- ID:
- ivo://CDS.VizieR/J/MNRAS/438/1288
- Title:
- SEDs of type I AGN in XMM-COSMOS. II.
- Short Name:
- J/MNRAS/438/1288
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mid-infrared-to-ultraviolet (0.1-10{mu}m) spectral energy distribution (SED) shapes of 407 X-ray-selected radio-quiet type 1 active galactic nuclei (AGN) in the wide-field 'Cosmic Evolution Survey' (COSMOS) have been studied for signs of evolution. For a sub-sample of 200 radio-quiet quasars with black hole mass estimates and host galaxy corrections, we studied their mean SEDs as a function of a broad range of redshift, bolometric luminosity, black hole mass and Eddington ratio, and compared them with the Elvis et al. (1994ApJS...95....1E, Cat. J/ApJS/95/1, hereafter E94) type 1 AGN mean SED. We found that the mean SEDs in each bin are closely similar to each other, showing no statistical significant evidence of dependence on any of the analysed parameters. We also measured the SED dispersion as a function of these four parameters, and found no significant dependences. The dispersion of the XMM-COSMOS SEDs is generally larger than E94 SED dispersion in the ultraviolet, which might be due to the broader 'window function' for COSMOS quasars, and their X-ray-based selection.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/136/2050
- Title:
- SEGUE stellar parameter pipeline. II.
- Short Name:
- J/AJ/136/2050
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We validate the accuracy and precision of the current SEGUE (Sloan Extension for Galactic Understanding and Exploration) Stellar Parameter Pipeline (SSPP), which determines stellar atmospheric parameters (effective temperature, surface gravity, and metallicity) and radial velocities (RVs), by comparing these estimates for selected members of three globular clusters (M 13, M 15, and M 2) and two open clusters (NGC 2420 and M 67) to the literature values. Spectroscopic and photometric data obtained during the course of the original Sloan Digital Sky Survey (SDSS-I) and its first extension (SDSS-II/SEGUE) are used to determine atmospheric parameter and RV estimates for stars in these clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/136/2070
- Title:
- SEGUE stellar parameter pipeline. III.
- Short Name:
- J/AJ/136/2070
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report high-resolution spectroscopy of 125 field stars previously observed as part of the Sloan Digital Sky Survey and its program for Galactic studies, the Sloan Extension for Galactic Understanding and Exploration (SEGUE). These spectra are used to measure radial velocities and to derive atmospheric parameters, which we compare with those reported by the SEGUE Stellar Parameter Pipeline (SSPP). The SSPP obtains estimates of these quantities based on SDSS ugriz photometry and low-resolution (R~2000) spectroscopy.
- ID:
- ivo://CDS.VizieR/J/AJ/141/90
- Title:
- SEGUE stellar parameter pipeline. V.
- Short Name:
- J/AJ/141/90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a method for the determination of [{alpha}/Fe] ratios from low-resolution (R=2000) SDSS/SEGUE stellar spectra. By means of a star-by-star comparison with degraded spectra from the ELODIE spectral library and with a set of moderately high-resolution (R=15000) and medium-resolution (R=6000) spectra of SDSS/SEGUE stars, we demonstrate that we are able to measure [{alpha}/Fe] from SDSS/SEGUE spectra (with S/N>20/1) to a precision of better than 0.1dex, for stars with atmospheric parameters in the range Teff=[4500,7000]K, logg=[1.5,5.0], and [Fe/H]=[-1.4,+0.3], over the range [{alpha}/Fe]=[-0.1,+0.6]. For stars with [Fe/H]<-1.4, our method requires spectra with slightly higher signal-to-noise to achieve this precision (S/N>25/1).
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/1131
- Title:
- Selection function of Milky Way field stars
- Short Name:
- J/MNRAS/460/1131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Gaia-ESO Survey was designed to target all major Galactic components (i.e. bulge, thin and thick discs, halo and clusters), with the goal of constraining the chemical and dynamical evolution of the Milky Way. This paper presents the methodology and considerations that drive the selection of the targeted, allocated and successfully observed Milky Way field stars. The detailed understanding of the survey construction, specifically the influence of target selection criteria on observed Milky Way field stars is required in order to analyse and interpret the survey data correctly. We present the target selection process for the Milky Way field stars observed with Very Large Telescope/Fibre Large Array Multi Element Spectrograph and provide the weights that characterize the survey target selection. The weights can be used to account for the selection effects in the Gaia-ESO Survey data for scientific studies. We provide a couple of simple examples to highlight the necessity of including such information in studies of the stellar populations in the Milky Way.
1526. Seven-year WMAP catalog
- ID:
- ivo://CDS.VizieR/J/ApJS/192/15
- Title:
- Seven-year WMAP catalog
- Short Name:
- J/ApJS/192/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present updated estimates of Galactic foreground emission using seven years of WMAP data. Using the power spectrum of differences between multi-frequency template-cleaned maps, we find no evidence for foreground contamination outside of the updated (KQ85y7) foreground mask. We place a 15uK upper bound on rms foreground contamination in the cleaned maps used for cosmological analysis. Further, the cleaning process requires only three power-law foregrounds outside of the mask. We find no evidence for polarized foregrounds beyond those from soft (steep-spectrum) synchrotron and thermal dust emission; in particular we find no indication in the polarization data of an extra "haze" of hard synchrotron emission from energetic electrons near the Galactic center. We provide an updated map of the cosmic microwave background (CMB) using the internal linear combination method, updated foreground masks, and updates to point source catalogs using two different techniques. With additional years of data, we now detect 471 point sources using a five-band technique and 417 sources using a three-band CMB-free technique. In total there are 62 newly detected point sources, a 12% increase over the five-year release.
1527. SEXSI catalog
- ID:
- ivo://CDS.VizieR/J/ApJ/596/944
- Title:
- SEXSI catalog
- Short Name:
- J/ApJ/596/944
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Serendipitous Extragalactic X-Ray Source Identification (SEXSI) program is designed to extend greatly the sample of identified extragalactic hard X-ray (2-10keV) sources at intermediate fluxes (~10^-13^ to 10^-15^erg/cm^2^/s). SEXSI, which studies sources selected from more than 2deg^2^, provides an essential complement to the Chandra Deep Fields, which reach depths of 5x10^-16^erg/cm^2^/s (2-10keV) but over a total area of less than 0.2deg^2^. In this paper we describe the characteristics of the survey and our X-ray data analysis methodology. We present the cumulative flux distribution for the X-ray sample of 1034 hard sources and discuss the distribution of spectral hardness ratios. Our logN-logS in this intermediate flux range connects to those found in the Deep Fields, and by combining the data sets, we constrain the hard X-ray population over the flux range in which the differential number counts change slope and from which the bulk of the 2-10keV X-ray background arises. We further investigate the logN-logS distribution separately for soft and hard sources in our sample, finding that while a clear change in slope is seen for the softer sample, the hardest sources are well described by a single power law down to the faintest fluxes, consistent with the notion that they lie at lower average redshift.
1528. SEXSI catalog. II
- ID:
- ivo://CDS.VizieR/J/ApJS/156/35
- Title:
- SEXSI catalog. II
- Short Name:
- J/ApJS/156/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Serendipitous Extragalactic X-ray Source Identification (SEXSI) Program is designed to expand significantly the sample of identified extragalactic hard X-ray sources at intermediate fluxes, 10^-13^ergs/cm^2^/s<~S_2-10keV_<10^-15^ergs/cm^2^/s. SEXSI, which includes sources derived from more than 2{deg}^2^ of Chandra images, provides the largest hard X-ray-selected sample yet studied, offering an essential complement to the Chandra Deep Fields (total area 0.2{deg}^2^). In this paper we describe R-band optical imaging of the SEXSI fields from the Palomar, MDM, and Keck observatories. We have identified counterparts or derived flux limits for nearly 1000 hard X-ray sources. Using the optical images, we derive accurate source positions. We investigate correlations between optical and X-ray flux, and optical flux and X-ray hardness ratio. We also study the density of optical sources surrounding X-ray counterparts, as well as the properties of optically faint, hard X-ray sources.
1529. SEXSI catalog. III
- ID:
- ivo://CDS.VizieR/J/ApJS/165/19
- Title:
- SEXSI catalog. III
- Short Name:
- J/ApJS/165/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the catalog of 477 spectra from the Serendipitous Extragalactic X-ray Source Identification (SEXSI) program, a survey designed to probe the dominant contributors to the 2-10keV cosmic X-ray background. Our survey covers 1deg^2^ of sky to 2-10keV fluxes of 1x10^-14^ergs/cm^2^/s, and 2deg^2^ for fluxes of 3x10^-14^ergs/cm^2^/s. Our spectra reach to R-band magnitudes of ~<24 and have produced identifications and redshifts for 438 hard X-ray sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/882/9
- Title:
- SFR & gas-phase metallicity in MaNGA gal.
- Short Name:
- J/ApJ/882/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The role of gas accretion in galaxy evolution is still a matter of debate. The presence of inflows of metal-poor gas that trigger star formation bursts of low metallicity has been proposed as an explanation for the local anticorrelation between star formation rate (SFR) and gas-phase metallicity (Z_g_) found in the literature. In the present study, we show how the anticorrelation is also present as part of a diversified range of behaviors for a sample of more than 700 nearby spiral galaxies from the SDSS-IV MaNGA survey. We have characterized the local relation between SFR and Z_g_ after subtracting the azimuthally averaged radial profiles of both quantities. Of the analyzed galaxies, 60% display an SFR-Z_g_ anticorrelation, with the remaining 40% showing no correlation (19%) or positive correlation (21%). Applying a random forest machine-learning algorithm, we find that the slope of the correlation is mainly determined by the average gas-phase metallicity of the galaxy. Galaxy mass, g-r colors, stellar age, and mass density seem to play a less significant role. This result is supported by the performed second-order polynomial regression analysis. Thus, the local SFR-Z_g_ slope varies with the average metallicity, with the more metal-poor galaxies presenting the lowest slopes (i.e., the strongest SFR-Z_g_ anticorrelations), and reversing the relation for more metal-rich systems. Our results suggest that external gas accretion fuels star formation in metal-poor galaxies, whereas in metal-rich systems, the gas comes from previous star formation episodes.
