We present a catalogue of galaxies in the northern Zone of Avoidance (ZoA), extracted from the shallow version of the blind HI survey with the Effelsberg 100m radio telescope, EBHIS, that has a sensitivity of 23mJy/beam at 10.24km/s velocity resolution. The catalogue comprises 170 detections in the region Dec>=-5{deg} and |b|<6{deg}. About a third of the detections (N=67) have not been previously recorded in HI. While 29 detections have no discernible counterpart at any wavelength other than HI, 48 detections (28%) have a counterpart visible on optical or NIR images but are not recorded as such in the literature. New HI detections were found as close as 7.5Mpc (EZOA J2120+45), and at the edge of the Local Volume, at 10.1Mpc, we have found two previously unknown dwarf galaxies (EZOA J0506+31 and EZOA J0301+56). Existing large-scale structures crossing the northern ZoA have been established more firmly by the new detections, with the possibility of new filaments. We conclude that the high rate of 39% new HI\detections in the northern ZoA, which has been extensively surveyed with targeted observations in the past, proves the power of blind HI surveys. The full EBHIS survey, which will cover the full northern sky with a sensitivity comparable to the HIPASS survey of the southern sky, is expected to add many new detections and uncover new structures in the northern ZoA.
We have used the Very Large Array (VLA) FIRST survey and the Automated Plate Measuring Facility (APM) catalog of the Palomar Observatory Sky Survey I (POSS-I) plates as the basis for constructing a new radio-selected sample of optically bright quasars. This is the first radio-selected sample that is competitive in size with current optically selected quasar surveys. Using only two basic criteria, radio-optical positional coincidence and optical morphology, quasars and BL Lac objects can be identified with 60% selection efficiency; the efficiency increases to 70% for objects fainter than 17 mag. We show that a more sophisticated selection scheme can predict with better than 85% reliability which candidates will turn out to be quasars. This paper presents the second installment of the FIRST Bright Quasar Survey (FBQS), with a catalog of 636 quasars distributed over 2682 deg^2^. The quasar sample is characterized and all spectra are displayed.
We present the results of an extension of the FIRST Bright Quasar Survey (FBQS) to the South Galactic cap, and to a fainter optical magnitude limit. Radio source counterparts with SERC R magnitudes brighter than 18.9 which meet the other FBQS criteria are included. We supplement this list with a modest number of additional objects to test our completeness for quasars with extended radio morphologies. The survey covers 589deg^2^ in two equatorial strips in the southern cap. We have obtained spectra for 86% of the 522 candidates and find 321 radio-selected quasars of which 264 are reported here for the first time. A comparison of this fainter sample with the FBQS sample shows the two to be generally similar. Fourteen new broad absorption line (BAL) quasars are included in this sample. When combined with the previously identified BAL quasars in our earlier papers, we can discern a break in the frequency of BAL quasars with radio loudness, namely that the relative number of high-ionization BAL quasars drops by a factor of 4 for quasars with a radio-loudness parameter R*>100.
he origin of carbon-enhanced metal-poor (CEMP) stars and their possible connection with the chemical elements produced by the first stellar generation is still highly debated. In contrast to the Galactic halo, not many CEMP stars have been found in the dwarf spheroidal galaxies around the Milky Way. Here we present detailed abundances from ESO VLT/UVES high-resolution spectroscopy for ET0097, the first CEMP star found in the Sculptor dwarf spheroidal, which is one of the best studied dwarf galaxies in the Local Group. This star has [Fe/H]=-2.03+/-0.10, [C/Fe]=0.51+/-0.10 and [N/Fe]=1.18+/-0.20, which is the first nitrogen measurement in this galaxy. The traditional definition of CEMP stars is [C/Fe]>=0.70, but taking into account that this luminous red giant branch star has undergone mixing, it was intrinsically less nitrogen enhanced and more carbon-rich when it was formed, and so it falls under the definition of CEMP stars, as proposed by Aoki et al. (2007ApJ...655..492A, Cat. J/ApJ/655/492) to account for this effect.
We present a new sample of distant ultraluminous infrared galaxies. The sample was selected from a positional cross-correlation of the IRAS Faint Source Catalog (Cat. <II/156>) with the FIRST database. Objects from this set were selected for spectroscopy by virtue of following the well-known star-forming galaxy correlation between 1.4 GHz and 60 {mu}m flux, and by being optically faint on the POSS. Optical identification and spectroscopy were obtained for 108 targets at the Lick Observatory 3 m telescope.
Using the Florida Multi-object Imaging Near-IR Grism Observational Spectrometer (FLAMINGOS), we have conducted the FLAMINGOS Extragalactic Survey (FLAMEX), a deep imaging survey covering 7.1{deg}^2^ within the 18.6{deg}^2^ NOAO Deep Wide-Field Survey (NDWFS) regions. FLAMEX is the first deep, wide-area, nearinfrared survey to image in both the J and Ks filters, and is larger than any previous NIR survey of comparable depth. The intent of FLAMEX is to facilitate the study of galaxy and galaxy cluster evolution at 1<z<2 by providing rest-frame optical photometry for the massive galaxy population at this epoch. This effort is designed to yield a public data set that complements and augments the suite of existing surveys in the NDWFS fields. We present an overview of FLAMEX and initial results based on ~150,000 Ks-selected sources in the Bootes field. We describe the observations and reductions, quantify the data quality, and verify that the number counts are consistent with results from previous surveys. Finally, we comment on the utility of this sample for detailed study of the ERO population, and present one of the first spectroscopically confirmed z>1 galaxy clusters detected using the joint FLAMEX, NDWFS, and Spitzer IRAC Shallow Survey data sets.
A possible pathway for understanding the events and the mechanisms involved in galaxy formation and evolution is an in-depth comprehension of the galactic and inter-galactic fossil sub-structures with long dynamical times-scales: stars in the field and in stellar clusters. This paper continues the series of the Fornax Deep Survey (FDS). Following the previous studies dedicated to extended Fornax cluster members, in this paper we present the catalogs of compact stellar systems in the Fornax cluster as well as extended background sources and point-like sources. We derive ugri photometry of ~1.7 million sources over the ~21 square degree area of FDS centered on the bright central galaxy NGC1399. For a wider area, of ~27 square degrees extending in the direction of NGC1316, we provide gri photometry for ~3.1 million sources. To improve the morphological characterization of sources we generate multi-band image stacks by coadding the best seeing gri-band single exposures with a cut at FWHM<=0.9". We use the multi-band stacks as master detection frames, with a FWHM improved by ~15% and a FWHM variability from field to field reduced by a factor of ~2.5 compared to the pass-band with best FWHM, namely the r-band. The identification of compact sources, in particular of globular clusters (GC), is obtained from a combination of photometric (e.g. colors, magnitudes) and morphometric (e.g. concentration index, elongation, effective radius) selection criteria, by also taking as reference the properties of sources with well-defined classification from spectroscopic or high-resolution imaging data. Using the FDS catalogs, we present a preliminary analysis of globular cluster (GC) distributions in the Fornax area. The study confirms and extends further previous results which were limited to a smaller survey area. We observe the inter-galactic population of GCs, a population of mainly blue GCs centered on NGC1399, extends over ~0.9Mpc, with an ellipticity ~0.65 and a small tilt in the direction of NGC1336. Several sub-structures extend over ~0.5Mpc along various directions. Two of these structures do not cross any bright galaxy; one of them appears to be connected to NGC1404, a bright galaxy close to the cluster core and particularly poor of GCs. Using the gri catalogs we analyze the GC distribution over the extended FDS area, and do not find any obvious GC sub-structure bridging the two brightest cluster galaxies, NGC1316 and NGC1399. Although NGC1316 is more than twice brighter of NGC1399 in optical bands, using gri data, we estimate a factor of ~3-4 richer GC population around NGC1399 compared to NGC1316, out to galactocentric distances of ~40' or ~230kpc
We present a catalogue and atlas of low-resolution spectra of a sample of 341 objects with reliable redshifts in the FORS Deep Field (FDF). The sample contains 42 stars, 8 QSOs, and 291 galaxies up to z=5.98 objects are at z>2. For z>1 most objects were selected using photometric redshifts. The limiting I magnitude has been I=24.5 for 2<z<4. All spectra were obtained using the FORS instruments at the ESO VLT and cover the wavelength range 3300-10000{AA}. The grism 150I with a 1" slit width was used, resulting in a spectral resolution element of our spectra of 18-24{AA}, depending on the light distribution in the slit. Most objects were observed several times. Typical exposure times were about 10h for our z>2 objects. The individual spectra were S/N-optimised co-added. The final spectra were flux calibrated, smoothed to the resolution element, and corrected for atmospheric extinction. Moreover, the spectra were corrected for the atmospheric A and B bands. Redshifts and rough object types were derived by cross-correlation of the galaxy spectra with six template spectra, which had been created from high-quality FDF spectroscopic data by an iterative procedure.
Studies of the stellar and the HI gas kinematics in dwarf and Low Surface Brightness (LSB) galaxies are essential for deriving constraints on their dark matter distribution. Moreover, a key component to unveil in the evolution of LSBs is why some of them can be classified as superthin. We aim to investigate the nature of the proto-typical superthin galaxy Fourcade-Figueroa (FF), to understand the role played by the dark matter halo in forming its superthin shape and to investigate the mechanism that explains the observed disruption in the approaching side of the galaxy. Combining new HI 21-cm observations obtained with the Giant Metrewave Radio Telescope with archival data from the Australia Telescope Compact Array we were able to obtain sensitive HI observations of the FF galaxy. These data were modeled with a 3D tilted ring model in order to derive the rotation curve and surface brightness density of the neutral hydrogen. We subsequently used this model, combined with a stellar profile from the literature, to derive the radial distribution of the dark matter in the FF galaxy. Additionally, we used a more direct measurement of the vertical HI gas distribution as a function of the galactocentric radius to determine the flaring of the gas disk. For the FF galaxy the Navarro-Frenk-White dark matter distribution provides the best fit to the observed rotation curve. However, the differences with a pseudo-isothermal halo are small. Both models indicate that the core of the dark matter halo is compact. Even though the FF galaxy classifies as superthin, the gas thickness about the galactic centre exhibits a steep flaring of the gas which is in agreement with the edge of the stellar disk. Besides, FF is clearly disrupted towards its north-west-side, clearly observed at both, optical and HI wavelengths. As suggested previously in the literature, the compact dark matter halo might be the main responsible for the superthin structure of the stellar disk in FF. This idea is strengthened through the detection of the mentioned disruption; the fact that the galaxy is disturbed also seems to support the idea that it is not isolation that cause its superthin structure.
The Murchison Widefield Array (MWA) has observed the entire southern sky (Declination, {delta}<30{deg}) at low radio-frequencies, over the range 72-231MHz. These observations constitute the GaLactic and Extragalactic All-sky MWA (GLEAM) Survey, and we use the extragalactic catalogue (Galactic latitude, |b|>10{deg}) to define the GLEAM 4-Jy (G4Jy) Sample. This is a complete sample of the 'brightest' radio-sources (S_151MHz_>4Jy), the majority of which are active galactic nuclei with powerful radio-jets. Crucially, low-frequency observations allow the selection of such sources in an orientation-independent way (i.e. minimising the bias caused by Doppler boosting, inherent in high-frequency surveys). We then use higher-resolution radio images, and information at other wavelengths, to morphologically classify the brightest components in GLEAM. We also conduct cross-checks against the literature, and perform internal matching, in order to improve sample completeness (which is estimated to be >95.5%). This results in a catalogue of 1,863 sources, making the G4Jy Sample over 10 times larger than that of the revised Third Cambridge Catalogue of Radio Sources (3CRR; S_178MHz_>10.9Jy). Of these G4Jy sources, 78 are resolved by the MWA (Phase-I) synthesised beam (~2' at 200MHz), and we label 67% of the sample as 'single', 26% as 'double', 4% as 'triple', and 3% as having 'complex' morphology at ~1GHz (45" resolution). We characterise the spectral behaviour of these objects in the radio, and find that the median spectral-index is {alpha}=-0.740+/-0.012 between 151MHz and 843MHz, and {alpha}=-0.786+/-0.006 between 151MHz and 1400MHz (assuming a power-law description, S_{nu}_{prop.to}{nu}^{alpha}^), compared to {alpha}=-0.829+/-0.006 within the GLEAM band. Alongside this, our value-added catalogue provides mid-infrared source associations (subject to 6" resolution at 3.4um) for the radio emission, as identified through visual inspection and thorough checks against the literature. As such, the G4Jy Sample can be used as a reliable training set for cross-identification via machine-learning algorithms. We also estimate the angular size of the sources, based on their associated components at ~1GHz, and perform a flux-density comparison for 67 G4Jy sources that overlap with 3CRR. Analysis of multi-wavelength data, and spectral curvature between 72MHz and 20GHz, will be presented in subsequent papers, and details for accessing all G4Jy overlays are provided at https://github.com/svw26/G4Jy.
