scholarly journals Open-cluster density profiles derived using a kernel estimator

2016 ◽  
Vol 456 (4) ◽  
pp. 3757-3773 ◽  
Author(s):  
Anton F. Seleznev
Keyword(s):  
Open Cluster ◽  
Kernel Estimator ◽  
Density Profiles ◽  
Cluster Density

scholarly journals Kernel Density Estimation in the Study of Star Clusters

2016 ◽  
Vol 25 (3) ◽  
Author(s):  
Anton F. Seleznev
Keyword(s):  
Luminosity Function ◽  
Open Cluster ◽  
Cluster Structure ◽  
Star Clusters ◽  
Kernel Estimator ◽  
Mass Function ◽  
Number Density ◽  
Density Profiles ◽  
Density Maps ◽  
Technical Details

AbstractThe kernel estimator method is used to evaluate the surface and spatial star number density in star clusters. Both density maps and radial density profiles are plotted. These estimates are used to derive the cluster size, the number of cluster stars and the cluster mass, and to study the cluster structure. The kernel estimator is also used to plot the luminosity function, mass function, the velocity distribution, and Hess diagrams for star clusters. The advantages of the kernel estimator method and technical details of its use are illustrated by modern results for the open cluster NGC 4337.

scholarly journals An analysis of galaxy cluster mis-centring using cosmological hydrodynamic simulations

2020 ◽  
Vol 493 (1) ◽  
pp. 1120-1129
Author(s):  
Z Yan ◽  
N Raza ◽  
L Van Waerbeke ◽  
A J Mead ◽  
I G McCarthy ◽  
...  
Keyword(s):  
Galaxy Cluster ◽  
Mass Range ◽  
Three Dimensions ◽  
Cumulative Distribution ◽  
Density Profiles ◽  
Hydrodynamic Simulations ◽  
The Galaxy ◽  
Cluster Density ◽  
Cluster Properties ◽  
Using Data

ABSTRACT The location of a galaxy cluster’s centroid is typically derived from observations of the galactic and/or gas component of the cluster, but these typically deviate from the true centre. This can produce bias when observations are combined to study average cluster properties. Using data from the BAryons and HAloes of MAssive Systems (BAHAMAS) cosmological hydrodynamic simulations, we study this bias in both two and three dimensions for 2000 clusters over the 1013–1015 M⊙ mass range. We quantify and model the offset distributions between observationally motivated centres and the ‘true’ centre of the cluster, which is taken to be the most gravitationally bound particle measured in the simulation. We fit the cumulative distribution function of offsets with an exponential distribution and a Gamma distribution fit well with most of the centroid definitions. The galaxy-based centres can be seen to be divided into a mis-centred group and a well-centred group, with the well-centred group making up about $60{{\ \rm per\ cent}}$ of all the clusters. Gas-based centres are overall less scattered than galaxy-based centres. We also find a cluster-mass dependence of the offset distribution of gas-based centres, with generally larger offsets for smaller mass clusters. We then measure cluster density profiles centred at each choice of the centres and fit them with empirical models. Stacked, mis-centred density profiles fit to the Navarro–Frenk–White dark matter profile and Komatsu–Seljak gas profile show that recovered shape and size parameters can significantly deviate from the true values. For the galaxy-based centres, this can lead to cluster masses being underestimated by up to $10{{\ \rm per\ cent}}$.

scholarly journals Cross-correlation Weak Lensing of SDSS galaxy Clusters II: Cluster Density Profiles and the Mass--Richness Relation

2007 ◽  
Author(s):  
David E. Johnston ◽  
Erin S. Sheldon ◽  
Risa H. Wechsler ◽  
Eduardo Rozo ◽  
Benjamin P. Koester ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Cross Correlation ◽  
Weak Lensing ◽  
Density Profiles ◽  
Cluster Density

scholarly journals Convergence and scatter of cluster density profiles

2004 ◽  
Vol 353 (2) ◽  
pp. 624-632 ◽  
Author(s):  
Jürg Diemand ◽  
Ben Moore ◽  
Joachim Stadel
Keyword(s):  
Density Profiles ◽  
Cluster Density

scholarly journals Are the globular clusters with significant internal [Fe/H] spreads all former dwarf galaxy nuclei?

2015 ◽  
Vol 11 (S317) ◽  
pp. 110-115 ◽  
Author(s):  
G. S. Da Costa
Keyword(s):  
Distribution Function ◽  
Globular Clusters ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Density Profiles ◽  
Cluster Density ◽  
Galactic Globular Clusters ◽  
Metallicity Distribution

AbstractIn this contribution the hypothesis that the Galactic globular clusters with substantial internal [Fe/H] abundance ranges are the former nuclei of disrupted dwarf galaxies is discussed. Evidence considered includes the form of the metallicity distribution function, the occurrence of large diffuse outer envelopes in cluster density profiles, and the presence of ([s-process/Fe], [Fe/H]) correlations. The hypothesis is shown to be plausible but with the caveat that if significantly more than the current nine clusters known to have [Fe/H] spreads are found, then re-evaluation will be required.

scholarly journals The effects of ellipticity and substructure on estimates of cluster density profiles based on lensing and kinematics

2007 ◽  
Vol 381 (1) ◽  
pp. 171-186 ◽  
Author(s):  
Massimo Meneghetti ◽  
Matthias Bartelmann ◽  
Adrian Jenkins ◽  
Carlos Frenk
Keyword(s):  
Density Profiles ◽  
Cluster Density

scholarly journals Cluster density profiles as a test of modified gravity

2012 ◽  
Vol 85 (10) ◽  
Author(s):  
Lucas Lombriser ◽  
Fabian Schmidt ◽  
Tobias Baldauf ◽  
Rachel Mandelbaum ◽  
Uroš Seljak ◽  
...  
Keyword(s):  
Modified Gravity ◽  
Density Profiles ◽  
Cluster Density

scholarly journals The cosmological dependence of cluster density profiles

1994 ◽  
Vol 434 ◽  
pp. 402 ◽  
Author(s):  
Mary M. Crone ◽  
August E. Evrard ◽  
Douglas O. Richstone
Keyword(s):  
Density Profiles ◽  
Cluster Density

scholarly journals The Three Hundred Project: The evolution of galaxy cluster density profiles

2018 ◽  
Vol 483 (3) ◽  
pp. 3390-3403 ◽  
Author(s):  
Robert Mostoghiu ◽  
Alexander Knebe ◽  
Weiguang Cui ◽  
Frazer R Pearce ◽  
Gustavo Yepes ◽  
...  
Keyword(s):  
Galaxy Cluster ◽  
Density Profiles ◽  
Cluster Density

scholarly journals Refilling process in the plasmasphere: a 3-D statistical characterization based on Cluster density observations

2013 ◽  
Vol 31 (2) ◽  
pp. 217-237 ◽  
Author(s):  
G. Lointier ◽  
F. Darrouzet ◽  
P. M. E. Décréau ◽  
X. Vallières ◽  
S. Kougblénou ◽  
...  
Keyword(s):  
Electron Density ◽  
Outer Part ◽  
Density Profiles ◽  
Statistical Characterization ◽  
Inner Magnetosphere ◽  
First Results ◽  
Cluster Density ◽  
Field Lines ◽  
Ap Index ◽  
Electron Density Profiles

Abstract. The Cluster mission offers an excellent opportunity to investigate the evolution of the plasma population in a large part of the inner magnetosphere, explored near its orbit's perigee, over a complete solar cycle. The WHISPER sounder, on board each satellite of the mission, is particularly suitable to study the electron density in this region, between 0.2 and 80 cm−3. Compiling WHISPER observations during 1339 perigee passes distributed over more than three years of the Cluster mission, we present first results of a statistical analysis dedicated to the study of the electron density morphology and dynamics along and across magnetic field lines between L = 2 and L = 10. In this study, we examine a specific topic: the refilling of the plasmasphere and trough regions during extended periods of quiet magnetic conditions. To do so, we survey the evolution of the ap index during the days preceding each perigee crossing and sort out electron density profiles along the orbit according to three classes, namely after respectively less than 2 days, between 2 and 4 days, and more than 4 days of quiet magnetic conditions (ap ≤ 15 nT) following an active episode (ap > 15 nT). This leads to three independent data subsets. Comparisons between density distributions in the 3-D plasmasphere and trough regions at the three stages of quiet magnetosphere provide novel views about the distribution of matter inside the inner magnetosphere during several days of low activity. Clear signatures of a refilling process inside an expended plasmasphere in formation are noted. A plasmapause-like boundary, at L ~ 6 for all MLT sectors, is formed after 3 to 4 days and expends somewhat further after that. In the outer part of the plasmasphere (L ~ 8), latitudinal profiles of median density values vary essentially according to the MLT sector considered rather than according to the refilling duration. The shape of these density profiles indicates that magnetic flux tubes are not fully replenished after 6 days of quiet conditions. In addition, the outer plasmasphere in the night and dawn sectors (22:00 to 10:00 MLT range) maintains an overall clear deficit of ionospheric population, when compared to the situation in the noon and dusk sectors (10:00 to 22:00 MLT range).

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