MaNGA: Mapping Nearby Galaxies at Apache Point Observatory

MaNGA (Mapping Nearby Galaxies at APO) is a galaxy integral-field spectroscopic survey within the fourth generation Sloan Digital Sky Survey (SDSS-IV). It will be mapping the composition and kinematics of gas and stars in 10,000 nearby galaxies, using 17 differently sized fiber bundles. MaNGA's goal is to provide new insights in galaxy formation and evolution, and to deliver a local benchmark for current and future high-redshift studies.Comment: 7 pages, 3 figures. To appear in the proceedings of the conference "Multi-Object Spectroscopy in the Next Decade: Big Questions, Large Surveys and Wide Fields", held in Santa Cruz de La Palma, Canary Islands from 2nd to 6th March 2015. Eds. I. Skillen and S. Trage

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[OIII] Emission and Gas Kinematics in a Lyman-alpha Blob at z ~ 3.1

We present spectroscopic measurements of the [OIII] emission line from two subregions of strong Lyman-alpha emission in a radio-quiet Lyman-alpha blob (LAB). The blob under study is LAB1 (Steidel et al. 2000) at z ~ 3.1, and the [OIII] detections are from the two Lyman break galaxies embedded in the blob halo. The [OIII] measurements were made with LUCIFER on the 8.4m Large Binocular Telescope and NIRSPEC on 10m Keck Telescope. Comparing the redshift of the [OIII] measurements to Lyman-alpha redshifts from SAURON (Weijmans et al. 2010) allows us to take a step towards understanding the kinematics of the gas in the blob. Using both LUCIFER and NIRSPEC we find velocity offsets between the [OIII] and Lyman-alpha redshifts that are modestly negative or consistent with 0 km/s in both subregions studied (ranging from -72 +/- 42 -- +6 +/- 33 km/s). A negative offset means Lyman-alpha is blueshifted with respect to [OIII], a positive offset then implies Lyman-alpha is redshifted with respect to [OIII]. These results may imply that outflows are not primarily responsible for Lyman alpha escape in this LAB, since outflows are generally expected to produce a positive velocity offset (McLinden et al. 2011). In addition, we present an [OIII] line flux upper limit on a third region of LAB1, a region that is unassociated with any underlying galaxy. We find that the [OIII] upper limit from the galaxy-unassociated region of the blob is at least 1.4 -- 2.5 times fainter than the [OIII] flux from one of the LBG-associated regions and has an [OIII] to Lyman-alpha ratio measured at least 1.9 -- 3.4 times smaller than the same ratio measured from one of the LBGs.Comment: submitted to Ap

The challenges of a public data release : behind the scenes of SDSS DR13

The Sloan Digitial Sky Surveys (SDSS) have been collecting imaging and spectoscopic data since 1998. These data as well as their derived data products are made publicly available through regular data releases, of which the 13th took place summer 2016. Although public data releases can be challenging to manage, they significantly increase the impact of a survey, both scientifically and educationally.Postprin

VADER - A Satellite Mission Concept For High Precision Dark Energy Studies

We present a satellite mission concept to measure the dark energy equation of state parameter w with percent-level precision. The Very Ambitious Dark Energy Research satellite (VADER) is a multi-wavelength survey mission joining X-ray, optical, and IR instruments for a simultaneous spectral coverage from 4microns (0.3eV) to 10keV over a field of view (FoV) of 1 square degree. VADER combines several clean methods for dark energy studies, the baryonic acoustic oscillations in the galaxy and galaxy cluster power spectrum and weak lensing, for a joint analysis over an unrivalled survey volume. The payload consists of two XMM-like X-ray telescopes with an effective area of 2,800cm^2 at 1.5keV and state-of-the-art wide field DEPFET pixel detectors (0.1-10keV) in a curved focal plane configuration to extend the FoV. The X-ray telescopes are complemented by a 1.5m optical/IR telescope with 8 instruments for simultaneous coverage of the same FoV from 0.3 to 4 microns. The 8 dichroic-separated bands (u,g,r,z,J,H,K,L) provide accurate photometric galaxy redshifts, whereas the diffraction-limited resolution of the central z-band allows precise shape measurements for cosmic shear analysis. The 5 year VADER survey will cover a contiguous sky area of 3,500 square degrees to a depth of z~2 and will yield accurate photometric redshifts and multi-wavelength object parameters for about 175,000 galaxy clusters, one billion galaxies, and 5 million AGN. VADER will not only provide unprecedented constraints on the nature of dark energy, but will additionally extend and trigger a multitude of cosmic evolution studies to very large (>10 Gyrs) look-back times.Comment: 14 pages, 7 figures, accepted for publication in the SPIE conference proceeding

HI Rich but Low Star Formation galaxies in MaNGA: Physical Properties and Comparison to Control Samples

Gas rich galaxies are typically star-forming. We make use of HI-MaNGA, a program of HI follow-up for the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey of the Sloan Digital Sky Surveys to construct a sample of unusual neutral hydrogen (HI, 21cm) rich galaxies which have low Star Formation Rates (SFRs); using infra-red color from the Wide-field Infrared Survey Explorer (WISE) as a proxy for specific SFR. Out of a set of 1575 MaNGA galaxies with HI-MaNGA detections, we find 83 (5%) meet our selection criteria to be HI rich with low SFR. We construct two stellar mass-matched control samples: HI rich galaxies with typical SFR (High SF Control) and HI poor galaxies with low SFR (Low HI Control). We investigate the properties of each of these samples, comparing physical parameters such as ionization state maps, stellar and ionized gas velocity and dispersion, environment measures, metallicity, and morphology to search for the reasons why these unusual HI rich galaxies are not forming stars. We find evidence for recent external accretion of gas in some galaxies (via high counter-rotating fractions), along with some evidence for AGN feedback (from a high cLIER and/or red geyser fraction), and bar quenching (via an enhanced strong bar fraction). Some galaxies in the sample are consistent with simply having their HI in a high angular momentum, large radius, low density disc. We conclude that no single physical process can explain all HI rich, low SFR galaxies.Comment: 15 pages, in press MNRAS. v2 following corrections noticed in proof

Mapping the dark matter halo of early-type galaxy NGC 2974 through orbit-based models with combined stellar and cold gas kinematics

We present an orbit-based method of combining stellar and cold gas kinematics to constrain the dark matter profile of early-type galaxies. We apply this method to early-type galaxy NGC 2974, using Pan-STARRS imaging and SAURON stellar kinematics to model the stellar orbits, and introducing H I kinematics from VLA observation as a tracer of the gravitational potential. The introduction of the cold gas kinematics shows a significant effect on the confidence limits of especially the dark halo properties: we exclude more than 95 per cent of models within the 1σ confidence level of Schwarzschild modelling with only stellar kinematics, and reduce the relative uncertainty of the dark matter fraction significantly to 10 per cent within 5Re. Adopting a generalized Navarro-Frenk-White (NFW) dark matter profile, we measure a shallow cuspy inner slope of 0.6^{+0.2}_{-0.3} when including the cold gas kinematics in our model. We cannot constrain the inner slope with the stellar kinematics alone.PostprintPeer reviewe

The HI Tully-Fisher Relation of Early-Type Galaxies

We study the HI K-band Tully-Fisher relation and the baryonic Tully-Fisher relation for a sample of 16 early-type galaxies, taken from the ATLAS3D sample, which all have very regular HI disks extending well beyond the optical body (> 5 R_eff). We use the kinematics of these disks to estimate the circular velocity at large radii for these galaxies. We find that the Tully-Fisher relation for our early-type galaxies is offset by about 0.5-0.7 magnitudes from the relation for spiral galaxies. The residuals with respect to the spiral Tully-Fisher relation correlate with estimates of the stellar mass-to-light ratio, suggesting that the offset between the relations is mainly driven by differences in stellar populations. We also observe a small offset between our Tully-Fisher relation with the relation derived for the ATLAS3D sample based on CO data representing the galaxies' inner regions (< 1 R_eff). This indicates that the circular velocities at large radii are systematically 10% lower than those near 0.5-1 R_eff, in line with recent determinations of the shape of the mass profile of early-type galaxies. The baryonic Tully-Fisher relation of our sample is distinctly tighter than the standard one, in particular when using mass-to-light ratios based on dynamical models of the stellar kinematics. We find that the early-type galaxies fall on the spiral baryonic Tully-Fisher relation if one assumes M/L_K = 0.54 M_sun/L_sun for the stellar populations of the spirals, a value similar to that found by recent studies of the dynamics of spiral galaxies. Such a mass-to-light ratio for spiral galaxies would imply that their disks are 60-70% of maximal. Our analysis increases the range of galaxy morphologies for which the baryonic Tully-Fisher relations holds, strengthening previous claims that it is a more fundamental scaling relation than the classical Tully-Fisher relation.Comment: Accepted for publication in Astronomy & Astrophysic