Morphology and kinematics of orbital components in CALIFA galaxies across the Hubble sequence

Ling Zhu; Glenn van de Ven; Jairo Méndez-Abreu; Aura Obreja

doi:10.1093/mnras/sty1521

paper

Morphology and kinematics of orbital components in CALIFA galaxies across the Hubble sequence

arXiv:1806.02886 · doi:10.1093/mnras/sty1521

Abstract

Based on the stellar orbit distribution derived from orbit-superposition Schwarzschild models, we decompose each of 250 representative present-day galaxies into four orbital components: cold with strong rotation, warm with weak rotation, hot with dominant random motion and counter-rotating (CR). We rebuild the surface brightness ( $Σ$ ) of each orbital component and we present in figures and tables a quantification of their morphologies using the Sersic index \textit{n}, concentration $C = lo g (Σ_{0.1 R_{e}} / Σ_{R_{e}})$ and intrinsic flattening $q_{Re}$ and $q_{Rmax}$ , with $R_{e}$ the half-light-radius and $R_{max}$ the CALIFA data coverage. We find that: (1) kinematic hotter components are generally more concentrated and rounder than colder components, and (2) all components become more concentrated and thicker/rounder in more massive galaxies; they change from disk-like in low mass late-type galaxies to bulge-like in high-mass early type galaxies. Our findings suggest that Sersic \textit{n} is not a good discriminator between rotating bulges and non-rotating bulges. The luminosity fraction of cold orbits $f_{cold}$ is well correlated with the photometrically-decomposed disk fraction $f_{disk}$ as $f_{cold} = 0.14 + 0.23 f_{disk}$ . Similarly, the hot orbit fraction $f_{hot}$ is correlated with the bulge fraction $f_{bulge}$ as $f_{hot} = 0.19 + 0.31 f_{bulge}$ . The warm orbits mainly contribute to disks in low-mass late-type galaxies, and to bulges in high-mass early-type galaxies. The cold, warm, and hot components generally follow the same morphology ( $ε = 1 - q_{Rmax}$ ) versus kinematics ( $σ_{z}^{2} / V_{tot}^{2}$ ) relation as the thin disk, thick disk/pseudo bulge, and classical bulge identified from cosmological simulations.

accepted by MNRAS

Morphology and kinematics of orbital components in CALIFA galaxies across the Hubble sequence

Abstract

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