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Meidt, Sharon E.,Schinnerer, Eva,Knapen, Johan H.,Bosma, Albert,Athanassoula, E.,Sheth, Kartik,Buta, Ronald J.,Zaritsky, Dennis,Laurikainen, Eija,Elmegreen, Debra,Elmegreen, Bruce G.,Gadotti, Dimitri IOP Publishing 2012 The Astrophysical journal Vol.744 No.1
<P>With the aim of constructing accurate two-dimensional maps of the stellar mass distribution in nearby galaxies from Spitzer Survey of Stellar Structure in Galaxies 3.6 and 4.5 mu m images, we report on the separation of the light from old stars from the emission contributed by contaminants. Results for a small sample of six disk galaxies (NGC 1566, NGC 2976, NGC 3031, NGC 3184, NGC 4321, and NGC 5194) with a range of morphological properties, dust content, and star formation histories are presented to demonstrate our approach. To isolate the old stellar light from contaminant emission (e.g., hot dust and the 3.3 mu m polycyclic aromatic hydrocarbon (PAH) feature) in the IRAC 3.6 and 4.5 mu m bands we use an independent component analysis (ICA) technique designed to separate statistically independent source distributions, maximizing the distinction in the [3.6]-[4.5] colors of the sources. The technique also removes emission from evolved red objects with a low mass-to-light ratio, such as asymptotic giant branch (AGB) and red supergiant (RSG) stars, revealing maps of the underlying old distribution of light with [3.6]-[4.5] colors consistent with the colors of K and M giants. The contaminants are studied by comparison with the non-stellar emission imaged at 8 mu m, which is dominated by the broad PAH feature. Using the measured 3.6 mu m/8 mu m ratio to select individual contaminants, we find that hot dust and PAHs together contribute between similar to 5% and 15% to the integrated light at 3.6 mu m, while light from regions dominated by intermediate-age (AGB and RSG) stars accounts for only 1%-5%. Locally, however, the contribution from either contaminant can reach much higher levels; dust contributes on average 22% to the emission in star-forming regions throughout the sample, while intermediate-age stars contribute upward of 50% in localized knots. The removal of these contaminants with ICA leaves maps of the old stellar disk that retain a high degree of structural information and are ideally suited for tracing stellar mass, as will be the focus in a companion paper.</P>
Kim, Taehyun,Sheth, Kartik,Hinz, Joannah L.,Lee, Myung Gyoon,Zaritsky, Dennis,Gadotti, Dimitri A.,Knapen, Johan H.,Schinnerer, Eva,Ho, Luis C.,Laurikainen, Eija,Salo, Heikki,Athanassoula, E.,Bosma, Al IOP Publishing 2012 The Astrophysical journal Vol.753 No.1
<P>Tidal debris around galaxies can yield important clues on their evolution. We have identified tidal debris in 11 early-type galaxies (T <= 0) from a sample of 65 early types drawn from the Spitzer Survey of Stellar Structure in Galaxies (S(4)G). The tidal debris includes features such as shells, ripples, and tidal tails. A variety of techniques, including two-dimensional decomposition of galactic structures, were used to quantify the residual tidal features. The tidal debris contributes similar to 3%-10% to the total 3.6 mu m luminosity of the host galaxy. Structural parameters of the galaxies were estimated using two-dimensional profile fitting. We investigate the locations of galaxies with tidal debris in the fundamental plane and Kormendy relation. We find that galaxies with tidal debris lie within the scatter of early-type galaxies without tidal features. Assuming that the tidal debris is indicative of recent gravitational interaction or merger, this suggests that these galaxies have either undergone minor merging events so that the overall structural properties of the galaxies are not significantly altered, or they have undergone a major merging events but already have experienced sufficient relaxation and phase mixing so that their structural properties become similar to those of the non-interacting early-type galaxies.</P>
Radio Selection of the Most Distant Galaxy Clusters
Daddi, E.,Jin, S.,Strazzullo, V.,Sargent, M. T.,Wang, T.,Ferrari, C.,Schinnerer, E.,Smolč,ić,, V.,Calabró,, A.,Coogan, R.,Delhaize, J.,Delvecchio, I.,Elbaz, D.,Gobat, R.,Gu, Q.,Liu, D. American Astronomical Society 2017 ASTROPHYSICAL JOURNAL LETTERS - Vol.846 No.2
Sargent, M. T.,Daddi, E.,Bournaud, F.,Onodera, M.,Feruglio, C.,Martig, M.,Gobat, R.,Dannerbauer, H.,Schinnerer, E. IOP Publishing 2015 ASTROPHYSICAL JOURNAL LETTERS - Vol.806 No.1
<P>Gas and dust in star-forming galaxies at the peak epoch of galaxy assembly are presently the topic of intense study, but little is known about the interstellar medium (ISM) of distant, passively evolving galaxies. We report on a deep 3 mm band search with the IRAM/Plateau de Bure Interferometer for molecular (H-2) gas in a massive (M-star similar to 6 x 10(11) M-circle dot) elliptical galaxy at z= 1.4277, the first observation of this kind ever attempted. We place a 3 sigma upper limit of 0.32 Jy kms(-1) on the flux of the CO-(J = 2 -> 1) line or L-CO' < 8.8 x 10(9) Kkms(-1) pc(2), assuming a disk-like CO-morphology and a circular velocity scaling with the stellar velocity dispersion as in local early-type galaxies (ETGs). This translates to an H-2 mass of < 3.9 x 10(10) (alpha(CO)/4.4) M-circle dot or a gas fraction of less than or similar to 6% assuming a Salpeter initial mass function and an ISM dominated by H-2, as observed in many local, high-mass ellipticals. This low value approaches that of local ETGs, suggesting that the low star formation activity in massive, high-z passive galaxies reflects a true dearth of gas and a lesser role for inhibitive mechanisms like morphological quenching.</P>
Cultured Bacterial Diversity and Human Impact on Alpine Glacier Cryoconite
Yung Mi Lee,So-Yeon Kim,Jia Jung,Eun Hye Kim,Kyeung Hee Cho,Franz Schinner,Rosa Margesin,Soon Gyu Hong,이홍금 한국미생물학회 2011 The journal of microbiology Vol.49 No.3
The anthropogenic effect on the microbial communities in alpine glacier cryoconites was investigated by cultivation and physiological characterization of bacteria from six cryoconite samples taken at sites with different amounts of human impact. Two hundred and forty seven bacterial isolates were included in Actinobacteria (9%, particularly Arthrobacter), Bacteroidetes (14%, particularly Olleya), Firmicutes (0.8%),Alphaproteobacteria (2%), Betaproteobacteria (16%, particularly Janthinobacterium), and Gammaproteobacteria (59%, particularly Pseudomonas). Among them, isolates of Arthrobacter were detected only in samples from sites with no human impact, while isolates affiliated with Enterobacteriaceae were detected only in samples from sites with strong human impact. Bacterial isolates included in Actinobacteria and Bacteroidetes were frequently isolated from pristine sites and showed low maximum growth temperature and enzyme secretion. Bacterial isolates included in Gammaproteobacteria were more frequently isolated from sites with stronger human impact and showed high maximum growth temperature and enzyme secretion. Ecotypic differences were not evident among isolates of Janthinobacterium lividum, Pseudomonas fluorescens, and Pseudomonas veronii, which were frequently isolated from sites with different degrees of anthropogenic effect.