2,817 research outputs found

    Fourth ABC Index and Fifth GA Index of Certain Special Molecular Graphs

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    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 z<0.7z<0.7

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    Taking advantage of the Photometric objects Around Cosmic webs (PAC) method developed in Paper I, we measure the excess surface density nˉ2wp\bar{n}_2w_{{\rm{p}}} of photometric objects around spectroscopic objects down to stellar mass 108.0M⊙10^{8.0}M_{\odot}, 109.2M⊙10^{9.2}M_{\odot} and 109.8M⊙10^{9.8}M_{\odot} in the redshift ranges of zs<0.2z_s<0.2, 0.2<zs<0.40.2<z_s<0.4 and 0.5<zs<0.70.5<z_s<0.7 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 nˉ2wp\bar{n}_2w_{{\rm{p}}} 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 zs=0.7z_s=0.7, 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

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    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

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    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

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    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

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    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.

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    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

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    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--2.1×1010M⊙\times 10^{10}M_\odot (adopting a CO-to-H2{\rm H_2} conversion factor αCO=0.8M⊙(Kkms−1pc2)−1\alpha_{\rm CO}=0.8 M_\odot {\rm (K km s^{-1} pc^2)^{-1}}). We find that the molecular gas properties of IR QSOs, such as the molecular gas mass, star formation efficiency (LFIR/LCO′L_{\rm FIR}/L^\prime_{\rm CO}) 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 LFIR_{\rm FIR} and LCO(1−0)′L^\prime_{\rm CO(1-0)} 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 ∼\sim 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

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    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

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    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 132^{132}Sn+124^{124}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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