588 research outputs found
A possible Macronova in the late afterglow of the `long-short' burst GRB 060614
Long-duration ( s) -ray bursts that are believed to originate
from the death of massive stars are expected to be accompanied by supernovae.
GRB 060614, that lasted 102 s, lacks a supernova-like emission down to very
stringent limits and its physical origin is still debated. Here we report the
discovery of near-infrared bump that is significantly above the regular
decaying afterglow. This red bump is inconsistent with even the weakest known
supernova. However, it can arise from a Li-Paczy\'{n}ski macronova the
radioactive decay of debris following a compact binary merger. If this
interpretation is correct GRB 060614 arose from a compact binary merger rather
than from the death of a massive star and it was a site of a significant
production of heavy r-process elements. The significant ejected mass favors a
black hole-neutron star merger but a double neutron star merger cannot be ruled
out.Comment: Minor revision; The version published in Nature Communication
HyperDID: Hyperspectral Intrinsic Image Decomposition with Deep Feature Embedding
The dissection of hyperspectral images into intrinsic components through
hyperspectral intrinsic image decomposition (HIID) enhances the
interpretability of hyperspectral data, providing a foundation for more
accurate classification outcomes. However, the classification performance of
HIID is constrained by the model's representational ability. To address this
limitation, this study rethinks hyperspectral intrinsic image decomposition for
classification tasks by introducing deep feature embedding. The proposed
framework, HyperDID, incorporates the Environmental Feature Module (EFM) and
Categorical Feature Module (CFM) to extract intrinsic features. Additionally, a
Feature Discrimination Module (FDM) is introduced to separate
environment-related and category-related features. Experimental results across
three commonly used datasets validate the effectiveness of HyperDID in
improving hyperspectral image classification performance. This novel approach
holds promise for advancing the capabilities of hyperspectral image analysis by
leveraging deep feature embedding principles. The implementation of the
proposed method could be accessed soon at https://github.com/shendu-sw/HyperDID
for the sake of reproducibility.Comment: Submitted to IEEE TGR
Understanding the Discrepancy between IRX and Balmer Decrement in Tracing Galaxy Dust Attenuation
Infrared Spectral Energy Distributions of z~0.7 Star-Forming Galaxies
We analyze the infrared (IR) spectral energy distributions (SEDs) for
10micron < lambda(rest) < 100micron for ~600 galaxies at z~0.7 in the extended
Chandra Deep Field South by stacking their Spitzer 24, 70 and 160micron images.
We place interesting constraints on the average IR SED shape in two bins: the
brightest 25% of z~0.7 galaxies detected at 24micron, and the remaining 75% of
individually-detected galaxies. Galaxies without individual detections at
24micron were not well-detected at 70micron and 160micron even through
stacking. We find that the average IR SEDs of z~0.7 star-forming galaxies fall
within the diversity of z~0 templates. While dust obscuration Lir/Luv seems to
be only a function of star formation rate (SFR; ~ Lir+Luv), not of redshift,
the dust temperature of star-forming galaxies (with SFR ~ 10 solar mass per
year) at a given IR luminosity was lower at z~0.7 than today. We suggest an
interpretation of this phenomenology in terms of dust geometry: intensely
star-forming galaxies at z~0 are typically interacting, and host dense
centrally-concentrated bursts of star formation and warm dust temperatures. At
z~0.7, the bulk of intensely star-forming galaxies are relatively undisturbed
spirals and irregulars, and we postulate that they have large amounts of
widespread lower-density star formation, yielding lower dust temperatures for a
given IR luminosity. We recommend what IR SEDs are most suitable for modeling
intermediate redshift galaxies with different SFRs.Comment: 12 pages, 11 figures, 2 tables, accepted for publication in Ap
The physical properties of star-forming galaxies with strong [oiii]lines at z=3.25
We present an analysis of physical properties of 34 [O III] emission-line galaxies (ELGs) at z = 3.254 ± 0.029 in
the Extended Chandra Deep Field South (ECDFS). These ELGs are selected from deep narrow H2S(1) and broad
Ks imaging of 383 arcmin2 obtained with CFHT/WIRCam. We construct spectral energy distributions (SEDs)
from U to Ks to derive the physical properties of ELGs. These [O III] ELGs are identified as starburst galaxies with
strong [O III] lines of LOIII ∼ 1042.6–1044.2 erg s−1 and have stellar masses of M* ∼ 109.0–1010.6 Me and star
formation rates of ∼10–210 Me yr−1
. Our results show that 24% of our sample galaxies are dusty with AV > 1 mag
and EW([O III])rest ∼ 70–500 Å, which are often missed in optically selected [O III] ELG samples
Mercury, Cadmium and Lead Biogeochemistry in the Soil–Plant–Insect System in Huludao City
Mercury, cadmium, and lead concentrations of ashed plants and insects samples were investigated and compared with those of soil to reveal their biogeochemical processes along food chains in Huludao City, Liaoning Province, China. Concentration factors of each fragments of the soil–plant–the herbivorous insect–the carnivorous insect food chain were 0.18, 6.57, and 7.88 for mercury; 6.82, 2.01, and 0.48 for cadmium; 1.47, 2.24, and 0.57 for lead, respectively. On the whole, mercury was the most largely biomagnified, but cadmium and lead were not greatly accumulated in the carnivorous insects as expected when the food chain extended to the secondary consumers. Results indicated that concentration factors depended on metals and insects species of food chains
Bis(2,2′-bipyridyl-κ2 N,N′)(sulfato-κ2 O,O′)cobalt(II) ethane-1,2-diol monosolvate
The title compound, [Co(SO4)(C10H8N2)2]·C2H6O2, has the Co2+ ion in a distorted octaÂhedral CoN4O2 coordination geometry. A twofold rotation axis passes through the Co and S atoms, and through the mid-point of the C—C bond of the ethaneÂdiol molÂecule. In the crystal, the [CoSO4(C10H8N2)2] and C2H6O2 units are held together by a pair of O—H⋯O hydrogen bonds
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