ILLUMINATING THE DARKEST GAMMA-RAY BURSTS WITH RADIO OBSERVATIONS

We present X-ray, optical, near-infrared (IR), and radio observations of gamma-ray bursts (GRBs) 110709B and 111215A, as well as optical and near-IR observations of their host galaxies. The combination of X-ray detections and deep optical/near-IR limits establish both bursts as "dark." Sub-arcsecond positions enabled by radio detections lead to robust host galaxy associations, with optical detections that indicate z ≾ 4 (110709B) and z ≈ 1.8-2.9 (111215A). We therefore conclude that both bursts are dark due to substantial rest-frame extinction. Using the radio and X-ray data for each burst we find that GRB 110709B requires A_V^(host) ≳ 5.3 mag and GRB 111215A requires A_V^(host) ≳ 8.5 mag (assuming z = 2). These are among the largest extinction values inferred for dark bursts to date. The two bursts also exhibit large neutral hydrogen column densities of N H, int ≳ 10^(22) cm^(–2) (z = 2) as inferred from their X-ray spectra, in agreement with the trend for dark GRBs. Moreover, the inferred values are in agreement with the Galactic A_V -N_H relation, unlike the bulk of the GRB population. Finally, we find that for both bursts the afterglow emission is best explained by a collimated outflow with a total beaming-corrected energy of E_γ + E_K ≈ (7-9) × 10^(51) erg (z = 2) expanding into a wind medium with a high density, Ṁ ≈ (6-20) x 10^(-5) M_☉ yr^(–1) (n ≈ 100-350 cm^(–3) at ≈ 10^(17) cm). While the energy release is typical of long GRBs, the inferred density may be indicative of larger mass-loss rates for GRB progenitors in dusty (and hence metal rich) environments. This study establishes the critical role of radio observations in demonstrating the origin and properties of dark GRBs. Observations with the JVLA and ALMA will provide a sample with sub-arcsecond positions and robust host associations that will help to shed light on obscured star formation and the role of metallicity in GRB progenitors

Search for dark matter produced in association with a hadronically decaying vector boson in pp collisions at sqrt (s) = 13 TeV with the ATLAS detector

A search is presented for dark matter produced in association with a hadronically decaying W or Z boson using 3.2 fb−1 of pp collisions at View the MathML sources=13 TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet compatible with a W or Z boson and with large missing transverse momentum are analysed. The data are consistent with the Standard Model predictions and are interpreted in terms of both an effective field theory and a simplified model containing dark matter

Being seen by others as we see ourselves: the congruence between the ingroup and outgroup perceptions of health and social care students

This paper examines inter-group processes amongst neophyte health and social care students about to embark on an inter-professional educational programme. Positive relationships between students of the different professions must be optimised to promote student learning of each other, a central objective of these courses. It has been proposed that to reduce conflict and promote harmonious inter-group relations during this IPE activity, students from each professional group should feel their own group (the in-group) to be distinctive from other professional groups (the out-group) on some key characteristics (intergroup differentiation). Good relations are further promoted if the characteristics they see as distinctive to their identities are also recognised as distinctive by other professional groups (mutual inter-group differentiation). The current paper considers the incidence of these two factors in neophyte health and social care students and identifies sources of potential inter-group conflict. The findings of the study suggest that all groups of neophyte health and social care students perceived their in-group as distinct from other professional groups with the exception of audiology students. The implications of this finding to the relationships between students participating in IPE are discussed. Further, in certain groups, there was evidence that students of these groups were seen by others as they saw themselves. This was particularly the case for doctors and social workers and implies these professions will suffer least from a threat to their group distinctiveness. However, there were instances where characteristics, seen as distinctive by the professional group itself, were not recognised by other groups. For example, physiotherapy students believe that being a team player, decision making and practical skills were all distinctive characteristics of their profession. However, these features were not recognised as distinctive by other professional groups. The implications of matches/mismatches in how students see themselves and how they may be viewed by others are discussed in terms of their impact on student learning experiences and relationships during inter-professional education.<br/