Overview of the SDSS-IV MaNGA Survey: Mapping Nearby Galaxies at Apache Point Observatory (1412.1482v1)

Abstract: We present an overview of a new integral field spectroscopic survey called MaNGA (Mapping Nearby Galaxies at Apache Point Observatory), one of three core programs in the fourth-generation Sloan Digital Sky Survey (SDSS-IV) that began on 2014 July 1. MaNGA will investigate the internal kinematic structure and composition of gas and stars in an unprecedented sample of 10,000 nearby galaxies. We summarize essential characteristics of the instrument and survey design in the context of MaNGA's key science goals and present prototype observations to demonstrate MaNGA's scientific potential. MaNGA employs dithered observations with 17 fiber-bundle integral field units that vary in diameter from 12" (19 fibers) to 32" (127 fibers). Two dual-channel spectrographs provide simultaneous wavelength coverage over 3600-10300 A at R~2000. With a typical integration time of 3 hr, MaNGA reaches a target r-band signal-to-noise ratio of 4-8 (per A, per 2" fiber) at 23 AB mag per sq. arcsec, which is typical for the outskirts of MaNGA galaxies. Targets are selected with stellar mass greater than 1e9 Msun using SDSS-I redshifts and i-band luminosity to achieve uniform radial coverage in terms of the effective radius, an approximately flat distribution in stellar mass, and a sample spanning a wide range of environments. Analysis of our prototype observations demonstrates MaNGA's ability to probe gas ionization, shed light on recent star formation and quenching, enable dynamical modeling, decompose constituent components, and map the composition of stellar populations. MaNGA's spatially resolved spectra will enable an unprecedented study of the astrophysics of nearby galaxies in the coming 6 yr.

• The paper demonstrates the use of integral field spectroscopy on 10,000 galaxies to deliver spatially resolved maps of kinematics and stellar populations.
• The paper details a technical setup with 17 fiber-bundle IFUs and dual-channel spectrographs, providing continuous spectra from 3600 to 10300 Å.
• The paper discusses how the survey advances understanding of galaxy evolution, star formation quenching, and disk growth in varied environments.

Overview of the SDSS-IV MaNGA Survey: Mapping Nearby Galaxies at Apache Point Observatory

The paper "Overview of the SDSS-IV MaNGA Survey: Mapping Nearby Galaxies at Apache Point Observatory" by Kevin Bundy et al. presents a comprehensive examination of the MaNGA project, a major component of the fourth-generation Sloan Digital Sky Survey (SDSS-IV). The MaNGA survey, standing for Mapping Nearby Galaxies at Apache Point Observatory, aims to investigate the internal kinematic structure and composition of gas and stars within a significantly large sample of 10,000 nearby galaxies. This paper leverages integral field spectroscopy to deliver spatially resolved spectra, enabling the examination of galaxies' astrophysical properties with unprecedented detail.

Instrumentation and Observational Strategy

MaNGA employs 17 fiber-bundle integral field units (IFUs), varying in diameter from 12 to 32 arcseconds, to gather light from galaxies across different regions of the sky. These IFUs feed into two BOSS dual-channel spectrographs, which offer a continuous wavelength coverage from 3600 to 10300 Å, achieving a resolving power of about R≈2000. This setup allows for a thorough exploration of emission and absorption features critical for studying star formation, metallicity, and other stellar population aspects.

The survey operates with a fixed strategy involving dithered observations, typically integrating for 3 hours to achieve a target r-band signal-to-noise ratio of 4-8 Å⁻¹ per 2 arcsec fiber, even in the outskirts of target galaxies. The sample selection criterion is designed to ensure uniform radial coverage and an approximately uniform distribution in stellar mass while extending over a comprehensive range of environmental conditions and galaxy types.

Science Goals and Methodological Advances

MaNGA's primary scientific objectives are multifaceted, aiming to elucidate processes related to galaxy growth and assembly, star formation quenching, and the formation of galaxy subcomponents. To this end, one critical goal is understanding how galaxy disks grow and the dynamics behind gas accretion within galactic environments. Additionally, MaNGA seeks to deconstruct the relative influences of mergers and secular processes on bulge formation and to assess the mechanics regulating star formation cessation.

Integral field spectroscopy allows MaNGA to overcome limitations observed in prior surveys by sampling small subregions or only one-dimensional slices of galaxies. With its spatially resolved capabilities, MaNGA offers a more comprehensive view of galaxy kinematics, dynamics, and constituent stellar populations, further facilitating the disaggregation of complex galaxy morphology into quantifiable metrics.

Potential Impact and Future Directions

The results expected from the MaNGA survey stand to impact both practical and theoretical frameworks within astrophysics significantly. By providing detailed maps of stellar and gas ionization properties, MaNGA data will enable the development of refined models for star formation and quenching mechanisms, improving the understanding of galaxy evolution as influenced by various external and internal drivers. The survey's large sample size and uniform coverage represent a robust basis for statistical analysis, offering insights with substantial power for generating predictive models applicable to different cosmic epochs.

Moreover, MaNGA's synergy with other SDSS projects and its integration with external observational campaigns will be instrumental in cross-disciplinary studies, elevating the pursuit of a more unified cosmic framework.

In conclusion, the MaNGA project encapsulates a pivotal step in the landscape of galaxy surveys, leveraging technological advancements to provide innovative data crucial for resolving enduring questions concerning galaxy formation and evolution. As MaNGA progresses through its six-year operational timeline, its contributions are poised to enrich the astrophysical community with data and findings that refine current models and theories pertaining to the life cycle of galaxies.