The MaNGA Survey (Mapping Nearby Galaxies at Apache Point Observatory) is one of three core programs in the Sloan Digital Sky Survey IV. It is obtaining integral field spectroscopy for 10,000nearby galaxies at a spectral resolution of R∼2000 from 3622 to 10354 Å. The design of the survey is driven by a set of science requirements on the precision of estimates of the following properties: star formation rate surface density, gas metallicity, stellar population age, metallicity, and abundance ratio, and their gradients; stellar and gas kinematics; and enclosed The Astronomical Journal, 152:197 (32pp) 1 gravitational mass as a function of radius. We describe how these science requirements set the depth of the observations and dictate sample selection. The majority of targeted galaxies are selected to ensure uniform spatial coverage in units of effective radius (R e ) while maximizing spatial resolution. About two-thirds of the sample is covered out to 1.5R e (Primary sample), and one-thirdof the sample is covered to 2.5R e (Secondary sample). We describe the survey execution with details that would be useful in the design of similar future surveys. We also present statistics on the achieved data quality, specificallythe point-spread function, sampling uniformity, spectral resolution, sky subtraction, and flux calibration. For our Primary sample, the median r-band signal-to-noise ratio is ∼70 per 1.4 Å pixel for spectra stacked between 1R e and 1.5R e . Measurements of various galaxy properties from the first-year data show that we are meeting or exceeding the defined requirements for the majority of our science goals.

We measure λ R e , a proxy for galaxy specific stellar angular momentum within one effective radius, and the ellipticity, , for about 2300 galaxies of all morphological types observed with integral field spectroscopy as part of the MaNGA survey, the largest such sample to date. We use the (λ R e , ) diagram to separate early-type galaxies into fast and slow rotators. We also visually classify each galaxy according to its optical morphology and two-dimensional stellar velocity field. Comparing these classifications to quantitative λ R e measurements reveals tight relationships between angular momentum and galaxy structure. In order to account for atmospheric seeing, we use realistic models of galaxy kinematics to derive a general approximate analytic correction for λ R e . Thanks to the size of the sample and the large number of massive galaxies, we unambiguously detect a clear bimodality in the (λ R e , ) diagram which may result from fundamental differences in galaxy assembly history. There is a sharp secondary density peak inside the region of the diagram with low λ R e and < 0.4, previously suggested as the definition for slow rotators. Most of these galaxies are visually classified as non-regular rotators and have high velocity dispersion. The intrinsic bimodality must be stronger, as it tends to be smoothed by noise and inclination. The large sample of slow rotators allows us for the first time to unveil a secondary peak at ±90°in their distribution of the misalignments between the photometric and kinematic position angles. We confirm that genuine slow rotators start appearing above a stellar mass of 2 × 10 11 M where a significant number of high-mass fast rotators also exist.

We study the link between the kinematic-morphology of galaxies, as inferred from integral-field stellar kinematics, and their relation between mass and star formation rate. Our sample consists of ∼3200 galaxies with integral-field spectroscopic data from the MaNGA survey (Mapping Nearby Galaxies at Apache Point Observatory) with available determinations of their effective stellar angular momentum within the half-light radius $\lambda _{R_e}$. We find that for star-forming galaxies, namely along the star formation main sequence (SFMS), the $\lambda _{R_e}$ values remain large and almost unchanged over about two orders of magnitude in stellar mass, with the exception of the lowest masses $\mathcal {M}_{\star }\lesssim 2\times 10^{9} \, \mathcal {M}_{\odot }$, where $\lambda _{R_e}$ slightly decreases. The SFMS is dominated by spiral galaxies with small bulges. Below the SFMS, but above the characteristic stellar mass $\mathcal {M}_{\rm crit}\approx 2\times 10^{11} \, \mathcal {M}_{\odot }$, there is a sharp decrease in $\lambda _{R_e}$ with decreasing star formation rate (SFR): massive galaxies well below the SFMS are mainly slow-rotator early-type galaxies, namely genuinely spheroidal galaxies without discs. Below the SFMS and below $\mathcal {M}_{\rm crit}$ the decrease of $\lambda _{R_e}$ with decreasing SFR becomes modest or nearly absent: low-mass galaxies well below the SFMS, are fast-rotator early-type galaxies, and contain fast-rotating stellar discs like their star-forming counterparts. We also find a small but clear environmental dependence for the massive galaxies: in the mass range $10^{10.9}\!-\!10^{11.5} \, \mathcal {M}_{\odot }$, galaxies in rich groups or denser regions or classified as central galaxies have lower values of $\lambda _{R_e}$. While no environmental dependence is found for galaxies of lower mass. We discuss how the above results can be understood as due to the different star formation and mass assembly histories of galaxies with varying mass.

By inverting the distributions of galaxies' apparent ellipticities and misalignment angles (measured around the projected half-light radius R e ) between their photometric and kinematic axes, we study the intrinsic shape distribution of 189 slow rotator early-type galaxies with stellar masses 2 × 10 11 M < M * < 2 × 10 12 M , extracted from a sample of about 2200 galaxies with integral-field stellar kinematics from the DR14 of the SDSS-IV MaNGA IFU survey. Thanks to the large sample of slow rotators, Graham+18 showed that there is clear structure in the misalignment angle distribution, with two peaks at both 0 • and 90 • misalignment (characteristic of oblate and prolate rotation respectively). Here we invert the observed distribution from Graham+18. The large sample allows us to go beyond the known fact that slow rotators are weakly triaxial and to place useful constraints on their intrinsic triaxiality distribution (around 1R e ) for the first time. The shape inversion is generally non-unique. However, we find that, for a wide set of model assumptions, the observed distribution clearly requires a dominant triaxial-oblate population. For some of our models, the data suggest a hint for a minor triaxial-prolate population, but a dominant prolate population is ruled out.

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