26 research outputs found

    Galaxy And Mass Assembly (GAMA): The Bright Void Galaxy Population in the Optical and Mid-IR

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    We examine the properties of galaxies in the Galaxies and Mass Assembly (GAMA) survey located in voids with radii >10 h−1>10~h^{-1} Mpc. Utilising the GAMA equatorial survey, 592 void galaxies are identified out to z~0.1 brighter than Mr=−18.4M_{r} = -18.4, our magnitude completeness limit. Using the WHαW_{\rm{H\alpha}} vs. [NII]/Hα\alpha (WHAN) line strength diagnostic diagram, we classify their spectra as star forming, AGN, or dominated by old stellar populations. For objects more massive than 5×1095\times10^{9} M⊙_{\odot}, we identify a sample of 26 void galaxies with old stellar populations classed as passive and retired galaxies in the WHAN diagnostic diagram, else they lack any emission lines in their spectra. When matched to WISE mid-IR photometry, these passive and retired galaxies exhibit a range of mid-IR colour, with a number of void galaxies exhibiting [4.6]-[12] colours inconsistent with completely quenched stellar populations, with a similar spread in colour seen for a randomly drawn non-void comparison sample. We hypothesise that a number of these galaxies host obscured star formation, else they are star forming outside of their central regions targeted for single fibre spectroscopy. When matched to a randomly drawn sample of non-void galaxies, the void and non-void galaxies exhibit similar properties in terms of optical and mid-IR colour, morphology, and star formation activity, suggesting comparable mass assembly and quenching histories. A trend in mid-IR [4.6]-[12] colour is seen, such that both void and non-void galaxies with quenched/passive colours <1.5 typically have masses higher than 101010^{10} M⊙_{\odot}, where internally driven processes play an increasingly important role in galaxy evolution

    Galaxy And Mass Assembly (GAMA): The Bright Void Galaxy Population in the Optical and Mid-IR

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    We examine the properties of galaxies in the Galaxies and Mass Assembly (GAMA) survey located in voids with radii >10 h−1>10~h^{-1} Mpc. Utilising the GAMA equatorial survey, 592 void galaxies are identified out to z~0.1 brighter than Mr=−18.4M_{r} = -18.4, our magnitude completeness limit. Using the WHαW_{\rm{H\alpha}} vs. [NII]/Hα\alpha (WHAN) line strength diagnostic diagram, we classify their spectra as star forming, AGN, or dominated by old stellar populations. For objects more massive than 5×1095\times10^{9} M⊙_{\odot}, we identify a sample of 26 void galaxies with old stellar populations classed as passive and retired galaxies in the WHAN diagnostic diagram, else they lack any emission lines in their spectra. When matched to WISE mid-IR photometry, these passive and retired galaxies exhibit a range of mid-IR colour, with a number of void galaxies exhibiting [4.6]-[12] colours inconsistent with completely quenched stellar populations, with a similar spread in colour seen for a randomly drawn non-void comparison sample. We hypothesise that a number of these galaxies host obscured star formation, else they are star forming outside of their central regions targeted for single fibre spectroscopy. When matched to a randomly drawn sample of non-void galaxies, the void and non-void galaxies exhibit similar properties in terms of optical and mid-IR colour, morphology, and star formation activity, suggesting comparable mass assembly and quenching histories. A trend in mid-IR [4.6]-[12] colour is seen, such that both void and non-void galaxies with quenched/passive colours <1.5 typically have masses higher than 101010^{10} M⊙_{\odot}, where internally driven processes play an increasingly important role in galaxy evolution

    Galaxy and mass assembly: the G02 field, Herschel–ATLAS target selection and data release 3

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    We describe data release 3 (DR3) of the Galaxy And Mass Assembly (GAMA) survey. The GAMA survey is a spectroscopic redshift and multiwavelength photometric survey in three equatorial regions each of 60.0 deg2 (G09, G12, and G15), and two southern regions of 55.7 deg2 (G02) and 50.6 deg2 (G23). DR3 consists of: the first release of data covering the G02 region and of data on H-ATLAS (Herschel – Astrophysical Terahertz Large Area Survey) sources in the equatorial regions; and updates to data on sources released in DR2. DR3 includes 154 809 sources with secure redshifts across four regions. A subset of the G02 region is 95.5 per cent redshift complete to r < 19.8 mag over an area of 19.5 deg2, with 20 086 galaxy redshifts, that overlaps substantially with the XXL survey (X-ray) and VIPERS (redshift survey). In the equatorial regions, the main survey has even higher completeness (98.5 per cent), and spectra for about 75 per cent of H-ATLAS filler targets were also obtained. This filler sample extends spectroscopic redshifts, for probable optical counterparts to HATLAS submillimetre sources, to 0.8 mag deeper (r < 20.6 mag) than the GAMA main survey. There are 25 814 galaxy redshifts for H-ATLAS sources from the GAMA main or filler surveys. GAMA DR3 is available at the survey website (www.gama-survey.org/dr3/)

    Galaxy And Mass Assembly (GAMA): the G02 field, Herschel-ATLAS target selection and Data Release 3

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    We describe data release 3 (DR3) of the Galaxy And Mass Assembly (GAMA) survey. The GAMA survey is a spectroscopic redshift and multi-wavelength photometric survey in three equatorial regions each of 60.0 deg^2 (G09, G12, G15), and two southern regions of 55.7 deg^2 (G02) and 50.6 deg^2 (G23). DR3 consists of: the first release of data covering the G02 region and of data on H-ATLAS sources in the equatorial regions; and updates to data on sources released in DR2. DR3 includes 154809 sources with secure redshifts across four regions. A subset of the G02 region is 95.5% redshift complete to r<19.8 over an area of 19.5 deg^2, with 20086 galaxy redshifts, that overlaps substantially with the XXL survey (X-ray) and VIPERS (redshift survey). In the equatorial regions, the main survey has even higher completeness (98.5%), and spectra for about 75% of H-ATLAS filler targets were also obtained. This filler sample extends spectroscopic redshifts, for probable optical counterparts to H-ATLAS sub-mm sources, to 0.8 mag deeper (r<20.6) than the GAMA main survey. There are 25814 galaxy redshifts for H-ATLAS sources from the GAMA main or filler surveys. GAMA DR3 is available at the survey website (www.gama-survey.org/dr3/)

    Galaxy And Mass Assembly (GAMA): Panchromatic Data Release (far-UV --- far-IR) and the low-z energy budget

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    We present the GAMA Panchromatic Data Release (PDR) constituting over 230deg2^2 of imaging with photometry in 21 bands extending from the far-UV to the far-IR. These data complement our spectroscopic campaign of over 300k galaxies, and are compiled from observations with a variety of facilities including: GALEX, SDSS, VISTA, WISE, and Herschel, with the GAMA regions currently being surveyed by VST and scheduled for observations by ASKAP. These data are processed to a common astrometric solution, from which photometry is derived for 221,373 galaxies with r<19.8 mag. Online tools are provided to access and download data cutouts, or the full mosaics of the GAMA regions in each band. We focus, in particular, on the reduction and analysis of the VISTA VIKING data, and compare to earlier datasets (i.e., 2MASS and UKIDSS) before combining the data and examining its integrity. Having derived the 21-band photometric catalogue we proceed to fit the data using the energy balance code MAGPHYS. These measurements are then used to obtain the first fully empirical measurement of the 0.1-500ÎŒ\mum energy output of the Universe. Exploring the Cosmic Spectral Energy Distribution (CSED) across three time-intervals (0.3-1.1Gyr, 1.1-1.8~Gyr and 1.8---2.4~Gyr), we find that the Universe is currently generating (1.5±0.3)×1035(1.5 \pm 0.3) \times 10^{35} h70_{70} W Mpc−3^{-3}, down from (2.5±0.2)×1035(2.5 \pm 0.2) \times 10^{35} h70_{70} W Mpc−3^{-3} 2.3~Gyr ago. More importantly, we identify significant and smooth evolution in the integrated photon escape fraction at all wavelengths, with the UV escape fraction increasing from 27(18)% at z=0.18 in NUV(FUV) to 34(23)% at z=0.06. The GAMA PDR will allow for detailed studies of the energy production and outputs of individual systems, sub-populations, and representative galaxy samples at z<0.5z<0.5. The GAMA PDR can be found at: http://gama-psi.icrar.org

    Galaxy And Mass Assembly (GAMA): end of survey report and data release 2

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    The Galaxy And Mass Assembly (GAMA) survey is one of the largest contemporary spectroscopic surveys of low-redshift galaxies. Covering an area of ~286 deg^2 (split among five survey regions) down to a limiting magnitude of r < 19.8 mag, we have collected spectra and reliable redshifts for 238,000 objects using the AAOmega spectrograph on the Anglo-Australian Telescope. In addition, we have assembled imaging data from a number of independent surveys in order to generate photometry spanning the wavelength range 1 nm - 1 m. Here we report on the recently completed spectroscopic survey and present a series of diagnostics to assess its final state and the quality of the redshift data. We also describe a number of survey aspects and procedures, or updates thereof, including changes to the input catalogue, redshifting and re-redshifting, and the derivation of ultraviolet, optical and near-infrared photometry. Finally, we present the second public release of GAMA data. In this release we provide input catalogue and targeting information, spectra, redshifts, ultraviolet, optical and near-infrared photometry, single-component S\'ersic fits, stellar masses, Hα\alpha-derived star formation rates, environment information, and group properties for all galaxies with r < 19.0 mag in two of our survey regions, and for all galaxies with r < 19.4 mag in a third region (72,225 objects in total). The database serving these data is available at http://www.gama-survey.org/

    Practitioner and scientist perceptions of successful amphibian conservation

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    Conservation requires successful outcomes. However, success is perceived in many different ways depending on the desired outcome, which can vary according to numerous factors. We analysed perceptions of success among 355 scientists and practitioners working on amphibian conservation from over 150 organisations in more than 50 countries. Respondents identified four types of success: species and habitat improvements (84% of respondents); effective programme management (36%); outreach initiatives such as education and public engagement (25%); and the application of science-based conservation (15%). The most significant factor influencing overall perceived success was reducing threats. Capacity building was rated least important. Perceptions were influenced by experience, professional affiliation, involvement in conservation practice, and country of residence. More experienced conservation practitioners associated success with improvements to species and habitats, and less so with education and engagement initiatives. Whilst science-based conservation was rated as important, this factor declined in importance as the number of programmes a respondent participated in increased, particularly amongst those from Less Economically Developed Countries. The ultimate measure of conservation success – population recovery – may be difficult to measure in many amphibians, difficult to relate to the conservation actions intended to drive it, and difficult to achieve within conventional funding timeframes. The relaunched Amphibian Conservation Action Plan provides a framework for capturing lower-level processes and outcomes, identifying gaps, and measuring progress
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