The Role Of Intra‐Cluster Gas In Dynamical Evolution Of The Galaxy Cluster Embedded In The Dark Matter Halo

2010 ◽  
Author(s):  
G. N. Dryomova ◽  
V. V. Dryomov ◽  
A. V. Tutukov
Keyword(s):  
Dark Matter ◽  
Dynamical Evolution ◽  
Galaxy Cluster ◽  
Dark Matter Halo ◽  
The Galaxy

scholarly journals The role of AGN activity in the building up of the BCG at z ∼ 1.6

2019 ◽  
Vol 15 (S356) ◽  
pp. 280-284
Author(s):  
Angela Bongiorno ◽  
Andrea Travascio
Keyword(s):  
Galaxy Cluster ◽  
Cluster Galaxy ◽  
X Ray ◽  
Groups Of Galaxies ◽  
Star Forming ◽  
The Core ◽  
The Galaxy ◽  
Multi Wavelength

AbstractXDCPJ0044.0-2033 is one of the most massive galaxy cluster at z ∼1.6, for which a wealth of multi-wavelength photometric and spectroscopic data have been collected during the last years. I have reported on the properties of the galaxy members in the very central region (∼ 70kpc × 70kpc) of the cluster, derived through deep HST photometry, SINFONI and KMOS IFU spectroscopy, together with Chandra X-ray, ALMA and JVLA radio data.In the core of the cluster, we have identified two groups of galaxies (Complex A and Complex B), seven of them confirmed to be cluster members, with signatures of ongoing merging. These galaxies show perturbed morphologies and, three of them show signs of AGN activity. In particular, two of them, located at the center of each complex, have been found to host luminous, obscured and highly accreting AGN (λ = 0.4−0.6) exhibiting broad Hα line. Moreover, a third optically obscured type-2 AGN, has been discovered through BPT diagram in Complex A. The AGN at the center of Complex B is detected in X-ray while the other two, and their companions, are spatially related to radio emission. The three AGN provide one of the closest AGN triple at z > 1 revealed so far with a minimum (maximum) projected distance of 10 kpc (40 kpc). The discovery of multiple AGN activity in a highly star-forming region associated to the crowded core of a galaxy cluster at z ∼ 1.6, suggests that these processes have a key role in shaping the nascent Brightest Cluster Galaxy, observed at the center of local clusters. According to our data, all galaxies in the core of XDCPJ0044.0-2033 could form a BCG of M* ∼ 1012Mȯ hosting a BH of 2 × 108−109Mȯ, in a time scale of the order of 2.5 Gyrs.

Studying the Patterns of the Universe

2011 ◽  
Vol 20 (2) ◽  
Author(s):  
T. Sepp ◽  
E. Tempel ◽  
M. Gramann ◽  
P. Nurmi ◽  
M. Haupt
Keyword(s):  
Dark Matter ◽  
Galaxy Cluster ◽  
Analytical Models ◽  
Matter Distribution ◽  
Galaxy Groups ◽  
The Galaxy ◽  
Dark Matter Distribution ◽  
Distribution Studies ◽  
The Universe ◽  
Good Agreement

AbstractThe SDSS galaxy catalog is one of the best databases for galaxy distribution studies. The SDSS DR8 data is used to construct the galaxy cluster catalog. We construct the clusters from the calculated luminosity density field and identify denser regions. Around these peak regions we construct galaxy clusters. Another interesting question in cosmology is how observable galaxy structures are connected to underlying dark matter distribution. To study this we compare the SDSS DR7 galaxy group catalog with galaxy groups obtained from the semi-analytical Millennium N-Body simulation. Specifically, we compare the group richness, virial radius, maximum separation and velocity dispersion distributions and find a relatively good agreement between the mock catalog and observations. This strongly supports the idea that the dark matter distribution and galaxies in the semi-analytical models and observations are very closely linked.

scholarly journals The Dark Blue Compact Dwarf Galaxy NGC 2915

1997 ◽  
Vol 14 (1) ◽  
pp. 77-80 ◽  
Author(s):  
Gerhardt R. Meurer
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Dwarf Galaxy ◽  
Dark Matter Halo ◽  
High Mass ◽  
Mass Star ◽  
Normal Galaxies ◽  
The Galaxy ◽  
Dark Blue ◽  
Blue Compact Dwarf Galaxy

AbstractRecent results on NGC 2915, the first blue compact dwarf galaxy to have its mass distribution modelled, are summarised. NGC 2915 is shown to have HI well beyond its detected optical extent. Its rotation curve is well determined and fit with maximum disk mass models. The dark matter halo dominates the mass distribution at nearly all radii, and has a very dense core compared to those of normal galaxies. High-mass star formation energises the HI in the centre of the galaxy, but appears to be maintained in viriai equilibrium with the dark matter halo. The implications of these results are briefly discussed.

scholarly journals Globular cluster ejection, infall, and the host dark matter halo of the Pegasus dwarf galaxy

2020 ◽  
Vol 492 (4) ◽  
pp. 5102-5120
Author(s):  
Ryan Leaman ◽  
Tomás Ruiz-Lara ◽  
Andrew A Cole ◽  
Michael A Beasley ◽  
Alina Boecker ◽  
...  
Keyword(s):  
Dark Matter ◽  
Relaxation Time ◽  
Density Profile ◽  
Globular Cluster ◽  
Dwarf Galaxy ◽  
Orbital Evolution ◽  
Dark Matter Halo ◽  
Host Galaxy ◽  
Structural Constraints ◽  
The Galaxy

ABSTRACT Recent photometric observations revealed a massive, extended (MGC ≳ 105 M⊙; Rh ∼ 14 pc) globular cluster (GC) in the central region (D3D ≲ 100 pc) of the low-mass (M* ∼ 5 × 106 M⊙) dwarf irregular galaxy Pegasus. This massive GC offers a unique opportunity to study star cluster inspiral as a mechanism for building up nuclear star clusters, and the dark matter (DM) density profile of the host galaxy. Here, we present spectroscopic observations indicating that the GC has a systemic velocity of ΔV = 3 ± 8 km s−1 relative to the host galaxy, and an old, metal-poor stellar population. We run a suite of orbital evolution models for a variety of host potentials (cored to cusped) and find that the GC’s observed tidal radius (which is ∼3 times larger than the local Jacobi radius), relaxation time, and relative velocity are consistent with it surviving inspiral from a distance of Dgal ≳ 700 pc (up to the maximum tested value of Dgal = 2000 pc). In successful trials, the GC arrives to the galaxy centre only within the last ∼1.4 ± 1 Gyr. Orbits that arrive in the centre and survive are possible in DM haloes of nearly all shapes, however to satisfy the GC’s structural constraints a galaxy DM halo with mass MDM ≃ 6 ± 2 × 109 M⊙, concentration c ≃ 13.7 ± 0.6, and an inner slope to the DM density profile of −0.9 ≤ γ ≤ −0.5 is preferred. The gas densities necessary for its creation and survival suggest the GC could have formed initially near the dwarf’s centre, but then was quickly relocated to the outskirts where the weaker tidal field permitted an increased size and relaxation time – with the latter preserving the former during subsequent orbital decay.

scholarly journals The gravitational force field of the Galaxy measured from the kinematics of RR Lyrae in Gaia

2019 ◽  
Vol 485 (3) ◽  
pp. 3296-3316 ◽  
Author(s):  
Christopher Wegg ◽  
Ortwin Gerhard ◽  
Marie Bieth
Keyword(s):  
Dark Matter ◽  
Dark Matter Halo ◽  
Galactic Centre ◽  
Gravitational Acceleration ◽  
Momentum Exchange ◽  
Acceleration Field ◽  
Rr Lyrae ◽  
Halo Stars ◽  
The Galaxy ◽  
Stellar Halo

Abstract From a sample of 15651 RR Lyrae with accurate proper motions in Gaia DR2, we measure the azimuthally averaged kinematics of the inner stellar halo between 1.5  and 20  kpc from the Galactic centre. We find that their kinematics are strongly radially anisotropic, and their velocity ellipsoid nearly spherically aligned over this volume. Only in the inner regions ${\lesssim } 5\, {\rm kpc}\,$ does the anisotropy significantly fall (but still with β > 0.25) and the velocity ellipsoid tilt towards cylindrical alignment. In the inner regions, our sample of halo stars rotates at up to $50\, {\rm km}\, {\rm s}^{-1}\,$, which may reflect the early history of the Milky Way, although there is also a significant angular momentum exchange with the Galactic bar at these radii. We subsequently apply the Jeans equations to these kinematic measurements in order to non-parametrically infer the azimuthally averaged gravitational acceleration field over this volume, and by removing the contribution from baryonic matter, measure the contribution from dark matter. We find that the gravitational potential of the dark matter is nearly spherical with average flattening $q_\Phi ={1.01 \pm 0.06\, }$ between 5 and 20 kpc, and by fitting parametric ellipsoidal density profiles to the acceleration field, we measure the flattening of the dark matter halo over these radii to be $q_\rho ={1.00 \pm 0.09\, }\!.$

scholarly journals Is the dark-matter halo spin a predictor of galaxy spin and size?

2019 ◽  
Vol 488 (4) ◽  
pp. 4801-4815 ◽  
Author(s):  
Fangzhou Jiang ◽  
Avishai Dekel ◽  
Omer Kneller ◽  
Sharon Lapiner ◽  
Daniel Ceverino ◽  
...  
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
High Redshift ◽  
General Relation ◽  
Retention Factor ◽  
Dark Matter Halo ◽  
High Redshift Galaxies ◽  
The Galaxy ◽  
One To One ◽  
Analytic Models

ABSTRACT The similarity between the distributions of spins for galaxies (λgal) and for dark-matter haloes (λhalo), indicated both by simulations and observations, is naively interpreted as a one-to-one correlation between the spins of a galaxy and its host halo. This is used to predict galaxy sizes in semi-analytic models via Re ≃ fjλhaloRvir, where Re is the half-mass radius of the galaxy, fj is the angular momentum retention factor, and Rvir is the halo radius. Using two suites of zoom-in cosmological simulations, we find that λgal and the λhalo of its host halo are in fact barely correlated, especially at z ≥ 1, in line with previous indications. Since the spins of baryons and dark matter are correlated at accretion into Rvir, the null correlation in the end reflects an anticorrelation between fj and λhalo, which can arise from mergers and a ‘wet compaction’ phase that many high-redshift galaxies undergo. It may also reflect that unrepresentative small fractions of baryons are tapped to the galaxies. The galaxy spin is better correlated with the spin of the inner halo, but this largely reflects the effect of the baryons on the halo. While λhalo is not a useful predictor for Re, our simulations reproduce a general relation of the form of Re = ARvir, in agreement with observational estimates. We find that the relation becomes tighter with A = 0.02(c/10)−0.7, where c is the halo concentration, which in turn introduces a dependence on mass and redshift.

scholarly journals Constraining the abundance of dark matter in the central region of the galaxy cluster MACS J1206.2−0847 with a free-form strong lensing analysis

2020 ◽  
Vol 639 ◽  
pp. A125
Author(s):  
Alberto Manjón-García ◽  
Jose M. Diego ◽  
Diego Herranz ◽  
Daniel Lam
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Central Region ◽  
Total Mass ◽  
Galaxy Cluster ◽  
Free Form ◽  
Matter Distribution ◽  
Strong Lensing ◽  
The Galaxy ◽  
Dark Matter Distribution

We performed a free-form strong lensing analysis of the galaxy cluster MACS J1206.2−0847 in order to estimate and constrain its inner dark matter distribution. The free-form method estimates the cluster total mass distribution without using any prior information about the underlying mass. We used 97 multiple lensed images belonging to 27 background sources and derived several models, which are consistent with the data. Among these models, we focus on those that better reproduce the radial images that are closest to the centre of the cluster. These radial images are the best probes of the dark matter distribution in the central region and constrain the mass distribution down to distances ∼7 kpc from the centre. We find that the morphology of the innermost radial arcs is due to the elongated morphology of the dark matter halo. We estimate the stellar mass contribution of the brightest cluster galaxy and subtracted it from the total mass in order to quantify the amount of dark matter in the central region. We fitted the derived dark matter density profile with a gNFW, which is characterised by rs = 167 kpc, ρs = 6.7 × 106 M⊙ kpc−3, and γgNFW = 0.70. These results are consistent with a dynamically relaxed cluster. This inner slope is smaller than the cannonical γ = 1 predicted by standard CDM models. This slope does not favour self-interacting models for which a shallower slope would be expected.

scholarly journals A DETECTION OF DARK MATTER HALO ELLIPTICITY USING GALAXY CLUSTER LENSING IN THE SDSS

2009 ◽  
Vol 695 (2) ◽  
pp. 1446-1456 ◽  
Author(s):  
Anna Kathinka Dalland Evans ◽  
Sarah Bridle
Keyword(s):  
Dark Matter ◽  
Galaxy Cluster ◽  
Dark Matter Halo

scholarly journals The Three Hundred project: shapes and radial alignment of satellite, infalling, and backsplash galaxies

2020 ◽  
Vol 495 (3) ◽  
pp. 3002-3013 ◽  
Author(s):  
Alexander Knebe ◽  
Matías Gámez-Marín ◽  
Frazer R Pearce ◽  
Weiguang Cui ◽  
Kai Hoffmann ◽  
...  
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Galaxy Cluster ◽  
Cluster Radius ◽  
Dynamical State ◽  
The Galaxy ◽  
Radial Orbit ◽  
Galaxy Halo ◽  
Satellite Galaxies

ABSTRACT Using 324 numerically modelled galaxy clusters, we investigate the radial and galaxy–halo alignment of dark matter subhaloes and satellite galaxies orbiting within and around them. We find that radial alignment depends on distance to the centre of the galaxy cluster but appears independent of the dynamical state of the central host cluster. Furthermore, we cannot find a relation between radial alignment of the halo or galaxy shape with its own mass. We report that backsplash galaxies, i.e. objects that have already passed through the cluster radius but are now located in the outskirts, show a stronger radial alignment than infalling objects. We further find that there exists a population of well radially aligned objects passing very close to the central cluster’s centre that were found to be on highly radial orbit.

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