Discovery of a high-redshift Einstein ring

We report the discovery of a partial Einstein ring of radius 1.48arcsec produced by a massive (and seemingly isolated) elliptical galaxy. The spectroscopic follow-up at the VLT reveals a 2L* galaxy at z=0.986, which is lensing a post-starburst galaxy at z=3.773. This unique configuration yields a very precise measure of the mass of the lens within the Einstein radius, (8.3e11 +- 0.4)/h70 Msolar. The fundamental plane relation indicates an evolution rate of d [log (M/L)B] / dz = -0.57+-0.04, similar to other massive ellipticals at this redshift. The source galaxy shows strong interstellar absorption lines indicative of large gas-phase metallicities, with fading stellar populations after a burst. Higher resolution spectra and imaging will allow the detailed study of an unbiased representative of the galaxy population when the universe was just 12% of its current age.Comment: 5 pages, 3 figures, accepted in A&A Le

Optical/Near-Infrared Observations of GRO J1744-28

We present results from a series of optical (g and r-band) and near-infrared (K'-band) observations of the region of the sky including the entire XTE and ROSAT error circles for the ``Bursting Pulsar'' GRO J1744-28. These data were taken with the Astrophysical Research Consortium's 3.5-m telescope at Apache Point Observatory and with the 2.2-m telescope at the European Southern Observatory. We see no new object, nor any significant brightening of any known object, in these error circles, with the exception of an object detected in our 8 February 1996 image. This object has already been proposed as a near-infrared counterpart to GRO J1744-28. While it is seen in only two of our ten 8 February frames, there is no evidence that this is an instrumental artifact, suggesting the possibility of near-infrared flares from GRO J1744-28, similar to those that have been reported from the Rapid Burster. The distance to the ``Bursting Pulsar'' must be more than 2 kpc, and we suggest that it is more than 7 kpc.Comment: 21 pages, 5 JPEG plates, 2 postscript figures. This paper will appear in the May 1, 1997 edition of the Astrophysical Journa

PHotometry Assisted Spectral Extraction (PHASE) and identification of SNLS supernovae

Aim: We present new extraction and identification techniques for supernova (SN) spectra developed within the Supernova Legacy Survey (SNLS) collaboration. Method: The new spectral extraction method takes full advantage of photometric information from the Canada-France-Hawai telescope (CFHT) discovery and reference images by tracing the exact position of the supernova and the host signals on the spectrogram. When present, the host spatial profile is measured on deep multi-band reference images and is used to model the host contribution to the full (supernova + host) signal. The supernova is modelled as a Gaussian function of width equal to the seeing. A chi-square minimisation provides the flux of each component in each pixel of the 2D spectrogram. For a host-supernova separation greater than <~ 1 pixel, the two components are recovered separately and we do not use a spectral template in contrast to more standard analyses. This new procedure permits a clean extraction of the supernova separately from the host in about 70% of the 3rd year ESO/VLT spectra of the SNLS. A new supernova identification method is also proposed. It uses the SALT2 spectrophotometric template to combine the photometric and spectral data. A galaxy template is allowed for spectra for which a separate extraction of the supernova and the host was not possible. Result: These new techniques have been tested against more standard extraction and identification procedures. They permit a secure type and redshift determination in about 80% of cases. The present paper illustrates their performances on a few sample spectra.Comment: 27 pages, 18 Figures, 1 Table. Accepted for publication in A&

Two superluminous supernovae from the early universe discovered by the Supernova Legacy Survey

We present spectra and lightcurves of SNLS 06D4eu and SNLS 07D2bv, two hydrogen-free superluminous supernovae discovered by the Supernova Legacy Survey. At z = 1.588, SNLS 06D4eu is the highest redshift superluminous SN with a spectrum, at M_U = -22.7 is one of the most luminous SNe ever observed, and gives a rare glimpse into the restframe ultraviolet where these supernovae put out their peak energy. SNLS 07D2bv does not have a host galaxy redshift, but based on the supernova spectrum, we estimate it to be at z ~ 1.5. Both supernovae have similar observer-frame griz lightcurves, which map to restframe lightcurves in the U-band and UV, rising in ~ 20 restframe days or longer, and declining over a similar timescale. The lightcurves peak in the shortest wavelengths first, consistent with an expanding blackbody starting near 15,000 K and steadily declining in temperature. We compare the spectra to theoretical models, and identify lines of C II, C III, Fe III, and Mg II in the spectrum of SNLS 06D4eu and SCP 06F6, and find that they are consistent with an expanding explosion of only a few solar masses of carbon, oxygen, and other trace metals. Thus the progenitors appear to be related to those suspected for SNe Ic. A high kinetic energy, 10^52 ergs, is also favored. Normal mechanisms of powering core- collapse or thermonuclear supernovae do not seem to work for these supernovae. We consider models powered by 56Ni decay and interaction with circumstellar material, but find that the creation and spin-down of a magnetar with a period of 2ms, magnetic field of 2 x 10^14 Gauss, and a 3 solar mass progenitor provides the best fit to the data.Comment: ApJ, accepted, 43 pages, 15 figure

The properties of the brightest Lyα emitters at z ∼ 5.7

We use deep Very Large Telescope (VLT) optical and near-infrared spectroscopy and deep Spitzer/IRAC imaging to examine the properties of two of the most luminous Lyα emitters at z= 5.7. The continuum redward of the Lyα line is clearly detected in both objects, thus facilitating a relatively accurate measurement (10-20 per cent uncertainties) of the observed rest-frame equivalent widths, which are around 160 Å for both objects. Through detailed modelling of the profile of the Lyα line with a 3D Monte Carlo radiative transfer code, we estimate the intrinsic rest-frame equivalent width of Lyα and find values that are around 300 Å, which is at the upper end of the range allowed for very young, moderately metal-poor star-forming galaxies. However, the uncertainties are large and values as high as 700 Å are permitted by the data. Both Lyα emitters are detected at 3.6 m in deep images taken with the Spitzer Space Telescope. We use these measurements, the measurement of the continuum redward of Lyα and other photometry to constrain the spectral energy distributions of these very luminous Lyα emitters and to compare them with three similar Lyα emitters from the literature. The contribution from nebular emission is included in our models: excluding it results in significantly higher masses. Four of the five Lyα emitters have masses of the order of ∼109 M⊙ and fairly high specific star formation rates (≳10-100 Gyr−1). While our two Lyα emitters appear similar in terms of the observed Lyα rest-frame equivalent width, they are quite distinct from each other in terms of age, mass and star formation history. Evidence for dust is found in all objects, and emission from nebular lines often makes a dominant contribution to the rest-frame 3.6 m flux. Rich in emission lines, these objects are prime targets for the next generation of extremely large telescopes, the James Webb Space Telescope (JWST) and the Atacama Large Millimeter Array (ALMA

Simulations of the OzDES AGN Reverberation Mapping Project

As part of the OzDES spectroscopic survey we are carrying out a large scale reverberation mapping study of $\sim$500 quasars over five years in the 30 deg$^2$ area of the Dark Energy Survey (DES) supernova fields. These quasars have redshifts ranging up to 4 and have apparent AB magnitudes between $16.8<r<22.5$ mag. The aim of the survey is to measure time lags between fluctuations in the quasar continuum and broad emission line fluxes of individual objects in order to measure black hole masses for a broad range of AGN and constrain the radius-luminosity ($R-L$) relationship. Here we investigate the expected efficiency of the OzDES reverberation mapping campaign and its possible extensions. We expect to recover lags for $\sim$35-45\% of the quasars. AGN with shorter lags and greater variability are more likely to yield a lag, and objects with lags $\lesssim$6 months or $\sim$1 year are expected be recovered the most accurately. The baseline OzDES reverberation mapping campaign is predicted to produce an unbiased measurement of the $R-L$ relationship parameters for H$\beta$, Mg II $\lambda$2798, and C IV $\lambda$1549. However, extending the baseline survey by either increasing the spectroscopic cadence, extending the survey season, or improving the emission line flux measurement accuracy will significantly improve the $R-L$ parameter constraints for all broad emission lines.Comment: Published online in MNRAS. 28 page

Ground-based follow-up observations of TRAPPIST-1 transits in the near-infrared

The TRAPPIST-1 planetary system is a favorable target for the atmospheric characterization of temperate earth-sized exoplanets by means of transmission spectroscopy with the forthcoming James Webb Space Telescope (JWST). A possible obstacle to this technique could come from the photospheric heterogeneity of the host star that could affect planetary signatures in the transit transmission spectra. To constrain further this possibility, we gathered an extensive photometric data set of 25 TRAPPIST-1 transits observed in the near-IR J band (1.2 $\mu$m) with the UKIRT and the AAT, and in the NB2090 band (2.1 $\mu$m) with the VLT during the period 2015-2018. In our analysis of these data, we used a special strategy aiming to ensure uniformity in our measurements and robustness in our conclusions. We reach a photometric precision of $\sim0.003$ (RMS of the residuals), and we detect no significant temporal variations of transit depths of TRAPPIST-1 b, c, e, and g over the period of three years. The few transit depths measured for planets d and f hint towards some level of variability, but more measurements will be required for confirmation. Our depth measurements for planets b and c disagree with the stellar contamination spectra originating from the possible existence of bright spots of temperature 4500 K. We report updated transmission spectra for the six inner planets of the system which are globally flat for planets b and g and some structures are seen for planets c, d, e, and f.Comment: accepted for publication in MNRA

An Optical Time-Delay for the Lensed BAL Quasar HE2149-2745

We present optical V and i-band light curves of the gravitationally lensed BAL quasar HE2149-2745. The data, obtained with the 1.5m Danish Telescope (ESO-La Silla) between October 1998 and December 2000, are the first from a long-term project aimed at monitoring selected lensed quasars in the Southern Hemisphere. A time delay of 103+/-12 days is determined from the light curves. In addition, VLT/FORS1 spectra of HE2149-2745 are deconvolved in order to obtain the spectrum of the faint lensing galaxy, free of any contamination by the bright nearby two quasar images. By cross-correlating the spectrum with galaxy-templates we obtain a tentative redshift estimate of z=0.495+/-0.01. Adopting this redshift, a Omega=0.3, Lambda=0.7 cosmology, and a chosen analytical lens model, our time-delay measurement yields a Hubble constant of H_0=66+/-8 km/s/Mpc with an estimated systematic error of +/-3 km/s/Mpc. Using non-parametric models yields H_0=65+/-8 km/s/Mpc and confirms that the lens exhibits a very dense/concentrated mass profile.Comment: 11 pages, accepted for publication in Astronomy & Astrophysic

Are transnational tobacco companies' market access strategies linked to economic development models? A case study of South Korea.

Transnational tobacco companies (TTCs) have used varied strategies to access previously closed markets. Using TTCs' efforts to enter the South Korean market from the late 1980s as a case study, this article asks whether there are common patterns in these strategies that relate to the broader economic development models adopted by targeted countries. An analytical review of the existing literature on TTCs' efforts to access emerging markets was conducted to develop hypotheses relating TTCs' strategies to countries' economic development models. A case study of Korea was then undertaken based on analysis of internal tobacco industry documents. Findings were consistent with the hypothesis that TTCs' strategies in Korea were linked to Korea's export-oriented economic development model and its hostile attitude towards foreign investment. A fuller understanding of TTCs' strategies for expansion globally can be derived by locating them within the economic development models of specific countries or regions. Of foremost importance is the need for governments to carefully balance economic and public health policies when considering liberalisation