scholarly journals Formation of the largest galactic cores through binary scouring and gravitational wave recoil

2021 ◽  
Vol 502 (4) ◽  
pp. 4794-4814
Author(s):  
Imran Tariq Nasim ◽  
Alessia Gualandris ◽  
Justin I Read ◽  
Fabio Antonini ◽  
Walter Dehnen ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
Surface Brightness ◽  
Elliptical Galaxies ◽  
Galactic Centre ◽  
Merging Galaxies ◽  
The Core ◽  
Major Merger ◽  
Minor Mergers ◽  
Light Profiles ◽  
Compact Cluster

ABSTRACT Massive elliptical galaxies are typically observed to have central cores in their projected radial light profiles. Such cores have long been thought to form through ‘binary scouring’ as supermassive black holes (SMBHs), brought in through mergers, form a hard binary and eject stars from the galactic centre. However, the most massive cores, like the $\sim 3{\, \mathrm{kpc}}$ core in A2261-BCG, remain challenging to explain in this way. In this paper, we run a suite of dry galaxy merger simulations to explore three different scenarios for central core formation in massive elliptical galaxies: ‘binary scouring’, ‘tidal deposition’, and ‘gravitational wave (GW) induced recoil’. Using the griffin code, we self-consistently model the stars, dark matter, and SMBHs in our merging galaxies, following the SMBH dynamics through to the formation of a hard binary. We find that we can only explain the large surface brightness core of A2261-BCG with a combination of a major merger that produces a small $\sim 1{\, \mathrm{kpc}}$ core through binary scouring, followed by the subsequent GW recoil of its SMBH that acts to grow the core size. Key predictions of this scenario are an offset SMBH surrounded by a compact cluster of bound stars and a non-divergent central density profile. We show that the bright ‘knots’ observed in the core region of A2261-BCG are best explained as stalled perturbers resulting from minor mergers, though the brightest may also represent ejected SMBHs surrounded by a stellar cloak of bound stars.

scholarly journals Forming bulges during galaxy minor mergers

2007 ◽  
Vol 3 (S245) ◽  
pp. 63-66 ◽  
Author(s):  
T. J. Cox ◽  
J. Younger ◽  
L. Hernquist ◽  
P. F. Hopkins
Keyword(s):  
Black Hole ◽  
Large Mass ◽  
Elliptical Galaxies ◽  
Equal Mass ◽  
Mass Ratio ◽  
Black Hole Growth ◽  
Major Merger ◽  
Hole Growth ◽  
Minor Mergers ◽  
Large Mass Ratio

AbstractThe hierarchical formation of structure suggests that dark halos, and the galaxies they host, are shaped by their merging history. While the idea that mergers between galaxies of equal mass, i.e., major merger, produce elliptical galaxies has received considerable attention, he galaxies that result from minor merger, i.e., mergers between galaxies with a large mass ratio, is much less understood. We have performed a large number of numerical simulations of minor mergers, including cooling, star formation, and black hole growth in order to study this process in more detail. This talk will present some preliminary results of this study, and in particular, the morphology and kinematics of minor merger remnants.

scholarly journals Dark Matter in Galaxies: Observational overview

2004 ◽  
Vol 220 ◽  
pp. 39-50 ◽  
Author(s):  
A. Bosma
Keyword(s):  
Dark Matter ◽  
Present State ◽  
Surface Brightness ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Elliptical Galaxies ◽  
The Core ◽  
Low Surface Brightness ◽  
Dwarf Spheroidals ◽  
Low Surface Brightness Galaxies

I review the observational side of the present state of the debate about the dark matter in galaxies, with emphasis on the core/cusp problem in low surface brightness galaxies, and the question of maximum/sub-maximum disks in spiral galaxies. Some remarks are made about the dwarf spheroidals around the Milky Way, and about elliptical galaxies.

scholarly journals An HST Survey of Cores of Early-Type Galaxies

1996 ◽  
Vol 171 ◽  
pp. 105-116 ◽  
Author(s):  
John Kormendy ◽  
Yong-Ik Byun ◽  
E. A. Ajhar ◽  
Tod R. Lauer ◽  
Alan Dressler ◽  
...  
Keyword(s):  
Outer Surface ◽  
Surface Brightness ◽  
Hubble Space Telescope ◽  
Elliptical Galaxies ◽  
Core Radius ◽  
Early Type ◽  
Late Type ◽  
Fundamental Plane ◽  
The Core ◽  
Oblate Spheroidal

Photometry of the central parts of bulges and elliptical galaxies with the Hubble Space Telescope (HST) confirms and extends ground-based results. Most giant ellipticals have cuspy cores: at the “break radius” rb (formerly the core radius rc), the steep outer surface brightness profile turns down to a shallow inner power law I(r) ∝ r–γ, 0 ≤ γ ≲ 0.25. The corresponding slope of the deprojected profile is derived; the flattest cores allow box orbits to survive. Cores continue to satisfy fundamental plane parameter correlations like those found from the ground. In particular, HST confirms that the luminosity sequence of elliptical galaxies (from cDs to M 32) is physically unrelated to spheroidal galaxies like Fornax. The latter are closely related to late-type dwarfs. Low-luminosity ellipticals do not show cores: 0.5 ≲ γ ≲ 1.3. The most important new result is that global and core properties both show signs of a dichotomy between (i) low-luminosity ellipticals that rotate rapidly, that are nearly isotropic and oblate-spheroidal, that have disky-distorted isophotes, and that are coreless and (ii) giant ellipticals that are essentially nonrotating, anisotropic, and moderately triaxial, that are boxy-distorted, and that have cuspy cores.

scholarly journals Surface brightness fluctuation distances for nearby dwarf elliptical galaxies

2001 ◽  
Vol 380 (1) ◽  
pp. 90-101 ◽  
Author(s):  
H. Jerjen ◽  
R. Rekola ◽  
L. Takalo ◽  
M. Coleman ◽  
M. Valtonen
Keyword(s):  
Surface Brightness ◽  
Elliptical Galaxies ◽  
Brightness Fluctuation ◽  
Dwarf Elliptical Galaxies

scholarly journals What drives the star formation in early-type galaxies at late epochs? - the case for minor mergers

2009 ◽  
Vol 5 (S262) ◽  
pp. 168-171 ◽  
Author(s):  
Sugata Kaviraj ◽  
Richard Ellis ◽  
Sukyoung Yi ◽  
Joseph Silk ◽  
Kevin Schawinski ◽  
...  
Keyword(s):  
Star Formation ◽  
Early Type ◽  
Principal Mechanism ◽  
Redshift Range ◽  
Low Level ◽  
Star Formation Activity ◽  
Multi Wavelength ◽  
Major Merger ◽  
Minor Mergers ◽  
Intermediate Redshift

AbstractMulti-wavelength photometry of early-type galaxies (ETGs) in the COSMOS survey is used to demonstrate that the low-level star formation activity in the ETG population at late epochs (z < 1) is likely to be driven by repeated minor mergers. While relaxed ETGs are almost entirely contained within the UV red sequence, their morphologically disturbed counterparts are largely found in the blue cloud, regardless of luminosity. Since empirically determined major-merger rates in the redshift range z < 1 are a few factors too low to account for the number fraction of disturbed ETGs, this suggests that minor mergers are the principal mechanism that drives star formation activity in ETGs at low and intermediate redshift.

scholarly journals The VISCACHA survey – II. Structure of star clusters in the Magellanic Clouds periphery

2020 ◽  
Vol 498 (1) ◽  
pp. 205-222
Author(s):  
João F C Santos ◽  
Francisco F S Maia ◽  
Bruno Dias ◽  
Leandro de O Kerber ◽  
Andrés E Piatti ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Structural Parameters ◽  
Star Clusters ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
The Core ◽  
Optical Images ◽  
Low Surface Brightness ◽  
Homogeneous Set ◽  
Stellar Density

ABSTRACT We provide a homogeneous set of structural parameters of 83 star clusters located at the periphery of the Small Magellanic Cloud (SMC) and the Large Magellanic Cloud (LMC). The clusters’ stellar density and surface brightness profiles were built from deep, AO assisted optical images, and uniform analysis techniques. The structural parameters were obtained from King and Elson et al. model fittings. Integrated magnitudes and masses (for a subsample) are also provided. The sample contains mostly low surface brightness clusters with distances between 4.5 and 6.5 kpc and between 1 and 6.5 kpc from the LMC and SMC centres, respectively. We analysed their spatial distribution and structural properties, comparing them with those of inner clusters. Half-light and Jacobi radii were estimated, allowing an evaluation of the Roche volume tidal filling. We found that: (i) for our sample of LMC clusters, the tidal radii are, on average, larger than those of inner clusters from previous studies; (ii) the core radii dispersion tends to be greater for LMC clusters located towards the southwest, with position angles of ∼200° and about ∼5° from the LMC centre, i.e. those LMC clusters nearer to the SMC; (iii) the core radius evolution for clusters with known age is similar to that of inner clusters; (iv) SMC clusters with galactocentric distances closer than 4 kpc are overfilling; (v) the recent Clouds collision did not leave marks on the LMC clusters’ structure that our analysis could reveal.

scholarly journals Kinematic Modelling of NGC 3379

1983 ◽  
Vol 100 ◽  
pp. 295-296
Author(s):  
Gary A. Mamon
Keyword(s):  
Surface Brightness ◽  
Elliptical Galaxies ◽  
Anisotropic Pressure ◽  
Velocity Anisotropy ◽  
Kinematic Modelling

Giant elliptical galaxies are now known to be supported by anisotropic pressure rather than by rotation (cf. Binney, 1981). This anisotropy can be derived from observable quantities for spherical systems as was shown by Binney and Mamon (1982) in their study of M87. We investigate here the velocity anisotropy of the El galaxy NGC 3379, a giant elliptical whose surface brightness constitutes an excellent illustration of the r1/4 law.

Sign in / Sign up

Export Citation Format

Share Document