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Model Tully-Fisher (TF) relation for disk-like objects at z = 0 in the Lambda CDM cosmogony. Stellar mass has been converted into I-band luminosity by adopting a mass-to-light ratio of 1.8 h solar units. The typical slope of the predictions nearly coincides with the observational value &alpha ~ 3.1 by Giovanelli et al. 1997 (dashed line).
Model FP relation for early-type galaxies embedded on NFW halos in the concordant Lambda CDM cosmogony. The thick solid line is calculated by using the median concentration c at a given halo mass, while the thick dotted lines encompass a 1 &sigma variation on the logarithm of this parameter. Predictions are compared against the SDSS data in the r* band of Bernardi et al. (2003) by assuming that the galaxies are observed at a mean redshift of 0.15.
Series of 40 grayscaled images uniformly spaced in time showing the evolution of the luminous matter density in a simulation of one of our pre-virialized low-mass groups of galaxies (# 8336). This experiment uses 5 million mass particles initially distributed among 25 galaxy halos with virial masses drawn from a Schechter mass function, with M/M* = 0.01 and &alpha = -1, and a uniform common background of dark matter. The simulation starts at z = 3 (top-leftmost images) and is evolved until the present epoch (bottom right). The darker the color in the snapshots the higher the density of particles. In the last Gyr of evolution this particular group resembles a typical fossil galaxy.
Evolution of the cumulative stellar mass function from a set of 20 O(10^7)-particle poor groups induced by the gravitational collapse of these systems. Top: Curves resulting from a density kernel estimation of the probability distribution function inferred at t = 0 (z = 3; dashed line) and t = 6 (z ≈ 0; solid line). Bottom: Difference between both curves. The dip obtained is reminiscent of the dip observed in the galaxy LF of the X-ray dim GEMS groups (Miles et al. 2004).
Same as in Figure on the left but now for 42 poor groups simulated using 5 million particles per group. Stellar mass has been converted into K-band luminosity by assuming that M/L(K) = 1 (see FP Figure below).
Comparison between the effective radius of the brightest group galaxy (BGG) measured from 42 of our simulated galaxy groups (along the three projections onto the main planes) and the corresponding estimates obtained from our fundamental plane-like best fit to the simulated data, given by Re = -7.4 + (1.52 ± 0.05)σv + (0.27 ± 0.01)μe. Note the small dispersion and the fact that the inferred coefficients are very close to those obtained by La Barbera et al. (2010) in the K band (-7.48, 1.48, 0.3) provide one assumes M/L(K) ≈ 1.
Magnitude gap between the first and second ranked galaxies versus the stellar masses of both objects. This graph shows that the gap is created at the expense of an increase in the mass of the first ranked galaxies and a decrease in the mass of the second brightest objects in about the same proportion.
fig_2-eps-converted-to.pdfResiduals of Fundamental Plane fitting along the dimensions of the standard plane. From top to bottom: (A) the effective radius, Re, (B) the mean stellar velocity dispersion within Re, σe, and (C) the mean stellar mass surface density within Re, μe. We use the following symbols for the data: big dark-blue circles for our mock first- ranked group galaxies, big red circles for our less-reliably-resolved second-ranked galaxies, big yellow circles for a homogeneous set of 85 BCGs extracted from clusters, big orange circles for the ETGs in the Norma and Coma clusters, green dots for the 6dFGSv catalog, and small gray circles for a volume-limited sample of ETGs based on SDSS-UKIDSS observations. In all panels the black diagonal line represents perfect agreement between real (Y axis) and estimated (X axis) values. The reasonably neutral behaviour of the residuals confirms that the model FP fits the observations well. Note that the samples containing the brightest objects, both simulated and observed, systematically show the smallest differences between expectations and measurements.
Comparison between predictions from the models of Boylan-Kolchin et al. 2008 (B08), Jiang et al. 2008 (J08 and J08e), and McCavana et al. 2012 (M12) and our measurements for the case of merger simulations with a reduced orbital energy of 4/3 and mass ratios 1:1 and 3:1 (panels a and b, respectively), and for equal-mass mergers with an ini- tial energy of 2.0 (panel c) as a function of the initial orbital circularity of the satellites. All ratios are shown with different offsets around the true values of the circularity for clarity.
fig_9.pdf
Final snapshots at z = 0 of 48 simulated groups. The lighter the color in the snapshots the higher the density of particles. This plot illustrates the enormous variety of final configurations produced by our experiments, as there are virtually no two groups alike. In some cases, first ranked galaxies remain largely unchanged over the entire simulation, while in others we observe the creation of a large, dominant BGG as the result of multiple mergers. Also note that practically all images show the presence of a significant amount of intragroup debris in various forms (extended low surface brightness features, shells, narrow streams, plume- and umbrella-shaped structures,...) which has been ripped from the galaxies mostly by the strong interactions that they experience during the highly nonlinear gravitational collapse of their parent groups.
Expected incidence of dual active BH in equal-mass mergers of spiral galaxies (of Sb type) in the nearby universe, as a function of the merger timescale, τmer. Pdagn is the intrinsic fraction of binary mergers with active BH pairs and Pdagn,spec is the fraction of these mergers observable through double-peaked narrow line features in the optical window. The panels on each column show results for different thresholds of nuclear activity. The panels in the two top rows show results for a BH lifetime, τagn, of 10² Myr, while the two bottom rows depict results for τagn = 10 Myr. Individual predictions are represented with green dots, while large red open circles and error bars show the median and interquartile range of the subsets of results inferred from the same initial orbital eccentricity which increases from left to right in each panel. This figure is for mergers starting with a reduced orbital energy rcirc,p = 4/3.
io_vs_oi_maps.pdfExamples of spectral maps and spectral profiles of S0 galaxies. The second, third, and fourth rows show, in this order, maps of the EW(Hα), L'(Hα), and D4000 spectral indices. Only spaxels with all quality flags equal to zero are drawn. The green and red horizontal lines included in the EW(Hα) panels indicate, respectively, the galaxies’ Petrosian half-light diameter in the r band and 2σPSF. The bottom row shows the vectorized spectral profiles of the galaxies in the PC1–PC2 subspace. The true color images of the galaxies are shown in the first row, with the overlapping violet hexagonal frames depicting the footprint of MaNGA’s bundles (images’ source: https://data.sdss.org/sas/dr15/manga/). Galaxies in columns (b), (c), and (d) show clear rings in EW(Hα), whereas no rings are observed for the galaxies in columns (a) and (e).
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