The MaNGA DynPop survey of nearby galaxies has just released four papers, two of which analyze a 10,000 galaxy data set, one of which looks at a 6,000 galaxy subset of that data. The last paper takes at deeper dive into the other data by combining it with other data set.
The quartet of papers were uploaded on April 23, 2023 and have been submitted to MNRAS. The papers are:
This is the first paper in our series on the combined analysis of the Dynamics and stellar Population (DynPop) for the MaNGA survey in the final SDSS Data Release 17 (DR17). Here we present a catalogue of dynamically-determined quantities for over 10000 nearby galaxies based on integral-field stellar kinematics from the MaNGA survey. The dynamical properties are extracted using the axisymmetric Jeans Anisotropic Modelling (JAM) method, which was previously shown to be the most accurate for this kind of study. We assess systematic uncertainties using eight dynamical models with different assumptions. We use two orientations of the velocity ellipsoid: either cylindrically-aligned JAMcyl or spherically-aligned JAMsph. We also make four assumptions for the models' dark vs. luminous matter distributions: (1) mass-follows-light, (2) free NFW dark halo, (3) cosmologically-constrained NFW halo, (4) generalized NFW dark halo, i.e. with free inner slope.
In this catalogue, we provide the quantities related to the mass distributions (e.g. the density slopes and enclosed mass within a sphere of a given radius for total mass, stellar mass, and dark matter mass components). We also provide the complete models which can be used to compute the full luminous and mass distribution of each galaxy.
Additionally, we visually assess the qualities of the models to help with model selections. We estimate the observed scatter in the measured quantities which decreases as expected with improvements in quality. For the best data quality, we find a remarkable consistency of measured quantities between different models, highlighting the robustness of the results.
We analyze the global stellar population, radial gradients and non-parametric star formation history of ∼10K galaxies from the MaNGA Survey final data release 17 (DR17), based on stellar population synthesis and full-spectrum fitting, and relate them with dynamical properties of galaxies.
We confirm that stellar population correlates with stellar velocity dispersion σ(e) better than with stellar mass M∗, but also find that younger galaxies are more metal-poor at fixed σ(e). Stellar age, metallicity, and mass-to-light ratio M∗/L all decrease with galaxy rotation, while radial gradients become more negative (i.e., younger, more metal-poor, and lower M∗/L in the outskirts). The trend between metallicity gradients and rotation reverses for slow rotators, which stand out for their more negative metallicity gradients than faster-rotating galaxies.
We highlight a population of massive disk galaxies on the green valley, on the (σ(e), Age) plane, that show steep negative age and metallicity gradients, consistent with their old central bulges surrounded by young star-forming disks and metal-poor gas accretion. Galaxies with high σ(e), steep total mass-density slope, low dark matter fraction, high M∗/L, and high metallicity have the highest star-formation rate at earlier times, and are currently quenched.
We discover a population of low-mass star-forming galaxies with low rotation but physically distinct from the massive slow rotators. A catalogue of the population properties is provided publicly.
We present dynamical scaling relations, combined with the stellar population properties, for a subsample of about 6000 nearby galaxies with the most reliable dynamical models extracted from the full MaNGA sample of 10K galaxies. We show that the inclination-corrected mass plane (MP) for both early-type galaxies (ETGs) and late-type galaxies (LTGs), which links dynamical mass, projected half-light radius R(e), and the second stellar velocity moment σ(e) within R(e), satisfies the virial theorem and is even tighter than the uncorrected one.
We find a clear parabolic relation between lg(M/L)(<R(e)), the total mass-to-light ratio within a sphere of radius R(e), and lg σ(e), with the M/L increasing with σ(e) and for older stellar populations. However, the relation for ETGs is linear and the one for the youngest galaxies is constant.
We confirm and improve the relation between average logarithmic total density slopes γT and σ(e): γT become steeper with increasing σ(e) until lg(σ(e)/kms^−1)≈2.2 and then remain constant around γT≈−2.2. The γT−σ(e) variation is larger for LTGs than ETGs. At fixed σ(e) the total density profiles steepen with galaxy age and for ETGs.
We find generally low dark matter fractions, median fDM(<R(e))=8 per cent, within a sphere of radius R(e). However, we find that fDM(<R(e)) depends on σ(e) better than stellar mass: dark matter increases to a median fDM=33 percent for galaxies with σ(e)≲100kms^−1. The increased fDM(<R(e)) at low σe explains the parabolic lg(M/L)(<R(e))−lgσ(e) relation.
We present the measurement of total and stellar/dark matter decomposed mass density profile around a sample of galaxy groups and clusters with dynamical masses derived from integral-field stellar kinematics from the MaNGA survey in Paper~I and weak lensing derived from the DECaLS imaging survey. Combining the two data sets enables accurate measurement of the radial density distribution from several kpc to Mpc scales.
Intriguingly, we find that the excess surface density derived from stellar kinematics in the inner region cannot be explained by simply adding an NFW dark matter halo extrapolated from lensing measurement at a larger scale to a stellar mass component derived from the NASA-Sloan Atlas (NSA) catalog. We find that a good fit to both data sets requires a stellar mass normalization about 3 times higher than that derived from the NSA catalog, which would require an unrealistically too-heavy initial mass function for stellar mass estimation. If we keep the stellar mass normalization to that of the NSA catalog but allow a varying inner dark matter density profile, we obtain an asymptotic slope of γgnfw= 1.82+0.15−0.25, γgnfw= 1.48+0.20−0.41 for the group bin and the cluster bin respectively, significantly steeper than the NFW case. We also compare the total mass inner density slopes with those from Illustris-TNG300 and find that the values from the simulation are lower than the observation by at least 3σ level.
This release has a very respectable sample size with some quite high quality data. But, digesting the analysis is non-trivial, particularly if you are looking for interpretations of it that are independent of already soundly disproven elements of the LambdaCDM model of cosmology.
Another interesting new paper (accepted for publication) looks at the scaling relations between globular cluster mass and apparent dark matter mass in galaxies:
The relation between the total mass contained in the globular clusters of a galaxy and the mass of its dark matter halo has been found observationally to be nearly linear over five decades of mass. However, the high-mass end of this relation is not well determined from previous data and shows large scatter.
We analyze the globular cluster systems (GCSs) of a homogeneous sample of 11 brightest cluster galaxies (BCGs) through DOLPHOT photometry of their deep Hubble Space Telescope (HST) images in the F814W filter. We standardize the definition of MGCS, the total GCS mass, by using the GC total population within a limiting radius of 0.1R(virial), while the dark-matter halo mass M(h) is determined from the weak-lensing calibration of M(h) versus M(bary).
When these 11 BCGs are added to the previously studied homogeneous catalogue of Virgo member galaxies, a total value for η=M(GCS)/M(h_ is found to be (3.0±1.8internal)×10^−5, slightly higher than previous estimates but with much reduced uncertainty. Perhaps more importantly, the results suggest that the relation continues to have a near-linear shape at the highest galaxy masses, strongly reinforcing the conclusion that accreted GCs make a major contribution to the GC populations at high galaxy mass.
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