Redshift estimate of a gravitational lens from the observed reddening of a multiply imaged quasar

Light rays from a multiply imaged quasar usually sample different path lengths across the deflector. Extinction in the lensing galaxy may thus lead to a differential obscuration and reddening between the observed macro-lensed QSO images. These effects naturally depend on the precise shape of the extinction law and on the redshift of the lens. By means of numerical Monte-Carlo simulations, using a least-squares fitting method and assuming an extinction law similar to that observed in the Galaxy, we show how accurate photometric observations of multiply imaged quasars obtained in several spectral bands could lead to the estimate of the lens redshift, irrespective of the visibility of the deflector. Observational requirements necessary to apply this method to real cases are thoroughly discussed. If extinction laws turn out to be too different from galaxy to galaxy, we find out that more promising observations should consist in getting high signal-to-noise low resolution spectra of at least three distinct images of a lensed quasar, over a spectral range as wide as possible, from which it should be straightforward to extract the precise shape of the redshifted extinction law. Very high signal-to-noise, low spectral resolution, VLT observations of H1413+117 and MG 0414+0534 should enable one to derive such a redshifted extinction law.Comment: 7 pages, 11 figures, to appear in Astronomy and Astrophysics (also available at http://vela.astro.ulg.ac.be/preprint/

The GL bibliography and an interactive database

It is now possible to directly access, via the Internet, a bibliographical database on Gravitational Lensing (GL) literature. The Interactive Gravitational Lensing Bibliography (IGLB) totalizes more than 2400 titles of published articles in scientific journals and meeting proceedings (except those fully dedicated to Gravitational Lenses) as well as papers submitted to the e-Print archive. This database is a product from the Gravitational Lensing Bibliography first presented in 1993 (Proceedings of the 31st Liege International Astrophysical Colloquium). It is easy to do field based searches for title keywords, authors (using boolean operators), year and journal (a pull-down list of the most cited journals is available). Access to the original version of published articles as well as to preprints submitted to the e-Print archive at the URL address http://xxx.lanl.gov/ is also provided. This database is updated approximately every two months. The "complete" bibliography of published articles is also available in the form of Latex and PostScript files. The IGLB can be accessed at the URL: http://vela.astro.ulg.ac.be/grav_lensComment: 2 pages, 2 figures, uses paspconf.sty. Poster contribution to "Gravitational Lensing: Recent Progress and Future Goals", Boston University 1999, eds. T. G. Brainerd and C. S. Kochane

Search for gravitational lens candidates in the XMM-LSS/CFHTLS common field

Our aim was to identify gravitational lens candidates among some 5500 optical counterparts of the X-ray point-like sources in the medium-deep ~11 sq. deg. XMM-LSS survey. We have visually inspected the optical counterparts of each QSOs/AGN using CFHTLS T006 images. We have selected compact pairs and groups of sources which could be multiply imaged QSO/AGN. We have measured the colors and characterized the morphological types of the selected sources using the multiple PSF fitting technique. We found three good gravitational lens candidates: J021511.4-034306, J022234.3-031616 and J022607.0-040301 which consist of pairs of point-like sources having similar colors. On the basis of a color-color diagram and X-ray properties we could verify that all these sources are good QSO/AGN candidates rather than stars. Additional secondary gravitational lens candidates are also reported.Comment: 6 pages, 3 figures, 1 table, Accepted for publication in MNRA

Multilateralism and international organisations: principles and instruments

Artykuł analizuje uzasadnienie dla globalnych polityk publicznych i rolę organizacji międzynarodowych w ich projektowaniu, wdrażaniu i ewaluacji. Opracowanie wskazuje na rosnące globalne współzależności i pokazuje użyteczność pojęcia globalnych dóbr publicznych w identyfikacji obszarów potencjalnej współpracy. Następnie, pokazana jest specyfika globalnych działań zbiorowych, które są niezbędne dla rozwiązania globalnych problemów. Multilateralizm jawi się jako zasada przewodnia dla zorientowanych na globalne problemy publiczne działań zbiorowych. W konkluzjach opracowanie wskazuje na rolę organizacji międzynarodowych w stabilizowaniu globalnych działań zbiorowych w ich wielu, różnorodnych postaciach.The article discusses the rationale for global public policies and the role of international organisations in their designing, implementation and evaluation. It commences with the recognition of the growing global interdependencies and the usefulness of the concept of global public goods in identifying the areas of common problems. Then, it points to the need for global collective actions to solve global problems and sees multilateralism as a principle helping to guide global collective actions. Subsequently, international organisations are discussed as agents serving to stabilise global collective actions in their multiple, and differentiated forms

2MASS Reveals a Large Intrinsic Fraction of BALQSOs

The intrinsic fraction of broad absorption line quasars (BALQSOs) is important in constraining geometric and evolutionary models of quasars. We present the fraction of BALQSOs in 2MASS detected quasars within the SDSS DR3 sample in the redshift range of 1.7 < z < 4.38. The fraction of BALQSOs is 40.4^{+3.4}_{-3.3}% in the 2MASS 99% database K_s band completeness sample, and 38.5^{+1.7}_{-1.7}% in the larger 2MASS sample extending below the completeness limit. These fractions are significantly higher than the 26% reported in the optical bands for the same parent sample. We also present the fraction of BALQSOs as functions of apparent magnitudes, absolute magnitudes, and redshift in the 2MASS and SDSS bands. The 2MASS fractions are consistently higher than the SDSS fractions in every comparison, and the BALQSO fractions steadily increase with wavelength from the SDSS u to the 2MASS K_s bands. Furthermore, the i - K_s color distributions of BALQSOs and non-BALQSOs indicate that BALQSOs are redder than non-BALQSOs, with a K-S test probability of 2e-12. These results are consistent with the spectral difference between BALQSOs and non-BALQSOs including both the absorption troughs and dust extinction in BALQSOs, which leads to significant selection biases against BALQSOs in the optical bands. Using a simple simulation incorporating the luminosity function of quasars and the amount of obscuration for BALQSOs, we simultaneously fit the BALQSO fractions in the SDSS and 2MASS bands. We obtain a true BALQSO fraction of 43\pm2% for luminous quasars (M_{K_s} \lesssim -30.1 mag).Comment: 20 pages, 6 figures, accepted by Ap

Succession planning in Polish family business. An exploratory investigation (chapter 4)

The main aim of the paper is to identify the succession strategies (especially the ways in which they attempt to balance the strive to maintain family’s control over the company with the goal of firm’s growth) of the first generation of Polish entrepreneurs. Research survey was conducted on a random sample of 496 family enterprises in first quarter of 2009 (first phase, survey) and 61 family enterprises in third quarter of 2009 (second phase, in-depth-interview). Research project “Succession Scenarios in First Generation of Polish Entrepreneurs” was conducted in the years 2008-2010 by Aleksander Surdej and Krzysztof Wach was financed by Polish Ministry of Science and Higher Education (Project no. 1326/B/H03/2008/34).family firms, succession, Poland, family entrepreneurship

Succession scenarios in Polish family firms. Empirical Study (Chapter 8)

The paper elaborates on succession planning among Polish family businesses. Research survey was conducted on a random sample of 496 family enterprises in first quarter of 2009 (first phase, survey) and 61 family enterprises in third quarter of 2009 (second phase, in-depth-interview). The main aim of the paper is to identify the succession strategies (especially the ways in which they attempt to balance the strive to maintain family’s control over the company with the goal of firm’s growth) of the first generation of Polish entrepreneurs.family businesses, family entrepreneurship, succession planning