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Abstract:

We present a sample of 213 early-type galaxies (ETGs) at redshifts 0.25 < z < 0.75. We combine deep integral-field spectroscopy from the MUSE-DEEP survey with high-resolution Hubble Space Telescope (HST) imaging to study the structure, kinematics, and stellar populations of these galaxies. We measure spatially resolved stellar kinematics and use the specific angular momentum proxy, λR, to classify galaxies into fast and slow rotators. The kinematic and photometric axes of fast rotators are generally well aligned, similar to their local counterparts. We find that global stellar population properties, such as age, metallicity, and mass-to-light ratio (M*/L), correlate strongly with the central velocity dispersion (σe), following trends established for local ETGs. Slow rotators are typically more massive, have higher σe, and are more metal rich than fast rotators. We also find a slow rotator fraction consistent with local Universe samples. Our findings indicate that the fundamental structural, kinematic, and stellar population scaling relations of massive ETGs were already in place by z ∼ 0.75, suggesting their evolutionary pathways have remained stable over the last ∼7 Gyr.

Abstract:

<p> MOSAIC is the Multi-Object Spectrograph currently under development for the ESO Extremely Large Telescope (ELT). The instrument will provide highly multiplexed spectroscopic capabilities over a wide field of view, combining visible and near-infrared observations with both low- and high-resolution modes. The Near-Infrared (NIR) channel is one of the major subsystems of MOSAIC and is designed to support both Multi-Object Spectroscopy (MOS) and multi-Integral Field Unit (mIFU) observations over the wavelength range from 0.95 &mu;m to 1.8 &mu;m. </p> <p> The NIR channel combines complex fiber-fed architecture, cryogenic operation, high multiplexing capability and demanding spectral performance requirements. Light collected at the ELT focal plane is transported through dedicated MOS and mIFU fiber systems towards two identical cryogenic spectrographs located on the Nasmyth platform. Each spectrograph provides low-resolution, LR, (R~4,000) observations across the full NIR J and H bands wavelength range and high-resolution, HR, (R~18,000) observations in a selected H-band spectral window (1.52 – 1.62 &mu;m). </p> <p> This paper presents an overview of the NIR channel architecture, including the fiber systems, spectrographs and detectors. We summarize the main technical challenges associated with the NIR channel architecture: for the fiber links are the high multiplexing, the light injection and the routing of 2604 fibers from the ELT focal plane to the pseudo-slits at the spectrographs inside the cryostat. On the spectrograph side, the challenging elements are the optical design to accommodate both low- and high- resolution modes in a limited envelope and tight mass assignment, an extremely fast camera, the large optical components, the LR/HR mechanism, and the thermal stability of the cryostat and the cold bench. </p> <p> The current development status towards a System PDR in 2027 and an instrument-PDR with ESO in February 2028. </p> <p> The MOSAIC NIR channel is being developed by a team of seven different Research institutes and universities. This paper introduces that team and the description of the work packages developed by each of the involved MOSAIC partners. The major Management challenge is the coordination of the common design of the NIR channel where each partner is funding their own contribution (also in hardware) and the preparation of the subsystem, System and Instrument Assembly, Integration and Tests at the different sites in Europe and the verification at the ELT in Chile. </p>

Abstract:

Understanding how the internal kinematics of massive galaxies evolve is key to constraining the physical processes that drive their assembly. We investigate the evolution of rotational support in massive ( logM*/M⊙≥10.6 ) early-type galaxies (ETGs) over the past ∼7 Gyr. We use MUSE integral-field spectroscopic (IFS) data for 212 ETGs at intermediate redshift (0.25 < z < 0.75) from the MAGNUS sample. We compare their kinematics to a carefully matched local sample of 787 ETGs (z ≤ 0.05) from the MaNGA survey. Using the specific stellar angular momentum proxy, λR, we quantify the balance between ordered rotation and random motions. We derive intrinsic λR values by applying a uniform correction for seeing and point-spread function (PSF) effects to both samples. We find a significant evolutionary trend: The intermediate-redshift ETGs are systematically more rotationally supported than their local counterparts. The median PSF-corrected λR for the MAGNUS sample is 0.48 ± 0.05, substantially higher than the median of 0.34 ± 0.03 for the matched MaNGA sample. This corresponds to a positive slope in the λR−z relation of dλR/dz = 0.25 ± 0.04 for the combined sample. The decline in rotational support is most pronounced for the most massive ( logM*/M⊙>11.3 ) and highest-velocity-dispersion (σe ≳ 200 km s−1) galaxies. Our results provide robust evidence that massive ETGs have undergone significant kinematic evolution, losing angular momentum as they evolve towards the present day, consistent with theoretical models where processes such as dry mergers play a crucial role in shaping the dynamical state of galaxies.