A deep survey of the European Large-Area ISO Survey (ELAIS) field in the southern celestial hemisphere (hereinafter S1) has been carried out with the Australia Telescope Compact Array (ATCA) at 1.4GHz. The S1 region, covering about 4deg^2^, has also been surveyed in the mid- and far-infrared (5-200mm) with the Infrared Space Observatory (ISO). The radio survey provides uniform coverage of the entire S1 region, with a sensitivity (5{sigma}) of 0.4mJy over the whole area and 0.2mJy in the centre. To this sensitivity, virtually all the radio counterparts of the far-infrared extragalactic ISO sources should be detected. This paper presents a radio sample -- complete at the 5{sigma} level -- consisting of 581 sources detected at 1.4GHz. Of these radio sources, 349 have peak flux density in the range 0.2-1mJy, forming a new homogeneous sample of sub-mJy radio sources. Due to its size, depth and multiwaveband coverage, the sample will allow us to study in greater detail the sub-mJy radio source population.
We develop a new data reduction technique for ISOCAM LW data and apply it to the European Large Area ISO Survey (ELAIS) LW3 (15-{mu}m) observations in the southern hemisphere (S1). This method, known as LARI technique and based on the assumption of the existence of two different time-scales in ISOCAM transients (accounting for either fast or slow detector response), is particularly designed for the detection of faint sources. In the ELAIS S1 field we obtain a catalogue of 462 15-{mu}m sources with signal-to-noise ratios >=5 and flux densities in the range 0.45-150mJy (filling the whole flux range between the Deep ISOCAM Surveys and the IRAS Faint Source Survey). The completeness at different flux levels and the photometric accuracy of this catalogue are tested with simulations. Here we present a detailed description of the method and discuss the results obtained by its application to the S1 LW3 data.
The FIRBACK (Far Infrared BACKground) survey is one of the deepest imaging surveys carried out at 170{mu}m with ISOPHOT onboard ISO, and is aimed at the study of the structure of the Cosmic Far Infrared Background. This paper provides the analysis of resolved sources. After a validated process of data reduction and calibration, we perform intensive simulations to optimize the source extraction, measure the confusion noise ({sigma}_c_=45mJy), and give the photometric and astrometric accuracies. 196 galaxies with flux S>3{sigma}_c_ are detected in the area of 3.89 square degrees. Counts of sources with flux S>4{sigma}_c_ present a steep slope of 3.3+/-0.6 on a differential ``logN-logS'' plot between 180 and 500mJy. As a consequence, the confusion level is high and will impact dramatically on future IR deep surveys. This strong evolution, compared with a slope of 2.5 from Euclidian geometry, is in line with models implying a strongly evolving Luminous Infrared Galaxy population. The resolved sources account for less than 10% of the Cosmic Infrared Background at 170{mu}m, which is expected to be resolved into sources in the 1 to 10mJy range.
We present a study of ISOGAL sources in the "intermediate" galactic bulge (|l|<2{deg}, |b|~1{deg}-4{deg}), observed by ISOCAM at 7 and 15{mu}m. In combination with near-infrared (I, J, Ks) data of DENIS survey, complemented by 2MASS data, we discuss the nature of the ISOGAL sources, their luminosities, the interstellar extinction and the mass-loss rates. A large fraction of the 1464 detected sources at 15{mu}m are AGB stars above the RGB tip, a number of them show an excess in ([7]-[15])_0_ and (Ks-[15])_0_ colours, characteristic of mass-loss. The latter, especially (Ks-[15])_0_, provide estimates of the mass-loss rates and show their distribution in the range 10^-8^ to 10^-5^M_{sun}_/yr.
We have developed a new ISOCAM data reduction technique based on wavelet analysis, especially designed for the detection of faint sources in mid-infrared surveys. This method, the Pattern REcognition Technique for Isocam data (PRETI) has been used to reduce the observations of the Hubble Deep Field (HDF) and flanking fields with ISOCAM at 6.75 (LW2) and 15{mu}m (LW3) (Rowan-Robinson et al. 1997MNRAS.289..490R). Simulations of ISOCAM data allow us to test the photometric accuracy and completeness of the reduction. According to these simulations, the PRETI source list is 95% complete in the 15{mu}m band at 200{mu}Jy and in the 6.75{mu}m band at 65{mu}Jy, using detection thresholds which minimize the number of false detections. We detect 49 objects in the ISO-HDF at high confidence secure level, 42 in the LW3 filter, 3 in the LW2 filter, and 4 in both filters. An additional, less secure, list of 100 sources is presented, of which 89 are detected at 15{mu}m only, 7 at 6.75{mu}m only and 4 in both filters. All ISO-HDF objects detected in the HDF itself have optical or infrared counterparts, except for one from the additional list. All except one of the radio sources detected in the field by Fomalont et al. (1997ApJ...475L...5F) are detected with ISOCAM. Using a precise correction for the field of view distortion of ISOCAM allows us to separate blended sources. This, together with the fact that PRETI allows to correct data on the tail of cosmic rays glitches, lead us to produce deeper source lists than previous authors. Our list of bright sources agree with those of Desert et al. (1999A&A...342..363D) in both filters, and with those of Goldschmidt et al. (1997MNRAS.289..465G) in the LW3 filter, with systematic difference in photometry. ISO is an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands and the United Kingdom) and with participation of ISAS and NASA.
This database is the ISO (Infrared Space Observatory) Observation Log of Validated Data. ISO is an ESA (European Space Agency) project with instruments funded by ESA member states (especially the PI countries of France, Germany, the Netherlands and the United Kingdom), and with the participation of ISAS (Japan) and NASA (USA). ISO operated from November 1995 till May 1998, almost a year longer than expected. As an unprecedented observatory for infrared astronomy, able to examine the cool and hidden places in the Universe, ISO successfully made nearly 30,000 scientific observations. The ISO data can be retrieved from the ISO Data Archive (<a href="http://iso.esac.esa.int/ida/">http://iso.esac.esa.int/ida/</a>), which is available at the ISO Data Centre (<a href="http://iso.esac.esa.int/">http://iso.esac.esa.int/</a>), and comprises about 150,000 observations, including calibration, parallel mode and serendipitous observations. The present catalog contains all observations performed in standard observing modes exempt from technical problems; special flags indicate calibration observations. The catalog gives observation details and provides links to quick-look images depicting the data and to observation-specific documentation. The ISO helpdesk can be reached at <a href="http://iso.esac.esa.int/esupport/">http://iso.esac.esa.int/esupport/</a> This online catalog was last updated by the HEASARC in September 2004 based on the machine-readable table <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VI/111/isolog.dat.gz">https://cdsarc.cds.unistra.fr/ftp/cats/VI/111/isolog.dat.gz</a> obtained from the CDS data center. This is a service provided by NASA HEASARC .
Compact elliptical galaxies form a rare class of stellar system (~30 presently known) characterized by high stellar densities and small sizes and often harboring metal-rich stars. They were thought to form through tidal stripping of massive progenitors, until two isolated objects were discovered where massive galaxies performing the stripping could not be identified. By mining astronomical survey data, we have now found 195 compact elliptical galaxies in all types of environment. They all share similar dynamical and stellar population properties. Dynamical analysis for nonisolated galaxies demonstrates the feasibility of their ejection from host clusters and groups by three-body encounters, which is in agreement with numerical simulations. Hence, isolated compact elliptical and isolated quiescent dwarf galaxies are tidally stripped systems that ran away from their hosts.
We determine some parameters of the far infrared radiation for a sample of isolated galaxies, namely, luminosity, color indices, dust temperature, and current star formation rate and efficiency.
The construction of catalogues of galaxies and the posterior study of galaxy properties in relation to their environment, have been hampered by the scarce redshift information. The new 3-dimensional (3D) surveys permit to distinguish small, faint, physically bound satellites from a background projected galaxy population, giving a more comprehensive 3D picture of the surroundings. We aim to provide representative samples of isolated galaxies, isolated pairs, and isolated triplets for testing galaxy evolution and secular processes in low density regions of the local Universe, as well as to characterise their local and large-scale environments. We use spectroscopic data from the tenth data release of the Sloan Digital Sky Survey (SDSS-DR10) to automatically and homogeneously compile catalogues of 3,702 isolated galaxies, 1,240 isolated pairs, and 315 isolated triplets in the local Universe (z<=0.080). To quantify the effects of their local and large-scale environments, we compute the projected density and the tidal strength for the brightest galaxy in each sample. We find evidence of isolated pairs and isolated triplets physically bound at projected separation up to d<=450kpc with radial velocity difference {Delta}v<=160km/s, where the effect of the companion typically accounts for more than 98% of the total tidal strength affecting the central galaxy. For galaxies in the catalogues, we provide their positions, redshifts, and degrees of relation with their physical and large-scale environments. The catalogues are publicly available to the scientific community. For isolated galaxies, isolated pairs, and isolated triplets there is no difference in their degree of interaction with the large-scale structure (up to 5Mpc), which may suggest that they have a common origin in their formation and evolution. We find that most of them belong to the outer parts of filaments, walls, and clusters, and generally differ from the void population of galaxies.
The present paper is devoted to the construction of a catalog of isolated galaxy pairs extracted from the HyperLEDA extragalactic database. The radial velocities of the galaxies in the pairs are in the range [3000, 16000]km/s. In order to get an unbiased pair catalog as complete as possible, we have limited the absolute magnitude of the galaxies to M<=-18.5). The criteria used to define the isolated galaxy pairs are the following: 1) Velocity criterion: radial velocity difference between the pair members {Delta}V<500km/s; 2) Interdistance criterion: projected distance between the members r_p_<1Mpc; 3) Reciprocity criterion: each member is the closest galaxy to the other one, which excludes multiplets; 4) Isolation criterion: we define a pair as isolated if the ratio {rho}=r_3_/r_p_ of the projected distance of the pair to its closest galaxy (this one having a velocity difference lower than 500km/s with respect to the pair) and the members projected interdistance r_p is larger than 2.5. We have searched for these closest galaxies first in HyperLEDA M-limited source catalog, then in the full one. We have managed not to suppress the small number of pairs having close-by but faint dwarf galaxy companions. The galaxy pair catalog lists the value of {rho} for each isolated pair. This method allows the user of the catalog to select any isolation level (beyond the chosen limit {rho}>2.5). Our final catalog contains 13114 galaxy pairs, of which 57% are fairly isolated with {rho}>5, and 30% are highly isolated with {rho}>=10.