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High-resolution OH 1612-MHz spectra are presented of the supergiant OH-IR sources VY CMa, VX Sgr, IRC 10420 and NML Cyg. The spectra have a resolution of 300 Hz. Narrow components in the spectra have linewidths as small as 550 Hz (0.1 km s-1) but there is no evidence for components narrower than this. These results are in accord with present understanding of maser line-narrowing and of the physical conditions in the OH maser regions. Many of the narrow components have an appreciable degree of circular polarization which is not apparent at the lower frequency resolutions usually employed. The circular polarization indicates the presence of magnetic fields of approximately 1 mG in the circumstellar envelopes, at distances of approximately 3x10(16) cm from the central stars. These fields are strong enough to influence the outflow from the stars, and may help to explain some of the asymmetries which are seen in their circumstellar envelopes.

We present a study of seven southern open clusters based on UBVRI CCD photometry (Johnsons-Cousins system) and Gaia DR2 data. Dias 4, Dias 6, and four other clusters had UBVRI photometric observations determined for the first time. From the observational UBVRI data we obtained photometric membership probability estimates and, using the proper motions from the UCAC5 catalogue, we also determined the kinematic membership. From Gaia DR2 astrometric data we determine the stellar membership using proper motions and parallaxes, taking into account the full covariance matrix. For both independent sets of data and membership we apply our non-subjective multidimensional global optimization tool to fit theoretical isochrones to determine the distance, age, reddening, metallicity, and binary fraction of the clusters. The results of the mean proper motions, distances, and ages are in agreement, but the ones obtained from Gaia DR2 data are more precise in both membership selection and estimated parameters. In the case of NGC 6087, the Cepheid S Nor, member of the open cluster, was used to obtain an independent distance estimate, confirming the one determined by our fitting method. We also report a serendipitous discovery of two new clusters in the extended field near what was originally Dias 4. [ABSTRACT FROM AUTHOR]

We describe here a novel design of a fast high-density robotized fiber positioner system for massive spectroscopic surveys. The fiber positioners are compact, robust, and they can be coordinated, allowing for a high spatial density. Furthermore, the high absolute accuracy removes the need for a metrology system and reduces the reconfiguration time. First, we present the requirements for such a high-density fiber positioner system and put them in relation with the science goals. Then, we discuss the positioner design that accomplishes these requirements (including mechanical design, local control electronics board, overall communication solution, and observation sequencing). Finally, the performance of the proposed design is measured using 25 mm pitch prototypes of the positioners, through a dedicated novel designed test-bench. The related results show that our prototypes fulfil the requirements particularly in terms of positioning precision (<20 µm rms for one single open loop move) and partially in tilt (<0.15 deg). [ABSTRACT FROM AUTHOR]

Large-scale surveys of galaxies require accurate theoretical predictions of the dark matter clustering for thousands of mock galaxy catalogues. We demonstrate that this goal can be achieved with the new Parallel Particle-Mesh (PM) N -body code GLAM at a very low computational cost. We run ∼22 000 simulations with ∼2 billion particles that provide ∼1 per cent accuracy of the dark matter power spectra P (k) for wavenumbers up to k ∼ 1  h  Mpc−1. Using this large data set we study the power spectrum covariance matrix. In contrast to many previous analytical and numerical results, we find that the covariance matrix normalized to the power spectrum C (k, k ′)/ P (k) P (k ′) has a complex structure of non-diagonal components: an upturn at small k, followed by a minimum at k  ≈ 0.1–0.2  h  Mpc−1, and a maximum at k  ≈ 0.5–0.6  h  Mpc−1. The normalized covariance matrix strongly evolves with redshift: C (k, k ′) ∝ δα(t) P (k) P (k ′), where δ is the linear growth factor and α ≈ 1–1.25, which indicates that the covariance matrix depends on cosmological parameters. We also show that waves longer than $$1\,h^{-1}\rm{\,Gpc}$$ have very little impact on the power spectrum and covariance matrix. This significantly reduces the computational costs and complexity of theoretical predictions: relatively small volume $${\sim } (1\,h^{-1}\rm{\,Gpc})^3$$ simulations capture the necessary properties of dark matter clustering statistics. As our results also indicate, achieving ∼1 per cent errors in the covariance matrix for k < 0.50  h  Mpc−1 requires a resolution better than $$\epsilon \sim 0.5\,h^{-1}\rm{\,Mpc}$$. [ABSTRACT FROM AUTHOR]

We present observations with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope of five star-forming galaxies at redshifts $$z$$ in the range 0.2993–0.4317 and with high emission-line flux ratios O32 = [O  iii ] λ5007/[O  ii ] λ3727 ∼ 8–27 aiming to detect the Lyman continuum (LyC) emission. We detect LyC emission in all galaxies with the escape fractions f esc(LyC) in a range of 2–72 per cent. A narrow Lyα emission line with two peaks in four galaxies and with three peaks in one object is seen in medium-resolution COS spectra with a velocity separation between the peaks V sep varying from ∼153 to ∼345 km s−1. We find a general increase of the LyC escape fraction with increasing O32 and decreasing stellar mass M ⋆, but with a large scatter of f esc(LyC). A tight anticorrelation is found between f esc(LyC) and V sep making V sep a good parameter for the indirect determination of the LyC escape fraction. We argue that one possible source driving the escape of ionizing radiation is stellar winds and radiation from hot massive stars. [ABSTRACT FROM AUTHOR]

We present a sample of 329 low-to intermediate-redshift (0.05 < z < 0.3) brightest cluster galaxies (BCGs) in X-ray-selected clusters from the SPectroscopic IDentification of eRosita Sources survey, a spectroscopic survey within Sloan Digital Sky Survey-IV (SDSS-IV). We define our BCGs by simultaneous consideration of legacy X-ray data from ROSAT, maximum-likelihood outputs from an optical cluster-finder algorithm and visual inspection. Using SDSS imaging data, we fit Sérsic profiles to our BCGs in three bands (g, r, i) with sigma a galfit -based software wrapper. We examine the reliability of our fits by running our pipeline on ∼104 point spread function-convolved model profiles injected into eight random cluster fields; we then use the results of this analysis to create a robust subsample of 198 BCGs. We outline three cluster properties of interest: overall cluster X-ray luminosity (L X), cluster richness as estimated by redMaPPer (λ),and cluster halo mass (M 200), which is estimated via velocity dispersion. In general, there are significant correlations with BCG stellar mass between all three environmental properties, but no significant trends arise with either Sérsic index or effective radius. There is no major environmental dependence on the strength of the relation between effective radius and BCG stellar mass. Stellar mass therefore arises as the most important factor governing BCG morphology. Our results indicate that our sample consists of a large number of relaxed, mature clusters containing broadly homogeneous BCGs up to z  ∼ 0.3, suggesting that there is little evidence for much ongoing structural evolution for BCGs in these systems. [ABSTRACT FROM AUTHOR]

The spectrum of a galaxy contains information about its physical properties. Classifying spectra using templates helps to elucidate the nature of a galaxy’s energy sources. In this paper, we investigate the use of self-organizing maps in classifying galaxy spectra against templates. We trained semi-supervised self-organizing map networks using a set of templates covering the wavelength range from far ultraviolet to near-infrared. The trained networks were used to classify the spectra of a sample of 142 galaxies with 0.5 < $$z$$ < 1 and the results compared to classifications performed using K -means clustering, a supervised neural network, and chi-squared minimization. Spectra corresponding to quiescent galaxies were more likely to be classified similarly by all methods while starburst spectra showed more variability. Compared to classification using chi-squared minimization or the supervised neural network, the galaxies classed together by the self-organizing map had more similar spectra. The class ordering provided by the 1D self-organizing maps corresponds to an ordering in physical properties, a potentially important feature for the exploration of large data sets. [ABSTRACT FROM AUTHOR]

The epoch of reionization (EoR) 21-cm signal is expected to be highly non-Gaussian in nature and this non-Gaussianity is also expected to evolve with the progressing state of reionization. Therefore the signal will be correlated between different Fourier modes (k). The power spectrum will not be able capture this correlation in the signal. We use a higher order estimator – the bispectrum – to quantify this evolving non-Gaussianity. We study the bispectrum using an ensemble of simulated 21-cm signal and with a large variety of k triangles. We observe two competing sources driving the non-Gaussianity in the signal: fluctuations in the neutral fraction (⁠|$x_{{{\rm H\,\small {I}}}\,}$|⁠) field and fluctuations in the matter density field. We find that the non-Gaussian contribution from these two sources varies, depending on the stage of reionization and on which k modes are being studied. We show that the sign of the bispectrum works as a unique marker to identify which among these two components is driving the non-Gaussianity. We propose that the sign change in the bispectrum, when plotted as a function of triangle configuration cos θ and at a certain stage of the EoR can be used as a confirmative test for the detection of the 21-cm signal. We also propose a new consolidated way to visualize the signal evolution (with evolving |$\bar{x}_{{{\rm H\,\small {I}}}}$| or redshift), through the trajectories of the signal in a power spectrum and equilateral bispectrum i.e. P (k) −  B (k, k, k) space. [ABSTRACT FROM AUTHOR]

We present a detailed analysis of the selection function of the LAMOST Spectroscopic Survey of the Galactic Anti-centre (LSS-GAC). LSS-GAC was designed to obtain low-resolution optical spectra for a sample of more than 3 million stars in the Galactic anti-centre. The second release of value-added catalogues of the LSS-GAC (LSS-GAC DR2) contains stellar parameters, including radial velocity, atmospheric parameters, elemental abundances, and absolute magnitudes deduced from 1.8 million spectra of 1.4 million unique stars targeted by the LSS-GAC between 2011 and 2014. For many studies using this data base, such as those investigating the chemodynamical structure of the Milky Way, a detailed understanding of the selection function of the survey is indispensable. In this paper, we describe how the selection function of the LSS-GAC can be evaluated to sufficient detail and provide selection function corrections for all spectroscopic measurements with reliable parameters released in LSS-GAC DR2. The results, to be released as new entries in the LSS-GAC value-added catalogues, can be used to correct the selection effects of the catalogue for scientific studies of various purposes. [ABSTRACT FROM AUTHOR]

We develop a Bayesian hierarchical modelling approach for cosmic shear power spectrum inference, jointly sampling from the posterior distribution of the cosmic shear field and its (tomographic) power spectra. Inference of the shear power spectrum is a powerful intermediate product for a cosmic shear analysis, since it requires very few model assumptions and can be used to perform inference on a wide range of cosmological models a posteriori without loss of information. We show that joint posterior for the shear map and power spectrum can be sampled effectively by Gibbs sampling, iteratively drawing samples from the map and power spectrum, each conditional on the other. This approach neatly circumvents difficulties associated with complicated survey geometry and masks that plague frequentist power spectrum estimators, since the power spectrum inference provides prior information about the field in masked regions at every sampling step. We demonstrate this approach for inference of tomographic shear E-mode, B-mode and EB-cross power spectra from a simulated galaxy shear catalogue with a number of important features; galaxies distributed on the sky and in redshift with photometric redshift uncertainties, realistic random ellipticity noise for every galaxy and a complicated survey mask. The obtained posterior distributions for the tomographic power spectrum coefficients recover the underlying simulated power spectra for both E- and B-modes. [ABSTRACT FROM AUTHOR]

We present DEIMOS multi-object spectroscopy (MOS) of 22 star-forming dwarf galaxies located in four gas-rich groups, including six newly discovered dwarfs. Two of the galaxies are strong tidal dwarf galaxy (TDG) candidates based on our luminosity-metallicity relation definition. We model the rotation curves of these galaxies. Our sample shows low mass-tolight ratios (M/L = 0.73 ± 0.39M☉/L☉) as expected for young, star-forming dwarfs. One of the galaxies in our sample has an apparently strongly falling rotation curve, reaching zero rotational velocity outside the turnover radius of rturn = 1.2re. This may be (1) a polar ring galaxy, with a tilted bar within a face-on disc; (2) a kinematic warp. These scenarios are indistinguishable with our current data due to limitations of slit alignment inherent to MOSmode observations. We consider whether TDGs can be detected based on their tidal radius, beyond which tidal stripping removes kinematic tracers such as Hα emission. When the tidal radius is less than about twice the turnover radius, the expected falling rotation curve cannot be reliably measured. This is problematic for as much as half of our sample, and indeed more generally, galaxies in groups like these. Further to this, the Hα light that remains must be sufficiently bright to be detected; this is only the case for three (14 per cent) galaxies in our sample. We conclude that the falling rotation curves expected of TDGs are intrinsically difficult to detect. [ABSTRACT FROM AUTHOR]

In the low-redshift Universe (z < 0.3), our view of galaxy evolution is primarily based on fibre optic spectroscopy surveys. Elaborate methods have been developed to address aperture effects when fixed aperture sizes only probe the inner regions for galaxies of ever decreasing redshift or increasing physical size. These aperture corrections rely on assumptions about the physical properties of galaxies. The adequacy of these aperture corrections can be tested with integralfield spectroscopic data. We use integral-field spectra drawn from 1212 galaxies observed as part of the SAMI Galaxy Survey to investigate the validity of two aperture correction methods that attempt to estimate a galaxy's total instantaneous star formation rate.We show that biases arise when assuming that instantaneous star formation is traced by broad-band imaging, and when the aperture correction is built only from spectra of the nuclear region of galaxies. These biases may be significant depending on the selection criteria of a survey sample. Understanding the sensitivities of these aperture corrections is essential for correct handling of systematic errors in galaxy evolution studies. [ABSTRACT FROM AUTHOR]

We extend the catalogue of two-dimensional, Point-Spread-Function-corrected de Vacouleurs, Sérsic, de Vacouleurs+Exponential, and Sérsic+Exponential fits of ~7 × 105 galaxies presented in Meert et al. to include the g and i bands. Fits are analysed using the physically motivated flagging system presented in the original text, making adjustments for the differing signal to noise when necessary. We compare the fits in each of the g, r, and i bands. Fixed aperture magnitudes and colours are also provided for all galaxies. The catalogues are available in electronic format. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the impact that realistic scale-dependent systematic effects may have on cosmic shear tomography. We model spatially varying residual galaxy ellipticity and galaxy size variations in weak lensing measurements and propagate these through to predicted changes in the uncertainty and bias of cosmological parameters. We show that the survey strategy -- whether it is regular or randomized -- is an important factor in determining the impact of a systematic effect: a purely randomized survey strategy produces the smallest biases, at the expense of larger parameter uncertainties, and a very regularized survey strategy produces large biases, but unaffected uncertainties. However, by removing, or modelling, the affected scales (l-modes) in the regular cases the biases are reduced to negligible levels. We find that the integral of the systematic power spectrum is not a good metric for dark energy performance, and we advocate that systematic effects should be modelled accurately in real space, where they enter the measurement process, and their effect subsequently propagated into power spectrum contributions. [ABSTRACT FROM AUTHOR]

Measurements are presented and analysed of the strength of the Ca II triplet lines in red giants in Galactic globular and open clusters, and in a sample of red giants in the LMC disc that have significantly different [Ca/Fe] abundance ratios to the Galactic objects. The Galactic objects are used to generate a calibration between Ca II triplet line strength and [Fe/H], which is then used to estimate [Fe/H]CaT for the LMC stars. The values are then compared with the [Fe/H]spec determinations from high-dispersion spectroscopy. After allowance for a small systematic offset, the two abundance determinations are in excellent agreement. Further, as found in earlier studies, the difference is only a very weak function of the [Ca/Fe] ratio. For example, changing [Ca/Fe] from +0.3 to -0.2 causes the Ca II-based abundance to underestimate [Fe/H]spec by only ~0.15 dex, assuming a Galactic calibration. Consequently, the Ca II triplet approach to metallicity determinations can be used without significant bias to study stellar systems that have substantially different chemical evolution histories. [ABSTRACT FROM AUTHOR]

ABSTRACT We present the results of a 500 ks long XMM-Newton observation and a 120 ks long quasi-simultaneous Chandra observation of the Narrow-Line Seyfert 1 galaxy 1H 0707−495 performed in 2010 September. Consistent with earlier results by Fabian et al. and Zoghbi et al., the spectrum is found to be dominated by relativistically broadened reflection features from an ionized accretion disc around a maximally rotating black hole. Even though the spectra changed between this observation and earlier XMM-Newton observations, the physical parameters of the black hole and accretion disc (i.e. spin and inclination) are consistent between both observations. We show that this reflection spectrum is slightly modified by absorption in a mildly relativistic, highly ionized outflow which changed velocity from around 0.11 c to 0.18 c between 2008 January and 2010 September. Alternative models, in which the spectral shape is dominated by absorption, lead to spectral fits of similar quality, however, the parameters inferred for the putative absorber are unphysical. [ABSTRACT FROM AUTHOR]

We present photometric and spectroscopic analysis of the bright detached eclipsing binary BG Ind. The masses of the components are found to be and and the radii to be and for primary and secondary stars, respectively. Spectra and isochrone fittings coupled with colour indices calibration yield . At an age of Gyr, BG Ind is well advanced in the main-sequence evolutionary phase - in fact, its primary is at TAMS or just beyond it. Together with three similar systems (BK Peg, BW Aqr and GX Gem), it offers an interesting opportunity to test the theoretical description of overshooting in the critical mass range 1.2-1.5 M. [ABSTRACT FROM AUTHOR]

We study the spectroscopic properties of a large sample of low surface brightness galaxies (LSBGs) [with B-band central surface brightness mag arcsec] selected from the Sloan Digital Sky Survey Data Release 4 (SDSS-DR4) main galaxy sample. A large sample of disc-dominated high surface brightness galaxies [HSBGs, with mag arcsec] are also selected for comparison simultaneously. To study them in more details, these sample galaxies are further divided into four subgroups according to (in units of mag arcsec): very low surface brightness galaxies (vLSBGs) (24.5-22.75), intermediate low surface brightness galaxies (iLSBGs) (22.75-22.0), intermediate high surface brightness galaxies (iHSBGs) (22.0-21.25) and very high surface brightness galaxies (vHSBGs) (<21.25). The diagnostic diagram from spectral emission-line ratios shows that the active galactic nucleus fractions of all the four subgroups are small (<9 per cent). The 21 032 star-forming galaxies with good-quality spectroscopic observations are further selected for studying their dust extinction, strong-line ratios, metallicities and stellar mass-metallicity relations. The vLSBGs have lower extinction values and have less metal-rich and massive galaxies than the other subgroups. The oxygen abundances of our LSBGs are not as low as those of the H regions in LSBGs studied in literature, which could be because our samples are more luminous, and because of the different metallicity calibrations used. We find a correlation between 12 + log(O/H) and for vLSBGs, iLSBGs and iHSBGs but show that this could be a result of correlation between and stellar mass and the well-known mass-metallicity relation. This large sample shows that LSBGs span a wide range in metallicity and stellar mass, and they lie nearly on the stellar mass versus metallicity and N/O versus O/H relations of normal galaxies. This suggests that LSBGs and HSBGs have not had dramatically different star formation and chemical enrichment histories. [ABSTRACT FROM AUTHOR]

The Spectral and Photometric Imaging Receiver on-board Herschel has been carrying out deep extragalactic surveys, one of the aims of which is to establish spectral energy distributions of individual galaxies spanning the infrared/submillimetre (IR/SMM) wavelength region. We report observations of the IR/SMM emission from the Lockman North field and Great Observatories Origins Deep Survey Field-North. Because galaxy images in the wavelength range covered by Herschel generally represent a blend with contributions from neighbouring galaxies, we present sets of galaxies in each field, especially free of blending at 250, 350 and 500 m. We identify the cumulative emission of these galaxies and the fraction of the FIR cosmic background radiation they contribute. Our surveys reveal a number of highly luminous galaxies at redshift and a novel relationship between IR and visible emission that shows a dependence on luminosity and redshift. [ABSTRACT FROM AUTHOR]

We report the first extrasolar planet observations from the 10.4-m Gran Telescopio Canarias (GTC), currently the world's largest, fully steerable, single-aperture optical telescope. We used the Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) tunable filter imager on the GTC to acquire high-precision, narrow-band photometry of the transits of the giant exoplanets, TrES-2b and TrES-3b. We obtained near-simultaneous observations in two near-infrared wavebands (790.2 and 794.4 ± 2.0 nm) specifically chosen to avoid water vapour absorption and skyglow so as to minimize the atmospheric effects that often limit the precision of ground-based photometry. Our results demonstrate a very-high photometric precision with minimal atmospheric contamination despite relatively poor atmospheric conditions and some technical problems with the telescope. We find the photometric precision for the TrES-2 observations to be 0.343 and 0.412 mmag for the 790.2- and 794.4-nm light curves, and the precision of the TrES-3 observations was found to be 0.470 and 0.424 mmag for the 790.2- and 794.4-nm light curves, respectively. We also discuss how future follow-up observations of transiting planets with this novel technique can contribute to the characterization of Neptune- and super-Earth-size planets to be discovered by space-based missions like CoRoT and Kepler, as well as measure atmospheric properties of giant planets, such as the strength of atmospheric absorption features. [ABSTRACT FROM AUTHOR]

We present a comprehensive spectral analysis of all INTEGRAL data obtained so far for the X-ray-bright Seyfert galaxy NGC 4151. We also use all contemporaneous data from RXTE, XMM-Newton, Swift and Suzaku. We find a linear correlation between the medium- and hard-energy X-ray fluxes measured by INTEGRAL, which indicates an almost constant spectral index over 6 yr. The majority of INTEGRAL observations were made when the source was either at a very bright or very dim hard-X-ray state. We find that thermal Comptonization models applied to the bright state yields the plasma temperature of ≃50-70 keV and its optical depth of ≃1.3-2.6, depending on the assumed source geometry. For the dim state, these parameters are in the ranges of ≃180-230 keV and ≃0.3-0.7, respectively. The Compton parameter is for all the spectra, indicating a stable geometry. Using this result, we can determine the reflection effective solid angles associated with the close and distant reprocessing media as and , respectively. The plasma energy balance, the weak disc reflection and a comparison of the UV fluxes illuminating the plasma to the observed ones are all consistent with an inner hot accretion surrounded by an outer cold disc. The disc truncation radius can be determined from an approximate equipartition between the observed UV and X-ray emission, and from the fitted disc blackbody model, as ∼15 gravitational radii. Alternatively, our results can be explained by a mildly relativistic coronal outflow. [ABSTRACT FROM AUTHOR]

We perform multidimensional radiative transfer simulations to compute spectra for a hydrodynamical simulation of a line-driven accretion disc wind from an active galactic nucleus. The synthetic spectra confirm expectations from parametrized models that a disc wind can imprint a wide variety of spectroscopic signatures including narrow absorption lines, broad emission lines and a Compton hump. The formation of these features is complex with contributions originating from many of the different structures present in the hydrodynamical simulation. In particular, spectral features are shaped both by gas in a successfully launched outflow and in complex flows where material is lifted out of the disc plane but ultimately falls back. We also confirm that the strong Fe Kα line can develop a weak, red-skewed line wing as a result of Compton scattering in the outflow. In addition, we demonstrate that X-ray radiation scattered and reprocessed in the flow has a pivotal part in both the spectrum formation and determining the ionization conditions in the wind. We find that scattered radiation is rather effective in ionizing gas which is shielded from direct irradiation from the central source. This effect likely makes the successful launching of a massive disc wind somewhat more challenging and should be considered in future wind simulations. [ABSTRACT FROM AUTHOR]

We report on the detailed study of the 2008 October outburst from the anomalous X-ray pulsar 1E 5408 discovered through the Swift/Burst Alert Telescope (BAT) detection of soft gamma-ray repeater like short X-ray bursts on 2008 October 3. The Swift/X-ray Telescope (XRT) started observing the source after less than 100 s since the BAT trigger, when the flux ( in the 2-10 keV range) was >50 times higher than its quiescent level. Swift monitored the outbursting activity of 1E 5408 on a daily basis for approximately three weeks. This strategy allowed us to find a phase-coherent solution for the source pulsations after the burst, which, besides P and , requires a positive term (spin-down increase). The time evolution of the pulse shape is complex and variable, with the pulsed fraction increasing from 20 to 50 per cent within the Swift observational window. The XRT spectra can be fitted well by means of a single component, either a power law (PL) or a blackbody. During the very initial phases of the outburst the spectrum is hard, with a PL photon index (or ), which steepens to (or ) within one day from the BAT trigger, though the two components are likely present simultaneously during the first-day spectra. An INTEGRAL observation carried out five days after the trigger provided an upper limit of to the emission of 1E 5408 in the 18-60 keV band. [ABSTRACT FROM AUTHOR]

Bolometric corrections based on the optical-to-ultraviolet continuum spectrum of quasars are widely used to quantify their radiative output, although such estimates are affected by a myriad of uncertainties, such as the generally unknown line-of-sight angle to the central engine. In order to shed light on these issues, we investigate the state-of-the-art models of Hubeny et al. that describe the continuum spectrum of thin accretion discs and include relativistic effects. We explore the bolometric corrections as a function of mass accretion rates, black hole masses and viewing angles, restricted to the parameter space expected for type 1 quasars. We find that a non-linear relationship with is favoured by the models and becomes tighter as the wavelength decreases. We calculate from the model the bolometric corrections corresponding to the wavelengths and . In particular, for we find and . We demonstrate that the often-made assumption that quasars emit isotropically may lead to severe systematic errors in the determination of L, when using the method of integrating the 'big blue bump' spectrum. For a typical viewing angle of to the quasar central engine, we obtain that the value of L resulting from the isotropy assumption has a systematic error of ≈30 per cent high compared to the value of L which incorporates the anisotropic emission of the accretion disc. These results are of direct relevance to observational determinations of the bolometric luminosities of quasars, and may be used to improve such estimates. [ABSTRACT FROM AUTHOR]

This is the first paper of a series presenting the Spheroids Panchromatic Investigation in Different Environmental Regions (SPIDER). The sample of spheroids consists of 5080 bright () early-type galaxies (ETGs), in the redshift range of 0.05 to 0.095, with optical () photometry and spectroscopy from the Sloan Digital Sky Survey Data Release 6 (SDSS-DR6) and near-infrared () photometry from the UKIRT Infrared Deep Sky Survey-Large Area Survey (UKIDSS-LAS) (DR4). We describe how homogeneous photometric parameters (galaxy colours and structural parameters) are derived using wavebands. We find no systematic steepening of the colour-magnitude relation when probing the baseline from to , implying that internal colour gradients drive most of the mass-metallicity relation in ETGs. As far as structural parameters are concerned we find that the mean effective radius of ETGs smoothly decreases, by 30 per cent, from g through K, while no significant dependence on waveband is detected for the axial ratio, Sersic index and a parameters. Furthermore, velocity dispersions are remeasured for all the ETGs using and compared to those obtained by SDSS. The velocity dispersions are rederived using a combination of simple stellar population models as templates, hence accounting for the kinematics of different galaxy stellar components. We compare our () measurements of total magnitude, effective radius and mean surface brightness with those obtained as part of the SDSS pipeline (). Significant differences are found and reported, including comparisons with a third and independent part. A full characterization of the sample completeness in all wavebands is presented, establishing the limits of application of the characteristic parameters presented here for the analysis of the global scaling relations of ETGs. [ABSTRACT FROM AUTHOR]

The ESA Rosetta mission, launched in 2004 March, will flyby the second asteroid target (21) Lutetia in 2010 July. This asteroid is quite different from (2867) Steins, encountered by Rosetta in 2008 September. Lutetia is in fact a much larger asteroid, approximately 100 km of diameter, as compared to the 5 km of Steins and also its surface composition seems fairly different. A wide international ground-based observational campaign has been carried out and is still going on to obtain information on the object. In this context, we observed Lutetia four times spectroscopically in the visible region totally covering its rotational period. In this paper we have compared all our observations, in order to try to shed more light on its nature. Moreover, an analysis of the geometric configuration of Lutetia during the several observations has also been performed. Our paper points out small variations of reflectance over the surface, possibly due to a large crater. However, the nature of Lutetia remains still elusive, probably because it could be a transition object between X and C taxonomic classes, pointing out to the crucial values of the forthcoming flyby to clarify the situation. Therefore, all the information we have gathered and here discussed have been very useful also to better define the observational strategy of the asteroid by Rosetta. [ABSTRACT FROM AUTHOR]

The presence of absorbing gas around the central engine of active galactic nuclei (AGN) is a common feature of these objects. Recent work has looked at the effect of the dust component of the gas, and how it enhances radiation pressure such that dusty gas can have a lower effective Eddington limit than ionized gas. In this work, we use multiwavelength data and X-ray spectra from the 2 Ms exposures of the Chandra Deep Field-North and Chandra Deep Field-South surveys to characterize the AGN in terms of their Eddington ratio (λ) and hydrogen column density ( N). Their distributions are then compared with what is predicted when considering the coupling between dust and gas. Our final sample consists of 234 objects from both fields, the largest and deepest sample of AGN for which this comparison has been made up to date. We find that most of the AGN in our sample tend to be found at low Eddington ratios (typically ) and high N (>10 cm), with black hole masses in the range . Their distribution is in agreement with that expected from the enhanced radiation pressure model, avoiding the area where we would predict the presence of outflows. We also investigate how the balance between AGN radiation pressure and gravitational potential influences the behaviour of clouds in the Galactic bulge, and describe a scenario where an enhanced radiation pressure can lead to the Fundamental Plane of black hole/galaxy scaling relations. [ABSTRACT FROM AUTHOR]

Spectroscopic analyses of hydrogen-rich WN 5-6 stars within the young star clusters NGC 3603 and R136 are presented, using archival Hubble Space Telescope and Very Large Telescope spectroscopy, and high spatial resolution near-IR photometry, including Multi-Conjugate Adaptive Optics Demonstrator (MAD) imaging of R136. We derive high stellar temperatures for the WN stars in NGC 3603 ( kK) and R136 ( kK) plus clumping-corrected mass-loss rates of M yr−1 which closely agree with theoretical predictions from Vink et al. These stars make a disproportionate contribution to the global ionizing and mechanical wind power budget of their host clusters. Indeed, R136a1 alone supplies ∼7 per cent of the ionizing flux of the entire 30 Doradus region. Comparisons with stellar models calculated for the main-sequence evolution of 85-500 M accounting for rotation suggest ages of ∼1.5 Myr and initial masses in the range 105-170 M for three systems in NGC 3603, plus 165-320 M for four stars in R136. Our high stellar masses are supported by consistent spectroscopic and dynamical mass determinations for the components of NGC 3603A1. We consider the predicted X-ray luminosity of the R136 stars if they were close, colliding wind binaries. R136c is consistent with a colliding wind binary system. However, short period, colliding wind systems are excluded for R136a WN stars if mass ratios are of order unity. Widely separated systems would have been expected to harden owing to early dynamical encounters with other massive stars within such a high-density environment. From simulated star clusters, whose constituents are randomly sampled from the Kroupa initial mass function, both NGC 3603 and R136 are consistent with an tentative upper mass limit of ∼300 M . The Arches cluster is either too old to be used to diagnose the upper mass limit, exhibits a deficiency of very massive stars, or more likely stellar masses have been underestimated - initial masses for the most luminous stars in the Arches cluster approach 200 M according to contemporary stellar and photometric results. The potential for stars greatly exceeding 150 M within metal-poor galaxies suggests that such pair-instability supernovae could occur within the local universe, as has been claimed for SN 2007bi. [ABSTRACT FROM AUTHOR]

Spectroscopy has shown the presence of CN band dichotomy and Na-O anticorrelations for 50-70 per cent of the investigated samples in the cluster 47 Tuc, otherwise considered a 'normal' prototype of high-metallicity clusters from its photometric analysis. These anomalies are also found in main-sequence stars, suggesting that a consistent second generation is present in 47 Tuc. Very recently, the reanalysis of a large number of archival Hubble Space Telescope ( HST) data of the cluster core has been able to provide evidence of the presence of structures in the subgiant branch: it has a brighter component with a spread in magnitude of ∼0.06 mag and a second one, consisting of about 10 per cent of the stars, a little fainter (by ∼0.05 mag). These data also show that the main sequence of the cluster has an intrinsic spread in colour, which can be interpreted as due to a small spread in helium abundance. In this work we examine in detail whether the horizontal-branch morphology and subgiant structure provide further independent indications that a real - although very small - helium spread is present in the cluster. We reanalyse the HST archival data for the horizontal branch of 47 Tuc, obtaining a sample of ∼500 stars with very small photometric errors, and build a population synthesis based on new models to show that its particular morphology can be better explained by taking into account a spread in helium abundance of 2 per cent in mass. The same variation in helium is able to explain the spread in luminosity of the subgiant branch, while a small part of the second generation is characterized by a small C+N+O increase and provides an explanation for the fainter subgiant branch. We conclude that three photometric features concur to form the paradigm that a small but real helium spread is present in a cluster that has no spectacular evidence for multiple populations like those shown by other massive clusters. This work thus shows that multiple populations in globular clusters are increasingly confirmed to be ubiquitous. [ABSTRACT FROM AUTHOR]

Accurate light and colour curves of the Mira variable in the dust-free symbiotic system K 46 are presented and discussed. They cover several consecutive pulsations cycles. The Mira mean period is 284.2 d, the reddening sums to and the distance is 10 kpc. Absolute spectrophotometry at both maximum and minimum brightness of the Mira is presented. The rich emission line and continuum spectrum of the H ii region ionized by the hard radiation of the white dwarf dominates at Mira minimum. From its photoionization analysis, it is found that the H ii region extends to a radius of 210 au, has a mass and it is ionized by a white dwarf of 158 000 K temperature and 0.06 R radius, stably burning hydrogen at its surface. The derived well match the ambient metallicity expected at K 46 at its 15 kpc galactocentric distance, and the overabundances in N, Ne and He are those expected if the H ii region is fed by the wind of the Mira and polluted by nuclearly processed material lost by the white dwarf companion. [ABSTRACT FROM AUTHOR]

We continue to explore the validity of the reflected-shock structure (RSS) picture in SNR 1987A that was proposed in our previous analyses of the X-ray emission from this object. We used an improved version of our RSS model in a global analysis of 14 CCD spectra from the monitoring program with Chandra. In the framework of the RSS picture, we are able to match both the expansion velocity curve deduced from the analysis of the X-ray images and light curve. Using a simplified analysis, we also show that the X-rays and the non-thermal radio emission may originate from the same shock structure (the blast wave). We believe that using the RSS model in the analysis of grating data from the Chandra monitoring program of SNR 1987A that cover a long enough time interval will allow us to build a more realistic physical picture and model of SNR 1987A. [ABSTRACT FROM AUTHOR]

A tool for representation of the one-dimensional astrometric signal of Gaia is described and investigated in terms of fit discrepancy and astrometric performance with respect to the number of parameters required. The proposed basis function is based on the aberration free response of the ideal telescope and its derivatives, weighted by the source spectral distribution. The influence of relative position of the detector pixel array with respect to the optical image is analysed, as well as the variation induced by the source spectral emission. The number of parameters required for micro-arcsec level consistency of the reconstructed function with the detected signal is found to be 11. Some considerations are devoted to the issue of calibration of the instrument response representation, taking into account the relevant aspects of source spectrum and focal plane sampling. Additional investigations and other applications are also suggested. [ABSTRACT FROM AUTHOR]

The temporal and spectral analysis of nine bright X-ray flares out of a sample of 113 flares observed by Swift reveals that the flare phenomenology is strictly analogous to the prompt γ-ray emission: high-energy flare profiles rise faster, decay faster and peak before the low-energy emission. However, flares and prompt pulses differ in one crucial aspect: flares evolve with time. As time proceeds, flares become wider, with larger peak lag, lower luminosities and softer emission. The flare spectral peak energy evolves to lower values following an exponential decay which tracks the decay of the flare flux. The two flares with best statistics show higher than expected isotropic energy and peak luminosity when compared to the and prompt correlations. is found to correlate with within single flares, giving rise to a time-resolved . Like prompt pulses, flares define a lag–luminosity relation: . The lag–luminosity is proven to be a fundamental law extending ∼5 decades in time and ∼5 decades in energy. Moreover, this is direct evidence that γ-ray burst (GRB) X-ray flares and prompt γ-ray pulses are produced by the same mechanism. Finally we establish a flare–afterglow morphology connection: flares are preferentially detected superimposed to one-break or canonical X-ray afterglows. [ABSTRACT FROM AUTHOR]

We study lensing magnification of source galaxies by intervening galaxy groups and clusters using a halo model. Haloes are modelled with truncated NFW profiles with ellipticity added to their lensing potential and propagated to observable lensing statistics. We present the formalism to calculate observable effects due to a distribution of haloes of different masses at different redshifts along the line of sight. We calculate the effects of magnification on the number counts of high-redshift galaxies. Using Balloon-borne Large Aperture Submillimetre Telescope (BLAST) survey data for submillimetre galaxies (SMGs), we find that magnification affects the steep, high flux part of the counts by about 60 per cent. The effect becomes much stronger if the intrinsic distribution is significantly steeper than observed. We also consider the effect of this high-redshift galaxy population on contaminating the Sunyaev–Zel'dovich (SZ) signal of massive clusters using the halo model approach. We find that for the majority of clusters expected to be detected with ongoing SZ surveys, there is significant contamination from the Poisson noise due to background SMGs. This contribution can be comparable to the SZ increment for typical clusters and can also contaminate the SZ decrement of low-mass clusters. Thus, SZ observations, especially for the increment part of the SZ spectrum, need to include careful modelling of this irreducible contamination for mass estimation. Lensing further enhances the contamination, especially close to the cores of massive clusters and for very disturbed clusters with large magnification cross-section. [ABSTRACT FROM AUTHOR]

Stellar population models of absorption-line indices are an important tool for the analysis of stellar population spectra. They are most accurately modelled through empirical calibrations of absorption-line indices with the stellar parameters such as effective temperature, metallicity and surface gravity, which are the so-called fitting functions. Here we present new empirical fitting functions for the 25 optical Lick absorption-line indices based on the new stellar library Medium resolution INT Library of Empirical Spectra (MILES). The major improvements with respect to the Lick/IDS library are the better sampling of stellar parameter space, a generally higher signal-to-noise ratio and a careful flux calibration. In fact, we find that errors on individual index measurements in MILES are considerably smaller than in Lick/IDS. Instead, we find the rms of the residuals between the final fitting functions and the data to be dominated by errors in the stellar parameters. We provide fitting functions for both Lick/IDS and MILES spectral resolutions and compare our results with other fitting functions in the literature. Afortran 90 code is available online in order to simplify the implementation in stellar population models. We further calculate the offsets in index measurements between the Lick/IDS system to a flux-calibrated system. For this purpose, we use the three libraries MILES, ELODIE and STELIB. We find that offsets are negligible in some cases, most notably for the widely used indices H , Mg b, Fe5270 and Fe5335. In a number of cases, however, the difference between the flux-calibrated library and Lick/IDS is significant with the offsets depending on index strengths. Interestingly, there is no general agreement between the three libraries for a large number of indices, which hampers the derivation of a universal offset between the Lick/IDS and flux-calibrated systems. [ABSTRACT FROM AUTHOR]

Motivated by suggestions of ‘cosmic downsizing’, in which the dominant contribution to the cosmic star formation rate density (SFRD) proceeds from higher to lower mass galaxies with increasing cosmic time, we describe the design and implementation of the Redshift One LDSS3 Emission line Survey (ROLES). This survey is designed to probe low-mass, galaxies directly for the first time with spectroscopy. ROLES is a K-selected ( ) survey for dwarf galaxies [ ] at drawn from two extremely deep fields [Great Observatories Origins Deep Survey-S (GOODS-S) and MS1054-Faint Infra-Red Extragalactic Survey]. Using the [O ii] emission line, we obtain redshifts and star formation rates (SFRs) for star-forming galaxies down to a limit of . We present the [O ii] luminosity function measured in ROLES and find a faint-end slope of , similar to that measured at in the Sloan Digital Sky Survey. By combining ROLES with higher mass surveys (Gemini Deep Deep Survey and European Southern Observatory GOOD-S public spectroscopy) we measure the SFRD as a function of stellar mass using [O ii] (with and without various empirical corrections) and using spectral energy distribution fitting to obtain the SFR from the rest-frame UV luminosity for galaxies with spectroscopic redshifts. Our best estimate of the corrected [O ii] SFRD and UV SFRD both independently show that the SFRD evolves equally for galaxies of all masses between and . The exact evolution in normalization depends on the indicator used, with the [O ii]-based estimate showing a change of a factor of ≈2.6 and the UV-based estimate a factor of ≈6. We discuss possible reasons for the discrepancy in normalization between the indicators, but note that the magnitude of this uncertainty is comparable to the discrepancy between indicators seen in other works. Our result that the shape of the SFRD as a function of stellar mass (and hence the mass range of galaxies dominating the SFRD) does not evolve between and is robust to the choice of indicator. [ABSTRACT FROM AUTHOR]

We propose a physical framework for interpreting the characteristic frequencies seen in the broad-band power spectra from black hole and neutron star binaries. We use the truncated disc/hot inner flow geometry, and assume that the hot flow is generically turbulent. Each radius in the hot flow produces fluctuations, and we further assume that these are damped on the viscous frequency. Integrating over radii gives broad-band continuum noise power between low- and high-frequency breaks which are set by the viscous time-scale at the outer and inner edge of the hot flow, respectively. Lense–Thirring (vertical) precession of the entire hot flow superimposes the low-frequency quasi-periodic oscillation (QPO) on this continuum power. We test this model on the power spectra seen in the neutron star systems (atolls) as these have the key advantage that the (upper) kHz QPO most likely independently tracks the truncation radius. These show that this model can give a consistent solution, with the truncation radius decreasing from 20 to while the inner radius of the flow remains approximately constant at i.e. 9.2 km. We use this very constrained geometry to predict the low-frequency QPO from Lense–Thirring precession of the entire hot flow from to . The simplest assumption of a constant surface density in the hot flow matches the observed QPO frequency to within 25 per cent. This match can be made even better by considering that the surface density should become increasingly centrally concentrated as the flow collapses into an optically thick boundary layer during the spectral transition. The success of the model opens up the way to use the broad-band power spectra as a diagnostic of accretion flows in strong gravity. [ABSTRACT FROM AUTHOR]

The surface brightness profile of Hα emission in galaxies is generally thought to be confined by a sharp truncation, sometimes speculated to coincide with a star formation threshold. Over the past years, observational evidence for both old and young stellar populations, as well as individual H ii regions, has demonstrated that the outer disc is an actively evolving part of a galaxy. To provide constraints on the origin of the aforementioned Hα truncation and the relation of Hα emission in the outer disc to the underlying stellar population, we measure the shape of the outer Hα surface brightness profile of 15 isolated, edge-on late-type disc galaxies using deep, long-slit spectroscopy. Tracing Hα emission up to 50 per cent beyond the optical radius, R25, we find a composite Hα surface brightness profile, well described by a broken-exponential law, that drops more steeply in the outer disc, but which is not truncated. The stellar continuum and Hα surface brightness both exhibit a break at , but the Hα emission drops more steeply than the stellar continuum beyond that break. Although profiles with truncations or single exponential laws correctly describe the Hα surface brightness profiles of some individual galaxies, flexible broken exponentials are required in most cases and are therefore the more appropriate generic description. The common existence of a significant second surface brightness component beyond the Hα break radius disfavours the hypothesis that this break is a purely stochastic effect. [ABSTRACT FROM AUTHOR]

We present a Very Large Telescope/Focal Reducer and Low Dispersion Spectrograph #1 (VLT/FORS1) imaging and spectroscopic survey of the Wolf–Rayet (WR) population in the Sculptor group spiral galaxy NGC 7793. We identify 74 emission-line candidates from archival narrow-band imaging, from which 39 were observed with the Multi Object Spectroscopy mode of FORS1. 85 per cent of these sources displayed WR features. Additional slits were used to observe H ii regions, enabling an estimate of the metallicity gradient of NGC 7793 using strong line calibrations, from which a central oxygen content of (O/H) + 12 = 8.6 was obtained, falling to 8.25 at . We have estimated WR populations using a calibration of line luminosities of Large Magellanic Cloud stars, revealing ∼27 WN and ∼25 WC stars from 29 sources spectroscopically observed. Photometric properties of the remaining candidates suggest an additional ∼27 WN and ∼8 WC stars. A comparison with the WR census of the LMC suggests that our imaging survey has identified ∼80 per cent of WN stars and ∼90 per cent for the WC subclass. Allowing for incompleteness, NGC 7793 hosts ∼105 WR stars for which N(WC)/ N(WN) ∼ 0.5. From our spectroscopy of H ii regions in NGC 7793, we revise the global H star formation rate of Kennicutt et al. upward by 50 per cent to 0.45 M yr−1. This allows us to obtain N(WR)/ N(O) ∼ 0.018, which is somewhat lower than that resulting from the WR census by Schild et al. of another Sculptor group spiral NGC 300, whose global physical properties are similar to NGC 7793. Finally, we also report the fortuitous detection of a bright ( mag) background quasar Q2358-32 at resulting from C iv 1548-51 redshifted to the 4684 passband. [ABSTRACT FROM AUTHOR]

We present the results of long-slit spectroscopy in several slit positions that cover different morphological structures of the central parts of three bright Galactic H ii regions: M8, M17 and NGC 7635. We study the spatial distributions of a large number of nebular parameters, such as the extinction coefficient, line fluxes, physical conditions and ionic abundances at the maximum spatial resolution attainable with our instrumentation. Particularly, our goal is to study the behaviour of the abundance discrepancy factor of [ ], defined as the logarithmic difference of the abundances derived from collisionally excited and recombination lines. We find that remains fairly constant along the slit positions of M8 and M17. For NGC 7635, we only detect the O ii recombination lines in the integrated spectrum along the whole slit, where reaches a remarkably high value of about 0.59 dex. We compare our results with previous results obtained for the Orion Nebula. We find much evidence to suggest the presence of a candidate Herbig–Haro object in M8. [ABSTRACT FROM AUTHOR]

We combine results from interferometry, asteroseismology and spectroscopy to determine accurate fundamental parameters of 23 bright solar-type stars, from spectral type F5 to K2 and luminosity classes III–V. For some stars we can use direct techniques to determine the mass, radius, luminosity and effective temperature, and we compare with indirect methods that rely on photometric calibrations or spectroscopic analyses. We use the asteroseismic information available in the literature to infer an indirect mass with an accuracy of 4–15 per cent. From indirect methods we determine luminosity and radius to 3 per cent. We find evidence that the luminosity from the indirect method is slightly overestimated ( per cent) for the coolest stars, indicating that their bolometric corrections (BCs) are too negative. For we find a slight offset of K between the spectroscopic method and the direct method, meaning the spectroscopic temperatures are too high. From the spectroscopic analysis we determine the detailed chemical composition for 13 elements, including Li, C and O. The metallicity ranges from to , and there is clear evidence for α-element enhancement in the metal-poor stars. We find no significant offset between the spectroscopic surface gravity and the value from combining asteroseismology with radius estimates. From the spectroscopy we also determine and we present a new calibration of macroturbulence and microturbulence. From the comparison between the results from the direct and spectroscopic methods we claim that we can determine , and [Fe/H] with absolute accuracies of 80 K, 0.08 and 0.07 dex. Photometric calibrations of Strömgren indices provide accurate results for and [Fe/H] but will be more uncertain for distant stars when interstellar reddening becomes important. The indirect methods are important to obtain reliable estimates of the fundamental parameters of relatively faint stars when interferometry cannot be used. This paper is the first to compare direct and indirect methods for a large sample of stars, and we conclude that indirect methods are valid, although slight corrections may be needed. [ABSTRACT FROM AUTHOR]

We study the spectroscopic properties and environments of red (or passive) spiral galaxies found by the Galaxy Zoo project. By carefully selecting face-on disc-dominated spirals, we construct a sample of truly passive discs (i.e. they are not dust reddened spirals, nor are they dominated by old stellar populations in a bulge). As such, our red spirals represent an interesting set of possible transition objects between normal blue spiral galaxies and red early types, making up 6 per cent of late-type spirals. We use optical images and spectra from Sloan Digital Sky Survey to investigate the physical processes which could have turned these objects red without disturbing their morphology. We find red spirals preferentially in intermediate density regimes. However, there are no obvious correlations between red spiral properties and environment suggesting that environment alone is not sufficient to determine whether a galaxy will become a red spiral. Red spirals are a very small fraction of all spirals at low masses ( M⊙), but are a significant fraction of the spiral population at large stellar masses showing that massive galaxies are red independent of morphology. We confirm that as expected, red spirals have older stellar populations and less recent star formation than the main spiral population. While the presence of spiral arms suggests that a major star formation could not have ceased a long ago (not more than a few Gyr), we show that these are also not recent post-starburst objects (having had no significant star formation in the last Gyr), so star formation must have ceased gradually. Intriguingly, red spirals are roughly four times as likely than the normal spiral population to host optically identified Seyfert/low-ionization nuclear emission region (LINER; at a given stellar mass and even accounting for low-luminosity lines hidden by star formation), with most of the difference coming from the objects with LINER-like emission. We also find a curiously large optical bar fraction in the red spirals ( verses per cent in blue spirals) suggesting that the cessation of star formation and bar instabilities in spirals are strongly correlated. We conclude by discussing the possible origins of these red spirals. We suggest that they may represent the very oldest spiral galaxies which have already used up their reserves of gas – probably aided by strangulation or starvation, and perhaps also by the effect of bar instabilities moving material around in the disc. We provide an online table listing our full sample of red spirals along with the normal/blue spirals used for comparison. [ABSTRACT FROM AUTHOR]

We present a comparative study of the galactic and small-scale environments of gamma-ray bursts (GRBs) and core-collapse supernovae (CCSNe). We use a sample of 34 GRB hosts at , and a comparison sample of 58 supernova hosts located within the Great Observatories Origins Deep Survey footprint. We fit template spectra to the available photometric data, which span the range 0.45–24 μm, and extract absolute magnitudes, stellar masses and star formation rates from the resulting fits. Our results broadly corroborate previous findings, but offer significant enhancements in spectral coverage and a factor 2–3 increase in sample size. Specifically, we find that CCSNe occur frequently in massive spirals (spiral fraction ∼50 per cent). In contrast GRBs occur in small, relatively low mass galaxies with high specific and surface star formation rates, and have a spiral fraction of only ∼10 per cent. A comparison of the rest-frame absolute magnitudes of the GRB and CCSN sample is less conclusive than found in previous work, suggesting that while GRB hosts are typically both smaller and bluer than those of CCSN their total blue light luminosities are only slightly lower. We suggest this is likely due to rapid periods of intensified star formation activity, as indicated by the high specific SFRs, which both create the GRB progenitors and briefly significantly enhance the host galaxy blue luminosity. Finally, our analysis of local environments of GRBs and CCSNe shows that GRBs are highly concentrated on their host light, and further occur in regions of higher absolute surface luminosity than CCSNe. [ABSTRACT FROM AUTHOR]

It has been known for nearly three decades that high-redshift radio galaxies exhibit steep radio spectra, and hence ultrasteep spectrum radio sources provide candidates for high-redshift radio galaxies. Nearly all radio galaxies with have been found using this redshift–spectral index correlation. We have started a programme with the Giant Metrewave Radio Telescope (GMRT) to exploit this correlation at flux density levels about 10 to 100 times deeper than the known high-redshift radio galaxies which were identified primarily using the already available radio catalogues. In our programme, we have obtained deep, high-resolution radio observations at 150 MHz with GMRT for several ‘ deep’ fields which are well studied at higher radio frequencies and in other bands of the electromagnetic spectrum, with an aim to detect candidate high-redshift radio galaxies. In this paper we present results from the deep 150-MHz observations of the LBDS-Lynx field, which has been already imaged at 327, 610 and 1412 MHz with the Westerbork Synthesis Radio Telescope and at 1400 and 4860 MHz with the Very Large Array. The 150-MHz image made with GMRT has an rms noise of 0.7 mJy beam and a resolution of arcsec . It is the deepest low-frequency image of the LBDS-Lynx field. The source catalogue of this field at 150 MHz has about 765 sources down to 20 per cent of the primary beam response, covering an area of about 15 deg . Spectral index was estimated by cross-correlating each source detected at 150 MHz with the available observations at 327, 610, 1400 and 4860 MHz and also using available radio surveys such as the Westerbork Northern Sky Survey at 327 MHz and the NRAO VLA Sky Survey and Faint Images of the Radio Sky at Twenty-cm at 1400 MHz. We find about 150 radio sources with spectra steeper than 1. About two-third of these are not detected in the Sloan Digital Sky Survey, hence are strong candidate high-redshift radio galaxies, which need to be further explored with deep infrared imaging and spectroscopy to estimate the redshift. [ABSTRACT FROM AUTHOR]

To exploit synergies between the Herschel Space Observatory and next generation radio facilities, we have extended the semi-empirical extragalactic radio continuum simulation of Wilman et al. to the mid- and far-infrared. Here, we describe the assignment of infrared spectral energy distributions (SEDs) to the star-forming galaxies and active galactic nuclei, using Spitzer 24, 70 and 160 μm and SCUBA 850 μm survey results as the main constraints. Star-forming galaxies dominate the source counts, and a model in which their far-infrared–radio correlation and infrared SED assignment procedure are invariant with redshift underpredicts the observed 24 and 70 μm source counts. The 70 μm deficit can be eliminated if the star-forming galaxies undergo stronger luminosity evolution than originally assumed for the radio simulation, a requirement which may be partially ascribed to known non-linearity in the far-infrared–radio correlation at low luminosity if it evolves with redshift. At 24 μm, the shortfall is reduced if the star-forming galaxies develop SEDs with cooler dust and correspondingly stronger polycyclic aromatic hydrocarbon emission features with increasing redshift at a given far-infrared luminosity, but this trend may reverse at in order not to overproduce the submillimetre source counts. The resulting model compares favourably with recent Balloon-borne Large Aperture Submillimetre Telescope ( BLAST) results, and we have extended the simulation data base to aid the interpretation of Herschel surveys. Such comparisons may also facilitate further model refinement and revised predictions for the Square Kilometre Array and its precursors. [ABSTRACT FROM AUTHOR]

We report on optical high-dispersion spectroscopic monitoring observations of the Be/X-ray binary A0535+26/V725 Tau, carried out from 2005 November to 2009 March. The main aim of these monitoring observations is to study spectral variabilities in the Be disc, on both the short (a week or so) and long (more than hundreds of days) time-scales, by taking long-term frequent observations. Our four-year spectroscopic observations indicate that the V/R ratio, i.e. the relative intensity of the violet (V) peak with respect to the red (R) one, of the double-peaked Hα line profile varies with a period of 500 d. The Hβ line profile also varies in phase with the Hα profile. With these observations covering two full cycles of the V/R variability, we reconstruct the two-dimensional structure of the Be disc by applying the Doppler tomography method to the Hα and Hβ emission-line profiles, using a rigidly rotating frame with the V/R variability period. The resulting disc structure reveals non-axisymmetric features, which can be explained by a one-armed perturbation in the Be disc. It is the first time that an eccentric disc structure is directly detected by using a method other than the interferometric one. [ABSTRACT FROM AUTHOR]

We use a model for the evolution of galaxies in the far-infrared (far-IR) based on the Λ-cold dark matter cosmology to make detailed predictions for the upcoming cosmological surveys with the Herschel Space Observatory. We use the combined GALFORM semi-analytical galaxy formation model and GRASIL spectrophotometric code to compute galaxy spectral energy distribution (SEDs) including the reprocessing of radiation by dust. The model, which is the same as that in Baugh et al., assumes two different initial mass functions (IMFs): a normal solar neighbourhood IMF for quiescent star formation in discs, and a very top-heavy IMF in starbursts triggered by galaxy mergers. We have shown previously that the top-heavy IMF appears necessary to explain the number counts and redshifts of faint submillimetre galaxies. In this paper, we present predictions for galaxy luminosity functions, number counts and redshift distributions in the Herschel imaging bands. We find that source confusion will be a serious problem in the deepest planned surveys. We also show predictions for physical properties such as star formation rates and stellar, gas and halo masses, together with fluxes at other wavelengths (from the far-ultraviolet to the radio) relevant for multi-wavelength follow-up observations. We investigate what fraction of the total IR emission from dust and of the high-mass star formation over the history of the Universe should be resolved by planned surveys with Herschel, and find a fraction ∼30–50 per cent, depending on confusion. Finally, we show that galaxies in Herschel surveys should be significantly clustered. [ABSTRACT FROM AUTHOR]