14138593
Sc and Mn abundances in disk and metal-rich halo stars
Sc and Mn abundances are determined for 119 F and G main-sequence stars with 1:4 < (Fe/H) < +0:1, represent- ing stars from the thin disk, the thick disk and the halo. The results indicate that Sc behaves like an element, showing a decreasing (Sc/Fe) with increasing metallicity in disk stars and a dual pattern in the kinematically selected halo stars. In contrast, Mn shows an increase from (Mn/Fe) ' 0:5 at (Fe/H) = 1:4 to zero at solar metallicity. There appears to be a discontinuity or sharp increase of (Mn/Fe) at (Fe/H) ' 0:7 corresponding to the transition between the thick and the thin disk. It is dis- cussed if supernovae of Type Ia are a major source of Mn in the Galactic disk or if the trend of (Mn/Fe) vs. (Fe/H) can be ex- plained by nucleosynthesis in Type II supernovae with a strong metallicity dependence of the yield.
118624022
Metallicity and Kinematic Distributions of Red Horizontal-branch Stars from the SDSS Survey
On the basis of a recently derived color-metallicity relation and stellar parameters from the Sloan Digital Sky Survey Data Release 7 spectroscopic survey, a large sample of red horizontal-branch (RHB) candidates have been selected to serve as standard candles. The metallicity and kinematic distributions of these stars indicate that they mainly originate from the thick-disk and the halo populations. The typical thick disk is characterized by the first group peaking at [Fe/H] ~ –0.6, V rot ~ 170 km s–1 with a vertical scale height around |Z| ~ 1.2 kpc, while stars with [Fe/H] 0 km s–1 (Halo I) shows a sign of metallicity gradient in the [Fe/H] versus |Z| diagram, while the other with V rot 10 kpc based on the star distribution in the R versus |Z| diagram.
117744661
Glueballs in charmonia radiative decays
Scalar [1] and tensor [2] glueballs created in J/ψ radiative decays are studied in quenched lattice QCD. Using two anisotropic lattices to approach the continuum limit, we compute the relevant form factors responsible for the decay rates for J/ψ → γG0++ and J/ψ → γG2++ . Comparing with the existing experimental data, it is argued that f0(1710) is a favorable candidate for scalar glueball. The decay rate for J/ψ → γG2++ is found to be quite substantial. A comprehensive search in the tensor channel on BESIII is therefore suggested.
15744505
Radio Luminosity, Black Hole Mass and Eddington Ratio for Quasars from the Sloan Digital Sky Survey
We investigate the MBH-O''.relation for radio-loud quasars with redshift z＜0.83 in Data Release 3 of the Sloan Digital Sky Survey (SDSS).The sample consists of 3772 quasars with better models of the H/~ and [O III] lines and available radio luminosity,including 306 radio-loud quasars,3466 radio-quiet quasars with measured radio luminosity or upper-limit of radio luminosity (181 radio-quiet quasars with measured radio luminosity).The virial supermassive black hole mass (MBH) is calculated from the broad H/line,and the host stellar velocity dispersion (σ*) is traced by the core [O III] gaseous velocity dispersion.The radio luminosity and radio loudness are derived from the FIRST catalog.Our results are as follows:(1) For radio-quiet quasars,we confirm that there is no obvious deviation from the MBH-O.relation defined for inactive galaxies when the uncertainties in MBH and the luminosity bias are concerned.(2) We find that the radio-loud quasars deviate more from the MBH-σ.relation than do the radio-quiet quasars.This deviation is only partly due to a possible cosmological evolution of the MBH-σ* relation and the luminosity bias.(3) The radioluminosity is proportional to M128+0.23-0.16 BH(LBol/LEdd)1.29+0.31-0.24 for radio-quiet quasars and to M3.10+0.6.-0.70(LBol.LEdd)4.18+1.40-1.10 for radio-loud quasars.The weaker dependence of the radio luminosity on the mass and the Eddington ratio for radio-loud quasars shows that other physical effects would account for their radio luminosities,such as the spin of the black hole.
118503079
Early Growth of Massive Black Holes in Quasars
Episodic activity of quasars is driving growth of supermassive black holes (SMBHs) via accretion of baryon gas. In this Letter, we develop a simple method to analyze the duty cycle of quasars up to the redshift -->z ~ 6 universe from luminosity functions (LFs). We find that the duty cycle below redshift -->z ~ 2 follows the cosmic history of star formation rate (SFR) density. Beyond -->z ~ 2, the evolutionary trends of the duty cycle are opposite to that of the cosmic SFR density history, implying the role of feedback from black hole activity. With the duty cycle, we get the net lifetime of quasars ( -->z ≤ 5) about ~109 yr. Based on the local SMBHs, the mean mass of SMBHs is obtained at any redshifts and their seeds are of -->105 M☉ at the reionization epoch ( -->zre) of the universe through the conservation of black hole number density in a comoving frame. We find that primordial black holes (~103 M☉) are able to grow up to the seeds via a moderate super-Eddington accretion of ~30 times the critical rate from -->z = 24 to -->zre. Highly super-Eddington accretion onto the primordial black holes is not necessary.
119187489
ABSORPTION-LINE PROBES OF THE PREVALENCE AND PROPERTIES OF OUTFLOWS IN PRESENT-DAY STAR-FORMING GALAXIES
We analyze star-forming galaxies drawn from SDSS DR7 to show how the interstellar medium (ISM) Nai λλ5890, 5896 (Na D) absorption lines depend on galaxy physical properties, and to look for evidence of galactic winds. We combine the spectra of galaxies with similar geometry/physical parameters to create composite spectra with signalto-noise ∼300. The stellar continuum is modeled using stellar population synthesis models, and the continuumnormalized spectrum is fit with two Nai absorption components. We find that (1) ISM Na D absorption lines with equivalent widths EW > 0.8 A are only prevalent in disk galaxies with specific properties—large extinction (AV ), high star formation rates (SFR), high SFR per unit area (ΣSFR), or high stellar mass (M∗); (2) the ISM Na D absorption lines can be separated into two components: a quiescent disk-like component at the galaxy systemic velocity and an outflow component; (3) the disk-like component is much stronger in the edge-on systems, and the outflow component covers a wide angle but is stronger within 60 ◦ of the disk rotation axis; (4) the EW and covering factor of the disk component correlate strongly with dust attenuation, highlighting the importance that dust shielding may play in the survival of Nai; (5) the EW of the outflow component depends primarily on ΣSFR and secondarily on AV ; and (6) the outflow velocity varies from ∼120 to 160 km s −1 but shows little hint of a correlation with galaxy physical properties over the modest dynamic range that our sample probes (1.2 dex in log ΣSFR and 1 dex in log M∗).
119301374
Balanced electric-magnetic dihole in Kaluza-Klein theory
A bstractWe present a four-dimensional double-black-hole (or dihole) solution in KaluzaKlein theory, describing a superposition of an electrically charged and a magnetically charged black hole. This system can be balanced for appropriately chosen parameters, and the resulting space-time is completely regular on and outside the event horizons. This solution was constructed using the inverse-scattering method in five-dimensional vacuum gravity, in which it describes a rotating black ring surrounding a static black hole on a Taub-NUT background space. Various properties of this solution are studied, from both a four- and five-dimensional perspective.