Negative / Null Result ReportOpen accessPhysics and Astronomy
Fengqiu Adam Dong, Kaitlyn Shin, Casey Law et al. · 2025 · The Astrophysical Journal Letters
Abstract We report the discovery of CHIME J1634+44, a long-period radio transient (LPT) unique for two aspects: it is the first known LPT to emit fully circularly polarized radio bursts, and it is the first LPT with a significant spin-up. Given that high circular polarization (>90%) has been observed in FRB 20201124A and in some giant pulses of PSR B1937+21, we discuss the implications of the high circular polarization of CHIME J1634+44 and conclude its emission mechanism is likely to be “pulsar-like.” While CHIME J1634+44 has a pulse period of 841 s, its burst arrival patterns are indicati
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Aayush Saxena, Alex J. Cameron, Harley Katz et al. · 2026 · Monthly Notices of the Royal Astronomical Society
ABSTRACT The ultraviolet (UV) continuum slope of galaxies, $\beta$, is a powerful diagnostic of the metallicity and ages of stars, nebular gas properties, dust content, and the escape of Lyman continuum (LyC) photons. In this study, we present $\beta$ measurements for 395 spectroscopically confirmed galaxies at $5 \lt z \lt 14.3$ selected primarily from JADES, using high-quality JWST (James Webb Space Telescope) NIRSpec/PRISM spectra. We find a median $\beta = -2.15$, finding a mild increase in blueness of $\beta$ with increasing redshift and fainter UV magnitudes. Interestingly, we find evide
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X. J. Li, Desheng Zhao, Desheng Jiang et al. · 2014 · Journal of Applied Physics
The significant effect of the thickness of Ni film on the performance of the Ohmic contact of Ni/Au to p-GaN is studied. The Ni/Au metal films with thickness of 15/50 nm on p-GaN led to better electrical characteristics, showing a lower…
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Chuneeta D. Nunhokee, Donald M. Null, Cathryn M. Trott et al. · 2025 · The Astrophysical Journal
Abstract This paper presents the spherically averaged 21 cm power spectrum derived from Epoch of Reionization (EoR) observations conducted with the Murchison Widefield Array (MWA). The analysis uses EoR0-field data, centered at (R.A. = 0 h , decl. = −27 ∘ ), collected between 2013 and 2023. Building on the improved methodology described in C. M. Trott et al. (2024), we incorporate additional data quality control techniques introduced in C. D. Nunhokee (2020). We report the lowest-power-level limits on the EoR power spectrum at redshifts z = 6.5, z = 6.8, and z = 7.0. These power levels, measur
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Sara Kurkowska, Julia Brosch-Lenz, Yuni K. Dewaraja et al. · 2025 · Journal of Nuclear Medicine
Individualized radiopharmaceutical therapies guided by patient-specific absorbed dose (AD) assessments using nuclear medicine imaging have the potential to improve both efficacy and safety. Understanding sources of variability in AD calculations is critical for standardization. The Society of Nuclear Medicine and Molecular Imaging Dosimetry Task Force launched the 177Lu Dosimetry Challenge to evaluate variability across steps within the dosimetry workflow. This work aimed to assess the variability in ADs due to different fitting and integration methods. Methods: Anonymized datasets from 2 pati
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Gonzalo Morrás, G. Pratten, P. Schmidt · 2026 · The Astrophysical Journal Letters
Abstract The observation of gravitational waves (GWs) from merging black holes and neutron stars provides a unique opportunity to discern information about their astrophysical environment. Two signatures that are considered powerful tracers to distinguish between different binary formation channels are general relativistic spin-induced orbital precession and orbital eccentricity. Both effects leave characteristic imprints in the GW signal that can be extracted from observations. To date, neither precession nor eccentricity has been confidently discerned in merging neutron star–black hole binar
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Callum T. Donnan, Mark Dickinson, Anthony J. Taylor et al. · 2025 · The Astrophysical Journal
Abstract We present JWST/NIRSpec PRISM observations of three luminous ( M UV < −20) galaxies at z ∼ 10 observed with the CANDELS-Area Prism Epoch of Reionization Survey (CAPERS) Cycle 3 program. These galaxies exhibit extreme UV slopes compared to typical galaxies at z = 10. Of the three sources, two of them are a close pair (0 . ″ 22) of blue galaxies at z = 9.800 ± 0.003 and z = 9.808 ± 0.002 with UV slopes of β = −2.87 ± 0.15 and β = −2.46 ± 0.10, respectively, selected from PRIMER COSMOS NIRCam imaging. We perform spectrophotometric modeling of the galaxies, which suggests extre
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Andrei Kudriashov, Xiong Zhou, Razmik A. Hovhannisyan et al. · 2025 · Science Advances
Josephson junctions (JJs) are key to superconducting quantum technologies and the search for self-conjugate quasiparticles potentially useful for fault-tolerant quantum computing. In topological insulator (TI)–based JJs, measuring the current-phase relation (CPR) can reveal unconventional effects such as Majorana bound states (MBS) and nonreciprocal transport. However, reconstructing CPR as a function of magnetic field has not been attempted. Here, we present a platform for field-dependent CPR measurements in planar JJs made of NbSe 2 and few-layer Bi 2 Se 3 . When a flux quantum Φ 0 thr
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R. J. Stewart, George Younes, A. K. Harding et al. · 2025 · The Astrophysical Journal Letters
Abstract We report on IXPE and NuSTAR observations beginning 40 days after the 2024 outburst onset of magnetar 1E 1841−045, marking the first IXPE observation of a magnetar in an enhanced state. Our spectropolarimetric analysis indicates that both a blackbody (BB) plus double power-law (PL) and a double blackbody plus power-law spectral model fit the phase-averaged intensity data well, with a hard PL tail (Γ = 1.19 and 1.35, respectively) dominating above ≈5 keV. For the former model, we find the soft PL (the dominant component at soft energies) exhibits a polarization degree (PD) of ≈30% whil
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Matthias Klein, J. J. Mohr, C. T. Davies · 2024 · Astronomy and Astrophysics
Galaxy clusters are useful cosmological probes and interesting astrophysical laboratories. As the cluster samples continue to grow in size, a deeper understanding of the sample characteristics and improved control of systematics becomes more crucial. For this analysis we created a new and larger ACT-DR5-based thermal Sunyaev–Zel’dovich Effect- (tSZE-) selected galaxy cluster catalog with improved control over sample purity and completeness. We employed the red sequence based cluster redshift and confirmation tool MCMF together with optical imaging data from the Legacy Survey DR-10 and infrared
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C.L. Wilson, J. Astbury, M.J. Ginsberg et al. · 2026 · Nuclear Fusion
Abstract To support the pre-concept design of Tokamak Energy’s (TEs) ST-E1 fusion power plant, we developed a new systems code, PyTok. PyTok codifies plasma physics and engineering constraints within a pure Python, object-oriented framework designed for rapid design iteration and exploration of the power-plant parameter space. The code base and its human- and machine-readable data structures enable coupling to external physics codes and data-analysis tools. Informed by TEs design philosophy and techno-economic analyses, the code was used to identify an initial reference design point for ST-E1.
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Alexandra Moroianu, Shivani Bhandari, Maria R. Drout et al. · 2025 · The Astrophysical Journal Letters
Abstract We report the milliarcsecond localization of a high (∼1379 pc cm −3 ) dispersion measure (DM) repeating fast radio burst (FRB), FRB 20190417A. Combining European VLBI Network detections of five repeat bursts, we confirm the FRB’s host to be a low-metallicity, star-forming dwarf galaxy at z = 0.12817, similar to the hosts of FRB 20121102A, FRB 20190520B, and FRB 20240114A. We also confirm that it is associated with a previously reported persistent radio source (PRS), which is compact on milliarcsecond scales. Visibility-domain model fitting constrains the transverse physical size of th
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P. Abratenko, D. Andrade Aldana, Luciano Arellano et al. · 2025 · Nature
Abstract The existence of three distinct neutrino flavours, ν e , ν μ and ν τ , is a central tenet of the Standard Model of particle physics 1,2 . Quantum-mechanical interference can allow a neutrino of one initial flavour to be detected sometime later as a different flavour, a process called neutrino oscillation. Several anomalous observations inconsistent with this three-flavour picture have motivated the hypothesis that an additional neutrino state exists, which does not interact directly with matter, termed as ‘sterile’ neutrino, ν s (refs. 3–9 ). This includes anomalous observations from
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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
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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
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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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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
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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
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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
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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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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
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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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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
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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.
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