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Register a new userExtending the Nearby Galaxy Heritage with WISE: First Results from the WISE Enhanced Resolution Galaxy Atlas
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The Wide-field Infrared Survey Explorer (WISE) mapped the entire sky at mid-infrared wavelengths 3.4, 4.6, 12 and 22 microns. The mission was primarily designed to extract point sources, leaving resolved and extended sources unexplored. We have begun a dedicated WISE Enhanced Resolution Galaxy Atlas (WERGA) project to fully characterize large, nearby galaxies and produce a legacy image atlas and source catalogue. Here we demonstrate the first results of the project for a sample of 17 galaxies, chosen to be of large angular size, diverse morphology, color, stellar mass and star formation. It includes many well-studied galaxies, such as M51, M81, M83, M87, M101, IC342. Photometry and surface brightness decomposition is carried out after special super-resolution processing, achieving spatial fidelity similar to that of Spitzer-IRAC. We present WISE, Spitzer and GALEX photometric and characterization measurements, combining the measurements to study the global properties. We derive star formation rates using the PAH-sensitive 12 micron (W3) fluxes, warm-dust sensitive 22 micron (W4) fluxes, and young massive-star sensitive UV fluxes. Stellar masses are estimated using the 3.4 micron (W1) and 4.6 micron (W2) measurements that trace the dominant stellar mass content. We highlight and showcase the detailed results of M83, comparing the infrared results with the ATCA HI gas distribution and GALEX UV emission, tracing the evolution from gas to stars. In addition to the enhanced images, WISE all-sky coverage provides a tremendous advantage over Spitzer for building a complete nearby galaxy catalog, tracing both stellar mass and star formation histories. We discuss the construction of a complete mid-infrared catalog of galaxies and its complementary role to study the assembly and evolution of galaxies in the local universe.
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After eight months of continuous observations, the Wide-field Infrared Survey Explorer (WISE) mapped the entire sky at 3.4 {mu}m, 4.6 {mu}m, 12 {mu}m and 22 {mu}m. We have begun a dedicated WISE High Resolution Galaxy Atlas (WHRGA) project to fully characterize large, nearby galaxies and produce a legacy image atlas and source catalogue. Here we summarize the deconvolution technique used to significantly improve the spatial resolution of WISE imaging, specifically designed to study the internal anatomy of nearby galaxies. As a case study, we present results for the galaxy NGC 1566, comparing the WISE super-resolution image processing to that of Spitzer, GALEX and ground-based imaging. The is the first paper in a two part series; results for a much larger sample of nearby galaxies is presented in the second paper.
We report the discovery by the Wide-field Infrared Survey Explorer of the z = 2.452 source WISE J181417.29+341224.9, the first hyperluminous source found in the WISE survey. WISE 1814+3412 is also the prototype for an all-sky sample of ~1000 extremely luminous W1W2-dropouts (sources faint or undetected by WISE at 3.4 and 4.6 microns and well detected at 12 or 22 microns). The WISE data and a 350 micron detection give a minimum bolometric luminosity of 3.7 x 10^13 Lsun, with ~10^14 Lsun plausible. Followup images reveal four nearby sources: a QSO and two Lyman Break Galaxies (LBGs) at z = 2.45, and an M dwarf star. The brighter LBG dominates the bolometric emission. Gravitational lensing is unlikely given the source locations and their different spectra and colors. The dominant LBG spectrum indicates a star formation rate ~300 Msun/yr, accounting for < 10% of the bolometric luminosity. Strong 22 micron emission relative to 350 microns implies that warm dust contributes significantly to the luminosity, while cooler dust normally associated with starbursts is constrained by an upper limit at 1.1 mm. Radio emission is ~10x above the far-infrared/radio correlation, indicating an active galactic nucleus is present. An obscured AGN combined with starburst and evolved stellar components can account for the observations. If the black hole mass follows the local M_BH-bulge mass relation, the implied Eddington ratio is >~4. WISE 1814+3412 may be a heavily obscured object where the peak AGN activity occurred prior to the peak era of star formation.
We describe The HI Nearby Galaxy Survey (THINGS), the largest program ever undertaken at the VLA to perform 21-cm HI observations of the highest quality (~7, <= 5 km/s resolution) of nearby galaxies. The goal of THINGS is to investigate key characteristics related to galaxy morphology, star formation and mass distribution across the Hubble sequence. A sample of 34 objects with distances between 3 and 10 Mpc will be observed, covering a wide range of evolutionary stages and properties. Data from THINGS will complement SINGS, the Spitzer Infrared Nearby Galaxy Survey. For the THINGS sample, high-quality observations at comparable resolution will thus be available from the X-ray regime through to the radio part of the spectrum. THINGS data can be used to investigate issues such as the small-scale structure of the ISM, its three-dimensional structure, the (dark) matter distribution and processes leading to star formation. To demonstrate the quality of the THINGS data products, we present some prelimary HI maps here of four galaxies from the THINGS sample.
We cross-matched Wide-field Infrared Survey Explorer (WISE) sources brighter than 1 mJy at 12um with the Sloan Digital Sky Survey (SDSS) galaxy spectroscopic catalog to produce a sample of ~10^5 galaxies at <z>=0.08, the largest of its kind. This sample is dominated (70%) by star-forming (SF) galaxies from the blue sequence, with total IR luminosities in the range ~10^8-10^12 L_sun. We identify which stellar populations are responsible for most of the 12um emission. We find that most (~80%) of the 12um emission in SF galaxies is produced by stellar populations younger than 0.6 Gyr. In contrast, the 12um emission in weak AGN (L[OIII]<10^7 L_sun) is produced by older stars, with ages of ~1-3 Gyr. We find that L_[12um] linearly correlates with stellar mass for SF galaxies. At fixed 12um luminosity, weak AGN deviate toward higher masses since they tend to be hosted by massive, early-type galaxies with older stellar populations. Star-forming galaxies and weak AGN follow different L_[12um]-SFR (star formation rate) relations, with weak AGN showing excess 12um emission at low SFR (~0.02-1 M_sun/yr). This is likely due to dust grains heated by older stars. While the specific star formation rate (SSFR) of SF galaxies is nearly constant, the SSFR of weak AGN decreases by ~3 orders of magnitude, reflecting the very different star formation efficiencies between SF galaxies and massive, early-type galaxies. Stronger type II AGN in our sample (L_[OIII]>10^7 L_sun), act as an extension of massive SF galaxies, connecting the SF and weak AGN sequences. This suggests a picture where galaxies form stars normally until an AGN (possibly after a starburst episode) starts to gradually quench the SF activity. We also find that 4.6-12um color is a useful first-order indicator of SF activity in a galaxy when no other data are available.
The WISE satellite surveyed the entire sky multiple times in four infrared wavelengths (3.4, 4.6, 12, and $22,mu$m; Wright et al. 2010). The unprecedented combination of coverage area and depth gives us the opportunity to measure the luminosity function of galaxies, one of the fundamental quantities in the study of them, at $2.4 mu$m to an unparalleled level of formal statistical accuracy in the near infrared. The big advantage of measuring luminosity functions at wavelengths in the window $approx 2$ to $3.5,mu$m is that it correlates more closely to the total stellar mass in galaxies than others. In this paper we report on the parameters for the $2.4,mu$m luminosity function of galaxies obtained from applying the spectroluminosity functional based methods defined in Lake et al. (2017b) to the data sets described in Lake et al. (2017a) using the mean and covariance of $2.4,mu$m normalized SEDs from Lake & Wright (2016). In terms of single Schechter function parameters evaluated at the present epoch, the combined result is: $phi_star = 5.8 pm [0.3_{mathrm{stat}},, 0.3_{mathrm{sys}}] times 10^{-3} operatorname{Mpc}^{-3}$, $L_star = 6.4 pm [0.1_{mathrm{stat}},, 0.3_{mathrm{sys}}] times 10^{10}, L_{2.4,mumathrm{m},odot}$ ($M_star = -21.67 pm [0.02_{mathrm{stat}},, 0.05_{mathrm{sys}}]operatorname{AB mag}$), and $alpha = -1.050 pm [0.004_{mathrm{stat}},, 0.03_{mathrm{sys}}]$, corresponding to a galaxy number density of $0.08operatorname{Mpc}^{-3}$ brighter than $10^6, L_{2.4,mumathrm{m},odot}$ ($10^{-3} operatorname{Mpc}^{-3}$ brighter than $L_star$) and a $2.4,mu$m luminosity density equivalent to $3.8times10^{8},L_{2.4,mumathrm{m},odot}operatorname{Mpc}^{-3}$. $ldots$
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