Aims: We present the stellar mass functions (SMFs) of star-forming and quiescent galaxies from observations of ten rich, red-sequence selected, clusters in the Gemini Cluster Astrophysics... Show moreAims: We present the stellar mass functions (SMFs) of star-forming and quiescent galaxies from observations of ten rich, red-sequence selected, clusters in the Gemini Cluster Astrophysics Spectroscopic Survey (GCLASS) in the redshift range 0.86 {lt} z {lt} 1.34. We compare our results with field measurements at similar redshifts using data from a K$_s$-band selected catalogue of the COSMOS/UltraVISTA field. Methods: We construct a K$_s$-band selected multi-colour catalogue for the clusters in eleven photometric bands covering u-8 {$μ$}m, and estimate photometric redshifts and stellar masses using spectral energy distribution fitting techniques. To correct for interlopers in our cluster sample, we use the deep spectroscopic component of GCLASS, which contains spectra for 1282 identified cluster and field galaxies taken with Gemini/GMOS. This allowed us to correct cluster number counts from a photometric selection for false positive and false negative identifications. Both the photometric and spectroscopic samples are sufficiently deep that we can probe the SMF down to masses of 10$^{10}$ M$_{⊙}$. Results: We distinguish between star-forming and quiescent galaxies using the rest-frame U - V versus V - J diagram, and find that the best-fitting Schechter parameters {$α$} and M$^{∗}$ are similar within the uncertainties for these galaxy types within the different environments. However, there is a significant difference in the shape and normalisation of the total SMF between the clusters and the field sample. This difference in the total SMF is primarily a reflection of the increased fraction of quiescent galaxies in high-density environments. We apply a simple quenching model that includes components of mass- and environment-driven quenching, and find that in this picture 45$_{-3}$$^{+4}$% of the star-forming galaxies, which normally would be forming stars in the field, are quenched by the cluster. Conclusions: If galaxies in clusters and the field quench their star formation via different mechanisms, these processes have to conspire in such a way that the shapes of the quiescent and star-forming SMF remain similar in these different environments. Appendices are available in electronic form at http://www.aanda.orgShow less
Beltrán, M.; Olmi, L.; Cesaroni, R.; Schisano, E.; Elia, D.; Molinari, S.; ... ; Thompson, M. 2013
Context. G29.96-0.02 is a high-mass star-forming cloud observed at 70, 160, 250, 350, and 500 {$μ$}m as part of the Herschel survey of the Galactic plane (Hi-GAL) during the science demonstration... Show moreContext. G29.96-0.02 is a high-mass star-forming cloud observed at 70, 160, 250, 350, and 500 {$μ$}m as part of the Herschel survey of the Galactic plane (Hi-GAL) during the science demonstration phase. Aims: We wish to conduct a far-infrared study of the sources associated with this star-forming region by estimating their physical properties and evolutionary stage, and investigating the clump mass function, the star formation efficiency and rate in the cloud. Methods: We have identified the Hi-GAL sources associated with the cloud, searched for possible counterparts at centimeter and infrared wavelengths, fitted their spectral energy distribution and estimated their physical parameters. Results: A total of 198 sources have been detected in all 5 Hi-GAL bands, 117 of which are associated with 24 {$μ$}m emission and 87 of which are not associated with 24 {$μ$}m emission. We called the former sources 24 {$μ$}m-bright and the latter ones 24 {$μ$}m-dark. The [70-160] color of the 24 {$μ$}m-dark sources is smaller than that of the 24 {$μ$}m-bright ones. The 24 {$μ$}m-dark sources have lower L$_{bol}$ and L$_{bol}$/M$_{env}$ than the 24 {$μ$}m-bright ones for similar M$_{env}$, which suggests that they are in an earlier evolutionary phase. The G29-SFR cloud is associated with 10 NVSS sources and with extended centimeter continuum emission well correlated with the 70 {$μ$}m emission. Most of the NVSS sources appear to be early B or late O-type stars. The most massive and luminous Hi-GAL sources in the cloud are located close to the G29-UC region, which suggests that there is a privileged area for massive star formation toward the center of the G29-SFR cloud. Almost all the Hi-GAL sources have masses well above the Jeans mass but only 5% have masses above the virial mass, which indicates that most of the sources are stable against gravitational collapse. The sources with M$_{env}$ {gt} M$_{virial}$ and that should be undergoing collapse and forming stars are preferentially located at {lsim}4' of the G29-UC region, which is the most luminous source in the cloud. The overall SFE of the G29-SFR cloud ranges from 0.7 to 5%, and the SFR ranges from 0.001 to 0.008 M$_{⊙}$ yr$^{-1}$, consistent with the values estimated for Galactic Hii regions. The mass spectrum of the sources with masses above 300 M$_{⊙}$, well above the completeness limit, can be well-fitted with a power law of slope {$α$} = 2.15 {plusmn} 0.30, consistent with the values obtained for the whole l = 30{deg}, associated with high-mass star formation, and l = 59{deg}, associated with low- to intermediate-mass star formation, Hi-GAL SDP fields. Tables 1-3 are available in electronic form at http://www.aanda.orgShow less
Gregorio-Monsalvo, I.; Ménard, F.; Dent, W.; Pinte, C.; López, C.; Klaassen, P.D.; ... ; Van Kempen, T. 2013
Aims: The aim of this work is to study the structure of the protoplanetary disk surrounding the Herbig Ae star HD 163296. Methods: We used high-resolution and high-sensitivity ALMA observations... Show moreAims: The aim of this work is to study the structure of the protoplanetary disk surrounding the Herbig Ae star HD 163296. Methods: We used high-resolution and high-sensitivity ALMA observations of the CO(3-2) emission line and the continuum at 850 {$μ$}m, as well as the three-dimensional Monte Carlo radiative transfer code, MCFOST, to model the data presented in this work. Results: The CO(3-2) emission unveils for the first time at submillimeter frequencies the vertical structure details of a gaseous disk in Keplerian rotation, showing the back and front sides of a flared disk. Continuum emission at 850 {$μ$}m reveals a compact dust disk with a 240 AU outer radius and a surface brightness profile that shows a very steep decline at radius larger than 125 AU. The gaseous disk is more than two times larger than the dust disk, with a similar critical radius but with a shallower radial profile. Radiative transfer models of the continuum data confirm the need for a sharp outer edge to the dust disk. The models for the CO(3-2) channel map require the disk to be slightly more geometrically thick than previous models suggested, and that the temperature at which CO gas becomes depleted (i.e., frozen out) from the outer regions of the disk midplane is T {lt} 20 K, in agreement with previous studies. Show less
Context. Dust is commonly present in weakly radio emitting star-forming galaxies and this dust may obscure the signatures of accreting black holes in these objects. Aims: We aim to uncover weak... Show moreContext. Dust is commonly present in weakly radio emitting star-forming galaxies and this dust may obscure the signatures of accreting black holes in these objects. Aims: We aim to uncover weak active galactic nuclei, AGN, in the faint radio source population by means of deep high-resolution radio observations. Methods: VLBI observations with a world-wide array at unparallelled sensitivity are carried out to assess the nature of the faint radio source population in the Hubble deep field north and its flanking fields. Results: Images of twelve compact, AGN-driven radio sources are presented. These represent roughly one quarter of the detectable faint radio source sample. Most, but not all of these low power AGN have X-ray detections. Conclusions: The majority of the faint radio source population must be star-forming galaxies. Faint AGN occur in a variety of (distant) host galaxies, and these are often accompanied by a dust-obscured starburst. Deep, high-resolution VLBI is a unique, powerful technique to assess the occurrence of faint AGN. Show less
Garrett, M.A.; Röttgering, H.J.A.; Jong, A.W. de; Iacobelli, M.; et al 2013
The low frequency array (LOFAR), is the first radio telescope designed with the capability to measure radio emission from cosmic-ray induced air showers in parallel with interferometric... Show moreThe low frequency array (LOFAR), is the first radio telescope designed with the capability to measure radio emission from cosmic-ray induced air showers in parallel with interferometric observations. In the first ~{}2 years of observing, 405 cosmic-ray events in the energy range of 10$^{16}$-10$^{18}$ eV have been detected in the band from 30-80 MHz. Each of these air showers is registered with up to ~{}1000 independent antennas resulting in measurements of the radio emission with unprecedented detail. This article describes the dataset, as well as the analysis pipeline, and serves as a reference for future papers based on these data. All steps necessary to achieve a full reconstruction of the electric field at every antenna position are explained, including removal of radio frequency interference, correcting for the antenna response and identification of the pulsed signal. Show less
Janssen, R.M.J.; Röttgering, H.J.A.; Best, P.N.; Brinchmann, J. 2012
Context. Current instrument developments at the largest telescopes worldwide involve the installation of multi-conjugated adaptive optics (MCAO) modules. The large field of view and more uniform... Show moreContext. Current instrument developments at the largest telescopes worldwide involve the installation of multi-conjugated adaptive optics (MCAO) modules. The large field of view and more uniform correction provided by these systems is not only highly beneficial for photometric studies but also for astrometric analysis of, e.g., large dense clusters and exoplanet detection and characterization. The Multi-conjugated Adaptive optics Demonstrator (MAD) is the first such instrument and was temporarily installed and tested at the ESO/VLT in 2007. Aims: We analyzed the first available MCAO imaging data in the layer-oriented mode obtained with the MAD instrument in terms of astrometric precision and stability. Methods: We analyzed two globular cluster data sets in terms of achievable astrometric precision. Data were obtained in the layer-oriented correction mode, one in full MCAO correction mode with two layers corrected (NGC 6388) and the other applying ground-layer correction only (47 Tuc). We calculated Strehl maps for each frame in both data sets. Distortion corrections were performed and the astrometric precision was analyzed by calculating mean stellar positions over all frames and by investigating the positional residuals present in each frame after transformation to a master-coordinate frame. Results: The mean positional precision for stars of brightnesses K = 14-18 mag is ≈ 1.2 mas in the full MCAO correction mode data of the cluster NGC 6388. The precision measured in the GLAO data (47 Tuc) reaches ≈1.0 mas for stars corresponding to 2MASS K magnitudes between 9 and 12. The observations were such that stars in these magnitude ranges correspond to the same detector flux range. The jitter movement used to scan a larger field of view introduced additional distortions in the frames, leading to a degradation of the achievable precision. Show less
Zhang, Y.; Moerkens, M.; Ramaiahgari, S.; Bont, H.J.G.M. de; Price, L.S.; Meerman, J.H.N.; Water, B. van de 2011
