137 research outputs found
The impact of filaments on dwarf galaxy properties in the Auriga simulations
With a hydrodynamical simulation using a simple galaxy formation model without taking into account feedback, our previous work has shown that dense and massive filaments at high redshift can provide potential wells to trap and compress gas, and hence affect galaxy formation in their resident low-mass haloes. In this paper, we make use of the Auriga simulations, a suite of high-resolution zoom-in hydrodynamical simulations of Milky Way-like galaxies, to study whether the conclusion still holds in the simulations with a sophisticated galaxy formation model. In agreement with the results of our previous work, we find that, compared to their counterparts with similar halo masses in the field, dwarf galaxies residing in filaments tend to have higher baryonic and stellar fractions. At the fixed parent halo mass, the filament dwarfs tend to have slightly higher star formation rates than those of field ones. But overall we do not find a clear difference in galaxy g - r colours between the filament and field populations. We also show that at high redshifts, the gas components in dwarf galaxies tend to have their spins aligned with the filaments in which they reside. Our results support a picture in which massive filaments at high redshift assist gas accretion and enhance star formation in their resident dwarf-sized dark matter haloes.Peer reviewe
Impacts of Land Use and Salinization on Soil Inorganic and Organic Carbon in the Middle-lower Yellow River Delta
ACKNOWLEDGEMENTS This study was financially supported by the National Natural Science Foundation of China (Nos. 41877028 and 41205104). This work also contributes to the activities of N-Circle projects, a UK-China Virtual Joint Centre on Nitrogen, funded by the Newton Fund via Biotechnology and Biological Sciences Research Council (BBSRC) (No. BB/N013484/1Peer reviewedPostprin
The abundance of dark matter haloes down to Earth mass
We use the Voids-within-Voids-within-Voids (VVV) simulations, a suite of
successive nested N-body simulations with extremely high resolution (denoted,
from low to high resolution, by L0 to L7), to test the Press-Schechter (PS),
Sheth-Tormen (ST), and extended Press-Schechter (EPS) formulae for the halo
abundance over the entire mass range, from mini-haloes of $10^{-6}\
\mathrm{M_\odot}10^{15}\ \mathrm{M_\odot}z=30z=0z=2\delta=010^{11-15}
~\mathrm{M_\odot}\delta<-0.6\lesssim 20\%10^{-6-12.5} ~\mathrm{M_\odot}z \sim 7-15z \sim 30$, the EPS prediction fits the simulations well
again. We further confirm our results by picking more subvolumes from the full
L0 simulation, finding that our conclusions depend only weakly on the size and
overdensity of the chosen region. Since at mean density the EPS reduces to the
PS mass function, its good agreement with the higher-level simulations implies
that the PS (or, even better, the ST) formula gives an accurate description of
the total halo mass function in representative regions of the universe.Comment: 10 pages, 5 figures (additional 2 figures in the appendix
The mass accretion history of dark matter haloes down to Earth mass
We take advantage of the unprecedented dynamical range provided by the
"Cosmic-Zoom" project to study the mass accretion history (MAH) of present-day
dark matter haloes over the entire mass range present in the CDM
paradigm when the dark matter is made of weakly interacting massive particles
of mass . In particular, we complement previous studies by
exploring the MAHs of haloes with mass from
down to Earth mass, . The formation redshift
of low-mass haloes anti-correlates weakly with mass, peaking at for
haloes of mass . Even lower masses are
affected by the free-streaming cutoff in the primordial spectrum of density
fluctuations and form at lower redshift. We compare MAHs in our simulations
with predictions from two analytical models based on the extended
Press-Schechter theory (EPS), and three empirical models derived by fitting and
extrapolating either results from cosmological -body simulations or Monte
Carlo realizations of halo growth. All models fit our simulations reasonably
well over the mass range for which they were calibrated. While the empirical
models match better for more massive haloes, $M>10^{10}\
h^{-1}\mathrm{M_{\odot}}20$ percent at high redshift. We conclude that EPS
theory predicts the hierarchical build-up of dark matter haloes quite well over
the entire mass range
Direct-Current Generator Based on Dynamic Water-Semiconductor Junction with Polarized Water as Moving Dielectric Medium
There is a rising prospective in harvesting energy from water droplets, as
microscale energy is required for the distributed sensors in the interconnected
human society. However, achieving a sustainable direct-current generating
device from water flow is rarely reported, and the quantum polarization
principle of the water molecular remains uncovered. Herein, we propose a
dynamic water-semiconductor junction with moving water sandwiched between two
semiconductors as a moving dielectric medium, which outputs a sustainable
direct-current voltage of 0.3 V and current of 0.64 uA with low internal
resistance of 390 kilohm. The sustainable direct-current electricity is
originating from the dynamic water polarization process in water-semiconductor
junction, in which water molecules are continuously polarized and depolarized
driven by the mechanical force and Fermi level difference, during the movement
of the water on silicon. We further demonstrated an encapsulated portable
power-generating device with simple structure and continuous direct-current
voltage, which exhibits its promising potential application in the field of
wearable electronic generators
Neutrino Physics with JUNO
The Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton multi-purposeunderground liquid scintillator detector, was proposed with the determinationof the neutrino mass hierarchy as a primary physics goal. It is also capable ofobserving neutrinos from terrestrial and extra-terrestrial sources, includingsupernova burst neutrinos, diffuse supernova neutrino background, geoneutrinos,atmospheric neutrinos, solar neutrinos, as well as exotic searches such asnucleon decays, dark matter, sterile neutrinos, etc. We present the physicsmotivations and the anticipated performance of the JUNO detector for variousproposed measurements. By detecting reactor antineutrinos from two power plantsat 53-km distance, JUNO will determine the neutrino mass hierarchy at a 3-4sigma significance with six years of running. The measurement of antineutrinospectrum will also lead to the precise determination of three out of the sixoscillation parameters to an accuracy of better than 1\%. Neutrino burst from atypical core-collapse supernova at 10 kpc would lead to ~5000inverse-beta-decay events and ~2000 all-flavor neutrino-proton elasticscattering events in JUNO. Detection of DSNB would provide valuable informationon the cosmic star-formation rate and the average core-collapsed neutrinoenergy spectrum. Geo-neutrinos can be detected in JUNO with a rate of ~400events per year, significantly improving the statistics of existing geoneutrinosamples. The JUNO detector is sensitive to several exotic searches, e.g. protondecay via the decay channel. The JUNO detector will providea unique facility to address many outstanding crucial questions in particle andastrophysics. It holds the great potential for further advancing our quest tounderstanding the fundamental properties of neutrinos, one of the buildingblocks of our Universe
Detection of the Diffuse Supernova Neutrino Background with JUNO
As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO
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