scholarly journals The stellar halos of ETGs in the IllustrisTNG simulations: The photometric and kinematic diversity of galaxies at large radii

2020 ◽  
Vol 641 ◽  
pp. A60 ◽  
Author(s):  
C. Pulsoni ◽  
O. Gerhard ◽  
M. Arnaboldi ◽  
A. Pillepich ◽  
D. Nelson ◽  
...  
Keyword(s):  
Mass Range ◽  
Stellar Mass ◽  
Velocity Fields ◽  
Gradual Transition ◽  
Early Type ◽  
Central Regions ◽  
Stellar Halo ◽  
Intrinsic Shape ◽  
Galaxy Sample ◽  
Kinematic Properties

Context. Early-type galaxies (ETGs) are found to follow a wide variety of merger and accretion histories in cosmological simulations. Aims. We characterize the photometric and kinematic properties of simulated ETG stellar halos, and compare them to the observations. Methods. We selected a sample of 1114 ETGs in the TNG100 simulation and 80 in the higher-resolution TNG50. These ETGs span a stellar mass range of 1010.3 − 1012 M⊙ and they were selected within the range of g − r colour and λ-ellipticity diagram populated by observed ETGs. We determined photometric parameters, intrinsic shapes, and kinematic observables in their extended stellar halos. We compared the results with central IFU kinematics and ePN.S planetary nebula velocity fields at large radii, studying the variation in kinematics from center to halo, and connecting it to a change in the intrinsic shape of the galaxies. Results. We find that the simulated galaxy sample reproduces the diversity of kinematic properties observed in ETG halos. Simulated fast rotators (FRs) divide almost evenly in one third having flat λ profiles and high halo rotational support, a third with gently decreasing profiles, and another third with low halo rotation. However, the peak of rotation occurs at larger R than in observed ETG samples. Slow rotators (SRs) tend to have increased rotation in the outskirts, with half of them exceeding λ = 0.2. For M* >  1011.5 M⊙ halo rotation is unimportant. A similar variety of properties is found for the stellar halo intrinsic shapes. Rotational support and shape are deeply related: the kinematic transition to lower rotational support is accompanied by a change towards rounder intrinsic shape. Triaxiality in the halos of FRs increases outwards and with stellar mass. Simulated SRs have relatively constant triaxiality profiles. Conclusions. Simulated stellar halos show a large variety of structural properties, with quantitative but no clear qualitative differences between FRs and SRs. At the same stellar mass, stellar halo properties show a more gradual transition and significant overlap between the two families, despite the clear bimodality in the central regions. This is in agreement with observations of extended photometry and kinematics.

scholarly journals The extended Planetary Nebula Spectrograph (ePN.S) early-type galaxy survey: The kinematic diversity of stellar halos and the relation between halo transition scale and stellar mass

2018 ◽  
Vol 618 ◽  
pp. A94 ◽  
Author(s):  
C. Pulsoni ◽  
O. Gerhard ◽  
M. Arnaboldi ◽  
L. Coccato ◽  
A. Longobardi ◽  
...  
Keyword(s):  
Absorption Line ◽  
Phase Formation ◽  
Velocity Dispersion ◽  
Stellar Mass ◽  
Early Type ◽  
Two Phase ◽  
Low Surface Brightness ◽  
Central Regions ◽  
Adaptive Kernel ◽  
Kinematic Properties

Context. In the hierarchical two-phase formation scenario, the halos of early type galaxies (ETGs) are expected to have different physical properties from the galaxies’ central regions. Aims. The ePN.S survey characterizes the kinematic properties of ETG halos using planetary nebulae (PNe) as tracers, overcoming the limitations of absorption line spectroscopy at low surface brightness. Methods. We present two-dimensional velocity and velocity dispersion fields for 33 ETGs, including fast (FRs) and slow rotators (SRs). The velocity fields were reconstructed from the measured PN velocities using an adaptive kernel procedure validated with simulations, and extend to a median of 5.6 effective radii (Re). We complemented the PN kinematics with absorption line data from the literature, for a complete description of the kinematics from the center to the outskirts. Results. ETGs typically show a kinematic transition between inner regions and halo. Estimated transition radii in units of Re anti-correlate with stellar mass. SRs have increased but still modest rotational support at large radii. Most of the FRs show a decrease in rotation, due to the fading of the inner disk in the outer, more slowly rotating spheroid. 30% of the FRs are dominated by rotation also at large radii. Most ETGs have flat or slightly falling halo velocity dispersion profiles, but 15% of the sample have steeply falling profiles. All of the SRs and 40% of the FRs show signatures of triaxial halos such as kinematic twists or misalignments. We show with illustrative photometric models that this is consistent with the distribution of isophote twists from extended photometry. Conclusions. ETGs have more diverse kinematic properties in their halos than in the central regions. FRs do contain inner disk components but these frequently fade in outer spheroids which are often triaxial. The observed kinematic transition to the halo and its dependence on stellar mass is consistent with ΛCDM simulations and supports a two-phase formation scenario.

scholarly journals A study of stellar orbit fractions: simulated IllustrisTNG galaxies compared to CALIFA observations

2019 ◽  
Vol 489 (1) ◽  
pp. 842-854 ◽  
Author(s):  
Dandan Xu ◽  
Ling Zhu ◽  
Robert Grand ◽  
Volker Springel ◽  
Shude Mao ◽  
...  
Keyword(s):  
Observational Data ◽  
Mass Range ◽  
Stellar Mass ◽  
Model Uncertainties ◽  
Massive Galaxies ◽  
Hubble Sequence ◽  
Galaxy Sample ◽  
The Mean ◽  
Stellar Orbit

ABSTRACT Motivated by the recently discovered kinematic ‘Hubble sequence’ shown by the stellar orbit-circularity distribution of 260 CALIFA galaxies, we make use of a comparable galaxy sample at z = 0 with a stellar mass range of $M_{*}/\mathrm{M}_{\odot }\in [10^{9.7},\, 10^{11.4}]$ selected from the IllustrisTNG simulation and study their stellar orbit compositions in relation to a number of other fundamental galaxy properties. We find that the TNG100 simulation broadly reproduces the observed fractions of different orbital components and their stellar mass dependences. In particular, the mean mass dependences of the luminosity fractions for the kinematically warm and hot orbits are well reproduced within model uncertainties of the observed galaxies. The simulation also largely reproduces the observed peak and trough features at $M_{*}\approx 1\rm {-}2\times 10^{10}\, \mathrm{M}_{\odot }$ in the mean distributions of the cold- and hot-orbit fractions, respectively, indicating fewer cooler orbits and more hotter orbits in both more- and less-massive galaxies beyond such a mass range. Several marginal disagreements are seen between the simulation and observations: the average cold-orbit (counter-rotating) fractions of the simulated galaxies below (above) $M_{*}\approx 6\times 10^{10}\, \mathrm{M}_{\odot }$ are systematically higher than the observational data by $\lesssim 10{{\ \rm per\ cent}}$ (absolute orbital fraction); the simulation also seems to produce more scatter for the cold-orbit fraction and less so for the non-cold orbits at any given galaxy mass. Possible causes that stem from the adopted heating mechanisms are discussed.

scholarly journals Kraken reveals itself – the merger history of the Milky Way reconstructed with the E-MOSAICS simulations

2020 ◽  
Vol 498 (2) ◽  
pp. 2472-2491 ◽  
Author(s):  
J M Diederik Kruijssen ◽  
Joel L Pfeffer ◽  
Mélanie Chevance ◽  
Ana Bonaca ◽  
Sebastian Trujillo-Gomez ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Milky Way ◽  
Mass Range ◽  
Stellar Mass ◽  
Host Galaxies ◽  
Stellar Halo ◽  
Major Merger ◽  
Virial Mass ◽  
Minor Mergers ◽  
Stellar Masses

ABSTRACT Globular clusters (GCs) formed when the Milky Way experienced a phase of rapid assembly. We use the wealth of information contained in the Galactic GC population to quantify the properties of the satellite galaxies from which the Milky Way assembled. To achieve this, we train an artificial neural network on the E-MOSAICS cosmological simulations of the co-formation and co-evolution of GCs and their host galaxies. The network uses the ages, metallicities, and orbital properties of GCs that formed in the same progenitor galaxies to predict the stellar masses and accretion redshifts of these progenitors. We apply the network to Galactic GCs associated with five progenitors: Gaia-Enceladus, the Helmi streams, Sequoia, Sagittarius, and the recently discovered ‘low-energy’ GCs, which provide an excellent match to the predicted properties of the enigmatic galaxy ‘Kraken’. The five galaxies cover a narrow stellar mass range [M⋆ = (0.6–4.6) × 108 M⊙], but have widely different accretion redshifts ($\mbox{$z_{\rm acc}$}=0.57\!-\!2.65$). All accretion events represent minor mergers, but Kraken likely represents the most major merger ever experienced by the Milky Way, with stellar and virial mass ratios of $\mbox{$r_{M_\star }$}=1$:$31^{+34}_{-16}$ and $\mbox{$r_{M_{\rm h}}$}=1$:$7^{+4}_{-2}$, respectively. The progenitors match the z = 0 relation between GC number and halo virial mass, but have elevated specific frequencies, suggesting an evolution with redshift. Even though these progenitors likely were the Milky Way’s most massive accretion events, they contributed a total mass of only log (M⋆, tot/M⊙) = 9.0 ± 0.1, similar to the stellar halo. This implies that the Milky Way grew its stellar mass mostly by in-situ star formation. We conclude by organizing these accretion events into the most detailed reconstruction to date of the Milky Way’s merger tree.

scholarly journals SDSS-IV MaNGA: Internal mass distributions and orbital structures of early-type galaxies and their dependence on environment

2019 ◽  
Author(s):  
Yunpeng Jin ◽  
Ling Zhu ◽  
R J Long ◽  
Shude Mao ◽  
Lan Wang ◽  
...  
Keyword(s):  
Dark Matter ◽  
Major Axis ◽  
Mass Range ◽  
Stellar Mass ◽  
Effective Radius ◽  
High Mass ◽  
Internal Mass ◽  
Early Type ◽  
Internal Structures ◽  
The Individual

Abstract In our earlier 2019 paper, we evaluated the reliability of Schwarzschild’s orbit-superposition dynamical modelling method in estimating the internal mass distribution, intrinsic stellar shapes and orbit distributions of early-type galaxies (ETGs) taken from the Illustris cosmological simulation. We now apply the same techniques to galaxies taken from the integral-field survey Mapping Nearby Galaxies with APO (MaNGA), using a sample of 149 ETGs in the mass range of 109.90 ∼ 1011.80M⊙ and made up of 105 central and 44 satellite galaxies. We find that low-mass ETGs with log (M*/M⊙) < 11.1 have an average dark matter fraction of ∼0.2 within one effective radius Re, tend to be oblate-like, and are dominated by rotation about their minor axis. High-mass ETGs with log (M*/M⊙) > 11.1 have an average dark matter fraction of ∼0.4 within one effective radius Re, tend to be prolate-like, and are dominated by rotation about their major axis and by centrophilic orbits. The changes of internal structures within one Re are dominated by the total stellar mass of the individual galaxies. We find no differences of internal structures between central and satellite ETGs for the same stellar masses. However, for similar stellar mass and colour distributions, we find that ETGs more prolate-like, or with more hot orbits, tend to have higher close neighbour counts at rp ∼ 40 kpc.

scholarly journals The merger-driven evolution of massive early-type galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 62-66
Author(s):  
Carlo Cannarozzo ◽  
Carlo Nipoti ◽  
Alessandro Sonnenfeld ◽  
Alexie Leauthaud ◽  
Song Huang ◽  
...  
Keyword(s):  
Mass Velocity ◽  
Selection Criteria ◽  
Velocity Dispersion ◽  
Ex Situ ◽  
Scaling Relations ◽  
Early Type ◽  
History Of ◽  
Kinematic Properties ◽  
Shed Light

AbstractThe evolution of the structural and kinematic properties of early-type galaxies (ETGs), their scaling relations, as well as their stellar metallicity and age contain precious information on the assembly history of these systems. We present results on the evolution of the stellar mass-velocity dispersion relation of ETGs, focusing in particular on the effects of some selection criteria used to define ETGs. We also try to shed light on the role that in-situ and ex-situ stellar populations have in massive ETGs, providing a possible explanation of the observed metallicity distributions.

Substructure in black hole scaling diagrams and implications for the coevolution of black holes and galaxies

2019 ◽  
Vol 15 (S359) ◽  
pp. 37-39
Author(s):  
Benjamin L. Davis ◽  
Nandini Sahu ◽  
Alister W. Graham
Keyword(s):  
Black Hole ◽  
Stellar Mass ◽  
Host Galaxy ◽  
Scaling Relations ◽  
Black Hole Mass ◽  
Physical Processes ◽  
Stellar Velocity ◽  
Galaxy Sample ◽  
Evolutionary Paths ◽  
Black Hole Masses

AbstractOur multi-component photometric decomposition of the largest galaxy sample to date with dynamically-measured black hole masses nearly doubles the number of such galaxies. We have discovered substantially modified scaling relations between the black hole mass and the host galaxy properties, including the spheroid (bulge) stellar mass, the total galaxy stellar mass, and the central stellar velocity dispersion. These refinements partly arose because we were able to explore the scaling relations for various sub-populations of galaxies built by different physical processes, as traced by the presence of a disk, early-type versus late-type galaxies, or a Sérsic versus core-Sérsic spheroid light profile. The new relations appear fundamentally linked with the evolutionary paths followed by galaxies, and they have ramifications for simulations and formation theories involving both quenching and accretion.

scholarly journals Assembly Histories and Observational Properties of Simulated Early-type Galaxies

2012 ◽  
Vol 8 (S295) ◽  
pp. 354-357
Author(s):  
Peter H. Johansson
Keyword(s):  
Star Formation ◽  
Initial Growth ◽  
Early Type ◽  
Massive Galaxies ◽  
Main Galaxy ◽  
Two Phases ◽  
Late Growth ◽  
Kinematic Properties

AbstractWe demonstrate that massive simulated galaxies assemble in two phases, with the initial growth dominated by compact in situ star formation, whereas the late growth is dominated by accretion of old stars formed in subunits outside the main galaxy. We also show that 1) gravitational feedback strongly suppresses late star formation in massive galaxies contributing to the observed galaxy colour bimodality that 2) the observed galaxy downsizing can be explained naturally in the two-phased model and finally that 3) the details of the assembly histories of massive galaxies are directly connected to their observed kinematic properties.

scholarly journals The emergence of the galactic stellar mass function from a non-universal IMF in clusters

2018 ◽  
Vol 614 ◽  
pp. A43 ◽  
Author(s):  
Sami Dib ◽  
Shantanu Basu
Keyword(s):  
Mass Range ◽  
Mass Function ◽  
Stellar Mass ◽  
Stellar Clusters ◽  
Galactic Clusters ◽  
Power Law Function ◽  
Low Mass ◽  
Mass Functions ◽  
Characteristic Mass ◽  
The Imf

We investigate the dependence of a single-generation galactic mass function (SGMF) on variations in the initial stellar mass functions (IMF) of stellar clusters. We show that cluster-to-cluster variations of the IMF lead to a multi-component SGMF where each component in a given mass range can be described by a distinct power-law function. We also show that a dispersion of ≈0.3 M⊙ in the characteristic mass of the IMF, as observed for young Galactic clusters, leads to a low-mass slope of the SGMF that matches the observed Galactic stellar mass function even when the IMFs in the low-mass end of individual clusters are much steeper.

scholarly journals WFPC2 Images of the Central Regions of Early-Type Galaxies. I. The Data

2001 ◽  
Vol 121 (5) ◽  
pp. 2431-2482 ◽  
Author(s):  
Armin Rest ◽  
Frank C. van den Bosch ◽  
Walter Jaffe ◽  
Hien Tran ◽  
Zlatan Tsvetanov ◽  
...  
Keyword(s):  
Early Type ◽  
Central Regions

The demographics of central massive black holes in low-mass early-type galaxies

2019 ◽  
Vol 14 (S353) ◽  
pp. 286-288
Author(s):  
Dieu D. Nguyen
Keyword(s):  
Black Holes ◽  
Adaptive Optics ◽  
Mass Range ◽  
Early Type ◽  
Host Galaxies ◽  
Seed Formation ◽  
Unique Constraint ◽  
Low Mass ◽  
Important Extension ◽  
Stellar Masses

AbstractThe existence intermediate mass black holes (IMBH, MBH ≲ 106M⊙) at the centers low-mass galaxies with stellar masses between (1–10)×10M⊙ are key to constraining the origin of black hole (BH) seeds and understanding the physics deriving the co-evolution of central BHs and their host galaxies. However, finding and weighing IMBH is challenging. Here, we present the first observational evidence for such IMBHs at the centers of the five nearest early-type galaxies (D < 3.5 Mpc, ETGs) revealed by adaptive optics kinematics from Gemini and VLT and high-resolution HST spectroscopy. We find that all five galaxies appear to host IMBHs with four of the five having masses below 1 million M⊙ and the lowest mass BH being only ∼7,000 M⊙. This work provides a first glimpse of the demographics of IMBHs in this galaxy mass range and at velocity dispersions < 70 km/s, and thus provides an important extension to the bulge mass and galaxy dispersion scaling relations. The ubiquity of central BHs in these galaxies provides a unique constraint on BH seed formation scenarios, favoring a formation mechanism that produces an abundance of low-mass seed BHs.

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