THE INFORMATION OF THE MILKY WAY FROM TWO MICRON ALL SKY SURVEY WHOLE SKY STAR COUNT: THE LUMINOSITY FUNCTION

2010 ◽  
Vol 724 (1) ◽  
pp. 182-188 ◽  
Author(s):  
Chan-Kao Chang ◽  
Chung-Ming Ko ◽  
Ting-Hung Peng
Keyword(s):  
Luminosity Function ◽  
Milky Way ◽  
Sky Survey ◽  
Star Count

scholarly journals CONSTRAINTS ON THE SHAPE OF THE MILKY WAY DARK MATTER HALO FROM JEANS EQUATIONS APPLIED TO SLOAN DIGITAL SKY SURVEY DATA

2012 ◽  
Vol 758 (1) ◽  
pp. L23 ◽  
Author(s):  
Sarah R. Loebman ◽  
Željko Ivezić ◽  
Thomas R. Quinn ◽  
Fabio Governato ◽  
Alyson M. Brooks ◽  
...  
Keyword(s):  
Dark Matter ◽  
Survey Data ◽  
Milky Way ◽  
Sloan Digital Sky Survey ◽  
Dark Matter Halo ◽  
Sky Survey

scholarly journals The Luminosity Function of the Milky Way Satellites

2008 ◽  
Vol 686 (1) ◽  
pp. 279-291 ◽  
Author(s):  
S. Koposov ◽  
V. Belokurov ◽  
N. W. Evans ◽  
P. C. Hewett ◽  
M. J. Irwin ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Milky Way

scholarly journals Estimation of Galactic model parameters in high latitudes with the SDSS and SCUSS

2013 ◽  
Vol 9 (S298) ◽  
pp. 404-404
Author(s):  
Cuihua Du ◽  
Yunpeng Jia ◽  
Xiyan Peng
Keyword(s):  
Model Parameters ◽  
High Latitudes ◽  
The South ◽  
Statistical Errors ◽  
Count Method ◽  
Sky Survey ◽  
Star Count ◽  
The Galaxy ◽  
Galactic Model

AbstractBased on the South Galactic Cap U-band Sky Survey (SCUSS) and SDSS observation, we adopted the star-count method to analyze the stellar distribution in different directions of the Galaxy. We find that these model parameters may be variable with observed direction, which cannot simply be attributed to statistical errors.

scholarly journals The Milky Way Revealed by Variable Stars. I. Sample Selection of RR Lyrae Stars and Evidence for Merger History

2022 ◽  
Vol 258 (1) ◽  
pp. 20
Author(s):  
Iminhaji Ablimit ◽  
Gang Zhao ◽  
Uy. Teklimakan ◽  
Jian-Rong Shi ◽  
Kunduz Abdusalam
Keyword(s):  
Milky Way ◽  
Sample Selection ◽  
Variable Stars ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Sky Survey ◽  
Spectroscopic Information ◽  
History Of ◽  
Dual Origin ◽  
Lyrae Stars

Abstract In order to study the Milky Way, RR Lyrae (RRL) variable stars identified by Gaia, ASAS-SN, and ZTF sky survey projects have been analyzed as tracers in this work. Photometric and spectroscopic information of 3417 RRLs including proper motions, radial velocity, and metallcity are obtained from observational data of Gaia, LAMOST, GALAH, APOGEE, and RAVE. Precise distances of RRLs with typical uncertainties less than 3% are derived by using a recent comprehensive period–luminosity–metallicity relation. Our results from kinematical and chemical analysis provide important clues for the assembly history of the Milky Way, especially for the Gaia–Sausage ancient merger. The kinematical and chemical trends found in this work are consistent with those of recent simulations that indicated that the Gaia–Sausage merger had a dual origin in the Galactic thick disk and halo. As recent similar works have found, the halo RRL sample in this work contains a subset of radially biased orbits besides a more isotropic component. This higher orbital anisotropy component amounts to β ≃ 0.8, and it contributes between 42% and 83% of the halo RRLs at 4 < R( kpc) < 20.

scholarly journals The optically selected 1.4-GHz quasar luminosity function below 1 mJy

2020 ◽  
Vol 492 (4) ◽  
pp. 5297-5312 ◽  
Author(s):  
Eliab Malefahlo ◽  
Mario G Santos ◽  
Matt J Jarvis ◽  
Sarah V White ◽  
Jonathan T L Zwart
Keyword(s):  
Luminosity Function ◽  
Significant Contribution ◽  
Detection Threshold ◽  
Simulated Data ◽  
Sloan Digital Sky Survey ◽  
Radio Luminosity ◽  
Host Galaxies ◽  
Star Forming ◽  
Sky Survey ◽  
Radio Luminosity Function

ABSTRACT We present the radio luminosity function (RLF) of optically selected quasars below 1 mJy, constructed by applying a Bayesian-fitting stacking technique to objects well below the nominal radio flux density limit. We test the technique using simulated data, confirming that we can reconstruct the RLF over three orders of magnitude below the typical 5σ detection threshold. We apply our method to 1.4-GHz flux densities from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey, extracted at the positions of optical quasars from the Sloan Digital Sky Survey over seven redshift bins up to z = 2.15, and measure the RLF down to two orders of magnitude below the FIRST detection threshold. In the lowest redshift bin (0.2 &lt; z &lt; 0.45), we find that our measured RLF agrees well with deeper data from the literature. The RLF for the radio-loud quasars flattens below $\log _{10}[L_{1.4}/{\rm W\, Hz}^{-1}] \approx 25.5$ and becomes steeper again below $\log _{10}[L_{1.4}/{\rm W\, Hz}^{-1}] \approx 24.8$, where radio-quiet quasars start to emerge. The radio luminosity where radio-quiet quasars emerge coincides with the luminosity where star-forming galaxies are expected to start dominating the radio source counts. This implies that there could be a significant contribution from star formation in the host galaxies, but additional data are required to investigate this further. The higher redshift bins show a similar behaviour to the lowest z bin, implying that the same physical process may be responsible.

scholarly journals The Extremely Luminous Quasar Survey in the Sloan Digital Sky Survey Footprint. III. The South Galactic Cap Sample and the Quasar Luminosity Function at Cosmic Noon

2019 ◽  
Vol 871 (2) ◽  
pp. 258 ◽  
Author(s):  
Jan-Torge Schindler ◽  
Xiaohui Fan ◽  
Ian D. McGreer ◽  
Jinyi Yang ◽  
Feige Wang ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Sloan Digital Sky Survey ◽  
The South ◽  
Sky Survey

The Luminosity Function of z>4 Quasars from the Second Palomar Sky Survey

1995 ◽  
Vol 110 ◽  
pp. 2553 ◽  
Author(s):  
J. D. Kennefick ◽  
S. G. Djorgovski ◽  
R. R. de Carvalho
Keyword(s):  
Luminosity Function ◽  
Sky Survey

scholarly journals Star Counts

1984 ◽  
Vol 78 ◽  
pp. 315-324
Author(s):  
Richard G. Kron
Keyword(s):  
Spatial Distribution ◽  
Density Function ◽  
Luminosity Function ◽  
Stellar Populations ◽  
Line Of Sight ◽  
Luminosity Functions ◽  
Star Count

The number of stars counted along a particular line of sight depends on the spatial distribution of stars, the luminosity function, and the absorption. Thus star count programs are designed to constrain or determine one or more of these functions. Early efforts to understand the structure of our Galaxy, including the fundamentals of stellar statistics, were largely based on work that involved star counts. Since then a growing appreciation has developed for the variety of forms the density function D(r) and the luminosity function Φ(M) can take, especially the recognition of different stellar populations, each with different density and luminosity functions. In the simplest formulation two distinct populations are considered: disk and halo. This suggests two distinct formation histories, but uncertainty in the picture remains (Eggen, Lynden-Bell and Sandage 1962; Ostriker and Thuan 1975; Saio and Yoshii 1979; Jones and Wyse 1983).

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