scholarly journals CHORUS. II. Subaru/HSC Determination of the Lyα Luminosity Function at z = 7.0: Constraints on Cosmic Reionization Model Parameter

2018 ◽  
Vol 867 (1) ◽  
pp. 46 ◽  
Author(s):  
Ryohei Itoh ◽  
Masami Ouchi ◽  
Haibin Zhang ◽  
Akio K. Inoue ◽  
Ken Mawatari ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Model Parameter

scholarly journals The Surface Density of Quasars

1978 ◽  
Vol 79 ◽  
pp. 295-303 ◽  
Author(s):  
J.G. Bolton ◽  
Ann Savage
Keyword(s):  
Surface Density ◽  
Luminosity Function ◽  
Statistical Significance ◽  
Comprehensive Investigation ◽  
Space Density ◽  
Close Pairs

A knowledge of the surface density of quasars as a function of magnitude is important for two reasons. Firstly it is necessary in order to assess the possible statistical significance of close pairs of quasars or the association between quasars and bright galaxies. Secondly it is a necessary step in the determination of the space density or luminosity function of QSOs. We have carried out what we believe to be currently the most comprehensive investigation into the surface density of quasars. Three techniques have been used in this investigation. These are

scholarly journals White Dwarf Crystallization

1994 ◽  
Vol 147 ◽  
pp. 161-185
Author(s):  
Enrique Garcia-Berro ◽  
Margarida Hernanz
Keyword(s):  
White Dwarf ◽  
Luminosity Function ◽  
Crystallization Process ◽  
Galactic Disk ◽  
Chemical Species ◽  
Galactic Chemical Evolution ◽  
Crucial Importance ◽  
Solidification Processes ◽  
Detailed Computation

AbstractThe inclusion of a detailed treatment of solidification processes in the cooling theory of carbon–oxygen white dwarfs is of crucial importance for the determination of their luminosity function. Carbon–oxygen separation at crystallization yields delays larger than 2 Gyr to cool down to luminosities corresponding to the observed cut–off. This leads to estimates of the age of the galactic disk 1.5 to 2 Gyr older than the ones obtained in previous studies (about 9 Gyr). Furthermore, the presence of minor chemical species, in particular 22Ne, alters significantly the crystallization process, and produces extra delays of 2 to 3 gigayears. However, the detailed computation of the theoretical white dwarf luminosity function, taking into account a reasonable model of galactic chemical evolution, and including the effect of these species, shows that the location of the cut–off, and then the estimated age of the disk, is not modified significantly.

scholarly journals The field luminosity function and nearby groups of galaxies

1978 ◽  
Vol 79 ◽  
pp. 271-273
Author(s):  
John Huchra
Keyword(s):  
Surface Brightness ◽  
Luminosity Function ◽  
High Surface ◽  
Homogeneous System ◽  
Velocity Data ◽  
Limited Sample ◽  
Groups Of Galaxies ◽  
Dynamical Properties ◽  
Radial Velocity Data

We have assembled a catalog of radial velocities and magnitudes on a homogeneous system (the corrected Harvard, B(o) magnitudes of de Vaucouleurs) for over 4000 galaxies. Using this catalog, we have compiled a magnitude limited sample of ~ 1000 galaxies with nearly complete radial velocity data. the magnitude limit is 13.0 and the galaxies are primarily from the Shapley-Ames catalog plus a few low and high surface brightness objects properly included in a magnitude limited sample. My colleagues, M. Davis, M. Geller and I are presently analyzing the dynamical properties of this sample. I would like to briefly describe a new determination of the field luminosity function and density plus our initial experiments with the use of a redshift catalog to select groups of galaxies.

scholarly journals The X-Ray Background and the AGN Luminosity Function

1999 ◽  
Vol 183 ◽  
pp. 200-209
Author(s):  
G. Hasinger
Keyword(s):  
Black Holes ◽  
Luminosity Function ◽  
Cosmic Time ◽  
Volume Density ◽  
Energy Bands ◽  
X Ray ◽  
Normal Galaxies ◽  
X Ray Background ◽  
Acid Test

ROSAT deep and shallow surveys have provided an almost complete inventory of the constituents of the soft X-ray background which led to a population synthesis model for the whole X-ray background with interesting cosmological consequences. According to this model the X-ray background is the “echo” of mass accretion onto supermassive black holes, integrated over cosmic time. A new determination of the soft X-ray luminosity function of active galactic nuclei (AGN) is consistent with pure density evolution, and the comoving volume density of AGN at redshift 2–3 approaches that of local normal galaxies. This indicates that many larger galaxies contain black holes and it is likely that the bulk of the black holes was produced before most of the stars in the universe. However, only X-ray surveys in the harder energy bands, where the maximum of the energy density of the X-ray background resides, will provide the acid test of this picture.

scholarly journals The Mid-Infrared luminosity function of galaxies using the AKARI mid-infrared All-Sky Survey Catalogue

2011 ◽  
Vol 7 (S284) ◽  
pp. 228-230
Author(s):  
Y. Toba ◽  
S. Oyabu ◽  
H. Matsuhara ◽  
D. Ishihara ◽  
M. Malkan ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Density Ratio ◽  
Number Density ◽  
Limited Sample ◽  
Local Universe ◽  
Mid Infrared ◽  
Star Forming ◽  
Sky Survey

AbstractWe present the first determination of the 18 μm luminosity function (LF) of galaxies at 0.006 < z < 0.7 (the average redshift is ~ 0.04) using the AKARI mid-infrared All-Sky Survey catalogue. We have selected a 18 μm flux-limited sample of 243 galaxies from the catalogue in the SDSS spectroscopic region. We then classified the sample into four types; Seyfert 1 galaxies (including QSOs), Seyfert 2 galaxies, LINERs and Star-Forming galaxies using mainly [OIII]/Hβ vs. [NII]/Hα line ratios obtained from the SDSS.As a result of constructing Seyfert 1 and Seyfert 2 LFs, we found the following results; (i) the number density ratio of Seyfert 2s to Seyfert 1s is 3.98 ± 0.41 obtained from Sy1 and Sy2 LFs; this value is larger than the results obtained from optical LFs. (ii) the fraction of Sy2s in the entire AGNs may be anti-correlated with 18 μm luminosity. These results suggest that the torus structure probably depends on the mid-infrared luminosity of AGNs and most of the AGNs in the local Universe are obscured by dust.

scholarly journals Extending the White Dwarf Sequence: Plans and Prospects

1978 ◽  
Vol 80 ◽  
pp. 437-440
Author(s):  
James Liebert
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Luminosity Function ◽  
Selection Effects ◽  
Number Density ◽  
Low Velocity ◽  
Luminosity Functions ◽  
Current Sample ◽  
The Many

The recent discovery that the parallax star LP701-29 is a white dwarf has firmly extended the degenerate sequence below MV= +16m(Dahnet al. 1978). As the search for white dwarfs extends to cooler and fainter stars, however, it becomes particularly important to develop a plan for selecting candidates among the many thousands of red proper motion stars. We begin by assessing the completeness of the known sample within 10 parsecs in the northern two thirds of the sky. Some color-dependent selection effects must be evaluated, however, since these may preferentially inhibit the discovery of cooler stars. A correction factor for the missing low velocity white dwarfs is estimated. Then, Green's(1977) recent determination of the number density of blue degenerates is used to normalize various theoretical luminosity functions, the benchmarks against which the current sample out to 10 pc can be compared. It is concluded that the sample may be approaching completeness in the northern sky for white dwarfs with tangential velocities (vT) ≥ 40 km/sec (μ ≥ 1″.0/yr.) and Mbol&lt; +15m. The implied luminosity function is thus consistent with that found by Sion and Liebert (1977). Below Mbol= +15mthe different theoretical functions predict substantially different numbers.

scholarly journals The Evolution of the Radio Galaxy Population as Determined from Deep Radio-Optical Surveys

1983 ◽  
Vol 104 ◽  
pp. 73-79
Author(s):  
Harry van der Laan ◽  
Peter Katgert ◽  
Rogier Windhorst ◽  
Marc Oort
Keyword(s):  
Luminosity Function ◽  
Birth Rate ◽  
Radio Galaxy ◽  
Rate Function ◽  
Light Curves ◽  
Log P ◽  
Galaxy Population ◽  
Optical Surveys ◽  
Radio Luminosity Function

A first step in the study of the evolution of the radio galaxy population is the determination of the radio luminosity function (RLF), i.e. ρ(log P, z), which results from (and must finally be interpreted in terms of) ‘light curves’ of individual objects (i.e. P(t)) and the ‘birth rate’ function ṅ (log P, t).

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