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.
10522140
Evolution of the most massive galaxies to z ∼ 0.6 – II. The link between radio AGN activity and star formation
We analyze the optical spectra of massive (log M∗/M⊙ > 11.4) radio-loud galaxies at z � 0.2 and z � 0.6. Our samples are generated by crossmatching the SDSS DR7 and BOSS spectroscopic galaxy catalogues with the FIRST and NVSS radio continuum surveys. By comparing stellar population parameters of these radio-loud samples with radio-quiet control samples matched in stellar mass, velocity dispersion and redshift, we investigate how the presence of a radio-emitting jet relates to the recent star formation history of the host galaxy. We also investigate how the emissionline properties of the radio galaxies evolve with redshift by stacking their spectra. Our main results are the following. (1) Both at low and at high redshift, half as many radio-loud as radio-quiet galaxies have experienced significant star formation in the past Gyr. This difference in star formation history is independent of the luminosity of the radio AGN, except at radio luminosities greater than 10 25.5 W Hz −1 , where it disappears. (2) The Balmer absorption line properties of massive galaxies that have experienced recent star formation show that star formation occurred as a burst in many of these systems. (3) Both the radio and the emission-line luminosity of radio AGN evolve significantly with redshift. The average [O iii] rest equivalent width increases by 1 dex from z = 0.2 to z = 0.6, and emission line ratios change from LINER-like at low redshift to Seyfert-like at high redshift. However, radio galaxies with similar stellar population parameters, have similar emission-line properties both at high- and at low-redshift. These results suggest that massive galaxies experience cyclical episodes of gas accretion, star formation and black hole growth, followed by the production of a radio jet that shuts down further activity. The behaviour of galaxies with log M∗/M⊙ > 11.4 is the same at z = 0.6 as it is at z = 0.2, except that higher redshift galaxies experience more star formation and black hole growth and produce more luminous radio jets during each accretion cycle.
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∗).
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.
118576878
Evolution of the most massive galaxies to z= 0.6 – I. A new method for physical parameter estimation
We use principal component analysis (PCA) to estimate stellar masses, mean stellar ages, star formation histories (SFHs), dust extinctions and stellar velocity dispersions for a set of ∼290 000 galaxies with stellar masses greater than 1011 M⊙ and redshifts in the range 0.4 < z < 0.7 from the Baryon Oscillation Spectroscopic Survey (BOSS). We find that the fraction of galaxies with active star formation first declines with increasing stellar mass, but then flattens above a stellar mass of 1011.5 M⊙ at z∼ 0.6. This is in striking contrast to z∼ 0.1, where the fraction of galaxies with active star formation declines monotonically with stellar mass. At stellar masses of 1012 M⊙, therefore, the evolution in the fraction of star-forming galaxies from z∼ 0.6 to the present day reaches a factor of ∼10. When we stack the spectra of the most massive, star-forming galaxies at z∼ 0.6, we find that half of their [O iii] emission is produced by active galactic nuclei. The black holes in these galaxies are accreting on average at ∼0.01 the Eddington rate. To obtain these results, we use the stellar population synthesis models of Bruzual & Charlot to generate a library of model spectra with a broad range of SFHs, metallicities, dust extinctions and stellar velocity dispersions. The PCA is run on this library to identify its principal components over the rest-frame wavelength range 3700–5500 A. We demonstrate that linear combinations of these components can recover information equivalent to traditional spectral indices such as the 4000-A break strength and HδA, with greatly improved signal-to-noise ratio (S/N). In addition, the method is able to recover physical parameters such as stellar mass-to-light ratio, mean stellar age, velocity dispersion and dust extinction from the relatively low S/N BOSS spectra. We examine in detail the sensitivity of our stellar mass estimates to the input parameters in our model library, showing that almost all changes result in systematic differences in logM* of 0.1 dex or less. The biggest differences are obtained when using different population synthesis models – stellar masses derived using Maraston et al. models are systematically smaller by up to 0.12 dex at young ages.
3661557
Stellar masses of SDSS-III/BOSS galaxies at z ∼ 0.5 and constraints to galaxy formation models
We calculate stellar masses for � 400,000 massive luminous galaxies at redshift � 0.2 0.7 using the first two years of data from the Baryon Oscillation S pectroscopic Survey (BOSS). Stellar masses are obtained by fitting model spec tral energy distributions to u,g,r,i,z magnitudes. Accurate BOSS spectroscopic redshifts are used to constrain the fits. We find that the distribution of stellar masses in BOSS is narr ow (� logM � 0.5 dex) and peaks at about log M/M⊙ � 11.3 (for a Kroupa initial stellar mass function), and that the mass sampling is uniform over the redshift range 0.2 to 0.6, in agreement with the intended BOSS target selection. The galaxy masses probed by BOSS extend over � 10 12 M⊙, providing unprecedented measurements of the high-mass end of the galaxy mass function. We find that the galaxy number density above � 2.5 · 10 11 M⊙ agrees with previous determinations within 2σ, but there is a slight offset towards lower number densities in BOSS. This alleviates a tension between the z �0.1 and the high-redshift mass function. We perform a comparison with semi-analytic galaxy formation models tailored to the BOSS target selection and volume, in order to contain incompleteness. The abundance of massive galaxies in the models compare well with the BOSS data. However, no evolution is detected from redshift � 0.6 to 0 in the data, whereas the abundance of massive galaxies in the models increases to redshift zero. BOSS data display colour-magnitude (mass) relations similar to those found in the local Universe, where the most massive galaxies are the reddest. On the other hand, the model colours do not display a dependence on stellar mass, span a narrower range and are typically bluer than the observations. We argue that the lack of a colour-mass relation in the models is mostly due to metallicity, which is too low in the models.
119214150
Metallicity calibration for solar type stars based on red spectra
Based on a high resolution and high signal-to-noise ratio (S/N) spectral analysis of 90 solar-type stars, we have established several new metallicity calibrations in the Teff range [5600, 6500] K based on red spectra with the wavelength range of 560–880 nm. The new metallicity calibrations are applied to determine the metallicity of solar analogs selected from Sloan Digital Sky Survey (SDSS) spectra. There is a good consistent result with the adopted value presented in SDSS-DR7 and a small scatter of 0.26 dex for stars with S/N > 50 being obtained. This study provides a new reliable way to derive the metallicity for solar-like stars with low resolution spectra. In particular, our calibrations are useful for finding metal-rich stars, which are missing in the SEGUE Stellar Parameter Pipeline.
18353027
An Observation of Autocorrelation of Wilson Loops on Lattice
An observation of the autocorrelation of Wilson loops on lattice is presented, especially for the small separation in Markov chain. We give a possible explanation for such behavior. We also present the dependence of autocorrelation behavior on the chosen operators in this paper.
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.
15339664
Lithium abundances for 185 main-sequence stars - Galactic evolution and stellar depletion of lithium
We present a survey of lithium abundances in 185 main-sequence field stars with $5600 \la T_{\rm eff} \la 6600$ K and $-1.4 \la {\rm [Fe/H]} \la +0.2$ based on new measurements of the equivalent width of the $\lambda 6708$ Lii line in high-resolution spectra of 130 stars and a reanalysis of data for 55 stars from Lambert et al. ([CITE]). The survey takes advantage of improved photometric and spectroscopic determinations of effective temperature and metallicity as well as mass and age derived from Hipparcos absolute magnitudes, offering an opportunity to investigate the behaviour of Li as a function of these parameters. An interesting result from this study is the presence of a large gap in the $\log \varepsilon ({\rm Li}) - T_{\rm eff}$ plane, which distinguishes "Li-dip"stars like those first identified in the Hyades cluster by Boesgaard & Tripicco ([CITE]) from other stars with a much higher Li abundance. The Li-dip stars concentrate on a certain mass, which decreases with metallicity from about 1.4 $M_{\odot}$ at solar metallicity to 1.1 $M_{\odot}$ at ${\rm [Fe/H]} \simeq -1.0$. Excluding the Li-dip stars and a small group of lower mass stars with $T_{\rm eff} < 5900$ K and $\log \varepsilon ({\rm Li}) < 1.5$, the remaining stars, when divided into four metallicity groups, may show a correlation between Li abundance and stellar mass. The dispersion around the $\log \varepsilon ({\rm Li})$-mass relation is about 0.2 dex below ${\rm [Fe/H]} \simeq -0.4$ and 0.3 dex above this metallicity, which cannot be explained by observational errors or differences in metallicity. Furthermore, there is no correlation between the residuals of the $\log \varepsilon ({\rm Li})$-mass relations and stellar age, which ranges from 1.5 Gyr to about 15 Gyr. This suggests that Li depletion occurs early in stellar life and that parameters other than stellar mass and metallicity affect the degree of depletion, e.g. initial rotation velocity and/or the rate of angular momentum loss. It cannot be excluded, however, that a cosmic scatter of the Li abundance in the Galaxy at a given metallicity contributes to the dispersion in Li abundance. These problems make it difficult to determine the Galactic evolution of Li from the data, but a comparison of the upper envelope of the distribution of stars in the $\log \varepsilon ({\rm Li}) - {\rm [Fe/H]}$ plane with recent Galactic evolutionary models by Romano et al. ([CITE]) suggests that novae are a major source for the Li production in the Galactic disk; their occurrence seems to be the explanation for the steep increase of Li abundance at ${\rm [Fe/H]} \simeq -0.4$.
119107777
The Roper Puzzle
We carried out a calculation of the Roper state with the Sequential Empirical Bayesian (SEB) method with overlap valence fermion on 2+1-flavor domain-wall fermion configurations on the 24^3 x 64 lattice with a^{-1} = 1.73 GeV. The light sea quark mass corresponds to a pion mass of 330 MeV. The mass of the Roper, chirally extrapolated to the physical pion mass, is 1404(112) MeV which is consistent with the experimental value at 1440 MeV. When compared to the Roper state calculation with variational method for Clover and twisted mass fermions, it is found that the Roper states from SEB with overlap fermion are systematically lower by 400 - 800 MeV for all the quark masses ranging from light to the strange mass region. We study the origin of the difference by exploring the size of the interpolation field in relation to the radial wavefunction of the Roper and also the dynamical influence of the higher Fock space.