118466086
Autocorrelations of stellar light and mass at z∼ 0 and ∼1: from SDSS to DEEP2
We present measurements of projected autocorrelation functions wp(rp) for the stellar mass of galaxies and for their light in the U, B and V bands, using data from the third data release of the DEEP2 Galaxy Redshift Survey and the final data release of the Sloan Digital Sky Survey (SDSS). We investigate the clustering bias of stellar mass and light by comparing these to projected autocorrelations of dark matter estimated from the Millennium Simulations (MS) at z = 1 and 0.07, the median redshifts of our galaxy samples. All of the autocorrelation and bias functions show systematic trends with spatial scale and waveband which are impressively similar at the two redshifts. This shows that the well-established environmental dependence of stellar populations in the local Universe is already in place at z = 1. The recent MS-based galaxy formation simulation of Guo et al. (2011) reproduces the scale-dependent clustering of luminosity to an accuracy better than 30% in all bands and at both redshifts, but substantially overpredicts mass autocorrelations at separations below about 2 Mpc. Further comparison of the shapes of our stellar mass bias functions with those predicted by the model suggests that both the SDSS and DEEP2 data prefer a fluctuation amplitude of σ8 � 0.8 rather than the σ8 = 0.9 assumed by the MS.
119299152
Spectral Classification and Redshift Measurement for the SDSS-III Baryon Oscillation Spectroscopic Survey
We describe the automated spectral classification, redshift determination, and parameter measurement pipeline in use for the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III (SDSS-III) as of the survey's ninth data release (DR9), encompassing 831,000 moderate-resolution optical spectra. We give a review of the algorithms employed, and describe the changes to the pipeline that have been implemented for BOSS relative to previous SDSS-I/II versions, including new sets of stellar, galaxy, and quasar redshift templates. For the color-selected "CMASS" sample of massive galaxies at redshift 0.4 ≲ z ≲ 0.8 targeted by BOSS for the purposes of large-scale cosmological measurements, the pipeline achieves an automated classification success rate of 98.7% and confirms 95.4% of unique CMASS targets as galaxies (with the balance being mostly M stars). Based on visual inspections of a subset of BOSS galaxies, we find that approximately 0.2% of confidently reported CMASS sample classifications and redshifts are incorrect, and about 0.4% of all CMASS spectra are objects unclassified by the current algorithm which are potentially recoverable. The BOSS pipeline confirms that ~51.5% of the quasar targets have quasar spectra, with the balance mainly consisting of stars and low signal-to-noise spectra. Statistical (as opposed to systematic) redshift errors propagated from photon noise are typically a few tens of km s–1 for both galaxies and quasars, with a significant tail to a few hundreds of km s–1 for quasars. We test the accuracy of these statistical redshift error estimates using repeat observations, finding them underestimated by a factor of 1.19-1.34 for galaxies and by a factor of two for quasars. We assess the impact of sky-subtraction quality, signal-to-noise ratio, and other factors on galaxy redshift success. Finally, we document known issues with the BOSS DR9 spectroscopic data set and describe directions of ongoing development.
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.
55427109
THE CHROMOSPHERIC ACTIVITY, AGE, METALLICITY, AND SPACE MOTIONS OF 36 WIDE BINARIES
We present the chromospheric activity (CA) levels, metallicities, and full space motions for 41 F, G, K, and M dwarf stars in 36 wide binary systems. Thirty-one of the binaries contain a white dwarf (WD) component. In such binaries, the total age can be estimated by adding the cooling age of the WD to an estimate of the progenitor's main-sequence lifetime. To better understand how CA correlates to stellar age, 14 cluster member stars were also observed. Our observations demonstrate for the first time that, in general, CA decays with age from 50 Myr to at least 8 Gyr for stars with 1.0 {<=} V - I {<=} 2.4. However, little change occurs in the CA level for stars with V - I < 1.0 between 1 Gyr and 5 Gyr, consistent with the results of Pace et al. Our sample also exhibits a negative correlation between the stellar age and metallicity, a positive correlation between the stellar age and W space velocity component, and the W velocity dispersion increases with age. Finally, the population membership of these wide binaries is examined based upon their U, V, W kinematics, metallicity, and CA. We conclude that wide binaries are similar tomore » field and cluster stars in these respects. More importantly, they span a much more continuous range in age and metallicity than is afforded by nearby clusters.« less
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.
119296598
THE CH(G) INDEX AS A NEW CRITERION FOR SELECTING RED GIANT STARS
We have measured the CH G band (CH(G)) index for evolved stars in the globular cluster M3 based on the Sloan Digital Sky Survey (SDSS) spectroscopic survey. It is found that there is a useful way to select red giant branch (RGB) stars from the contamination of other evolved stars such as asymptotic giant branch (AGB) and red horizontal branch (RHB) stars by using the CH(G) index versus (g – r)0 diagram if the metallicity is known from the spectra. When this diagram is applied to field giant stars with similar metallicity, we establish a calibration of CH(G) = 1.625(g – r)0 – 1.174(g – r)2 0 – 0.934. This method is confirmed by stars with [Fe/H] ~ –2.3 where spectra of member stars in globular clusters M15 and M92 are available in the SDSS database. We thus extend this kind of calibration to every individual metallicity bin ranging from [Fe/H] ~ –3.0 to [Fe/H] ~ 0.0 by using field red giant stars with 0.4 ≤ (g – r)0 ≤ 1.0. The metallicity-dependent calibrations give CH(G) = 1.625(g – r)0 – 1.174(g – r)2 0 + 0.060[Fe/H] – 0.830 for –3.0 < [Fe/H] ≤ –1.2 and CH(G) = 0.953(g – r)0 – 0.655(g – r)2 0 + 0.060[Fe/H] – 0.650 for –1.2 < [Fe/H] < 0.0. The calibrations are valid for the SDSS spectroscopic data set, and they cannot be applied blindly to other data sets. With the two calibrations, a significant number of the contaminating stars (AGB and RHB stars) were excluded and thus a clear sample of red giant stars is obtained by selecting stars within ±0.05 mag of the calibration. The sample is published online and it is expected that this large and clean sample of RGB stars will provide new information on the formation and evolution of the Galaxy.
16273589
Chemical composition of 90 F and G disk dwarfs
High resolution, high S/N spectra have been obtained for a sample of 90 F and G main-sequence disk stars covering the metallicity range 1:0 < (Fe/H) < +0:1, and have been analysed in a parallel way to the work of Edvardsson et al. (1993a) in order to re-inspect their re- sults and to reveal new information on the chemical evo- lution of the Galactic disk. Compared to Edvardsson et al. the present study in- cludes several improvements. Eective temperatures are based on the Alonso et al. (1996) calibration of color in- dices by the infrared flux method and surface gravities are calculated from Hipparcos parallaxes, which also allow more accurate ages to be calculated from a comparison of MV and Te with isochrones. In addition, more reli- able kinematical parameters are derived from Hipparcos distances and proper motions in combination with accu- rate radial velocities. Finally, a larger spectral coverage, 5600 8800 A, makes it possible to improve the abundance accuracy by studying more lines and to discuss several el- ements not included in the work of Edvardsson et al. The present paper provides the data and discusses some general results of the abundance survey. A group of stars in the metallicity range of 1:0 < (Fe/H) < 0:6 having a small mean Galactocentric distance in the stellar orbits, Rm < 7 kpc, are shown to be older than the other disk stars and probably belong to the thick disk. Excluding these stars, a slight decreasing trend of (Fe/H) with increasing Rm and age is found, but a large scatter in (Fe/H) (up to 0.5 dex) is present at a given age andRm. Abundance ratios with respect to Fe show, on the other hand, no signicant scatter at a given (Fe/H). The derived
118331890
Rotating black rings on Taub-NUT
A bstractIn this paper, we construct new solutions describing rotating black rings on Taub-NUT using the inverse-scattering method. These are five-dimensional vacuum spacetimes, generalising the Emparan-Reall and extremal Pomeransky-Sen’kov black rings to a Taub-NUT background space. When reduced to four dimensions in Kaluza-Klein theory, these solutions describe (possibly rotating) electrically charged black holes in superposition with a finitely separated magnetic monopole. Various properties of these solutions are studied, from both a five- and four-dimensional perspective.