Aims. We present a kinematic study of a sample of 298 planetary nebulas (PNs) in the outer halo of the central Virgo galaxy M 87 (NGC 4486). The line-of-sight velocities of these PNs are used to ...identify subcomponents, to measure the angular momentum content of the main M 87 halo, and to constrain the orbital distribution of the stars at these large radii. Methods. We use Gaussian mixture modelling to statistically separate distinct velocity components and identify the M 87 smooth halo component, its unrelaxed substructures, and the intra-cluster (IC) PNs. We compute probability weighted velocity and velocity dispersion maps for the smooth halo, and its specific angular momentum profile (λR) and velocity dispersion profile. Results. The classification of the PNs into smooth halo and ICPNs is supported by their different PN luminosity functions. Based on a Kolmogorov–Smirnov (K–S) test, we conclude that the ICPN line-of-sight velocity distribution (LOSVD) is consistent with the LOSVD of the galaxies in Virgo subcluster A. The surface density profile of the ICPNS at 100 kpc radii has a shallow logarithmic slope, −αICL ≃ −0.8, dominating the light at the largest radii. Previous B − V colour and resolved star metallicity data indicate masses for the ICPN progenitor galaxies of a few ×108 M⊙. The angular momentum-related λR profile for the smooth halo remains below 0.1, in the slow rotator regime, out to 135 kpc average ellipse radius (170 kpc major axis distance). Combining the PN velocity dispersion measurements for the M 87 halo with literature data in the central 15 kpc, we obtain a complete velocity dispersion profile out to Ravg = 135 kpc. The σhalo profile decreases from the central 400 km s−1 to about 270 km s−1 at 2–10 kpc, then rises again to ≃300 ± 50 km s−1 at 50–70 kpc, to finally decrease sharply to σhalo ∼ 100 km s−1 at Ravg = 135 kpc. The steeply decreasing outer σhalo profile and the surface density profile of the smooth halo can be reconciled with the circular velocity curve inferred from assuming hydrostatic equilibrium for the hot X-ray gas. Because this rises to νc,X ∼ km s−1 at 200 kpc, the orbit distribution of the smooth M 87 halo is required to change strongly from approximately isotropic within Ravg ∼ 60 kpc to very radially anisotropic at the largest distances probed. Conclusions. The extended LOSVD of the PNs in the M 87 halo allows the identification of several subcomponents: the ICPNs, the “crown” accretion event, and the smooth M 87 halo. In galaxies like M 87, the presence of these subcomponents needs to be taken into account to avoid systematic biases in estimating the total enclosed mass. The dynamical structure inferred from the velocity dispersion profile indicates that the smooth halo of M 87 steepens beyond Ravg = 60 kpc and becomes strongly radially anisotropic, and that the velocity dispersion profile is consistent with the X-ray circular velocity curve at these radii without non-thermal pressure effects.
We present a quantitative, direct comparison of constraints on sterile neutrinos derived from neutrino oscillation experiments and from Planck data, interpreted assuming standard cosmological ...evolution. We extend a
1
+
1
model, which is used to compare exclusion contours at the 95% Cl derived from Planck data to those from
ν
e
-disappearance measurements, to a
3
+
1
model. This allows us to compare the Planck constraints with those obtained through
ν
μ
→
ν
e
appearance searches, which are sensitive to more than one active-sterile mixing angle. We find that the cosmological data fully exclude the allowed regions published by the LSND, MiniBooNE and Neutrino-4 collaborations, and those from the gallium and rector anomalies, at the 95% Cl. Compared to the exclusion region from the Daya Bay
ν
e
-disappearance search, the Planck data are more strongly excluding above
|
Δ
m
41
2
|
≈
0.1
eV
2
and
m
eff
sterile
≈
0.2
eV
, with the Daya Bay exclusion being stronger below these values. Compared to the combined Daya Bay/Bugey/MINOS exclusion region on
ν
μ
→
ν
e
appearance, the Planck data is more strongly excluding above
Δ
m
41
2
≈
5
×
10
-
2
eV
2
, with the exclusion strengths of the Planck data and the Daya Bay/Bugey/MINOS combination becoming comparable below this value.
Combustion power plants emit carbon dioxide (CO2), which is a major contributor to climate change. Direct emissions measurement is cost-prohibitive globally, while reporting varies in detail, ...latency, and granularity. To fill this gap and greatly increase the number of power plants worldwide with independent emissions monitoring, we developed and applied machine learning (ML) models using power plant water vapor plumes as proxy signals to estimate electric power generation and CO2 emissions using Landsat 8, Sentinel-2, and PlanetScope imagery. Our ML models estimated power plant activity on each image snapshot, then an aggregation model predicted plant utilization over a 30-day period. Lastly, emission factors specific to region, fuel, and plant technology were used to convert the estimated electricity generation into CO2 emissions. Models were trained with reported hourly electricity generation data in the US, Europe, and Australia and were validated with additional generation and emissions data from the US, Europe, Australia, Türkiye, and India. All results with sufficiently large sample sizes indicate that our models outperformed the baseline approaches. In validating our model results against available generation and emissions reported data, we calculated the root mean square error as 1.75 TWh (236 plants across 17 countries over 4 years) and 2.18 Mt CO2 (207 plants across 17 countries over 4 years), respectively. Ultimately, we applied our ML method to plants that constitute 32% of global power plant CO2 emissions, as estimated by Climate TRACE, averaged over the period 2015–2022. This dataset is the most comprehensive independent and free-of-cost global power plant point-source emissions monitoring system currently known to the authors and is made freely available to the public to support global emissions reduction.
Abstract
We present a quantitative, direct comparison of constraints on sterile neutrinos derived from neutrino oscillation experiments and from Planck data, interpreted assuming standard ...cosmological evolution. We extend a
$$1+1$$
1
+
1
model, which is used to compare exclusion contours at the 95% Cl derived from Planck data to those from
$$\nu _{e}$$
ν
e
-disappearance measurements, to a
$$3+1$$
3
+
1
model. This allows us to compare the Planck constraints with those obtained through
$$\nu _{\mu }\rightarrow \nu _{e}$$
ν
μ
→
ν
e
appearance searches, which are sensitive to more than one active-sterile mixing angle. We find that the cosmological data fully exclude the allowed regions published by the LSND, MiniBooNE and Neutrino-4 collaborations, and those from the gallium and rector anomalies, at the 95% Cl. Compared to the exclusion region from the Daya Bay
$$\nu _{e}$$
ν
e
-disappearance search, the Planck data are more strongly excluding above
$$|\Delta m^{2}_{41}|\approx 0.1\,\mathrm {eV}^{2}$$
|
Δ
m
41
2
|
≈
0.1
eV
2
and
$$m_\mathrm {eff}^\mathrm {sterile}\approx 0.2\,\mathrm {eV}$$
m
eff
sterile
≈
0.2
eV
, with the Daya Bay exclusion being stronger below these values. Compared to the combined Daya Bay/Bugey/MINOS exclusion region on
$$\nu _{\mu }\rightarrow \nu _{e}$$
ν
μ
→
ν
e
appearance, the Planck data is more strongly excluding above
$$\Delta m^{2}_{41}\approx 5\times 10^{-2}\,\mathrm {eV}^{2}$$
Δ
m
41
2
≈
5
×
10
-
2
eV
2
, with the exclusion strengths of the Planck data and the Daya Bay/Bugey/MINOS combination becoming comparable below this value.
We present a novel electrical technique to measure the tension of wires in multi-wire drift chambers. We create alternating electric fields by biasing adjacent wires on both sides of a test wire with ...a superposition of positive and negative DC voltages on an AC signal (VAC±VDC). The resulting oscillations of the wire will display a resonance at its natural frequency, and the corresponding change of the capacitance will lead to a measurable current. This scheme is scalable to multiple wires and therefore enables us to precisely measure the tension of a large number of wires in a short time. This technique can also be applied at cryogenic temperatures making it an attractive solution for future large time-projection chambers such as the DUNE detector. We present the concept, an example implementation and its performance in a real-world scenario and discuss the limitations of the sensitivity of the system in terms of voltage and wire length.
Light Higgs production at a photon collider Söldner-Rembold, Stefan; Jikia, Georgi
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2001, Letnik:
472, Številka:
1
Journal Article
Recenzirano
We present a preliminary study of the production of a light Higgs boson with a mass between 120 and
160
GeV
in photon–photon collisions at a Compton collider. The event generator for the backgrounds ...to a Higgs signal due to
b
̄
b
and
c
̄
c
heavy quark pair production in polarized
γγ collisions is based on a complete next-to-leading order (NLO) perturbative QCD calculation. For
J
z
=0 the large double-logarithmic corrections up to four loops are also included. It is shown that the two-photon width of the Higgs boson can be measured with high statistical accuracy of about 2–10% for integrated
γγ luminosity in the hard part of the spectrum of
43
fb
−1
. From this result the total Higgs boson width can be derived in a model independent way.
Calorimeter development for the SuperNEMO double beta decay experiment Barabash, A.S.; Basharina-Freshville, A.; Blot, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2017, Letnik:
868, Številka:
C
Journal Article
Recenzirano
Odprti dostop
SuperNEMO is a double-β decay experiment, which will employ the successful tracker–calorimeter technique used in the recently completed NEMO-3 experiment. SuperNEMO will implement 100 kg of double-β ...decay isotope, reaching a sensitivity to the neutrinoless double-β decay (0νββ) half-life of the order of 1026 yr, corresponding to a Majorana neutrino mass of 50–100 meV. One of the main goals and challenges of the SuperNEMO detector development programme has been to reach a calorimeter energy resolution, ΔE∕E, around 3%∕E(MeV)σ, or 7%∕E(MeV) FWHM (full width at half maximum), using a calorimeter composed of large volume plastic scintillator blocks coupled to photomultiplier tubes. We describe the R&D programme and the final design of the SuperNEMO calorimeter that has met this challenging goal.
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