Shocked POststarbust Galaxy Survey I: Candidate Poststarbust Galaxies with Emission Line Ratios Consistent with Shocks

[Abridged] The Shocked POststarburst Galaxy Survey (SPOGS) aims to identify transforming galaxies, in which the nebular lines are excited via shocks instead of through star formation processes. Utilizing the OSSY measurements on the Sloan Digital Sky Survey Data Release 7 catalog, we applied Balmer absorption and shock boundary criteria to identify 1,067 SPOG candidates (SPOGs*) within z=0.2. SPOGs* represent 0.2% of the OSSY sample galaxies that exceed the continuum signal-to-noise cut (and 0.7% of the emission line galaxy sample). SPOGs* colors suggest that they are in an earlier phase of transition than OSSY galaxies that meet an E+A selection. SPOGs* have a 13% 1.4GHz detection rate from the Faint Images of the Radio Sky at Twenty centimeters survey, higher than most other subsamples, and comparable only to low-ionization nuclear emission line region hosts, suggestive of the presence of active galactic nuclei. SPOGs* also have stronger NaD absorption than predicted from the stellar population, suggestive of cool gas being driven out in galactic winds. It appears that SPOGs* represent an earlier phase in galaxy transformation than traditionally selected poststarburst galaxies, and that a large proportion of SPOGs* also have properties consistent with disruption of their interstellar media, a key component to galaxy transformation. It is likely that many of the known pathways to transformation undergo a SPOG phase. Studying this sample of SPOGs* further, including their morphologies, active galactic nuclei properties, and environments, has the potential for us to build a more complete picture of the initial conditions that can lead to a galaxy evolving.Comment: 19 pages, 19 figures, 3 tables, accepted to ApJ Supplements (Apr 13), full sample is available on www.spogs.or

A subarcsecond near-infrared view of massive galaxies at z > 1 with Gemini Multiconjugate Adaptive Optics

We present images taken using the Gemini South Adaptive Optics Imager (GSAOI) with the Gemini Multiconjugate Adaptive Optics System (GeMS) in three 2 arcmin$^2$ fields in the Spitzer Extragalactic Representative Volume Survey. These GeMS/GSAOI observations are among the first $\approx 0.1^{''}$ resolution data in the near-infrared spanning extragalactic fields exceeding $1.5^{\prime}$ in size. We use these data to estimate galaxy sizes, obtaining results similar to those from studies with the Hubble Space Telescope, though we find a higher fraction of compact star forming galaxies at $z>2$. To disentangle the star-forming galaxies from active galactic nuclei (AGN), we use multiwavelength data from surveys in the optical and infrared, including far-infrared data from Herschel, as well as new radio continuum data from the Australia Telescope Compact Array and Very Large Array. We identify ultraluminous infrared galaxies (ULIRGs) at $z \sim 1-3$, which consist of a combination of pure starburst galaxies and Active Galactic Nuclei (AGN)/starburst composites. The ULIRGs show signs of recent merger activity, such as highly disturbed morphologies and include a rare candidate triple AGN. We find that AGN tend to reside in hosts with smaller scale sizes than purely star-forming galaxies of similar infrared luminosity. Our observations demonstrate the potential for MCAO to complement the deeper galaxy surveys to be made with the James Webb Space Telescope.Comment: 20 pages, AJ, in pres

Welcome to the Twilight Zone: The Mid-Infrared Properties of Poststarburst Galaxies

We investigate the optical and Wide-field Survey Explorer (WISE) colors of "E+A" identified post-starburst galaxies, including a deep analysis on 190 post-starbursts detected in the 2{\mu}m All Sky Survey Extended Source Catalog. The post-starburst galaxies appear in both the optical green valley and the WISE Infrared Transition Zone (IRTZ). Furthermore, we find that post-starbursts occupy a distinct region [3.4]-[4.6] vs. [4.6]-[12] WISE colors, enabling the identification of this class of transitioning galaxies through the use of broad-band photometric criteria alone. We have investigated possible causes for the WISE colors of post-starbursts by constructing a composite spectral energy distribution (SED), finding that mid-infrared (4-12{\mu}m) properties of post-starbursts are consistent with either 11.3{\mu}m polycyclic aromatic hydrocarbon emission, or Thermally Pulsating Asymptotic Giant Branch (TP-AGB) and post-AGB stars. The composite SED of extended post- starburst galaxies with 22{\mu}m emission detected with signal to noise >3 requires a hot dust component to produce their observed rising mid-infrared SED between 12 and 22{\mu}m. The composite SED of WISE 22{\mu}m non-detections (S/N<3), created by stacking 22{\mu}m images, is also flat, requiring a hot dust component. The most likely source of this mid-infrared emission of these E+A galaxies is a buried active galactic nucleus. The inferred upper limit to the Eddington ratios of post-starbursts are 1e-2 to 1e-4, with an average of 1e-3. This suggests that AGNs are not radiatively dominant in these systems. This could mean that including selections able to identify active galactic nuclei as part of a search for transitioning and post-starburst galaxies would create a more complete census of the transition pathways taken as a galaxy quenches its star formation.Comment: 13 pages, 11 figures, accepted for publication in the Astrophysical Journa

Catching Quenching Galaxies: The Nature of the WISE Infrared Transition Zone

We present the discovery of a prominent bifurcation between early-type galaxies and late-type galaxies, in [4.6]–[12] μm colors from the Wide Field Infrared Survey Explorer (WISE). We then use an emission-line diagnostic comparison sample to explore the nature of objects found both within and near the edges of this WISE infrared transition zone (IRTZ). We hypothesize that this bifurcation might be due to the presence of hot dust and polyaromatic hydrocarbon (PAH) emission features in late-type galaxies. Using a sample of galaxies selected through the Shocked Poststarburst Galaxy Survey (SPOGS), we are able to identify galaxies with strong Balmer absorption (EW(Hδ) > 5 Å) as well as emission lines inconsistent with star formation (deemed SPOG candidates, or SPOGs*) that lie within the optical green valley. Seyferts and low-ionization nuclear emission line regions, whose u − r colors tend to be red, are strongly represented within IRTZ, whereas SPOGs* tend to sit near the star-forming edge. Although active galactic nuclei are well represented in the IRTZ, we argue that the dominant IRTZ population is composed of galaxies that are in late stages of transitioning across the optical green valley, shedding the last of their remnant interstellar media

Food Storage in Permafrost and Seasonally Frozen Ground in Chukotka and Alaska Communities

Food cellars, otherwise referred to as ice or meat cellars, (lednik in Russian, k’aetyran in Chukchi, siġļuaq in Iñupiaq, and siqlugaq in Yupik) are a natural form of refrigeration in permafrost or seasonally frozen ground used to preserve, age, and ferment foods harvested for subsistence, including marine mammals, birds, fish, and plants. Indigenous peoples throughout the Arctic have constructed cellars in frozen ground for millennia. This paper focuses on cellars in Russian and American coastal and island communities of the Bering Strait, the region otherwise known as Beringia. This area has a unique, culturally rich, and politically dynamic history. Many traditions associated with cellars are threatened in Chukchi communities in Russia because of the impacts of climate change, relocation, dietary changes, and industrial development. However, even with warmer temperatures, cellars still provide a means to age and ferment food stuffs following traditional methods. In cooperation with local stakeholders, we measured internal temperatures of 18 cellars in 13 communities throughout the Bering Strait region and northern Alaska. Though cellars are widely used in permafrost regions, their structure, usage, and maintenance methods differ and exhibit influences of local climates, traditions, and economic activities. Monitoring internal temperatures and recording structural descriptions of cellars is important in the face of climate change to better understand the variety and resilience of living adaptations in different cold regions.Les caves à denrées, aussi connues sous le nom de caves à glace ou de caves à viande (lednik en russe, k’aetyran en tchouktche, siġļuaq en iñupiaq, et siqlugaq en yupik) constituent une forme de réfrigération naturelle dans le pergélisol ou dans le gélisol saisonnier permettant de conserver, de maturer et de fermenter les denrées récoltées à des fins de subsistance, dont les mammifères marins, les oiseaux, les poissons et les plantes. Cela fait des millénaires que les peuples autochtones de l’Arctique construisent des caves dans le gélisol. Cet article porte sur les caves se trouvant dans les localités côtières et insulaires russes et américaines du détroit de Béring, région qui porte également le nom de Béringie. L’histoire de cette région est unique, culturellement riche et politiquement dynamique. De nombreuses traditions liées aux caves des localités tchouktches de la Russie sont menacées en raison des incidences du changement climatique, de la délocalisation, du changement des régimes alimentaires et de l’expansion industrielle. Cependant, malgré les températures plus élevées, les caves constituent toujours un moyen de maturer et de fermenter les denrées alimentaires selon les méthodes traditionnelles. En collaboration avec les parties prenantes de la région, nous avons mesuré les températures internes de 18 caves situées dans 13 localités de la région du détroit de Béring et du nord de l’Alaska. Bien que les caves soient courantes dans les régions de pergélisol, leur structure, leur usage et les méthodes d’entretien diffèrent, et elles sont à l’image des influences des traditions, des activités économiques et des climats locaux. La surveillance des températures internes et l’enregistrement des descriptions structurales des caves revêtent de l’importance à la lumière du changement climatique, car elles permettent de mieux comprendre la variété et la résilience des adaptations de vie dans différentes régions froides.называемые иногда мясными ямами (лéдник по-русски, к’этыран по-чукотски, Siġļuaq или Siqlugaq по-эскимосски), обустроены как в вечномёрзлых породах, так и в сезонноталом слое и являются естественной формой заморозки для сохранения, выдержки и ферментации пищевых продуктов, добытых для пропитания: мясо морских млекопитающих, дичь, рыба, растения и др. Коренные жители Арктики обустраивали хранилища в мерзлоте на протяжении тысячелетий. Данная статья посвящена подземным хранилищам в российских и американских поселениях на берегах Берингова пролива – региона, также называемого Берингией. Эта территория имеет уникальную, богатую культурой и политически динамичную историю. Многие традиции, связанные с хранилищами в поселениях Чукотки, находятся под угрозой исчезновения из-за климатических изменений, миграции жителей, изменений в рационе и промышленного освоения территории. Однако даже при повышении температуры воздуха в хранилищах по-прежнему можно выдерживать и ферментировать пищу традиционными способами. При сотрудничестве с местным населением мы измерили температуры внутреннего воздуха в 18 лéдниках в 13 поселениях в регионе Берингова пролива и на севере Аляски. Несмотря на широкое использование таких хранилищ в криолитозоне, их структура, использование и методы обслуживания различаются под влиянием климатических условий, традиций и особенностей промысла. Мониторинг внутренней температуры воздуха в лéдниках и описание их конструкций важны в контексте изменения климата для лучшего понимания разнообразия и эффективности различных способов адаптации к жизни в холодных регионах

A pilgrimage to gravity on GPUs

In this short review we present the developments over the last 5 decades that have led to the use of Graphics Processing Units (GPUs) for astrophysical simulations. Since the introduction of NVIDIA's Compute Unified Device Architecture (CUDA) in 2007 the GPU has become a valuable tool for N-body simulations and is so popular these days that almost all papers about high precision N-body simulations use methods that are accelerated by GPUs. With the GPU hardware becoming more advanced and being used for more advanced algorithms like gravitational tree-codes we see a bright future for GPU like hardware in computational astrophysics.Comment: To appear in: European Physical Journal "Special Topics" : "Computer Simulations on Graphics Processing Units" . 18 pages, 8 figure

The MASSIVE Survey. VI. The spatial sistribution and kinematics of warm ionized gas in the most massive local early-type galaxies

We present the first systematic investigation of the existence, spatial distribution, and kinematics of warm ionized gas as traced by the [O ii] 3727 Å emission line in 74 of the most massive galaxies in the local universe. All of our galaxies have deep integral-field spectroscopy from the volume- and magnitude-limited MASSIVE survey of early-type galaxies with stellar mass $\mathrm{log}({M}_{* }/{M}_{\odot })\gt 11.5$ (M K < −25.3 mag) and distance D < 108 Mpc. Of the 74 galaxies in our sample, we detect warm ionized gas in 28, which yields a global detection fraction of 38 ± 6% down to a typical [O ii] equivalent width limit of 2 Å. MASSIVE fast rotators are more likely to have gas than MASSIVE slow rotators with detection fractions of 80 ± 10% and 28 ± 6%, respectively. The spatial extents span a wide range of radii (0.6–18.2 kpc; 0.1–4R e ), and the gas morphologies are diverse, with 17/28 ≈ 61 ± 9% being centrally concentrated, 8/28 ≈ 29 ± 9% exhibiting clear rotation out to several kiloparsecs, and 3/28 ≈ 11 ± 6% being extended but patchy. Three out of four fast rotators show kinematic alignment between the stars and gas, whereas the two slow rotators with robust kinematic measurements available exhibit kinematic misalignment. Our inferred warm ionized gas masses are roughly ~105 M ⊙. The emission line ratios and radial equivalent width profiles are generally consistent with excitation of the gas by the old underlying stellar population. We explore different gas origin scenarios for MASSIVE galaxies and find that a variety of physical processes are likely at play, including internal gas recycling, cooling out of the hot gaseous halo, and gas acquired via mergers