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We investigate the optical morphologies of candidate active galaxies identified at radio, X-ray, and mid-infrared wavelengths. We use the Advanced Camera for Surveys General Catalog (ACS-GC) to identify 372, 1360, and 1238 AGN host galaxies from the VLA, XMM-Newton and Spitzer Space Telescope observations of the COSMOS field, respectively. We investigate both quantitative (GALFIT) and qualitative (visual) morphologies of these AGN host galaxies, split by brightness in their selection band. We find that the radio-selected AGN are most distinct, with a very low incidence of having unresolved optical morphologies and a high incidence of being hosted by early-type galaxies. In comparison to X-ray selected AGN, mid-IR selected AGN have a slightly higher incidence of being hosted by disk galaxies. These morphological results conform with the results of Hickox et al. 2009 who studied the colors and large-scale clustering of AGN, and found a general association of radio-selected AGN with ``red sequence'' galaxies, mid-IR selected AGN with ``blue cloud'' galaxies, and X-ray selected AGN straddling these samples in the ``green valley.'' In the general scenario where AGN activity marks and regulates the transition from late-type disk galaxies into massive elliptical galaxies, this work suggests that the earlier stages are most evident as mid-IR selected AGNs. Mid-IR emission is less susceptible to absorption than the relatively soft X-rays probed by XMM-Newton, which are seen at later stages in the transition. Radio-selected AGN are then typically associated with minor bursts of activity in the most massive galaxies.

Nearby Type III (galaxy-spanning) Kardashev supercivilizations would have high mid-infrared (MIR) luminosities. We have used the Wide-field Infrared Survey Explorer (WISE) to survey ~\\(1 \\times 10^5\\) galaxies for extreme MIR emission, \\(10^3\\) times more galaxies than the only previous such search. We have calibrated the WISE All-sky Catalog pipeline products to improve its photometry for extended sources. We present 563 extended sources with \\(|b| \\ge 10\\) and red MIR colors, having visually vetted them to remove artifacts. No galaxies in our sample host an alien civilization reprocessing more than 85% of its starlight into the MIR, and only 50 galaxies, including Arp 220, have MIR luminosities consistent with >50% reprocessing. Ninety of these (likely) extragalactic sources have little literature presence; in most cases they are likely barely resolved galaxies or pairs of galaxies undergoing large amounts of star formation. Five are new to science and deserve further study. The Be star 48 Librae sits within a MIR nebula, and we suggest that it may be creating dust. WISE, 2MASS, and Spitzer imagery shows that IRAS 04287+6444 is consistent with a previously unnoticed, heavily extinguished cluster of young stellar objects. We identify five \"passive\" (i.e. red) spiral galaxies with unusually high MIR and low NUV luminosity. We search a set of optically \"dark\" HI galaxies for MIR emission, and find none. These 90 poorly understood sources and five anomalous passive spirals deserve follow-up via both SETI and conventional astrophysics.

We present the data release paper for the Galaxy Zoo: Hubble (GZH) project. This is the third phase in a large effort to measure reliable, detailed morphologies of galaxies by using crowdsourced visual classifications of colour composite images. Images in GZH were selected from various publicly-released Hubble Space Telescope Legacy programs conducted with the Advanced Camera for Surveys, with filters that probe the rest-frame optical emission from galaxies out to \\(z \\sim 1\\). The bulk of the sample is selected to have \\(m_{I814W} < 23.5\\),but goes as faint as \\(m_{I814W} < 26.8\\) for deep images combined over 5 epochs. The median redshift of the combined samples is \\(z = 0.9 \\pm 0.6\\), with a tail extending out to \\(z \\sim 4\\). The GZH morphological data include measurements of both bulge- and disk-dominated galaxies, details on spiral disk structure that relate to the Hubble type, bar identification, and numerous measurements of clump identification and geometry. This paper also describes a new method for calibrating morphologies for galaxies of different luminosities and at different redshifts by using artificially-redshifted galaxy images as a baseline. The GZH catalogue contains both raw and calibrated morphological vote fractions for 119,849 galaxies, providing the largest dataset to date suitable for large-scale studies of galaxy evolution out to \\(z \\sim 1\\).

We present a sample of brown dwarfs identified with the {\\it Wide-field Infrared Survey Explorer} (WISE) for which we have obtained {\\it Hubble Space Telescope} ({\\it HST}) Wide Field Camera 3 (WFC3) near-infrared grism spectroscopy. The sample (twenty-two in total) was observed with the G141 grism covering 1.10\\(-\\)1.70 \\(\\mu\\)m, while fifteen were also observed with the G102 grism, which covers 0.90\\(-\\)1.10 \\(\\mu\\)m. The additional wavelength coverage provided by the G102 grism allows us to 1) search for spectroscopic features predicted to emerge at low effective temperatures (e.g.\\ ammonia bands) and 2) construct a smooth spectral sequence across the T/Y boundary. We find no evidence of absorption due to ammonia in the G102 spectra. Six of these brown dwarfs are new discoveries, three of which are found to have spectral types of T8 or T9. The remaining three, WISE J082507.35\\(+\\)280548.5 (Y0.5), WISE J120604.38\\(+\\)840110.6 (Y0), and WISE J235402.77\\(+\\)024015.0 (Y1) are the nineteenth, twentieth, and twenty-first spectroscopically confirmed Y dwarfs to date. We also present {\\it HST} grism spectroscopy and reevaluate the spectral types of five brown dwarfs for which spectral types have been determined previously using other instruments.

The WISE mission has unveiled a rare population of high-redshift (\\(z=1-4.6\\)), dusty, hyper-luminous galaxies, with infrared luminosities \\(L_{\\rm IR} > 10^{13}~L_{\\odot}\\), and sometimes exceeding \\(10^{14}~L_{\\odot}\\). Previous work has shown that their dust temperatures and overall far-IR SEDs are significantly hotter than expected for star-formation. We present here an analysis of the rest-frame optical through mid-IR SEDs for a large sample of these so-called \"Hot, Dust-Obscured Galaxies\" (Hot DOGs). We find that the SEDs of Hot DOGs are generally well modeled by the combination of a luminous, yet obscured AGN that dominates the rest-frame emission at \\(\\lambda > 1\\mu\\rm m\\) and the bolometric luminosity output, and a less luminous host galaxy that is responsible for the bulk of the rest optical/UV emission. Even though the stellar mass of the host galaxies may be as large as \\(10^{11}-10^{12}~M_{\\odot}\\), the AGN emission, with luminosities comparable to those of the most luminous QSOs known, require that either Hot DOGs have black hole masses significantly in excess of the local relations, or that they radiate significantly above the Eddington limit. We show that, while rare, the number density of Hot DOGs is comparable to that of equally luminous but unobscured (i.e., Type 1) QSOs. This is inconsistent with the trend of a diminishing fraction of obscured objects with increasing luminosity found for less luminous QSOs, possibly indicating a reversal in this relation at high luminosity, and that Hot DOGs are not the torus-obscured counterparts of the known optically selected, largely unobscured Hyper-Luminous QSOs. Hot DOGs may represent a different type of galaxy and thus a new component of the galaxy evolution paradigm. Finally, we discuss the environments of Hot DOGs and show that these objects are in regions as dense as those of known high-redshift proto-clusters.(Abridged)