4,302 research outputs found
Dissecting the Mid-Infrared Heart of M83 with JWST
We present a first look at the MRS observations of the nucleus of the spiral
galaxy M83, taken with MIRI onboard JWST. The observations show a rich set of
emission features from the ionized and warm molecular gas, as well as traces of
the dust properties in this highly star forming environment. To begin
dissecting the complex processes taking place in this part of the galaxy, we
divide the nucleus observations into four different regions. We find that the
strength of the emission features appears to strongly vary in all four regions,
with the south-east region displaying the weakest features tracing both the
dust continuum and ISM properties. Comparison between the cold molecular gas
traced by the CO (1-0) transition with ALMA and the H 0-0 S(1)
transition showed a similar spatial distribution throughout the nucleus. This
is in contrast to the distribution of the much warmer H emission from the
S(7) transition found to be concentrated mainly around the optical nucleus. We
modeled the H excitation using the rotational emission lines and estimate a
total molecular gas mass accounting for the warm H component of M(50
K) = 59.33 () 10 M. We
compared this value to the total molecular gas mass inferred by probing the
cold H gas through the CO (1-0) emission, M(CO) =
14.99 10 M. Our findings indicate that 75\% of
the total molecular gas mass in the core of M83 is contained in the warm H
component. We also identify [OIV]25.89 m and [FeII]25.99 m emission
(indicative of shocks) in all four nuclear regions with the strongest emission
originating from the north-west section. We propose that the diffuse
[FeII]25.99 m emission is an indication of the combined effects of both
the collective supernova explosions and the starbursts themselves.Comment: 13 pages, 3 Tables, 8 Figures, to be submitted to Ap
Smartpixels: Towards on-sensor inference of charged particle track parameters and uncertainties
The combinatorics of track seeding has long been a computational bottleneck
for triggering and offline computing in High Energy Physics (HEP), and remains
so for the HL-LHC. Next-generation pixel sensors will be sufficiently
fine-grained to determine angular information of the charged particle passing
through from pixel-cluster properties. This detector technology immediately
improves the situation for offline tracking, but any major improvements in
physics reach are unrealized since they are dominated by lowest-level hardware
trigger acceptance. We will demonstrate track angle and hit position
prediction, including errors, using a mixture density network within a single
layer of silicon as well as the progress towards and status of implementing the
neural network in hardware on both FPGAs and ASICs.Comment: 6 pages, 3 figures, submitted to Neural Information Processing
Systems 2023 (NeurIPS
hls4ml: An Open-Source Codesign Workflow to Empower Scientific Low-Power Machine Learning Devices
Accessible machine learning algorithms, software, and diagnostic tools for
energy-efficient devices and systems are extremely valuable across a broad
range of application domains. In scientific domains, real-time near-sensor
processing can drastically improve experimental design and accelerate
scientific discoveries. To support domain scientists, we have developed hls4ml,
an open-source software-hardware codesign workflow to interpret and translate
machine learning algorithms for implementation with both FPGA and ASIC
technologies. We expand on previous hls4ml work by extending capabilities and
techniques towards low-power implementations and increased usability: new
Python APIs, quantization-aware pruning, end-to-end FPGA workflows, long
pipeline kernels for low power, and new device backends include an ASIC
workflow. Taken together, these and continued efforts in hls4ml will arm a new
generation of domain scientists with accessible, efficient, and powerful tools
for machine-learning-accelerated discovery.Comment: 10 pages, 8 figures, TinyML Research Symposium 202
Gas Accretion and Star Formation Rates
Cosmological numerical simulations of galaxy evolution show that accretion of
metal-poor gas from the cosmic web drives the star formation in galaxy disks.
Unfortunately, the observational support for this theoretical prediction is
still indirect, and modeling and analysis are required to identify hints as
actual signs of star-formation feeding from metal-poor gas accretion. Thus, a
meticulous interpretation of the observations is crucial, and this
observational review begins with a simple theoretical description of the
physical process and the key ingredients it involves, including the properties
of the accreted gas and of the star-formation that it induces. A number of
observations pointing out the connection between metal-poor gas accretion and
star-formation are analyzed, specifically, the short gas consumption time-scale
compared to the age of the stellar populations, the fundamental metallicity
relationship, the relationship between disk morphology and gas metallicity, the
existence of metallicity drops in starbursts of star-forming galaxies, the
so-called G dwarf problem, the existence of a minimum metallicity for the
star-forming gas in the local universe, the origin of the alpha-enhanced gas
forming stars in the local universe, the metallicity of the quiescent BCDs, and
the direct measurements of gas accretion onto galaxies. A final section
discusses intrinsic difficulties to obtain direct observational evidence, and
points out alternative observational pathways to further consolidate the
current ideas.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics
and Space Science Library, eds. A. J. Fox & R. Dav\'e, to be published by
Springe
Measurement of the Forward-Backward Asymmetry in the B -> K(*) mu+ mu- Decay and First Observation of the Bs -> phi mu+ mu- Decay
We reconstruct the rare decays , , and in a data sample
corresponding to collected in collisions at
by the CDF II detector at the Fermilab Tevatron
Collider. Using and decays we report the branching ratios. In addition, we report
the measurement of the differential branching ratio and the muon
forward-backward asymmetry in the and decay modes, and the
longitudinal polarization in the decay mode with respect to the squared
dimuon mass. These are consistent with the theoretical prediction from the
standard model, and most recent determinations from other experiments and of
comparable accuracy. We also report the first observation of the {\mathcal{B}}(B^0_s \to
\phi\mu^+\mu^-) = [1.44 \pm 0.33 \pm 0.46] \times 10^{-6}27 \pm 6B^0_s$ decay observed.Comment: 7 pages, 2 figures, 3 tables. Submitted to Phys. Rev. Let
Search for a New Heavy Gauge Boson Wprime with Electron + missing ET Event Signature in ppbar collisions at sqrt(s)=1.96 TeV
We present a search for a new heavy charged vector boson decaying
to an electron-neutrino pair in collisions at a center-of-mass
energy of 1.96\unit{TeV}. The data were collected with the CDF II detector
and correspond to an integrated luminosity of 5.3\unit{fb}^{-1}. No
significant excess above the standard model expectation is observed and we set
upper limits on . Assuming standard
model couplings to fermions and the neutrino from the boson decay to
be light, we exclude a boson with mass less than
1.12\unit{TeV/}c^2 at the 95\unit{%} confidence level.Comment: 7 pages, 2 figures Submitted to PR
Measurements of the properties of Lambda_c(2595), Lambda_c(2625), Sigma_c(2455), and Sigma_c(2520) baryons
We report measurements of the resonance properties of Lambda_c(2595)+ and
Lambda_c(2625)+ baryons in their decays to Lambda_c+ pi+ pi- as well as
Sigma_c(2455)++,0 and Sigma_c(2520)++,0 baryons in their decays to Lambda_c+
pi+/- final states. These measurements are performed using data corresponding
to 5.2/fb of integrated luminosity from ppbar collisions at sqrt(s) = 1.96 TeV,
collected with the CDF II detector at the Fermilab Tevatron. Exploiting the
largest available charmed baryon sample, we measure masses and decay widths
with uncertainties comparable to the world averages for Sigma_c states, and
significantly smaller uncertainties than the world averages for excited
Lambda_c+ states.Comment: added one reference and one table, changed order of figures, 17
pages, 15 figure
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