scholarly journals An HI Selected Sample of Galaxies: The HI Mass Function and the Surface Brightness Distribution

1997 ◽  
Vol 14 (1) ◽  
pp. 126-129 ◽  
Author(s):  
Martin Zwaan ◽  
Frank Briggs ◽  
David Sprayberry
Keyword(s):  
Surface Brightness ◽  
Mass Density ◽  
Mass Function ◽  
Brightness Distribution ◽  
Present Epoch ◽  
Observational Selection ◽  
Central Surface

AbstractResults from the Arecibo HI Strip Survey, an unbiased extragalactic HI survey, combined with optical and 21 cm follow-up observations, determine the HI mass function and the cosmological mass density of HI at the present epoch. Both are consistent with earlier estimates, computed for the population of optically selected galaxies. This consistency occurs because, although the distribution of optical central surface brightnesses among galaxies is flat, we fail to find a population of galaxies with central surface brightnesses fainter than 24 B-mag arcsec−2, even though there is no observational selection against them.

scholarly journals Systematic errors in strong gravitational lensing reconstructions, a numerical simulation perspective

2020 ◽  
Vol 496 (2) ◽  
pp. 1718-1729 ◽  
Author(s):  
Wolfgang Enzi ◽  
Simona Vegetti ◽  
Giulia Despali ◽  
Jen-Wei Hsueh ◽  
R Benton Metcalf
Keyword(s):  
Gravitational Lensing ◽  
Time Delays ◽  
Surface Brightness ◽  
Mass Density ◽  
Control Sample ◽  
Brightness Distribution ◽  
Gravitational Lens ◽  
Galactic Potentials ◽  
Fractional Error ◽  
Approximate Bayesian

ABSTRACT We present the analysis of a sample of 24 SLACS-like galaxy–galaxy strong gravitational lens systems with a background source and deflectors from the Illustris-1 simulation. We study the degeneracy between the complex mass distribution of the lenses, substructures, the surface brightness distribution of the sources, and the time delays. Using a novel inference framework based on Approximate Bayesian Computation, we find that for all the considered lens systems, an elliptical and cored power-law mass density distribution provides a good fit to the data. However, the presence of cores in the simulated lenses affects most reconstructions in the form of a Source Position Transformation. The latter leads to a systematic underestimation of the source sizes by 50 per cent on average, and a fractional error in H0 of around $25_{-19}^{+37}$ per cent. The analysis of a control sample of 24 lens systems, for which we have perfect knowledge about the shape of the lensing potential, leads to a fractional error on H0 of $12_{-3}^{+6}$ per cent. We find no degeneracy between complexity in the lensing potential and the inferred amount of substructures. We recover an average total projected mass fraction in substructures of fsub < 1.7–2.0 × 10−3 at the 68 per cent confidence level in agreement with zero and the fact that all substructures had been removed from the simulation. Our work highlights the need for higher resolution simulations to quantify the lensing effect of more realistic galactic potentials better, and that additional observational constraint may be required to break existing degeneracies.

scholarly journals Galaxy disc central surface brightness distribution in the optical and near-infrared bands

2019 ◽  
Vol 484 (2) ◽  
pp. 1549-1562
Author(s):  
L Zhou ◽  
W Du ◽  
H Wu ◽  
Y C Liang ◽  
M He ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Near Infrared ◽  
Brightness Distribution ◽  
Central Surface

scholarly journals GAMA/H-ATLAS: the local dust mass function and cosmic density as a function of galaxy type – a benchmark for models of galaxy evolution

2018 ◽  
Vol 479 (1) ◽  
pp. 1077-1099 ◽  
Author(s):  
R A Beeston ◽  
A H Wright ◽  
S Maddox ◽  
H L Gomez ◽  
L Dunne ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Mass Density ◽  
Mass Function ◽  
Brightness Distribution ◽  
Stellar Mass ◽  
Density Parameter ◽  
Galaxy Type ◽  
Dust Mass ◽  
Local Dust ◽  
High Dust

ABSTRACT We present the dust mass function (DMF) of 15 750 galaxies with redshift $z$ < 0.1, drawn from the overlapping area of the GAMA and H-ATLAS surveys. The DMF is derived using the density corrected Vmax method, where we estimate Vmax using: (i) the normal photometric selection limit (pVmax) and (ii) a bivariate brightness distribution (BBD) technique, which accounts for two selection effects. We fit the data with a Schechter function, and find $M^{*}=(4.65 \pm 0.18)\times 10^{7}\,h^2_{70}\, \mathrm{ M}_{\odot }$, α = (−1.22 ± 0.01), $\phi ^{*}=(6.26 \pm 0.28)\times 10^{-3}\,h^3_{70}\,\rm Mpc^{-3}\,dex^{-1}$. The resulting dust mass density parameter integrated down to 104 M⊙ is Ωd = (1.11 ± 0.02) × 10−6 which implies the mass fraction of baryons in dust is $f_{m_\mathrm{ b}}=(2.40\pm 0.04)\times 10^{-5}$; cosmic variance adds an extra  7–17 per cent uncertainty to the quoted statistical errors. Our measurements have fewer galaxies with high dust mass than predicted by semi-analytic models. This is because the models include too much dust in high stellar mass galaxies. Conversely, our measurements find more galaxies with high dust mass than predicted by hydrodynamical cosmological simulations. This is likely to be from the long time-scales for grain growth assumed in the models. We calculate DMFs split by galaxy type and find dust mass densities of Ωd = (0.88 ± 0.03) × 10−6 and Ωd = (0.060 ± 0.005) × 10−6 for late types and early types, respectively. Comparing to the equivalent galaxy stellar mass functions (GSMF) we find that the DMF for late types is well matched by the GSMF scaled by (8.07 ± 0.35) × 10−4.

scholarly journals Bimodality of galaxy disc central surface brightness distribution in the Spitzer 3.6  μm band

2013 ◽  
Vol 433 (1) ◽  
pp. 751-758 ◽  
Author(s):  
Jenny G. Sorce ◽  
Hélène M. Courtois ◽  
Kartik Sheth ◽  
R. Brent Tully
Keyword(s):  
Surface Brightness ◽  
Brightness Distribution ◽  
Central Surface

scholarly journals When Darwin Met Einstein: Gravitational Lens Inversion with Genetic Algorithms

2005 ◽  
Vol 22 (2) ◽  
pp. 128-135 ◽  
Author(s):  
Brendon J. Brewer ◽  
Geraint F. Lewis
Keyword(s):  
Genetic Algorithms ◽  
Gravitational Lensing ◽  
Surface Brightness ◽  
Initial Study ◽  
Brightness Distribution ◽  
Gravitational Lens ◽  
Atmospheric Effects ◽  
Lens Model ◽  
New Approach ◽  
Genetic Algorithm Approach

AbstractGravitational lensing can magnify a distant source, revealing structural detail which is normally unresolvable. Recovering this detail through an inversion of the influence of gravitational lensing, however, requires optimisation of not only lens parameters, but also of the surface brightness distribution of the source. This paper outlines a new approach to this inversion, utilising genetic algorithms to reconstruct the source profile. In this initial study, the effects of image degradation due to instrumental and atmospheric effects are neglected and it is assumed that the lens model is accurately known, but the genetic algorithm approach can be incorporated into more general optimisation techniques, allowing the optimisation of both the parameters for a lensing model and the surface brightness of the source.

scholarly journals Dwarf Galaxies in Nearby Groups

1999 ◽  
Vol 171 ◽  
pp. 154-156
Author(s):  
T. Bremnes ◽  
B. Binggeli ◽  
P. Prugniel
Keyword(s):  
Surface Brightness ◽  
Dwarf Galaxies ◽  
Photometric Data ◽  
Preliminary Results ◽  
Central Surface ◽  
Total Magnitude ◽  
Evolutionary Connection

AbstractWe present preliminary results from two observing campaigns where global photometric data for most dwarf galaxies in the M81 and M101 groups as well as some field dwarfs were obtained. The galaxies in the denser M81 group are more often of dwarf elliptical type and are redder and fainter than those of the M101 group and surrounding field, which are mostly of the dwarf irregular types. But both types follow the same total magnitude - central surface brightness relation, so there might be an evolutionary connection between the two classes.

scholarly journals The NIBLES bivariate luminosity–H I mass distribution function revised using Arecibo follow-up observations

2020 ◽  
Vol 642 ◽  
pp. A175
Author(s):  
Z. Butcher ◽  
W. van Driel ◽  
S. Schneider
Keyword(s):  
Mass Distribution ◽  
Radio Telescope ◽  
Luminosity Function ◽  
Mass Function ◽  
Bivariate Analysis ◽  
Dimensional Distribution ◽  
Low Mass ◽  
The One ◽  
Mass Distribution Function

We present a modified optical luminosity–H I mass bivariate luminosity function based on H I line observations from the Nançay Interstellar Baryons Legacy Extragalactic Survey (NIBLES), including data from our new, four times more sensitive follow-up H I line observations obtained with the Arecibo radio telescope. The follow-up observations were designed to probe the underlying H I mass distribution of the NIBLES galaxies that were undetected or marginally detected in H I at the Nançay Radio Telescope. Our total follow-up sample consists of 234 galaxies, and it spans the entire luminosity and color range of the parent NIBLES sample of 2600 nearby (900 <  cz <  12 000 km s−1) SDSS galaxies. We incorporated the follow-up data into the bivariate analysis by scaling the NIBLES undetected fraction by an Arecibo-only distribution. We find the resulting increase in low H I mass-to-light ratio densities to be about 10% for the bins −1.0 ≤ log(MHI/M⊙/Lr/L⊙) ≤ −0.5, which produces an increased H I mass function (HIMF) low mass slope of α = −1.14 ± 0.07, being slightly shallower than the values of −1.35 ± 0.05 obtained by recent blind H I surveys. Applying the same correction to the optically corrected bivariate luminosity function from our previous paper produces a larger density increase of about 0.5 to 1 dex in the lowest H I mass-to-light ratio bins for a given luminosity while having a minimal effect on the resulting HIMF low mass slope, which still agrees with blind survey HIMFs. This indicates that while low H I-mass-to-light ratio galaxies do not contribute much to the one-dimensional HIMF, their inclusion has a significant impact on the densities in the two-dimensional distribution.

scholarly journals Identification of NR0B1 Gene Mutation and Analysis of Bone Damages and Drug Treatment Effect in a Big Family With X-linked Adrenal Hypoplasia Congenita: a Case Report

2021 ◽  
Author(s):  
XIAOHUI TAO ◽  
LI LIU ◽  
XIAOYUN LIN ◽  
TIAN XU ◽  
HUA YUE ◽  
...  
Keyword(s):  
Mass Density ◽  
Hypogonadotropic Hypogonadism ◽  
Clinical Manifestations ◽  
Osteonecrosis Of The Jaw ◽  
Bone Mass Density ◽  
Insertion Mutation ◽  
Case Presentation ◽  
Skeletal Complications ◽  
Adrenal Hypoplasia

Abstract Background: X-linked congenital adrenocortical hypoplasia (XL-AHC) is a rare disorder, which is characterized by primary adrenal insufficiency and hypogonadotropic hypogonadism. However, the skeletal complications caused by the disease were rarely reported, not to mention the treatment.Case presentation: The patient from a big family with XL-AHC was identified carrying a homozygous insertion mutation（p.Thr193GlyfsX13）in DAX-1 gene. The diagnosis of secondary osteoporosis was made after imaging, laboratory and bone mass density examinations. However, he showed a suboptimal response to bisphosphonates during 2 years of follow-up, even suffered from atypical femoral fracture (AFF). Now it had been replaced by menatetrenone, bone healing was satisfactory. Conclusions: We harbored the idea that clinicians should not only focus on typical clinical manifestations of XL-AHC, but also pay attention to the skeletal complications in clinical practice. Conventional anti-osteoporosis drugs may cause side effects such as AFF and osteonecrosis of the jaw (ONJ), which was rare in general osteoporosis patients. In other words, anabolic agent may be a better choice.

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