., $w_0=-0.88^{+0.04}_{-0.05}$ in $w_{\phi}$CDM and $w_0 = -0.85^{+0.07}_{-0.06}$ in $w_0w_a$CDM, while $w_a = -0.48^{+0.46}_{-0.44}$ remains consistent with zero.
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All authors TDCOSMO Collaboration, Simon Birrer, Michele Cappellari, Frédéric Courbin, Christopher D. Fassnacht, Pierre Fleury, Joshua A. Frieman, Aymeric Galan, Xiang-Yu Huang, Daniel P. Johnson, Sanjana Khanolkar, Shawn Knabel, Hrvoje Krizic, Martin Millon, Takahiro Morishita, Veronica Motta, Pritom Mozumdar, Eric Paic, Hadrien Paugnat, Allan G. Schweinfurth, Anowar J. Shajib, William Sheu, Dominique Sluse, Massimo Stiavelli, Sherry H. Suyu, Tommaso Treu, Felipe Urcelay, Devon M. Williams, Kenneth C. Wong