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At least 217 records · Page 12Linked to original sources

Distributed Quantum Computing in Silicon

Commercially impactful quantum algorithms such as quantum chemistry and Shor's algorithm require a number of qubits and gates far beyond the capacity of any existing quantum processor. Distributed architectures, which scale horizontally by networking modules, provide a route to commercial utility and will eventually surpass the capability of any single quantum computing module. Such processors consume remote entanglement distributed between modules to realize distributed quantum logic. Networked quantum computers will therefore require the capability to rapidly distribute high fidelity entanglement between modules. Here we present preliminary demonstrations of some key distributed quantum computing protocols on silicon T centres in isotopically-enriched silicon. We demonstrate the distribution of entanglement between modules and consume it to apply a teleported gate sequence, establishing a proof-of-concept for T centres as a distributed quantum computing and networking platform.

quant-ph↗

Discovery of the Remarkably Red L/T Transition Object VHS J183135.58-551355.9

We present the discovery of VHS J183135.58$-$551355.9 (hereafter VHS J1831$-$5513), an L/T transition dwarf identified as a result of its unusually red near-infrared colors ($J-K_{\rm S}=3.633\pm0.277$ mag; $J-W2=6.249\pm0.245$ mag) from the VISTA Hemisphere Survey and CatWISE2020 surveys. We obtain low resolution near-infrared spectroscopy of VHS J1831$-$5513 using Magellan/FIRE to confirm its extremely red nature and assess features sensitive to surface gravity (i.e., youth). Its near-infrared spectrum shows multiple CH$_{\rm 4}$ absorption features, indicating an exceptionally low effective temperature for its spectral type. Based on proper motion measurements from CatWISE2020 and a photometric distance derived from its $K_{\rm S}$-band magnitude, we find that VHS J1831$-$5513 is a likely ($\sim$85$\%$ probability) kinematic member of the $β$ Pictoris moving group. Future radial velocity and trigonometric parallax measurements will clarify such membership. Follow-up mid-infrared or higher resolution near-infrared spectroscopy of this object will allow for further investigation as to the cause(s) of its redness, such as youth, clouds, and viewing geometry.

astro-ph.SR↗

Study of non-standard interaction mediated by a scalar field at ESSnuSB experiment

In this paper we study non-standard interactions mediated by a scalar field (SNSI) in the context of ESSnuSB experiment. In particular we study the capability of ESSnuSB to put bounds on the SNSI parameters and also study the impact of SNSI in the measurement of the leptonic CP phase $δ_{\rm CP}$. Existence of SNSI modifies the neutrino mass matrix and this modification can be expressed in terms of three diagonal real parameters ($η_{ee}$, $η_{μμ}$ and $η_{ττ}$) and three off-diagonal complex parameters ($η_{e μ}$, $η_{eτ}$ and $η_{μτ}$). Our study shows that the upper bounds on the parameters $η_{μμ}$, $η_{ττ}$ and $η_{μτ}$ depend upon how $Δm^2_{31}$ is minimized in the theory. However, this is not the case when one tries to measure the impact of SNSI on $δ_{\rm CP}$. Further, we show that the CP sensitivity of ESSnuSB can be completely lost for certain values of $η_{ee}$ and $η_{μτ}$ for which the appearance channel probability becomes independent of $δ_{\rm CP}$.

hep-ex↗

Exploring Eco-Friendly Gas Mixtures for Resistive Plate Chambers: A Comprehensive Study on Performance and Aging

Resistive Plate Chambers (RPCs) are gaseous detectors widely used in high energy physics experiments, operating with a gas mixture primarily containing Tetrafluoroethane (C$_{2}$H$_{2}$F$_{4}$), commonly known as R-134a, which has a global warming potential (GWP) of 1430. To comply with European regulations and explore environmentally friendly alternatives, the RPC EcoGas@GIF++ collaboration, involving ALICE, ATLAS, CMS, LHCb/SHiP, and EP-DT communities, has undertaken intensive R\&D efforts to explore new gas mixtures for RPC technology. A leading alternative under investigation is HFO1234ze, boasting a low GWP of 6 and demonstrating reasonable performance compared to R-134a. Over the past few years, RPC detectors with slightly different characteristics and electronics have been studied using HFO and CO$_{2}$-based gas mixtures at the CERN Gamma Irradiation Facility. An aging test campaign was launched in August 2022, and during the latest test beam in July 2023, all detector systems underwent evaluation. This contribution will report the results of the aging studies and the performance evaluations of the detectors with and without irradiation.

physics.ins-det↗

Chasing Gravitational Waves with the Cherenkov Telescope Array

The detection of gravitational waves from a binary neutron star merger by Advanced LIGO and Advanced Virgo (GW170817), along with the discovery of the electromagnetic counterparts of this gravitational wave event, ushered in a new era of multimessenger astronomy, providing the first direct evidence that BNS mergers are progenitors of short gamma-ray bursts (GRBs). Such events may also produce very-high-energy (VHE, > 100GeV) photons which have yet to be detected in coincidence with a gravitational wave signal. The Cherenkov Telescope Array (CTA) is a next-generation VHE observatory which aims to be indispensable in this search, with an unparalleled sensitivity and ability to slew anywhere on the sky within a few tens of seconds. New observing modes and follow-up strategies are being developed for CTA to rapidly cover localization areas of gravitational wave events that are typically larger than the CTA field of view. This work will evaluate and provide estimations on the expected number of of gravitational wave events that will be observable with CTA, considering both on- and off-axis emission. In addition, we will present and discuss the prospects of potential follow-up strategies with CTA.

astro-ph.HE↗

DeepSeek LLM: Scaling Open-Source Language Models with Longtermism

The rapid development of open-source large language models (LLMs) has been truly remarkable. However, the scaling law described in previous literature presents varying conclusions, which casts a dark cloud over scaling LLMs. We delve into the study of scaling laws and present our distinctive findings that facilitate scaling of large scale models in two commonly used open-source configurations, 7B and 67B. Guided by the scaling laws, we introduce DeepSeek LLM, a project dedicated to advancing open-source language models with a long-term perspective. To support the pre-training phase, we have developed a dataset that currently consists of 2 trillion tokens and is continuously expanding. We further conduct supervised fine-tuning (SFT) and Direct Preference Optimization (DPO) on DeepSeek LLM Base models, resulting in the creation of DeepSeek Chat models. Our evaluation results demonstrate that DeepSeek LLM 67B surpasses LLaMA-2 70B on various benchmarks, particularly in the domains of code, mathematics, and reasoning. Furthermore, open-ended evaluations reveal that DeepSeek LLM 67B Chat exhibits superior performance compared to GPT-3.5.

cs.CL↗

LBNF/DUNE Cryostats and Cryogenics Infrastructure for the DUNE Far Detector, Design Report

DUNE is an international experiment dedicated to addressing some of the questions at the forefront of particle physics and astrophysics, including the mystifying preponderance of matter over antimatter in the early universe. The dual-site experiment will employ an intense neutrino beam focused on both a near detector and a cryogenic far detector. The DUNE far detector implements liquid argon time-projection chamber (LArTPC) technology, and combines many tens-of-kilotons of fiducial mass with sub-centimeter spatial resolution to collect neutrino events and image them with high precision. Given its size, this detector will be implemented as a set of up to four modules, each of which will require its own cryostat that will contain approximately 17.5 metric kilotons of ultra-pure liquid argon (LAr). The cryogenics infrastructure to support the detector modules includes systems to receive, transfer, store, purify, and maintain the LAr. This design report describes the cryostats and the cryogenics infrastructure required for the first two detector modules; this infrastructure is designed to support expansion to up to four far detector modules.

physics.ins-det↗

WRAP: A Tool for Efficient Cross-Identification of Proper Motion Objects Spanning Multiple Surveys

We introduce the Wide-field Retrieval of Astrodata Program (WRAP), a tool created to aid astronomers in gathering photometric and astrometric data for point sources that may confuse simple cross-matching algorithms because of their faintness or motion. WRAP allows astronomers to correctly cross-identify objects with proper motion across multiple surveys by wedding the catalog data with its underlying images, thus providing visual confirmation of cross-associations in real time. Developed within the Backyard Worlds: Planet 9 citizen science project, WRAP aims to aid in the characterization of faint, high motion sources by this collaboration (and others).

astro-ph.IM↗

The Initial Mass Function Based on the Full-sky 20-pc Census of $\sim$3,600 Stars and Brown Dwarfs

A complete accounting of nearby objects -- from the highest-mass white dwarf progenitors down to low-mass brown dwarfs -- is now possible, thanks to an almost complete set of trigonometric parallax determinations from Gaia, ground-based surveys, and Spitzer follow-up. We create a census of objects within a Sun-centered sphere of 20-pc radius and check published literature to decompose each binary or higher-order system into its separate components. The result is a volume-limited census of $\sim$3,600 individual star formation products useful in measuring the initial mass function across the stellar ($<8 M_\odot$) and substellar ($\gtrsim 5 M_{Jup}$) regimes. Comparing our resulting initial mass function to previous measurements shows good agreement above 0.8$M_\odot$ and a divergence at lower masses. Our 20-pc space densities are best fit with a quadripartite power law, $ξ(M) = dN/dM \propto M^{-α}$ with long-established values of $α= 2.3$ at high masses ($0.55 < M < 8.00 M_\odot$) and $α= 1.3$ at intermediate masses ($0.22 < M < 0.55 M_\odot$), but at lower masses we find $α= 0.25$ for $0.05 < M <0.22 M_\odot$ and $α= 0.6$ for $0.01 < M < 0.05 M_\odot$. This implies that the rate of production as a function of decreasing mass diminishes in the low-mass star/high-mass brown dwarf regime before increasing again in the low-mass brown dwarf regime. Correcting for completeness, we find a star to brown dwarf number ratio of, currently, 4:1, and an average mass per object of 0.41 $M_\odot$.

astro-ph.SR↗

Prospects for Time-Domain and Multi-Messenger Science with AXIS

The Advanced X-ray Imaging Satellite (AXIS) promises revolutionary science in the X-ray and multi-messenger time domain. AXIS will leverage excellent spatial resolution (<1.5 arcsec), sensitivity (80x that of Swift), and a large collecting area (5-10x that of Chandra) across a 24-arcmin diameter field of view to discover and characterize a wide range of X-ray transients from supernova-shock breakouts to tidal disruption events to highly variable supermassive black holes. The observatory's ability to localize and monitor faint X-ray sources opens up new opportunities to hunt for counterparts to distant binary neutron star mergers, fast radio bursts, and exotic phenomena like fast X-ray transients. AXIS will offer a response time of <2 hours to community alerts, enabling studies of gravitational wave sources, high-energy neutrino emitters, X-ray binaries, magnetars, and other targets of opportunity. This white paper highlights some of the discovery science that will be driven by AXIS in this burgeoning field of time domain and multi-messenger astrophysics.

astro-ph.HE↗

DES Y3 + KiDS-1000: Consistent cosmology combining cosmic shear surveys

We present a joint cosmic shear analysis of the Dark Energy Survey (DES Y3) and the Kilo-Degree Survey (KiDS-1000) in a collaborative effort between the two survey teams. We find consistent cosmological parameter constraints between DES Y3 and KiDS-1000 which, when combined in a joint-survey analysis, constrain the parameter $S_8 = σ_8 \sqrt{Ω_{\rm m}/0.3}$ with a mean value of $0.790^{+0.018}_{-0.014}$. The mean marginal is lower than the maximum a posteriori estimate, $S_8=0.801$, owing to skewness in the marginal distribution and projection effects in the multi-dimensional parameter space. Our results are consistent with $S_8$ constraints from observations of the cosmic microwave background by Planck, with agreement at the $1.7σ$ level. We use a Hybrid analysis pipeline, defined from a mock survey study quantifying the impact of the different analysis choices originally adopted by each survey team. We review intrinsic alignment models, baryon feedback mitigation strategies, priors, samplers and models of the non-linear matter power spectrum.

astro-ph.CO↗

CWISE J105512.11+544328.3: A Nearby Y Dwarf Spectroscopically Confirmed with Keck/NIRES

Y dwarfs, the coolest known spectral class of brown dwarfs, overlap in mass and temperature with giant exoplanets, providing unique laboratories for studying low-temperature atmospheres. However, only a fraction of Y dwarf candidates have been spectroscopically confirmed. We present Keck/NIRES near-infrared spectroscopy of the nearby ($d \approx 6-8$ pc) brown dwarf CWISE J105512.11+544328.3. Although its near-infrared spectrum aligns best with the Y0 standard in the $J$-band, no standard matches well across the full $YJHK$ wavelength range. The CWISE J105512.11+544328.3 NH$_3$-$H$ = 0.427 $\pm$ 0.0012 and CH$_4$-$J$ = 0.0385 $\pm$ 0.0007 absorption indices and absolute Spitzer [4.5] magnitude of 15.18 $\pm$ 0.22 are also indicative of an early Y dwarf rather than a late T dwarf. CWISE J105512.11+544328.3 additionally exhibits the bluest Spitzer [3.6]$-$[4.5] color among all spectroscopically confirmed Y dwarfs. Despite this anomalously blue Spitzer color given its low luminosity, CWISE J105512.11+544328.3 does not show other clear kinematic or spectral indications of low metallicity. Atmospheric model comparisons yield a log(g) $\le$ 4.5 and $T_{\rm eff} \approx 500 \pm 150$ K for this source. We classify CWISE J105512.11+544328.3 as a Y0 (pec) dwarf, adding to the remarkable diversity of the Y-type population. JWST spectroscopy would be crucial to understanding the origin of this Y dwarf's unusual preference for low-gravity models and blue 3-5 $μ$m color.

astro-ph.SR↗

Ground observations of a space laser for the assessment of its in-orbit performance

The wind mission Aeolus of the European Space Agency was a groundbreaking achievement for Earth observation. Between 2018 and 2023, the space-borne lidar instrument ALADIN onboard the Aeolus satellite measured atmospheric wind profiles with global coverage which contributed to improving the accuracy of numerical weather prediction. The precision of the wind observations, however, declined over the course of the mission due to a progressive loss of the atmospheric backscatter signal. The analysis of the root cause was supported by the Pierre Auger Observatory in Argentina whose fluorescence detector registered the ultraviolet laser pulses emitted from the instrument in space, thereby offering an estimation of the laser energy at the exit of the instrument for several days in 2019, 2020 and 2021. The reconstruction of the laser beam not only allowed for an independent assessment of the Aeolus performance, but also helped to improve the accuracy in the determination of the laser beam's ground track on single pulse level. The results presented in this paper set a precedent for the monitoring of space lasers by ground-based telescopes and open new possibilities for the calibration of cosmic-ray observatories.

astro-ph.IM↗

An Investigation of New Brown Dwarf Spectral Binary Candidates From the Backyard Worlds: Planet 9 Citizen Science Initiative

We present three new brown dwarf spectral binary candidates: CWISE J072708.09$-$360729.2, CWISE J103604.84$-$514424.4, and CWISE J134446.62$-$732053.9, discovered by citizen scientists through the Backyard Worlds: Planet 9 project. Follow-up near-infrared spectroscopy shows that each of these objects is poorly fit by a single near-infrared standard. We constructed binary templates and found significantly better fits, with component types of L7+T4 for CWISE J072708.09$-$360729.2, L7+T4 for CWISE J103604.84$-$514424.4, and L7+T7 for CWISE J134446.62$-$732053.9. However, further investigation of available spectroscopic indices for evidence of binarity and large amplitude variability suggests that CWISE J072708.09$-$360729.2 may instead be a strong variability candidate. Our analysis offers tentative evidence and characterization of these peculiar brown dwarf sources, emphasizing their value as promising targets for future high-resolution imaging or photometric variability studies.

astro-ph.SR↗

Discovery of a Radiation Component from the Vela Pulsar Reaching 20 Teraelectronvolts

Gamma-ray observations have established energetic isolated pulsars as outstanding particle accelerators and antimatter factories in the Galaxy. There is, however, no consensus regarding the acceleration mechanisms and the radiative processes at play, nor the locations where these take place. The spectra of all observed gamma-ray pulsars to date show strong cutoffs or a break above energies of a few gigaelectronvolt (GeV). Using the H.E.S.S. array of Cherenkov telescopes, we discovered a novel radiation component emerging beyond this generic GeV cutoff in the Vela pulsar's broadband spectrum. The extension of gamma-ray pulsation energies up to at least 20 teraelectronvolts (TeV) shows that Vela pulsar can accelerate particles to Lorentz factors higher than $4\times10^7$. This is an order of magnitude larger than in the case of the Crab pulsar, the only other pulsar detected in the TeV energy range. Our results challenge the state-of-the-art models for high-energy emission of pulsars while providing a new probe, i.e. the energetic multi-TeV component, for constraining the acceleration and emission processes in their extreme energy limit.

astro-ph.HE↗

A multi-wavelength investigation of PSR J2229+6114 and its pulsar wind nebula in the radio, X-ray, and gamma-ray bands

G106.3$+$2.7, commonly considered a composite supernova remnant (SNR), is characterized by a boomerang-shaped pulsar wind nebula (PWN) and two distinct ("head" & "tail") regions in the radio band. A discovery of very-high-energy (VHE) gamma-ray emission ($E_γ> 100$ GeV) followed by the recent detection of ultra-high-energy (UHE) gamma-ray emission ($E_γ> 100$ TeV) from the tail region suggests that G106.3$+$2.7 is a PeVatron candidate. We present a comprehensive multi-wavelength study of the Boomerang PWN (100" around PSR J2229+6114) using archival radio and Chandra data obtained from two decades ago, a new NuSTAR X-ray observation from 2020, and upper limits on gamma-ray fluxes obtained by Fermi and VERITAS observatories. The NuSTAR observation allowed us to detect a 51.67 ms spin period from the pulsar PSR J2229+6114 and the PWN emission characterized by a power-law model with $Γ= 1.52\pm0.06$ up to 20 keV. Contrary to the previous radio study by Kothes et al. 2006, we prefer a much lower PWN B-field ($B\sim3$ $μ$G) and larger distance ($d \sim 8$ kpc) based on (1) the non-varying X-ray flux over the last two decades, (2) the energy-dependent X-ray PWN size resulting from synchrotron burn-off and (3) the multi-wavelength spectral energy distribution (SED) data. Our SED model suggests that the PWN is currently re-expanding after being compressed by the SNR reverse shock $\sim 1000$ years ago. In this case, the head region should be formed by GeV--TeV electrons injected earlier by the pulsar propagating into the low density environment.

astro-ph.HE↗

Measurement of $C\!P$ asymmetries and branching-fraction ratios for $B^\pm \to DK^\pm$ and $Dπ^\pm$ with $D\to K^0_{\rm S} K^\pmπ^\mp$ using Belle and Belle II data

We measure $C\!P$ asymmetries and branching-fraction ratios for $B^\pm \to DK^\pm$ and $Dπ^\pm$ decays with $D\to K^0_{\rm S} K^\pmπ^\mp$, where $D$ is a superposition of $D^0$ and $\bar{D}^0$. We use the full data set of the Belle experiment, containing $772\times 10^6~B\bar{B}$ pairs, and data from the Belle~II experiment, containing $387\times 10^6~B\bar{B}$ pairs, both collected in electron-positron collisions at the $Υ(4S)$ resonance. Our results provide model-independent information on the unitarity triangle angle $ϕ_3$.

hep-ex↗

Multi-Point Detection of the Powerful Gamma Ray Burst GRB221009A Propagation through the Heliosphere on October 9, 2022

We present the results of processing the effects of the powerful Gamma Ray Burst GRB221009A captured by the charged particle detectors (electrostatic analyzers and solid-state detectors) onboard spacecraft at different points in the heliosphere on October 9, 2022. To follow the GRB221009A propagation through the heliosphere we used the electron and proton flux measurements from solar missions Solar Orbiter and STEREO-A; Earth magnetosphere and the solar wind missions THEMIS and Wind; meteorological satellites POES15, POES19, MetOp3; and MAVEN - a NASA mission orbiting Mars. GRB221009A had a structure of four bursts: less intense Pulse 1 - the triggering impulse - was detected by gamma-ray observatories at 131659 UT (near the Earth); the most intense Pulses 2 and 3 were detected on board all the spacecraft from the list, and Pulse 4 detected in more than 500 s after Pulse 1. Due to their different scientific objectives, the spacecraft, which data was used in this study, were separated by more than 1 AU (Solar Orbiter and MAVEN). This enabled tracking GRB221009A as it was propagating across the heliosphere. STEREO-A was the first to register Pulse 2 and 3 of the GRB, almost 100 seconds before their detection by spacecraft in the vicinity of Earth. MAVEN detected GRB221009A Pulses 2, 3, and 4 at the orbit of Mars about 237 seconds after their detection near Earth. By processing the time delays observed we show that the source location of the GRB221009A was at RA 288.5 degrees, Dec 18.5 degrees (J2000) with an error cone of 2 degrees

astro-ph.HE↗