GRB 051008: A long, spectrally hard dust-obscured GRB in a lyman-break galaxy at z ≈ 2.8*

We present observations of the dark gamma-ray burst GRB 051008 provided by Swift/BAT, Swift/XRT, Konus-WIND, INTEGRAL/SPI-ACS in the high-energy domain and the Shajn, Swift/UVOT, Tautenburg, NOT, Gemini and Keck I telescopes in the optical and near-infrared bands. The burst was detected only in gamma- and X-rays and neither a prompt optical nor a radio afterglow was detected down to deep limits. We identified the host galaxy of the burst, which is a typical Lyman-break galaxy (LBG) with R-magnitude of 24.06 ± 0.10 mag. A redshift of the galaxy of z = 2.77+0.15-0.20 is measured photometrically due to the presence of a clear, strong Lyman-break feature. The host galaxy is a small starburst galaxy with moderate intrinsic extinction (AV = 0.3) and has a star formation rate of ~60M( yr-1 typical for LBGs. It is one of the few cases where a GRB host has been found to be a classical LBG. Using the redshift we estimate the isotropic-equivalent radiated energy of the burst to be Eiso = (1.15 ± 0.20) × 1054 erg.We also provide evidence in favour of the hypothesis that the darkness ofGRB051008 is due to local absorption resulting from a dense circumburst medium © 2014 The Authors

The Spectral Evolution of the First Galaxies. III. Simulated James Webb Space Telescope Spectra of Reionization-epoch Galaxies with Lyman-continuum Leakage

Using four different suites of cosmological simulations, we generate synthetic spectra for galaxies with different Lyman continuum escape fractions (fesc) at redshifts z=7-9, in the rest-frame wavelength range relevant for the James Webb Space Telescope (JWST) NIRSpec instrument. By investigating the effects of realistic star formation histories and metallicity distributions on the EW(Hb)-beta diagram (previously proposed as a tool for identifying galaxies with very high fesc), we find that neither of these effects are likely to jeopardize the identification of galaxies with extreme Lyman continuum leakage. Based on our models, we expect essentially all z=7-9 galaxies that exhibit rest-frame EW(Hb)0.5. Incorrect assumptions concerning the ionizing fluxes of stellar populations or the dust properties of z>6 galaxies can in principle bias the selection, but substantial model deficiencies of this type will at the same time reveal themselves as an offset between the observed and simulated distribution of z>6 galaxies in the EW(Hb)-beta diagram. Such offsets would thereby allow JWST/NIRSpec measurements of these observables to serve as input for further model refinement.Comment: 12 pages, 8 figures, v.2: ApJ, accepted. Model grids are available from http://www.astro.uu.se/~ez/lycan/lycan.htm

Monotonicity of optimal policies in a zero sum game: a flow control model

The purpose of this paper is to illustrate how value iteration can be used in a zero-sum game to obtain structural results on the optimal (equilibrium) value and policy. This is done through the following example. We consider the problem of dynamic flow control of arriving customers into a finite buffer. The service rate may depend on the state of the system, may change in time and is unknown to the controller. The goal of the controller is to design a policy that guarantees the best performance under the worst case service conditions. The cost is composed of a holding cost, a cost for rejecting customers and a cost that depends on the quality of the service. We consider both discounted and expected average cost. The problem is studied in the framework of zero-sum Markov games where the server, called player 1, is assumed to play against the flow controller, called player 2. Each player is assumed to have the information of all previous actions of both players as well as the current and past states of the system. We show that there exists an optimal policy for both players which is stationary (that does not depend on the time). A value iteration algorithm is used to obtain monotonicity properties of the optimal policies. For the case that only two actions are available to one of the players, we show that his optimal policy is of a threshold type, and optimal policies exist for both players that may need randomization in at most one state

A Waste of Space? Controversies Surrounding the Working-Class Parlour in Inter-War Britain

This article uncovers the fierce inter-war debate provoked by the British Government’s decision to remove state subsidies for building larger “parlour-type” houses in 1923. Examining the various defences that were put forward in support of the working-class parlour it argues that the parlour was seen as a key marker of respectability in working-class communities with the potential to shape the behaviours and outlook of its inhabitants. Drawing on a variety of contemporary and autobiographical sources it suggests that the occasional use of the parlour, a keystone of its opponents’ criticisms was precisely what gave most value to the room for its owners. Recent controversy over the bedroom tax in Britain suggests that “extra” space remains a contentious issue in subsidised homes today