We report on the technical design and expected performance of a 592 kg heavy-water-Cherenkov detector to measure the absolute neutrino flux from the pion-decay-at-rest neutrino source at the ...Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). The detector will be located roughly 20 m from the SNS target and will measure the neutrino flux with better than 5% statistical uncertainty in 2 years. This heavy-water detector will serve as the first module of a two-module detector system to ultimately measure the neutrino flux to 2–3% at both the First Target Station and the planned Second Target Station of the SNS. This detector will significantly reduce a dominant systematic uncertainty for neutrino cross-section measurements at the SNS, increasing the sensitivity of searches for new physics.
ABSTRACT We present simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cygni at the end of its 2015 outburst. From 2015 July 11-August 5, we monitored V404 Cygni with ...Chandra, Swift, and NuSTAR in the X-ray, and with the Karl G. Jansky Very Large Array and the Very Long Baseline Array in the radio, spanning a range of luminosities that were poorly covered during its previous outburst in 1989 (our 2015 campaign covers ). During our 2015 campaign, the X-ray spectrum evolved rapidly from a hard photon index of (at ) to a softer (at ). We argue that V404 Cygni reaching marks the beginning of the quiescent spectral state, which occurs at a factor of 3-4 higher X-ray luminosity than the average pre-outburst luminosity of . V404 Cygni falls along the same radio/X-ray luminosity correlation that it followed during its previous outburst in 1989, implying a robust disk-jet coupling. We exclude the possibility that a synchrotron-cooled jet dominates the X-ray emission in quiescence, leaving synchrotron self-Compton from either a hot accretion flow or from a radiatively cooled jet as the most likely sources of X-ray radiation, and/or particle acceleration along the jet becoming less efficient in quiescence. Finally, we present the first indications of correlated radio and X-ray variability on minute timescales in quiescence, tentatively measuring the radio emission to lag the X-ray by minute, suggestive of X-ray variations propagating down a jet with a length of <3.0 au.
Coherent elastic neutrino-nucleus scattering (CEvNS) is calculated to be the dominant neutrino scattering channel for neutrinos of energy Eν<100 MeV. We report a limit for this process from data ...collected in an engineering run of the 29 kg CENNS-10 liquid argon detector located 27.5 m from the pion decay-at-rest neutrino source at the Oak Ridge National Laboratory Spallation Neutron Source (SNS) with 4.2×1022 protons on target. The dataset provided constraints on beam-related backgrounds critical for future measurements and yielded <7.4 candidate CEvNS events which implies a cross section for the process, averaged over the SNS pion decay-at-rest flux, of <3.4×10−39 cm2, a limit within twice the Standard Model prediction. This is the first limit on CEvNS from an argon nucleus and confirms the earlier CsINa nonstandard neutrino interaction constraints from the collaboration. This run demonstrated the feasibility of the ongoing experimental effort to detect CEvNS with liquid argon.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
MAXI J1836−194 is a Galactic black hole candidate X-ray binary that was discovered in 2011 when it went into outburst. In this paper, we present the full radio monitoring of this system during its ...‘failed’ outburst, in which the source did not complete a full set of state changes, only transitioning as far as the hard intermediate state. Observations with the Karl G. Jansky Very Large Array (VLA) and Australia Telescope Compact Array (ATCA) show that the jet properties changed significantly during the outburst. The VLA observations detected linearly polarized emission at a level of ∼1 per cent early in the outburst, increasing to ∼3 per cent as the outburst peaked. High-resolution images with the Very Long Baseline Array (VLBA) show an ∼15 mas jet along the position angle −21 ± 2°, in agreement with the electric vector position angle found from our polarization results (−21 ± 4°), implying that the magnetic field is perpendicular to the jet. Astrometric observations suggest that the system required an asymmetric natal kick to explain its observed space velocity. Comparing quasi-simultaneous X-ray monitoring with the 5 GHz VLA observations from the 2011 outburst shows an unusually steep hard-state radio/X-ray correlation of
$L_{\rm R} \propto L_{\rm X}^{1.8\pm 0.2}$
, where L
R and L
X denote the radio and X-ray luminosities, respectively. With ATCA and Swift monitoring of the source during a period of re-brightening in 2012, we show that the system lay on the same steep correlation. Due to the low inclination of this system, we then investigate the possibility that the observed correlation may have been steepened by variable Doppler boosting.
We present an intensive radio and X-ray monitoring campaign on the 2009 outburst of the Galactic black hole candidate X-ray binary H1743−322. With the high angular resolution of the Very Long ...Baseline Array, we resolve the jet ejection event and measure the proper motions of the jet ejecta relative to the position of the compact core jets detected at the beginning of the outburst. This allows us to accurately couple the moment when the jet ejection event occurred with X-ray spectral and timing signatures. We find that X-ray timing signatures are the best diagnostic of the jet ejection event in this outburst, which occurred as the X-ray variability began to decrease and the Type C quasi-periodic oscillations disappeared from the X-ray power density spectrum. However, this sequence of events does not appear to be replicated in all black hole X-ray binary outbursts, even within an individual source. In our observations of H1743−322, the ejection was contemporaneous with a quenching of the radio emission, prior to the start of the major radio flare. This contradicts previous assumptions that the onset of the radio flare marks the moment of ejection. The jet speed appears to vary between outbursts, with a possible positive correlation with outburst luminosity. The compact core radio jet reactivated on transition to the hard intermediate state at the end of the outburst, and not when the source reached the low hard spectral state. Comparison with the known near-infrared behaviour of the compact jets suggests a gradual evolution of the compact jet power over a few days near the beginning and end of an outburst.
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
The reproducible radio outbursts of SS Cygni Russell, T. D; Miller-Jones, J. C. A; Sivakoff, G. R ...
Monthly notices of the Royal Astronomical Society,
08/2016, Volume:
460, Issue:
4
Journal Article
Peer reviewed
Open access
We present the results of our intensive radio observing campaign of the dwarf nova SS Cyg during its 2010 April outburst. We argue that the observed radio emission was produced by synchrotron ...emission from a transient radio jet. Comparing the radio light curves from previous and subsequent outbursts of this system (including high-resolution observations from outbursts in 2011 and 2012) shows that the typical long and short outbursts of this system exhibit reproducible radio outbursts that do not vary significantly between outbursts, which is consistent with the similarity of the observed optical, ultraviolet and X-ray light curves. Contemporaneous optical and X-ray observations show that the radio emission appears to have been triggered at the same time as the initial X-ray flare, which occurs as disc material first reaches the boundary layer. This raises the possibility that the boundary region may be involved in jet production in accreting white dwarf systems. Our high spatial resolution monitoring shows that the compact jet remained active throughout the outburst with no radio quenching.
Abstract
We report on a search for electron antineutrinos (
ν
¯
e
) from astrophysical sources in the neutrino energy range 8.3–30.8 MeV with the KamLAND detector. In an exposure of 6.72 kton-year of ...the liquid scintillator, we observe 18 candidate events via the inverse beta decay reaction. Although there is a large background uncertainty from neutral current atmospheric neutrino interactions, we find no significant excess over background model predictions. Assuming several supernova relic neutrino spectra, we give upper flux limits of 60–110 cm
−2
s
−1
(90% confidence level, CL) in the analysis range and present a model-independent flux. We also set limits on the annihilation rates for light dark matter pairs to neutrino pairs. These data improve on the upper probability limit of
8
B solar neutrinos converting into
ν
¯
e
,
P
ν
e
→
ν
¯
e
<
3.5
×
10
−
5
(90% CL) assuming an undistorted
ν
¯
e
shape. This corresponds to a solar
ν
¯
e
flux of 60 cm
−2
s
−1
(90% CL) in the analysis energy range.
The decay of the primordial isotopes 238U, 235U, 232Th, and 40K has contributed to the terrestrial heat budget throughout the Earth's history. Hence, the individual abundance of those isotopes are ...key parameters in reconstructing contemporary Earth models. The geoneutrinos produced by the radioactive decays of uranium and thorium have been observed with the Kamioka Liquid‐Scintillator Antineutrino Detector (KamLAND). Those measurements have been improved with more than 18‐year observation time, and improvement in detector background levels mainly with an 8‐year nearly reactor‐free period, which now permit spectroscopy with geoneutrinos. Our results yield the first constraint on both uranium and thorium heat contributions. The KamLAND result is consistent with geochemical estimations based on elemental abundances of chondritic meteorites and mantle peridotites. The High‐Q model is disfavored at 99.76% C.L. and a fully radiogenic model is excluded at 5.2σ assuming a homogeneous heat producing element distribution in the mantle.
Plain Language Summary
The energy to drive the Earth's engine comes from two different sources: primordial and radiogenic. Primordial energy comes from the added heat by collisions of accreting material and less so by the energy accompanying the sinking of metal to form the core. The radioactive decays of heat producing elements (i.e., potassium, thorium, and uranium) also generate energy and some of these decaying elements produce antineutrinos (geoneutrinos). Geoneutrino measurements provide the Earth's fuel gauge for its radiogenic power supply and insights into the planet's cooling history. The measurement accuracy of the KamLAND experiment has been improved by an 18‐year long‐term observation and a reduction of the significant background generated by commercial reactors. Consequently, modern geoneutrino measurements have entered an era of distinct spectroscopic contributions coming from uranium and thorium. The KamLAND result is consistent with compositional models for the bulk silicate Earth (the crust plus the mantle) predicting low to medium radiogenic heat (10–20 TW (1012 W)) and disfavor high concentration models (30 TW). This constraint sets the best limit on the permissible radiogenic energy budget in the Earth. Geoneutrino observations now begin to make significant contributions to the understanding of fundamental driving forces powering the Earth dynamic behavior.
Key Points
Geoneutrino measurement with low reactor neutrino backgrounds improves the distinct spectroscopic contributions of U and Th
Radiogenic power in the Earth estimated from this geoneutrino measurement is consistent with a range of models and disfavors the higher power model
Identifying the Earth's mantle contribution to the total geoneutrino flux strongly depends on an accurate estimation of the crustal contribution
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