The GalMer database: galaxy mergers in the virtual observatory

Chilingarian, Igor; Matteo, P. Di; Combes, F.; Melchior, A. L.; Semelin, B.

doi:10.1051/0004-6361/200912938

Cited by 93 publications

(146 citation statements)

References 89 publications

(113 reference statements)

Supporting

Mentioning

135

Contrasting

Order By: Relevance

“…The initial Toomre parameter of both stars and gas is taken to be Q = 1.2 as the initial condition of the tree-SPH simulations and particle velocities are initialized with the method described in Hernquist (1993). Full details of the simulations are given in Di Matteo et al (2007) and Chilingarian et al (2010). Because the gaseous discs are set initially as MiyamotoNagai density distributions with arbitrary scale-heights, they are not in hydrostatic equilibrium.…”

Section: Description Of the Simulationsmentioning

confidence: 99%

Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts

Minchev

Famaey

Quillen

et al. 2012

A&A

Self Cite

186

208

View full text Add to dashboard Cite

We investigate the evolution of galactic discs in N-body tree-SPH simulations. We find that discs, initially truncated at three scalelengths, can triple their radial extent, solely driven by secular evolution. At the same time, the initial radial metallicity gradients are flattened and even reversed in the outer discs. Both Type I (single exponential) and Type II (down-turning) observed disc surfacebrightness profiles can be explained by our findings. We show that profiles with breaks beyond the bar's outer Lindblad resonance, at present only explained as the effect of star-formation threshold, can occur even if no star formation is considered. We explain these results with the strong angular momentum outward transfer, resulting from torques and radial migration associated with multiple patterns, such as central bars and spiral waves of different multiplicity. We find that even for stars ending up on cold orbits, the changes in angular momentum exhibit complex structure as a function of radius, unlike the expected effect of transient spirals alone. We show that the bars in all of our simulations are the most effective drivers of radial migration through their corotation resonance, throughout the 3 Gyr of evolution studied. Focussing on one of our models, we find evidence for non-linear coupling among m = 1, 2, 3 and 4 density waves, where m is the pattern multiplicity. In this way the waves involved conspire to carry the energy and angular momentum extracted by the first mode from the inner parts of the disc much farther out than a single mode could. We suggest that the naturally occurring larger resonance widths at galactic radii beyond four scale-lengths may have profound consequences on the formation and location of breaks in disc density profiles, provided spirals are present at such large distances. We also consider the effect of gas inflow and show that when in-plane smooth gas accretion of ∼5 M /yr is included, the outer discs become more unstable, leading to a strong increase in the stellar velocity dispersion. This, in turn, causes the formation of a Type III (up-turning) profile in the old stellar population. We propose that observations of Type III surface brightness profiles, combined with an up-turn in the stellar velocity dispersions beyond the disc break, could be a signature of ongoing gas-accretion. The results of this study suggest that disc outskirts comprised of stars migrated from the inner disc would have relatively large radial velocity dispersions (>30 km s −1 at 6 scale-lengths for Milky Way-size systems), and significant thickness when seen edge-on.

show abstract

Section: Description Of the Simulationsmentioning

confidence: 99%

Evolution of galactic discs: multiple patterns, radial migration, and disc outskirts

Minchev

Famaey

Quillen

et al. 2012

A&A

Self Cite

186

208

View full text Add to dashboard Cite

show abstract

“…For each pair of interacting galaxies, we performed 24 simulations, varying the galaxies orbital initial conditions (initial orbital energy E and angular momentum L) and taking into account both direct and retrograde orbits. The initial orbital parameters (initial distance between the two galaxies, initial relative velocity, specific angular momentum, orbital energy and spin) for the different runs are fully described in Table 7 of Chilingarian et al (2010), and we refer the reader to this paper for their complete description.…”

Section: Models and Initial Conditionsmentioning

confidence: 99%

“…The numerical recipes used to implement star formation and metal enrichment have been fully described elsewhere (Di Matteo et al 2007;Chilingarian et al 2010), thus here we only summarise those features that are most directly relevant to our analysis. Star formation efficiency has been parametrised as:…”

Section: Star Formation and Metal Enrichmentmentioning

confidence: 99%

“…The value of kin has been chosen such that the total amount of kinetic energy received by a gas particle due to the contribution from all the surrounding neighbours, is less than 1 km s −1 , thus preventing a rapid growth of the vertical thickness of the gaseous disk. A more detailed description of the implementation of feedback recipes used in our code is given in Semelin & Combes (2002); Chilingarian et al (2010).…”

Section: Star Formation and Metal Enrichmentmentioning

confidence: 99%

See 1 more Smart Citation

The dilution peak, metallicity evolution, and dating of galaxy interactions and mergers

Montuori¹,

Matteo

Lehnert

et al. 2010

A&A

Self Cite

116

View full text Add to dashboard Cite

Strong inflows of gas from the outer disk to the inner kiloparsecs are induced during the interaction of disk galaxies. This inflow of relatively low-metallicity gas dilutes the metallicity of the circumnuclear gas. This process is critical for the galaxy evolution. We have investigated several aspects of the process as the timing and duration of the dilution and its correlation with the induced star formation. We analysed major (1:1) gas-rich interactions and mergers, spanning a range of initial orbital characteristics. Star formation and metal enrichment from SNe are included in our model. Our results show that the strongest trend is between the star formation rate and the dilution of the metals in the nuclear region; i.e., the more intense the central burst of star formation, the more the gas is diluted. This trend comes from strong inflows of relatively metal-poor gas from the outer regions of both disks, which fuels the intense star formation and lowers the overall metallicity for a time. The strong inflows happen on timescales of about 10 8 years or less (i.e., on an internal dynamical time of the disk in the simulations), and the most intense star formation and lowest gas phase metallicities are seen generally after the first pericentre passage. As the star formation proceeds and the merger advances, the dilution reduces and enrichment becomes dominant -ultimately increasing the metallicity of the circumnuclear gas to a level higher than the initial metallicities of the merging galaxies. The "fly-bys" -pairs that interact but do not merge -also cause some dilution. We even see some dilution early in the merger or in the "fly-bys" and thus do not observe a strong trend between the nuclear metallicities and separation in our simulations until the merger is well advanced. We also analyse the O and Fe enrichment of the ISM, and show that the evolution of the α/Fe ratios, as well as the dilution of the central gas metallicity, can be used as a clock for dating the interaction.

show abstract

“…Interestingly, the goodness-of-fit measure does not increase smoothly, but rather in jumps. At present, alternatives include "expert-learning" systems like the Barnes/Hibbard Identikit (Barnes & Hibbard 2009) or Chilingarian et al's GalMer database (Chilingarian, et al 2010).…”

Section: Iaus270 Star Formation In Interacting Galaxiesmentioning

confidence: 99%