Stellar Kinematics of Merging Galaxies: Clues to the Origins of Elliptical Galaxies

1998 ◽  
Vol 497 (1) ◽  
pp. 163-167 ◽  
Author(s):  
L. M. Shier ◽  
J. Fischer
Keyword(s):  
Elliptical Galaxies ◽  
Stellar Kinematics ◽  
Merging Galaxies

scholarly journals The Radial Velocities of Planetary Nebulae in NGC 3379

1993 ◽  
Vol 155 ◽  
pp. 570-570
Author(s):  
Robin Ciardullo ◽  
George Jacoby
Keyword(s):  
Radial Velocity ◽  
Absorption Line ◽  
Planetary Nebula ◽  
Velocity Dispersion ◽  
Planetary Nebulae ◽  
Elliptical Galaxies ◽  
Emission Lines ◽  
Surface Photometry ◽  
Stellar Kinematics ◽  
Velocity Measurements

Several authors have analyzed the kinematics of elliptical galaxies using surface photometry in combination with absorption line velocity dispersion measurements. However, these analyses never explore the halos of galaxies, since the best absorption line measurements extend only ∼1 re. The only way to extend our knowledge of stellar kinematics to larger radii is to use the emission lines of planetary nebula for radial velocity measurements.

scholarly journals Dust and the observed dark matter content of galaxies

2004 ◽  
Vol 220 ◽  
pp. 343-344 ◽  
Author(s):  
Maarten Baes ◽  
Herwig Dejonghe ◽  
Jonathan I. Davies
Keyword(s):  
Dark Matter ◽  
Interstellar Dust ◽  
Optical Rotation ◽  
Elliptical Galaxies ◽  
Matter Content ◽  
Dark Matter Halo ◽  
Stellar Kinematics ◽  
The Galaxy ◽  
Dust Attenuation ◽  
Radiative Transfer Modeling

Using detailed Monte Carlo radiative transfer modeling, we examine the effects of absorption and scattering by interstellar dust on the observed kinematics of galaxies. Our modeling results have a direct impact on the derivation of the properties of dark matter haloes around both elliptical and spiral galaxies. We find that interstellar dust has a very significant effect on the observed stellar kinematics of elliptical galaxies, in the way that it mimics the presence of a dark matter halo. Taking dust into account in kinematical modeling procedures can reduce or even eliminate the need for dark matter at a few effective radii. Dust profoundly affects the optical rotation curve and stellar kinematics of edge-on disc galaxies. This effect, however, is significantly reduced when the galaxy is more than a few degrees from strictly edge-on. These results demonstrate that dust attenuation cannot be invoked as a possible mechanism to reconcile the discrepancies between the observed shallow slopes of LSB galaxy rotation curves and the dark matter cusps found in CDM cosmological simulations.

scholarly journals Stellar Kinematics of Elliptical Galaxies in Pairs

1990 ◽  
Vol 124 ◽  
pp. 33-36
Author(s):  
Rainer Madejsky ◽  
Ralf Bender
Keyword(s):  
Radial Velocity ◽  
Elliptical Galaxy ◽  
Orbital Plane ◽  
Elliptical Galaxies ◽  
Line Of Sight ◽  
Stellar Kinematics ◽  
Velocity Difference ◽  
The Moment ◽  
Inner Parts ◽  
Very High

Observations of elliptical galaxy pairs allow the study of different states of tidal interaction between galaxies. The comparison with normal elliptical galaxies directly reveals the disturbed morphological and kinematical properties. Numerical simulations have shown that with the known initial luminosity profile, the time elapsed since closest approach between two galaxies can be estimated from the radial position of the disturbances (Aguilar and White, 1986).The two galaxy pairs Arp 166 (NGC 750/1) and 3C 278 (NGC 4782/3) considered here exhibit distorted and nonconcentric isophotes (cf. Madejsky, 1989). In Arp 166 the major relative shift of the centers of the isophotes occurs in the outer parts while in 3C 278 the nonconcentric isophotes are more pronounced in the inner parts of the galaxies, suggesting that more time ha&elapsed since the moment of closest approach in Arp 166 than in 3C 278. Furthermore, in Arp 166, both galaxies have the same radial velocity, implying that their orbital plane is perpendicular to the line of sight. In turn, the galaxies NGC 4782 and NGC 4783 are moving with a very high radial velocity difference of 680kms-1. Taking into account the location of both galaxies, which are the dominant members of a small group of about 25 galaxies (De Souza and Quintana, 1990), the true velocity difference probably is not much higher than the observed radial velocity difference. Therefore it is very likely that we are viewing at high inclination onto (i.e. nearly parallel to) the orbital plane of the galaxies NGC 4782 and 4783.

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 Extended stellar kinematics of elliptical galaxies in the Fornax cluster

1998 ◽  
Vol 133 (3) ◽  
pp. 325-336 ◽  
Author(s):  
A. W. Graham ◽  
M. M. Colless ◽  
G. Busarello ◽  
S. Zaggia ◽  
G. Longo
Keyword(s):  
Elliptical Galaxies ◽  
Stellar Kinematics ◽  
Fornax Cluster

scholarly journals Dynamical Evolution of Globular Cluster Systems

2005 ◽  
Vol 13 ◽  
pp. 193-194
Author(s):  
E. Vesperini
Keyword(s):  
Stellar Evolution ◽  
Globular Cluster ◽  
Dynamical Evolution ◽  
Mass Function ◽  
Elliptical Galaxies ◽  
Host Galaxy ◽  
Dynamical Friction ◽  
Evolutionary Processes ◽  
Merging Galaxies ◽  
Cluster Systems

AbstractI present the results of a number of simulations of the dynamical evolution of globular cluster systems (GCS) in elliptical galaxies including the effects of two-body relaxation, dynamical friction, stellar evolution and the effects of the tidal field of the host galaxy. The results of detailed models for the evolution of the M87 GCS are also presented. A significant number of clusters are disrupted by evolutionary processes and the properties of many of the clusters which survive are effected by dynamical evolution. In spite of large differences in the efficiency of evolutionary processes in different galaxies, the final galaxy-to-galaxy variation of the GCS mean mass and its radial variation within individual galaxies in my simulations are small and consistent with observations. The effects of dissolution of low-concentration clusters due to mass loss through stellar evolution are also discussed and are shown to play an important role in the evolution of a power-law GCS mass function (GCMF), similar to that observed in young cluster systems in merging galaxies, towards a final GCMF with properties consistent with observations.

scholarly journals An Ultraluminous IRAS Galaxy with an Extremely Soft X-Ray Spectrum

1997 ◽  
Vol 159 ◽  
pp. 434-436
Author(s):  
X.Y. Xia ◽  
Th. Boiler ◽  
Z.G. Deng
Keyword(s):  
Evolutionary Process ◽  
Far Infrared ◽  
Elliptical Galaxies ◽  
Disk Galaxies ◽  
Galaxy Interactions ◽  
Merging Galaxies ◽  
Redshift Surveys ◽  
Ultraluminous Infrared Galaxies ◽  
Evolutionary Connection ◽  
Iras Galaxy

Redshift surveys of the extragalactic IRAS sources have revealed a class of galaxies, ultraluminous infrared galaxies (ULIRGs), that radiate an enormous amount of energy in the far-infrared (Soifer et al. 1986), typically LIR ≥ 1012L⊙, which is comparable to the luminosities of quasars. The energy source for most ULIRGs is believed to be massive nuclear starbursts triggered by galaxy interactions or mergers (Rigopoulou et al. 1996, Crawford et al. 1996). There is much debate about the evolution of ULIRGs. Sanders et al. (1988) suggested that ULIRGs are forming QSOs. However, it is not clear how merging galaxies evolve to QSOs. Meanwhile, observations and N-body simulations show that mergers between disk galaxies can form ellipticals. Some ULIRGs, such as Arp 220 and NGC 6240, do have elliptical characteristics. What is the evolutionary connection between QSOs and elliptical galaxies? About 10% of ULIRGs are IR QSOs or Seyfert 1 galaxies, on the basis of their optical spectra and appearance. Some of them are hosted in ellipticals (Hutchings et al. 1988, Lipari et al. 1994). Also, most of them are strong Fen emitters. Studying this subsample of ULIRGs in detail may give some clues to understanding the evolutionary process mentioned above.

scholarly journals The Cold Interstellar Medium in Elliptical Galaxies – Observations of HI and Radio Continuum Emission

1987 ◽  
Vol 127 ◽  
pp. 145-154
Author(s):  
G. R. Knapp
Keyword(s):  
Interstellar Medium ◽  
Large Mass ◽  
Elliptical Galaxies ◽  
Current Data ◽  
Solar Neighborhood ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Stellar Kinematics ◽  
Stellar Content ◽  
Continuum Source

About 10% of nearby elliptical galaxies contain HI, with typical values of M(HI) ~ 5 × 108 M⊙ and M(HI)/LB ~ 0.03 M⊙/L⊙. The HI content is unrelated to the stellar content, (unlike the situation in spiral galaxies) suggesting that the HI in early-type galaxies has an external origin and is not produced by mass loss. This conclusion is strengthened by the distribution and kinematics of the HI structures, which lie outside the main optical body of the galaxies, have much larger specific angular momentum than do the stars, and are often highly inclined to the kinematic and distribution axes of the optical bodies.The HI and stellar kinematics show that the rotation curves of E and SO galaxies are approximately flat from small (a few hundred pc) to large (10-20 kpc) radii, as is the case for spirals. Likewise, large mass-to-light ratios are found for some systems. Comparison with mass models derived from X-ray emission suggests that these may in some cases overestimate the mass.The presence of HI is shown to enhance the likelihood that an E/SO galaxy has a nuclear radio continuum source, in agreement with models which suggest that the central engine is fuelled by cold gas. Current data suggest that the gas-to-dust ratio for the cold interstellar medium in ellipticals has a value similar to that found in the solar neighborhood.

scholarly journals LOCAL GROUP DWARF ELLIPTICAL GALAXIES. II. STELLAR KINEMATICS TO LARGE RADII IN NGC 147 AND NGC 185

2010 ◽  
Vol 711 (1) ◽  
pp. 361-373 ◽  
Author(s):  
M. Geha ◽  
R. P. van der Marel ◽  
P. Guhathakurta ◽  
K. M. Gilbert ◽  
J. Kalirai ◽  
...  
Keyword(s):  
Local Group ◽  
Elliptical Galaxies ◽  
Stellar Kinematics ◽  
Dwarf Elliptical Galaxies
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