243 research outputs found

    The 10k zCOSMOS: Morphological Transformation of Galaxies in the Group Environment Since z ~1

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    We study the evolution of galaxies inside and outside of the group environment since z = 1 using a large well-defined set of groups and galaxies from the zCOSMOS-bright redshift survey in the COSMOS field. The fraction of galaxies with early-type morphologies increases monotonically with M_B luminosity and stellar mass and with cosmic epoch. It is higher in the groups than elsewhere, especially at later epochs. The emerging environmental effect is superposed on a strong global mass-driven evolution, and at z ~ 0.5 and log(M _*/M_⊙) ~ 10.2, the "effect" of the group environment is equivalent to (only) about 0.2 dex in stellar mass or 2 Gyr in time. The stellar mass function of galaxies in groups is enriched in massive galaxies. We directly determine the transformation rates from late to early morphologies, and for transformations involving color and star formation indicators. The transformation rates are systematically about twice as high in the groups as outside, or up to three to four times higher correcting for infall and the appearance of new groups. The rates reach values as high as 0.3-0.7 Gyr^(–1) in the groups (for masses around the crossing mass 10^(10.5) M_⊙), implying transformation timescales of 1.4-3 Gyr, compared with less than 0.2 Gyr^(–1), i.e., timescales >5 Gyr, outside of groups. All three transformation rates decrease at higher stellar masses, and must also decrease at lower masses below 10^(10) M _⊙ which we cannot probe well. The rates involving color and star formation are consistently higher than those for morphology, by a factor of about 50%. Our conclusion is that the transformations that drive the evolution of the overall galaxy population since z ~ 1 must occur at a rate two to four times higher in groups than outside of them

    Block diagonalization of nearly diagonal matrices

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    In this paper we study the effect of block diagonalization of a nearly diagonal matrix by iterating the related Riccati equations. We show that the iteration is fast, if a matrix is diagonally dominant or scaled diagonally dominant and the block partition follows an appropriately defined spectral gap. We also show that both kinds of diagonal dominance are not destroyed after the block diagonalization

    Block diagonalization of nearly diagonal matrices

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    In this paper we study the effect of block diagonalization of a nearly diagonal matrix by iterating the related Riccati equations. We show that the iteration is fast, if a matrix is diagonally dominant or scaled diagonally dominant and the block partition follows an appropriately defined spectral gap. We also show that both kinds of diagonal dominance are not destroyed after the block diagonalization

    A blind H i survey in the Canes Venatici region

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    We have carried out a blind H i survey using the Westerbork Synthesis Radio Telescope to make an inventory of objects with small H i masses (between 106 and 108 M⊙) and to constrain the low-mass end of the H i mass function. The survey has been conducted in a part of the volume containing the nearby Canes Venatici groups of galaxies. The surveyed region covers an area on the sky of about 86 deg2 and a range in velocity from about −450 to about 1330 km s−1. We find 70 sources in the survey by applying an automated searching algorithm. Two of the detections have not been catalogued previously, but they can be assigned an optical counterpart, based on visual inspection of the second-generation Digital Sky Survey images. Only one of the H i detections is without an optical counterpart. This object is detected in the vicinity of NGC 4822, and it has been already detected in previous H i studies. 19 of the objects have been detected for the first time in the 21-cm emission line in this survey. The distribution of the H i properties of our detections confirms our ability to find low-mass objects. 86 per cent of the detections have profile widths less than 130 km s−1, and they can be considered dwarf galaxy candidates. The H i fluxes measured imply that this survey goes about 10 times deeper than any previous blind H i survey. The H i mass function and the optical properties of the detected sources will be discussed in future paper

    Book Reviews

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    Crtomtr Nučić: Oris razvoja kemije v starom veku (S. Miholić) Gmelins Handbuch der anorganischen Chemie: Calcium (V. J. Kovač) Gmelins Handbuch der anorganischen Chemie: Kupfer (V. J . Kovač) Gmelins Handbuch der anorganischen Chemie: Systematik der Sachverhalte (V. J. Kovač) Prace Konferencji Polarograftcznej w Warszawie 1956 (I. Filipović) K. Weber: Optičke metode u kemiji i farmaciji (K. Schulz

    Book Reviews

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    Crtomtr Nučić: Oris razvoja kemije v starom veku (S. Miholić) Gmelins Handbuch der anorganischen Chemie: Calcium (V. J. Kovač) Gmelins Handbuch der anorganischen Chemie: Kupfer (V. J . Kovač) Gmelins Handbuch der anorganischen Chemie: Systematik der Sachverhalte (V. J. Kovač) Prace Konferencji Polarograftcznej w Warszawie 1956 (I. Filipović) K. Weber: Optičke metode u kemiji i farmaciji (K. Schulz

    Characterization of the distribution of the Lly\alpha emitters in the 53W002 field at z = 2.4

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    We present the results of our wide-field narrow band imaging of the field around the radio galaxy 53W002 at z = 2.390 with Subaru/Suprime-Cam. A custom made filter NB413 centered at 4140 \AA\ with the width of 83 \AA\ is used to observe the 31' x 24' area around the radio galaxy. We detected 204 Ly\alpha emitters (LAEs) at z = 2.4 with a rest frame equivalent width larger than 25 \AA\ to the depth of 26 AB mag (in NB413). The entire LAE population in the 53W002 field has an average number density and distributions of equivalent width and size that are similar to those of other fields at z ~ 2. We identify a significant high density region (53W002F-HDR) that spreads over ~ 5' x 4' near 53W002 where the LAE number density is nearly four times as large as the average of the entire field. Using the probability distribution function of density fluctuation, we evaluate the rareness probability of the 53W002F-HDR to be 0.9^{+2.4}_{-0.62}%, which corresponds to a moderately rich structure. No notable environmental dependency at the comoving scale of 10 Mpc is found for the distributions of the Ly\alpha equivalent width and luminosity in the field. We also detected 4 Ly\alpha blobs (LABs), one of which is newly discovered. They are all found to be located in the rims of high density regions. The biased location and unique morphologies in Ly\alpha suggest that galaxy interaction play a key role in their formation.Comment: 26 pages, 12 figure

    The Impact of Delay: Evidence from Formal Out-of-Court Restructuring

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    Bankruptcy restructuring procedures are used in most legal systems to decide the fate of businesses facing financial hardship. We study how bargaining failures in such procedures impact the economic performance of participating firms in the context of Croatia, which introduced a "pre-bankruptcy settlement" (PBS) process in the wake of the Great Recession of 2007 - 2009. Local institutions left over from the communist era provide annual financial statements for both sides of more than 180,000 debtor-creditor pairs, enabling us to address selection into failed negotiations by matching a rich set of creditor and debtor characteristics. Failures to settle at the PBS stage due to idiosyncratic bargaining problems, which effectively delays entry into the standard bankruptcy procedure, leads to a lower rate of survival among debtors as well as reduced employment, revenue, and profits. We also track how bargaining failures diffuse through the network of creditors, finding a significant negative effect on small creditors, but not others. Our results highlight the impact of delay and the importance of structuring bankruptcy procedures to rapidly resolve uncertainty about firms' future prospects

    Book Reviews

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    J. Van Alphen: Rubber Chemicals (P. Mildner) E. H. Rodd: Chemistry of Carbon Compounds. Vol. III B (K. Balenović) F. Feigel: Spot Tests in Organic Analysis (K. Balenović) F. R. Eirich: RheoLogy - Theory and Applications (J. Kratohvil) Gmelins Handbuch der anorganischen Chemie: Calcium (V. J. Kovač) Gmelins Handbuch der anorganischen Chemie: Platin (V. J. Kovač) W. I. Perelman: Taschenbuch der Chemie (K. Weber) H. Herold: Antibiotika (V. Johanides
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