A. Hempel

VELOCITY DISPERSIONS AND STELLAR POPULATIONS OF THE MOST COMPACT AND MASSIVE EARLY-TYPE GALAXIES AT REDSHIFT ∼1

We present Gran-Telescopio-Canarias/OSIRIS optical spectra of 4 of the most compact and massive early-type galaxies in the Groth Strip Survey at redshift z~1, with effective radii Reff=0.5-2.4 kpc and photometric stellar masses Mstar=1.2-4x10^11 Msun. We find these galaxies have velocity dispersions sigma=156-236 km/s. The spectra are well fitted by single stellar population models with approximately 1 Gyr of age and solar metallicity. We find that: i) the dynamical masses of these galaxies are systematically smaller by a factor of ~6 than the published stellar masses using BRIJK photometry; ii) when estimating stellar masses as 0.7xMdyn, a combination of passive luminosity fading with mass/size growth due to minor mergers can plausibly evolve our objects to match the properties of the local population of early-type galaxies.

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

This work is supported by the Swiss National Science Foundation (SNSF). S. H. Suyu and D. C. Y. Chao thank the Max Planck Society for support through the Max Planck Research Group for SHS. T. Treu acknowledges support by the National Science Foundation through grant 1450141, by the Packard Foundation through a Packard Research Fellowship and by the UCLA Dean of Physical Sciences. K. Rojas is supported by Becas de Doctorado Nacional CONICYT 2017. T. Anguita and M. Chijani acknowledge support by proyecto FONDECYT 11130630 and by the Ministry for the Economy, Development, and Tourism’s Programa Inicativa Cientifica Milenio through grant IC 12009, awarded to The Millennium Institute of Astrophysics (MAS). M. Tewes acknowledges support from the DFG grant Hi 1495/2-1. J. Garcia-Bellido is supported by the Research Project FPA2015-68048 [MINECO-FEDER], and the Centro de Excelencia Severo Ochoa Program SEV-2012-0249. C. D. Fassnacht acknowledges support from the National Science Foundation grant AST-1312329 and from the UC Davis Physics Department and Dean of Math and Physical Sciences. Funding for the DES Projects has been provided by the US Department of Energy, the US National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico and the Ministerio da Ciencia, Tecnologia e Inovacao, the Deutsche Forschungsgemeinschaft and the Collaborating Institutions in the Dark Energy Survey ... The DES data management system is supported by the National Science Foundation under Grant Number AST-1138766. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-88861, FPA2015-68048, SEV-2012-0234, SEV-2012-0249, and MDM-2015-0509, some of which include ERDF funds from the European Union. IFAE is partially funded by the CERCA programme of the Generalitat de Catalunya.

Evolutionary paths among different red galaxy types at 0.3 < z < 1.5 and the late buildup of massive E-S0s through major mergers

Some recent observations seem to disagree with hierarchical theories of galaxy formation about the role played by major mergers in the late buildup of massive E-S0s. We re-address this question by analysing the morphology, structural distortion level and star formation enhancement of a sample of massive galaxies (M_* > 5x10^10M_⨀) lying on the Red Sequence and its surroundings at 0.3 10^11 M_⨀ at z = 0 through gas-rich major mergers has frozen since z similar to 0.6. All these facts support that major mergers have played a dominant role in the definitive buildup of present-day E-S0s with M-* > 10(11) M-circle dot at 0.6 < z < 1.2, in good agreement with hierarchical scenarios of galaxy formation.

On the Period-Luminosity-Colour-Metallicity relation and the pulsational characteristics of λ Bootis type stars

Generally, chemical peculiarity found for stars on the upper main sequence excludes Scuti type pulsation (e.g. Ap and Am stars), but for the group of Bootis stars it is just the opposite. This makes them very interesting for asteroseismological investigations. The group of Bootis type stars comprises late B- to early F-type, Population I objects which are basically metal weak, in particular the Fe group elements, but with the clear exception of C, N, O and S. The present work is a continuation of the studies by Paunzen et al. (1997, 1998), who presented first results on the pulsational characteristics of the Bootis stars. Since then, we have observed 22 additional objects; we found eight new pulsators and confirmed another one. Furthermore, new spectroscopic data (Paunzen 2001) allowed us to sort out misidentified candidates and to add true members to the group. From 67 members of this group, only two are not photometrically investigated yet which makes our analysis highly representative. We have compared our results on the pulsational behaviour of the Bootis stars with those of a sample of Scuti type objects. We find that at least 70% of all Bootis type stars inside the classical instability strip pulsate, and they do so with high overtone modes (Q< 0.020 d). Only a few stars, if any, pulsate in the fundamental mode. Our photometric results are in excellent agreement with the spectroscopic work on high-degree nonradial pulsations by Bohlender et al. (1999). Compared to the Scuti stars, the cool and hot borders of the instability strip of the Bootis stars are shifted by about 25 mmag, towards smaller (b y)0. Using published abundances and the metallicity sensitive indices of the Geneva 7-colour and Stromgren uvby systems, we have derived (Z) values which describe the surface abundance of the heavier elements for the group members. We find that the Period- Luminosity-Colour relation for the group of Bootis stars is within the errors identical with that of the normal Scuti stars. No clear evidence for a statistically significant metallicity term was detected.

Evidence for negatively charged vacancy defects in 6H-SiC after low-energy proton implantation

We have used pulsed-slow-positron-beam-based positron lifetime spectroscopy to investigate the nature of acceptors and charge states of vacancy-type defects in low-energy proton-implanted 6H-SiC(H). We can infer from the temperature dependence of the lifetime spectra that neutral and negatively charged vacancy clusters exist in the track region. Depending on annealing, they give rise to positron lifetimes of 257±2, 281±4, and 345±2 ps, respectively. The 281 ps cluster likely has an ionization level near the middle of the band gap. By comparison with theory, the 257 and 280 ps are identified as (VC–VSi)2 and (VC–VSi)3 clusters, respectively. In addition, other acceptors of ionic type act as strong trapping centers at low temperature (T<150 K). Neutral monovacancy-like complexes are also detected with a lifetime of 160±2 after 900 °C annealing.

The VVV Templates Project Towards an automated classification of VVV light-curves - I. Building a database of stellar variability in the near-infrared

Context. The Vista Variables in the Via Lactea (VVV) ESO Public Survey is a variability survey of the Milky Way bulge and an adjacent section of the disk carried out from 2010 on ESO Visible and Infrared Survey Telescope for Astronomy (VISTA). The VVV survey will eventually deliver a deep near-IR atlas with photometry and positions in five passbands (ZY JHKS) and a catalogue of 1−10 million variable point sources – mostly unknown – that require classifications. Aims. The main goal of the VVV Templates Project, which we introduce in this work, is to develop and test the machine-learning algorithms for the automated classification of the VVV light-curves. As VVV is the first massive, multi-epoch survey of stellar variability in the near-IR, the template light-curves that are required for training the classification algorithms are not available. In the first paper of the series we describe the construction of this comprehensive database of infrared stellar variability. Methods. First, we performed a systematic search in the literature and public data archives; second, we coordinated a worldwide observational campaign; and third, we exploited the VVV variability database itself on (optically) well-known stars to gather high-quality infrared light-curves of several hundreds of variable stars. Results. We have now collected a significant (and still increasing) number of infrared template light-curves. This database will be used as a training-set for the machine-learning algorithms that will automatically classify the light-curves produced by VVV. The results of such an automated classification will be covered in forthcoming papers of the series.Context. The Vista Variables in the Via Lactea (VVV) ESO Public Survey is a variability survey of the Milky Way bulge and an adjacent section of the disk carried out from 2010 on ESO Visible and Infrared Survey Telescope for Astronomy (VISTA). The VVV survey will eventually deliver a deep near-IR atlas with photometry and positions in five passbands (ZYJHKS) and a catalogue of 1−10 million variable point sources – mostly unknown – that require classifications. Aims. The main goal of the VVV Templates Project, which we introduce in this work, is to develop and test the machine-learning algorithms for the automated classification of the VVV light-curves. As VVV is the first massive, multi-epoch survey of stellar variability in the near-IR, the template light-curves that are required for training the classification algorithms are not available. In the first paper of the series we describe the construction of this comprehensive database of infrared stellar variability. Methods. First, we performed a systematic search in the literature and public data archives; second, we coordinated a worldwide observational campaign; and third, we exploited the VVV variability database itself on (optically) well-known stars to gather high-quality infrared light-curves of several hundreds of variable stars. Results. We have now collected a significant (and still increasing) number of infrared template light-curves. This database will be used as a training-set for the machine-learning algorithms that will automatically classify the light-curves produced by VVV. The results of such an automated classification will be covered in forthcoming papers of the series.

Comparison of Sunyaev-Zel’dovich measurements from Planck and from the Arcminute Microkelvin Imager for 99 galaxy clusters

We present observations and analysis of a sample of 123 galaxy clusters from the 2013 Planck catalogue of Sunyaev-Zel’dovich sources with the Arcminute Microkelvin Imager (AMI), a ground-based radio interferometer. AMI provides an independent measurement with higher angular resolution, 3 arcmin compared to the Planck beams of 5–10 arcmin. The AMI observations thus provide validation of the cluster detections, improved positional estimates, and a consistency check on the fitted size (θs) and flux (Ytot) parameters in the generalised Navarro, Frenk and White (GNFW) model. We detect 99 of the clusters. We use the AMI positional estimates to check the positional estimates and error-bars produced by the Planck algorithms PowellSnakes and MMF3. We find that Ytot values as measured by AMI are biased downwards with respect to the Planck constraints, especially for high Planck-S/N clusters. We perform simulations to show that this can be explained by deviation from the universal pressure profile shape used to model the clusters. We show that AMI data can constrain the α and β parameters describing the shape of the profile in the GNFW model for individual clusters provided careful attention is paid to the degeneracies between parameters, but one requires information on a wider range of angular scales than are present in AMI data alone to correctly constrain all parameters simultaneously.

The rapidly oscillating Ap star HD 99563 and its distorted dipole pulsation mode

We undertook a time-series photometric multisite campaign for the rapidly oscillating Ap (roAp) star HD 99563 and also acquired mean light observations over four seasons. The pulsations of the star, which show flatter light maxima than minima, can be described with a frequency quintuplet centred on 1557.653 µHz and some first harmonics of it. The amplitude of the pulsation is modulated with the rotation period of the star that we determine with 2.91179 ± 0.00007 d from the analysis of the stellar pulsation spectrum and of the mean light data. We break up the distorted oscillation mode into its pure spherical harmonic components and find it is dominated by the � = 1 pulsation, and also has a notable � = 3 contribution, with weak � = 0 and 2 components. The geometrical configuration of the star allows us to see both pulsation poles for about the same amount of time; HD 99563 is only the fourth roAp star for which both pulsation poles are seen and only the third where the distortion of the pulsation modes has been modelled. We point out that HD 99563 is very similar to the well-studied roAp star HR 3831. Finally, we note that the visual companion of HD 99563 is located in the δ Scuti instability strip and may thus show pulsation. We show that if the companion was physical, the roAp star would be a 2.03-M� , object, seen at a rotational inclination of 44 ◦ , which then predicts a magnetic obliquity β = 86. ◦ 4.

Influence of growth temperature on the microcrystallinity and native defect structure of hydrogenated amorphous silicon

The microstructure of hydrogenated amorphous silicon grown by hot-wire chemical vapour deposition (HW-CVD) on glass substrates, at different substrate temperatures ranging from 300 to 500 °C, has been studied using X-ray diffraction and positron annihilation techniques. In previous studies it has been shown that recrystallization is accompanied by a relaxation of the defect structure with an increase in the free volume at the positron annihilation site. The object of this work is to relate the initial defect configuration to the degree of order in the structure, which has been characterized through its radial density function giving accurate estimates of the nearest-neighbour separation and bond angles.

Discovery of an exceptionally bright giant arc at z = 2.369, gravitationally lensed by the Planck cluster PSZ1 G311.65−18.48

As part of an all-sky follow-up of the Planck catalogue of Sunyaev-Zeldovich (SZ) cluster candidates detected in the first 14 months of data, we are observing cluster candidates in the southern sky in the optical imaging and spectroscopy through an ESO Large Programme. Inspection of ESO New Technology Telescope (NTT) R -and z -band imaging data from our programme has revealed an unusually large and bright arc in the field of PSZ1 G311.65−18.48. We establish the basic photometric and morphological properties of the arc and provide conclusive evidence for the gravitational lensing nature of this object. Guided by the NTT images, we have obtained a long-slit spectrum with IMACS on the Magellan-I Baade Telescope, covering a part of the arc and the brightest cluster galaxy of PSZ1 G311.65−18.48. Our imaging data confirm the presence of a galaxy cluster coinciding (within 0.6) with the position of the Planck SZ source. The arc is separated by ~30″ from the brightest cluster galaxy, which closely coincides with the center of curvature of the arc. A photometric analysis yields integrated (Vega) magnitudes of ( R,z,J, K s ) = (17.82,17.38,16.75,15.43) for the arc, more than one magnitude brighter than any previously known lensed arc at z ~ 2–3. The arc is a vigorously star-forming galaxy at z = 2.369, while the Planck SZ cluster lens is at z = 0.443.Even when allowing for lensing magnifications as high as μ = 100 still leads to the conclusion that the source galaxy is among the intrinsically most luminous normal (i.e., non-AGN) galaxies known at z ~ 2–3.