This paper documents the 16th data release (DR16) from the Sloan Digital Sky Surveys (SDSS), the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the ...Southern Hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey and new data from the SPectroscopic IDentification of ERosita Survey programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17).
Twenty years have passed since first light for the Sloan Digital Sky Survey (SDSS). Here, we release data taken by the fourth phase of SDSS (SDSS-IV) across its first three years of operation (2014 ...July-2017 July). This is the third data release for SDSS-IV, and the 15th from SDSS (Data Release Fifteen; DR15). New data come from MaNGA-we release 4824 data cubes, as well as the first stellar spectra in the MaNGA Stellar Library (MaStar), the first set of survey-supported analysis products (e.g., stellar and gas kinematics, emission-line and other maps) from the MaNGA Data Analysis Pipeline, and a new data visualization and access tool we call "Marvin." The next data release, DR16, will include new data from both APOGEE-2 and eBOSS; those surveys release no new data here, but we document updates and corrections to their data processing pipelines. The release is cumulative; it also includes the most recent reductions and calibrations of all data taken by SDSS since first light. In this paper, we describe the location and format of the data and tools and cite technical references describing how it was obtained and processed. The SDSS website (www.sdss.org) has also been updated, providing links to data downloads, tutorials, and examples of data use. Although SDSS-IV will continue to collect astronomical data until 2020, and will be followed by SDSS-V (2020-2025), we end this paper by describing plans to ensure the sustainability of the SDSS data archive for many years beyond the collection of data.
The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, one of three core programs of the fourth-generation Sloan Digital Sky Survey (SDSS-IV), is producing a massive, ...high-dimensional integral field spectroscopic data set. However, leveraging the MaNGA data set to address key questions about galaxy formation presents serious data-related challenges due to the combination of its spatially interconnected measurements and sheer volume. For each galaxy, the MaNGA pipelines produce relatively large data files to preserve the spatial correlations of the spectra and measurements, but this comes at the expense of storing the data set in coarse units or "chunks." This coarse chunking and the total volume of the data make it time-consuming to download and curate locally stored data. Thus, accessing, querying, visually exploring, and performing statistical analyses across the whole data set at a fine-grained scale is extremely challenging using just FITS files. To overcome these challenges, we have developed Marvin, a toolkit consisting of a Python package, Application Programming Interface, and web application utilizing a remote database. Marvin allows users to seamlessly work with MaNGA data by abstracting both remote and local (on-disk) interactions to behind-the-scenes data-handling functions. Combining this capability with additional processing and querying tools, users can create powerful Python workflows that are easy to import and share. Marvin's web application uses these tools to enable "point-and-click" examination of data cubes and derived maps, as well as search queries for all publicly released MaNGA galaxies. Marvin's robust and sustainable design minimizes maintenance, while facilitating user-contributed extensions such as high-level analysis code.
ABSTRACT
We present the star formation histories of 39 galaxies with high-quality rest-frame optical spectra at 0.5 < z < 1.3 selected to have strong Balmer absorption lines and/or Balmer break, and ...compare to a sample of spectroscopically selected quiescent galaxies at the same redshift. Photometric selection identifies a majority of objects that have clear evidence for a recent short-lived burst of star formation within the last 1.5 Gyr, i.e. ‘post-starburst’ galaxies, however we show that good quality continuum spectra are required to obtain physical parameters such as burst mass fraction and burst age. Dust attenuation appears to be the primary cause for misidentification of post-starburst galaxies, leading to contamination in spectroscopic samples where only the O ii emission line is available, as well as a small fraction of objects lost from photometric samples. The 31 confirmed post-starburst galaxies have formed 40–90 per cent of their stellar mass in the last 1–1.5 Gyr. We use the derived star formation histories to find that the post-starburst galaxies are visible photometrically for 0.5–1 Gyr. This allows us to update a previous analysis to suggest that 25–50 per cent of the growth of the red sequence at z ∼ 1 could be caused by a starburst followed by rapid quenching. We use the inferred maximum historical star formation rates of several 100–1000 M⊙ yr−1 and updated visibility times to confirm that sub-mm galaxies are likely progenitors of post-starburst galaxies. The short quenching time-scales of 100–200 Myr are consistent with cosmological hydrodynamic models in which rapid quenching is caused by the mechanical expulsion of gas due to an acive galactic neucleus.
Post-starburst galaxies in SDSS-IV MaNGA Chen, Yan-Mei; Shi, Yong; Wild, Vivienne ...
Monthly Notices of the Royal Astronomical Society,
11/2019, Volume:
489, Issue:
4
Journal Article
Peer reviewed
Open access
ABSTRACT
Post-starburst galaxies, identified by their unusually strong Balmer absorption lines and weaker than average emission lines, have traditionally been selected based on their central stellar ...populations. Here we identify 360 galaxies with post-starburst regions from the MaNGA integral field survey and classify these galaxies into three types: 31 galaxies with central post-starburst regions (CPSB), 37 galaxies with off-centre ring-like post-starburst regions (RPSB), and 292 galaxies with irregular post-starburst regions (IPSB). Focusing on the CPSB and RPSB samples, and comparing their radial gradients in Dn4000, HδA, and W(H α) to control samples, we find that while the CPSBs have suppressed star formation throughout their bulge and disc, and there is clear evidence of rapid decline of star formation in the central regions, the RPSBs only show clear evidence of recently rapidly suppressed star formation in their outer regions and an ongoing central starburst. The radial profiles in mass-weighted age and stellar v/σ indicate that CPSBs and RPSBs are not simply different evolutionary stages of the same event, rather the CPSB galaxies are caused by a significant disruptive event, while the RPSB galaxies are caused by disruption of gas fuelling to the outer regions. Compared to the control samples, both CPSB and RPSB galaxies show a higher fraction of interactions/mergers, misaligned gas, or bars that might be the cause of the gas inflows and subsequent quenching.
ABSTRACT
We present the first study of the large-scale clustering of post-starburst (PSB) galaxies in the high-redshift Universe (0.5 < z < 3.0). We select ∼4000 PSB galaxies photometrically, the ...largest high-redshift sample of this kind, from two deep large-scale near-infrared surveys: the UKIDSS Ultra Deep Survey Data Release 11 and the Cosmic Evolution Survey. Using angular cross-correlation techniques, we estimate the halo masses for this large sample of PSB galaxies and compare them with quiescent and star-forming galaxies selected in the same fields. We find that low-mass, low-redshift (0.5 < z < 1.0) PSB galaxies preferentially reside in very high mass dark matter haloes (Mhalo > 1014 M⊙), suggesting that they are likely to be infalling satellite galaxies in cluster-like environments. High-mass PSB galaxies are more weakly clustered at low redshifts, but they reside in higher mass haloes with increasing look-back time, suggesting strong redshift-dependent halo downsizing. These key results are consistent with previous results, suggesting that two main channels are responsible for the rapid quenching of galaxies. While high-redshift (z > 1) galaxies appear to be quenched by secular feedback mechanisms, processes associated with dense environments are likely to be the key driver of rapid quenching in the low-redshift Universe (z < 1). Finally, we show that the clustering of photometrically selected PSBs is consistent with them being direct descendants of highly dust-enshrouded submillimetre galaxies, providing tantalizing evidence for the oft-speculated evolutionary pathway from starburst to quiescence.
ABSTRACT
We conduct the first study of how the relative quenching probability of galaxies depends on environment over the redshift range 0.5 < z < 3, using data from the UKIDSS Ultra Deep Survey. By ...constructing the stellar mass functions for quiescent and post-starburst (PSB) galaxies in high-, medium-, and low-density environments to z = 3, we find an excess of quenched galaxies in dense environments out to at least z ∼ 2. Using the growth rate in the number of quenched galaxies, combined with the star-forming galaxy mass function, we calculate the probability that a given star-forming galaxy is quenched per unit time. We find a significantly higher quenching rate in dense environments (at a given stellar mass) at all redshifts. Massive galaxies (M* > 1010.7 M⊙) are on average 1.7 ± 0.2 times more likely to quench per Gyr in the densest third of environments compared to the sparsest third. Finally, we compare the quiescent galaxy growth rate to the rate at which galaxies pass through a PSB phase. Assuming a visibility time-scale of 500 Myr, we find that the PSB route can explain ∼50 per cent of the growth in the quiescent population at high stellar mass (M* > 1010.7 M⊙) in the redshift range 0.5 < z < 3, and potentially all of the growth at lower stellar masses.
ABSTRACT
Post-starburst galaxies (PSBs) are transition galaxies showing evidence of recent rapid star formation quenching. To understand the role of galaxy mergers in triggering quenching, we ...investigate the incidence of PSBs and resolved PSB properties in post-merger galaxies using both SDSS single-fibre spectra and MaNGA resolved IFU spectra. We find post-mergers have a PSB excess of 10–20 times that relative to their control galaxies using single-fibre PSB diagnostics. A similar excess of ∼ 19 times is also found in the fraction of central (C)PSBs and ring-like (R)PSBs in post-mergers using the resolved PSB diagnostic. However, 60 per cent of the CPSBs + RPSBs in both post-mergers and control galaxies are missed by the single-fibre data. By visually inspecting the resolved PSB distribution, we find that the fraction of outside-in quenching is seven times higher than inside-out quenching in PSBs in post-mergers while PSBs in control galaxies do not show large differences in these quenching directions. In addition, we find a marginal deficit of H i gas in PSBs relative to non-PSBs in post-mergers using the MaNGA-H i data. The excesses of PSBs in post-mergers suggest that mergers play an important role in triggering quenching. Resolved IFU spectra are important to recover the PSBs missed by single-fibre spectra. The excess of outside-in quenching relative to inside-out quenching in post-mergers suggests that AGNs are not the dominant quenching mechanism in these galaxies, but that processes from the disc (gas inflows/consumption and stellar feedback) play a more important role.
ABSTRACT
We present star formation rates based on cold and ionized gas measurements of Mrk 266 (NGC 5256), a system composed of two colliding gas-rich galaxies, each hosting an active galactic ...nucleus. Using 12CO (1-0) observations with the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), we find a total H2 mass in the central region of 1.1 ± 0.3 × 1010 M⊙ which leads to a possible future star formation rate of 25 ± 10 M⊙ yr−1. With the Fourier Transform Spectrograph (SITELLE) on the Canada–France–Hawaii Telescope, we measure an integrated H α luminosity and estimate a present-day star formation rate of 15 ± 2 M⊙ yr−1 in the core of the system (avoiding the two active nuclei). These results confirm that Mrk 266 is an intermediate stage merger with a relatively high recent star formation rate and enough molecular gas to sustain it for a few hundred million years. Inflowing gas associated with the merger may have triggered both the starburst episode and two active galactic nuclei but the two galaxy components differ: the region around the south-western nucleus appears to be more active than the north-east nucleus, which seems relatively quiet. We speculate that this difference may originate in the properties of the interstellar medium in the two systems.
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