2,817 research outputs found
Fourth ABC Index and Fifth GA Index of Certain Special Molecular Graphs
Several chemical indices have been introduced in theoretical chemistry to measure the properties of molecular structures, such as atom bond connectivity index and geometric-arithmetic index. In this paper, we present the fourth atom bond connectivity index and fifth geometric-arithmetic index of fan molecular graph, wheel molecular graph, gear fan molecular graph, gear wheel molecular graph, and their r-corona molecular graphs
Photometric Objects Around Cosmic Webs (PAC) Delineated in a Spectroscopic Survey. IV. High Precision Constraints on the Evolution of Stellar-Halo Mass Relation at Redshift
Taking advantage of the Photometric objects Around Cosmic webs (PAC) method
developed in Paper I, we measure the excess surface density
of photometric objects around spectroscopic objects
down to stellar mass , and
in the redshift ranges of , and
respectively, using the data from the DESI Legacy Imaging Surveys
and the spectroscopic samples of Slogan Digital Sky Survey (i.e. Main, LOWZ and
CMASS samples). We model the measured in N-body
simulation using abundance matching method and constrain the stellar-halo mass
relations (SHMR) in the three redshift ranges to percent level. With the
accurate modeling, we demonstrate that the stellar mass scatter for given halo
mass is nearly a constant, and that the empirical form of Behroozi et al
describes the SHMR better than the double power law form at low mass. Our SHMR
accurately captures the downsizing of massive galaxies since , while
it also indicates that small galaxies are still growing faster than their host
halos. The galaxy stellar mass functions (GSMF) from our modeling are in
perfect agreement with the {\it model-independent} measurements in Paper III,
though the current work extends the GSMF to a much smaller stellar mass. Based
on the GSMF and SHMR, we derive the stellar mass completeness and halo
occupation distributions for the LOWZ and CMASS samples, which are useful for
correctly interpreting their cosmological measurements such as galaxy-galaxy
lensing and redshift space distortion.Comment: 18 + 9 (appendix) pages, 12 + 7 (appendix) figures. Main results in
Figure 6-9. Submitted to ApJ. arXiv admin note: text overlap with
arXiv:2207.1242
Hybrid quantum device based on NV centers in diamond nanomechanical resonators plus superconducting waveguide cavities
We propose and analyze a hybrid device by integrating a microscale diamond
beam with a single built-in nitrogen-vacancy (NV) center spin to a
superconducting coplanar waveguide (CPW) cavity. We find that under an ac
electric field the quantized motion of the diamond beam can strongly couple to
the single cavity photons via dielectric interaction. Together with the strong
spin-motion interaction via a large magnetic field gradient, it provides a
hybrid quantum device where the dia- mond resonator can strongly couple both to
the single microwave cavity photons and to the single NV center spin. This
enables coherent information transfer and effective coupling between the NV
spin and the CPW cavity via mechanically dark polaritons. This hybrid
spin-electromechanical de- vice, with tunable couplings by external fields,
offers a realistic platform for implementing quantum information with single NV
spins, diamond mechanical resonators, and single microwave photons.Comment: Accepted by Phys. Rev. Applie
Powerful High Velocity-Dispersion Molecular Hydrogen Associated with an Intergalactic Shock Wave in Stephan's Quintet
We present the discovery of strong mid-infrared emission lines of molecular
hydrogen of apparently high velocity dispersion (~870 km/s) originating from a
group-wide shock wave in Stephan's Quintet. These Spitzer Space Telescope
observations reveal emission lines of molecular hydrogen and little else. this
is the first time an almost pure H_2 line spectrum has been seen in an
extragalactic object. Along with the absence of PAH features and very low
excitation ionized gas tracers, the spectra resemble shocked gas seen in
Galactic supernova remnants, but on a vast scale. The molecular emission
extends over 24 kpc along the X-ray emitting shock-front, but has ten times the
surface luminosity as the soft X-rays, and about one-third the surface
luminosity of the IR continuum. We suggest that the powerful H_2 emission is
generated by the shock wave caused when a high-velocity intruder galaxy
collides with filaments of gas in the galaxy group. Our observations suggest a
close connection between galaxy-scale shock-waves and strong broad H_2 emission
lines, like those seen in the spectra of Ultraluminous Infrared Galaxies where
high-speed collisions between galaxy disks are common.Comment: 4 pages, 4 figures and 1 tabl
The dust emission SED of X-ray emitting regions in Stephan's Quintet
We analysed the Spitzer maps of Stephan's Quintet in order to investigate the
nature of the dust emission associated with the X-ray emitting regions of the
large scale intergalactic shock and of the group halo. This emission can in
principle be powered by dust-gas particle collisions, thus providing efficient
cooling of the hot gas. However the results of our analysis suggest that the
dust emission from those regions is mostly powered by photons. Nonetheless dust
collisional heating could be important in determining the cooling of the IGM
gas and the large scale star formation morphology observed in SQ.Comment: Conference proceedings IAU Symposium 284 "The Spectral energy
distribution of galaxies", 5-9 September 2011, Preston, U
The star formation efficiency in Stephan's Quintet intragroup regions
We investigated the star formation efficiency for all the dust emitting
sources in Stephan's Quintet (SQ). We inferred star formation rates using
Spitzer MIR/FIR and GALEX FUV data and combined them with gas column density
measurements by various authors, in order to position each source in a
Kennicutt-Schmidt diagram. Our results show that the bright IGM star formation
regions in SQ present star formation efficiencies consistent with those
observed within local galaxies. On the other hand, star formation in the
intergalactic shock region seems to be rather inhibited.Comment: Conference proceedings "Galaxy Mergers in an evolving Universe",
23-28 October 2011, Hualien, Taiwa
Inkjet-printed stretchable and low voltage synaptic transistor array.
Wearable and skin electronics benefit from mechanically soft and stretchable materials to conform to curved and dynamic surfaces, thereby enabling seamless integration with the human body. However, such materials are challenging to process using traditional microelectronics techniques. Here, stretchable transistor arrays are patterned exclusively from solution by inkjet printing of polymers and carbon nanotubes. The additive, non-contact and maskless nature of inkjet printing provides a simple, inexpensive and scalable route for stacking and patterning these chemically-sensitive materials over large areas. The transistors, which are stable at ambient conditions, display mobilities as high as 30 cm2 V-1 s-1 and currents per channel width of 0.2 mA cm-1 at operation voltages as low as 1 V, owing to the ionic character of their printed gate dielectric. Furthermore, these transistors with double-layer capacitive dielectric can mimic the synaptic behavior of neurons, making them interesting for conformal brain-machine interfaces and other wearable bioelectronics
Molecular Gas in Infrared Ultraluminous QSO Hosts
We report CO detections in 17 out of 19 infrared ultraluminous QSO (IR QSO)
hosts observed with the IRAM 30m telescope. The cold molecular gas reservoir in
these objects is in a range of 0.2--2.1 (adopting a
CO-to- conversion factor ). We find that the molecular gas properties of IR QSOs,
such as the molecular gas mass, star formation efficiency () and the CO (1-0) line widths, are indistinguishable
from those of local ultraluminous infrared galaxies (ULIRGs). A comparison of
low- and high-redshift CO detected QSOs reveals a tight correlation between
L and for all QSOs. This suggests that,
similar to ULIRGs, the far-infrared emissions of all QSOs are mainly from dust
heated by star formation rather than by active galactic nuclei (AGNs),
confirming similar findings from mid-infrared spectroscopic observations by
{\it Spitzer}. A correlation between the AGN-associated bolometric luminosities
and the CO line luminosities suggests that star formation and AGNs draw from
the same reservoir of gas and there is a link between star formation on
kpc scale and the central black hole accretion process on much smaller scales.Comment: 30 pages, 9 figures, accepted for publication in The Astrophysical
Journa
Entropic force and its cosmological implications
We investigate a possibility of realizing the entropic force into the
cosmology. A main issue is how the holographic screen is implemented in the
Newtonian cosmology. Contrary to the relativistic realization of Friedmann
equations, we do not clarify the connection between Newtonian cosmology and
entropic force because there is no way of implementing the holographic screen
in the Newtonian cosmology.Comment: 16 pages, no figures, version "Accepted for publication in
Astrophysics & Space Science
Effect of the momentum dependence of nuclear symmetry potential on the transverse and elliptic flows
In the framework of the isospin-dependent Boltzmann-Uehling-Uhlenbeck
transport model, effect of the momentum dependence of nuclear symmetry
potential on nuclear transverse and elliptic flows in the neutron-rich reaction
Sn+Sn at a beam energy of 400 MeV/nucleon is studied. We find
that the momentum dependence of nuclear symmetry potential affects the rapidity
distribution of the free neutron to proton ratio, the neutron and the proton
transverse flows as a function of rapidity. The momentum dependence of nuclear
symmetry potential affects the neutron-proton differential transverse flow more
evidently than the difference of neutron and proton transverse flows as well as
the difference of proton and neutron elliptic flows. It is thus better to probe
the symmetry energy by using the difference of neutron and proton flows since
the momentum dependence of nuclear symmetry potential is still an open
question. And it is better to probe the momentum dependence of nuclear symmetry
potential by using the neutron-proton differential transverse flow and the
rapidity distribution of the free neutron to proton ratio.Comment: 6 pages, 6 figures, to be published by EPJ
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