Negative / Null Result ReportOpen accessPhysics and Astronomy
Chris J. Willott, Yoshihisa Asada, Kartheik G. Iyer et al. · 2025 · The Astrophysical Journal
Abstract We present JWST observations of a gravitationally lensed, extremely metal-poor galaxy at redshift z = 8.203 ± 0.001 from the CANUCS survey. Based on the low oxygen to Balmer line ratios, we infer a gas-phase metallicity of 12 + log(O/H) = 6.85 (1.4% solar), making CANUCS-A370-z8-LAE one of the most metal-poor galaxies known at z > 7. The galaxy has a high H β equivalent width of 225 ± 50 Å, small half-light radius of only r hl = 3 8 − 19 + 3 pc, and high star formation rate density of 50–100 M ⊙ yr −1 kpc −2 . The galaxy shows high-equivalent-width Ly α emission with an i
View details →Negative / Null Result ReportOpen accessPhysics and Astronomy
Himanshu Chaudhary, Vipin Kumar Sharma, Salvatore Capozzıello et al. · 2026 · The Astrophysical Journal Supplement Series
Abstract Observational data play a pivotal role in identifying cosmological models that are both theoretically consistent and empirically viable. In this work, we investigate the level of preference for dynamical dark energy over a cosmological constant using current late-time observational datasets, including cosmic chronometers (CC), baryon acoustic oscillations from Dark Energy Spectroscopic Instrument (DESI) DR2, and different Type Ia supernova catalogs (Pantheon + , DES-Dovekie, Union3). We analyze various dynamical dark-energy models, including ω CDM, o ω CDM, ω 0 ω a CDM, logarithmic, e
View details →Negative / Null Result ReportOpen accessPhysics and Astronomy
Lalitwadee Kawinwanichakij, Karl Glazebrook, Themiya Nanayakkara et al. · 2026 · The Astrophysical Journal
Abstract We present the morphological properties of 17 spectroscopically confirmed massive quiescent galaxies ( 10.2 < log ( M * / M ⊙ ) < 11.2 ) at 3.0 < z < 4.3, observed with JWST/NIRSpec and NIRCam. Using Sérsic profile fits to F277W and F444W imaging, we derive the size–mass relation and find typical sizes of ∼0.6–0.8 kpc at M * = 5 × 10 10 M ⊙ , consistent with ∼7× growth from z ∼ 4 to the present, including ∼2× by z ∼ 2. We find tentative evidence that formation history and morphology jointly influence galaxy sizes: late-forming bulge-dominated galaxies appear more compact by ∼0.2–0.3 d
View details →Negative / Null Result ReportOpen accessPhysics and Astronomy
Eliza Neights, Eric Burns, Chris L. Fryer et al. · 2025 · Monthly Notices of the Royal Astronomical Society
ABSTRACT Gamma-ray bursts are the most luminous electromagnetic events in the Universe. Their prompt gamma-ray emission has typical durations between a fraction of a second and several minutes. A rare subset of these events have durations in excess of a thousand seconds, referred to as ultra-long gamma-ray bursts. Here, we report the discovery of the longest gamma-ray burst ever seen with a $\sim$25 000 s gamma-ray duration, GRB 250702B, and characterize this event using data from four instruments in the InterPlanetary Network and the Monitor of All-sky X-ray Image. We find a hard spectrum, su
View details →Negative / Null Result ReportOpen accessPhysics and Astronomy
Zhuoming Zhang, Tengpeng Xu, Yun Chen · 2026 · The Astrophysical Journal
Abstract We present a Bayesian comparative analysis of five cosmological models: ΛCDM, w CDM, w 0 w a CDM, ϕ CDM (with scalar-field dark energy), and an interacting dark energy scenario (the ξ -index model), to investigate dark energy evolution and the Hubble tension. Utilizing the latest data from the second data release of the Dark Energy Spectroscopic Instrument (Baryon Acoustic Oscillations, BAO), Pantheon+ (type Ia supernovae, SNIa), and cosmic microwave background (CMB) data (including lensing) from Planck and the Atacama Cosmology Telescope, we report three key findings. First, the Hubb
View details →Negative / Null Result ReportOpen accessPhysics and Astronomy
Joss Bland‐Hawthorn, Thor Tepper-García, Oscar Agertz et al. · 2025 · The Astrophysical Journal
Abstract In response to recent observations from JWST and Atacama Large Millimeter Array, we explore a new class of dynamically self-consistent models that mimics a plausible progenitor of the Milky Way over a wide range of disk gas fractions, f gas . The high gas surface densities encourage vigorous star formation, which in turn couples with the gas to drive turbulence. We show that this coupling through momentum recoil drives a random walk of the baryonic potential minimum with respect to total gravitational potential, Φ tot ( R , ϕ , z ). The amplitude of the bulk motion depends on the feed
View details →Failed Experiment ReportOpen accessPhysics and Astronomy
Rafael Navarro-Carrera, K. I. Caputi, Edoardo Iani et al. · 2025 · The Astrophysical Journal
Abstract Making use of JWST NIRSpec and NIRCam data, we conduct a detailed analysis of GN- z 8-LAE, a strong Ly α emitter at z = 8.279. We investigate the interstellar medium (ISM) conditions that enable the Ly α detection in this source at the Epoch of Reionization (EoR) and scrutinize GN- z 8-LAE as an early reionizer. In agreement with previous results, we find that GN- z 8-LAE is a young galaxy (age ∼10 Myr) with a lower stellar mass ( M ⋆ ∼ 10 7.66 M ⊙ ) than most Ly α emitters (LAEs) at similar redshifts. The derived stellar-mass and star formation rate surface densities are Σ M ⋆ ∼ 355
View details →Negative / Null Result ReportOpen accessPhysics and Astronomy
Lucie E. Rowland, Mauro Stefanon, R. J. Bouwens et al. · 2026 · Monthly Notices of the Royal Astronomical Society
ABSTRACT Metallicity is a crucial tracer of galaxy evolution, providing insights into gas accretion, star formation, and feedback. At high redshift, these processes reveal how early galaxies assembled and enriched their interstellar medium. In this work, we present rest-frame optical spectroscopy of 12 massive ($\log (M_*/\mathrm{{\rm M}_{\odot }})&gt;9$) galaxies at $z\sim 6$–8 from the Reionization Era Bright Emission Line Survey (REBELS) Atacama Large Millimetre/submillimetre Array (ALMA) large program, observed with the James Webb Space Telescope (JWST) NIRSpec integral field unit spec
View details →Negative / Null Result ReportPhysics and Astronomy
Zengyou He, Hao Liang, Zheng Chen et al. · 2020 · IEEE Transactions on Knowledge and Data Engineering
Community detection is a key data analysis problem across different fields. During the past decades, numerous algorithms have been proposed to address this issue. However, most work on community detection does not address the issue of…
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Xiangdong Ji, Yang Chen · 2026 · Nuclear Physics B
Momentum current density (MCD) $T^{ij}$ is a general physics concept describing the momentum conservation through momentum flow generated from both the kinetic motion of particles and the interacting forces among them. It has been suggested by M. Polyakov et al. that the MCD in the nucleon, characterized by the form factor $C/D$ of the QCD energy-momentum tensor, can be interpreted as the pressure and shear forces between adjacent parts of the system because the nucleon interior approximates a continuous medium. While intuitively appealing, we find that the interpretation is hard to justify fr
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Tamara Evstafyeva, Nils Peter Siemonsen, William E. East · 2026 · Physical review. D/Physical review. D.
We reinvestigate the stability properties of ultracompact spinning boson stars with a stable light ring using fully nonlinear 3+1 and 2+1 numerical relativity simulations and two different formulations of the Einstein equations. We find no…
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George Yumnam, Parul R. Raghuvanshi, J. D. Budai et al. · 2025 · Cell Reports Physical Science
We provide experimental evidence for the absence of a magnetic moment in bulk RuO 2 , a candidate altermagnetic material, by using a combination of Mössbauer spectroscopy, nuclear forward scattering, inelastic X-ray and neutron scattering,…
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R. Abbasi, M. Ackermann, J. Adams et al. · 2026 · The Astrophysical Journal Letters
Abstract Recently, IceCube reported neutrino emission from the Seyfert galaxy NGC 1068. Using 13.1 yr of IceCube data, we present a follow-up search for neutrino sources in the northern sky. NGC 1068 remains the most significant neutrino source among 110 preselected gamma-ray emitters while also being spatially compatible with the most significant location in the northern sky. Its energy spectrum is characterized by an unbroken power-law with spectral index γ = 3.4 ± 0.2. Consistent with previous results, the observed neutrino flux exceeds its gamma-ray counterpart by at least 2 orders of magn
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M. Rossi, Stefania Salvadori, Á. Skúladóttir et al. · 2025 · The Astrophysical Journal
Abstract The elusive properties of the first (Population III or Pop III) stars can be indirectly unveiled by uncovering their true descendants. To this end, we exploit our data-calibrated model for the best-studied ultrafaint dwarf galaxy (UFD), Boötes I, which tracks the chemical evolution (from carbon to zinc) of individual stars from their formation to the present day. We explore the chemical imprint of Pop III supernovae (SNe), with different explosion energies and masses, showing that they leave distinct chemical signatures in their descendants. We find that UFDs are strongly affected by
View details →Negative / Null Result ReportOpen accessPhysics and Astronomy
S. H. Suyu, Ana Acebrón, C. Grillo et al. · 2026 · Astronomy and Astrophysics
Robust mass modeling of strong-lensing galaxy clusters is crucial for studying cosmology and galaxy evolution. We present and compare seven mass models of the galaxy cluster MACS J0138−2155, constructed using six independent modeling software programs, including parametric and free-form approaches. By conducting a blind analysis where all the mass-modeling teams constructed their models independently without exchanging results, we quantified uncertainties arising from modeling software and assumptions. MACS J0138−2155 is unique as the only cluster found to strongly lens two supernovae (SNe), R
View details →Negative / Null Result ReportOpen accessPhysics and Astronomy
A. J. Nayana, R. Margutti, Eli Wiston et al. · 2025 · The Astrophysical Journal Letters
Abstract We present X-ray (0.3–79 keV) and radio (0.25–203 GHz) observations of the most luminous fast blue optical transient (LFBOT) AT 2024wpp at z = 0.0868, spanning 2–280 days after first light. AT 2024wpp shows luminous ( L X ≈ 1.5 × 10 43 erg s −1 ), variable X-ray emission with a Compton hump peaking at δt ≈ 50 days. The X-ray spectrum evolves from a soft ( F ν ∝ ν −0.6 ) to an extremely hard state ( F ν ∝ ν 1.26 ) accompanied by a rebrightening at δt ≈ 50 days. The X-ray emission properties favor an embedded high-energy source shining through asymmetric expanding ejecta. We detect radi
View details →Failed Experiment ReportOpen accessPhysics and Astronomy
Luca Boccioli, David Vartanyan, Evan O’Connor et al. · 2025 · Monthly Notices of the Royal Astronomical Society
ABSTRACT Massive stars can end their lives with a successful supernova explosion (leaving behind a neutron star or, more rarely, a black hole), or a failed explosion that leaves behind a black hole. The density structure of the pre-collapse progenitor star already encodes much of the information regarding the outcome and properties of the explosion. However, the complexity of the collapse and subsequent shock expansion phases prevents drawing a straightforward connection between the pre-collapse and post-explosion properties. In order to derive such a connection several explodability studies h
View details →Negative / Null Result ReportOpen accessPhysics and Astronomy
Junyao Li, Ming-Yang Zhuang, Yue Shen et al. · 2025 · The Astrophysical Journal
Abstract Kiloparsec-scale dual and offset active galactic nuclei (AGNs) are signposts of accreting supermassive black holes (SMBHs) triggered during late-stage galaxy mergers, offering crucial insights into the coevolution of SMBHs and galaxies. However, robustly confirmed systems at high redshift (e.g., z > 1) are scarce and biased toward the most luminous and unobscured systems. In this study, we systematically search for kiloparsec-scale (projected separation <15 kpc) dual and offset AGNs around 571 moderate-luminosity, X-ray-selected AGNs, including the obscured population, utilizing
View details →Negative / Null Result ReportOpen accessPhysics and Astronomy
W. V. Jacobson-Galán, Luc Dessart, Kyle W. Davis et al. · 2025 · The Astrophysical Journal
Abstract We present analysis of the plateau and late-time phase properties of a sample of 39 Type II supernovae (SNe II) that show narrow, transient, high-ionization emission lines (i.e., “IIn-like”) in their early-time spectra from interaction with confined, dense circumstellar material (CSM). Originally presented by W. V. Jacobson-Galán et al., this sample also includes multicolor light curves and spectra extending to late-time phases of 35 SNe with no evidence for IIn-like features at <2 days after first light. We measure photospheric phase light-curve properties for the distance-correct
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Davide Faccialà, M. Bonanomi, Bruno Nunes Cabral Tenorio et al. · 2025 · Journal of the American Chemical Society
High Resolution Image Download MS PowerPoint Slide We report a study of the electronic and nuclear relaxation dynamics of the photoexcited RNA base uracil in the gas phase using time-resolved core-level photoelectron spectroscopy together with high-level calculations. The dynamics was investigated by trajectory surface hopping calculations, and the core ionization energies were calculated for geometries sampled from these. The molecule was excited by a UV laser and dynamics probed on the oxygen, nitrogen, and carbon sites by core electron spectroscopy. We find that the main de-excitation chann
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K. D. Alexander, R. Margutti, Sebastian Gomez et al. · 2026 · The Astrophysical Journal
Abstract Recent observations presented in Y. Cendes et al. show that optically selected tidal disruption events (TDEs) commonly produce delayed radio emission that can peak years after disruption. Here, we explore the multiwavelength properties of a sample of radio-observed optically selected TDEs, to shed light on the physical process(es) responsible for the late-rising radio emission. We combine new late-time X-ray observations with archival optical, UV, X-ray, and radio data to conclude that a diversity of accretion-driven outflows may power the delayed radio emission in TDEs. Our analysis
View details →Negative / Null Result ReportOpen accessPhysics and Astronomy
I. Delvecchio, E. Daddi, B. Magnelli et al. · 2025 · Astronomy and Astrophysics
Little red dots (LRDs) are a puzzling population of extragalactic sources whose origin is highly debated. In this work, we performed a comprehensive stacking analysis of NIRCam, MIRI, and ALMA images of a large and homogeneously selected sample of LRDs from multiple JWST Legacy fields. We report clear evidence of hot-dust emission in the median stacked spectral energy distribution (SED) that features a rising near-infrared continuum up to rest-frame λ rest ∼ 3 μm, which is best explained by a standard dusty active galactic nucleus (AGN) structure. Although LRDs are likely to be a heterogeneous
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A. M. Farah, A. Vijaykumar, M. Fishbach · 2026 · The Astrophysical Journal Letters
Abstract There is growing evidence from gravitational-wave (GW) observations that some merging black holes (BHs) are created from previous mergers. Using the prediction that these hierarchically merged BHs have dimensionless spin magnitudes of χ ≈ 0.69, we identify a subpopulation in the GW data consistent with a hierarchical-merger origin in dense star clusters. This subpopulation’s primary mass distribution peaks at 17 . 0 − 4.4 + 18.3 M ⊙ , which is approximately twice as large as its secondary mass distribution’s mode ( 10 . 5 − 4.7 + 29.7 M ⊙ ), and its spin tilt distribution is consisten
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Stella Koch Ocker, J. M. Cordes · 2026 · The Astrophysical Journal
Abstract Free electrons in the Galactic interstellar medium (ISM) disperse and scatter coherent radio waves, by amounts that depend on the distance to the radio source. Models of the Galactic electron density are thus widely used to predict distances and scattering of compact radio sources (including pulsars, fast radio bursts, and long-period transients), in addition to mitigating ISM foregrounds in Galactic and extragalactic studies. We use a sample of 171 precise pulsar distances, based entirely on parallaxes and globular cluster associations, as well as scattering measurements of 568 pulsa
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Tim Linden, Thong T. Q. Nguyen, Tim M. P. Tait · 2026 · Journal of Cosmology and Astroparticle Physics
Abstract We model and constrain the unique indirect detection signature produced by dark matter particles that annihilate through a U(1) gauge symmetry into dark photons that subsequently decay into three-photon final states. We focus on scenarios where the dark photon is long-lived, and show that γ-ray probes of celestial objects can set strong constraints on the dark matter/baryon scattering cross section that in many cases surpass the power of current direct detection constraints, and in some cases even peer into the neutrino fog.
View details →Replication FailureOpen accessPhysics and Astronomy
D. W. P. Amaral, Dennis G. Uitenbroek, Tjerk H. Oosterkamp et al. · 2025 · Physical Review Letters
We perform the first search for ultralight dark matter using a magnetically levitated particle. A submillimeter permanent magnet is levitated in a superconducting trap with a measured force sensitivity of 0.2 fN/sqrt[Hz]. We find no evidence of a signal and derive limits on dark matter coupled to the difference between baryon and lepton number, B-L, in the mass range (1.10360-1.10485)×10^{-13} eV/c^{2}. Our most stringent limit on the coupling strength is g_{B-L}≲2.98×10^{-21}. We propose the POLONAISE (Probing Oscillations using Levitated Objects for Novel Accelerometry In Searches of Exotic
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Yin-Jie Li, Yuan-Zhu Wang, Shao-Peng Tang et al. · 2025 · The Astrophysical Journal
Abstract The origin of the correlation between the effective spins ( χ eff ) and mass ratios ( q ) of LIGO–Virgo–KAGRA’s binary black holes (BBHs) is still an open question. Motivated by the recent identification of two subpopulations of the BBHs, in this work we investigate the potential χ eff – q correlation for each subpopulation. Surprisingly, the χ eff – q correlation either significantly weakens or disappears for the low-mass subpopulation if we introduce a second χ eff distribution for the high-mass subpopulation, which likely originates from hierarchical mergers. This suggests that the
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