A Deep Search for Host Galaxies of GRBs with no Detected Optical Afterglow

Context. Gamma-ray bursts (GRBs) can provide information about star formation at high redshifts. Even in the absence of a bright optical/near-infrared/radio afterglow, the high detection rate of X-ray afterglows by Swift/XRT and its localization precision of 2–3 arcsec facilitates the identification and the study of GRB host galaxies. Aims. We focus on the search for the host galaxies of 17 bursts with arcsec-sized XRT error circles but no detected long-wavelength afterglow, in spite of their deep and rapid follow-up observations. Three of these events can also be classified as truly dark bursts, i.e., the observed upper limit on the optical flux of the afterglow was less than expected based on the measured X-ray flux. Our goals are to identify the GRB host galaxy candidates and characterize their phenomenological parameters. Methods. Our study is based on deep RC and Ks-band observations performed with FORS1, FORS2, VIMOS, ISAAC, and HAWK-I at the ESO/VLT, partly supported by observations with the seven-channel imager GROND at the 2.2-m telescope on La Silla, and supplemented by observations with NEWFIRM at the 4-m telescope on Kitt Peak. To be conservative, we searched for host galaxy candidates within an area of twice the radius of each associated 90% c.l. Swift/XRT error circle. Results. For 15 of the 17 bursts, we find at least one galaxy within the searching area, and in the remaining two cases only a deep upper limit to RC and Ks can be provided. In seven cases, we discover extremely red objects in the error circles, at least four of which might be dust-enshrouded galaxies. The most remarkable case is the host of GRB 080207, which has a color of (RC −Ks)AB ∼4.7 mag, and is one of the reddest galaxies ever associated with a GRB. As a by-product of our study we identify the optical afterglow of GRB 070517. Conclusions. Only a minority of optically dim afterglows are due to Lyman dropout ( \u3c 1/3). Extinction by dust in the host galaxies might explain all other events. Thereby, a seemingly non-negligible fraction of these hosts are globally dust-enshrouded, extremely red galaxies. This suggests that at least a fraction of GRB afterglows trace a subpopulation of massive starburst galaxies, which are markedly different from the main body of the GRB host galaxy population, namely the blue, subluminous, compact galaxies

The South Asian Association of Regional Cooperation:problems and prospects

Regionalism has been an important force in international relations since 1945. Most regional organizations that came into existence after the end of the Second World War dealt primarily with defence and security issues. With the passage of time, however, regional trading blocs have considerably gained in importance. The aim of this article is to look at the only regional organization in South Asia, the South Asian Association for Regional Cooperation (SAARC). The article argues that regionalism in contemporary South Asia has been problematic right from the start because South Asia has been plagued with ongoing conflicts both at the interstate level and at the domestic level. The main interstate conflict in South Asia has been the Kashmir conflict between India and Pakistan, the two dominant forces in the region. Internal problems within India include the Maoist insurgency and secessionist movements in the Indian northeast. Pakistan has also struggled with major internal problems such as Islamist terrorism. Since these countries have been giving their time and attention to their internal problems, developing a unified approach to deal with regional problems and also a collective sense of identity has proven to be very problematic. These internal problems within the national boundaries of each of these South Asian countries and the interstate conflicts in the region especially between India and Pakistan have most certainly undermined regionalism in the past in South Asia, and continue to do so. Finally, the article takes a security studies approach whilst making an assessment of the SAARC

The effect of multilingualism/multiculturalism on personality: no gain without pain for third culture kids?

The present study investigates the link between multilingualism/multiculturalism, acculturation and the personality profile (as measured by the Multicultural Personality Questionnaire) of 79 young London teenagers, half of whom were born abroad and had settled down in London during their childhood 'Third Culture Kids' (TCKs; Pollock & Van Reken, 2001). Statistical analyses revealed that TCKs scored higher on the dimension of Openmindedness and Cultural Empathy and scored lower on Emotional Stability. Language dominance (first language (L1), L1 and one or two other languages (multidominance), or any language which is not the L1 (LX) had a significant effect on the participants' personality profile, with the multidominant group scoring significantly higher on Openmindedness, marginally higher on Cultural Empathy and significantly lower on Emotional Stability than participants dominant in one language only. The number of languages known by participants was also significantly linked to their personality profile, with functional multilinguals scoring significantly higher than incipient bilinguals on Openmindedness, marginally higher on Cultural Empathy and significantly lower on Emotional Stability. These findings confirm that personality is shaped by social and biographical factors. Acculturation is stressful but the experience of having to fit in and being in contact with different languages and cultures strengthens Cultural Empathy and Openmindedness. Adapted from the source documen