Wide-field mid-infrared and millimetre imaging of the high-redshift radio galaxy, 4C41.17

We present deep 350- and 1200-micron imaging of the region around 4C41.17 -- one of the most distant (z = 3.792) and luminous known radio galaxies -- obtained with the Submillimeter High Angular Resolution Camera (SHARC-II) and the Max Planck Millimeter Bolometer Array (MAMBO). The radio galaxy is robustly detected at 350- and 1200-micron, as are two nearby 850-micron-selected galaxies; a third 850-micron source is detected at 350-micron and coincides with a ~ 2-sigma feature in the 1200-micron map. Further away from the radio galaxy an additional nine sources are detected at 1200-micron, bringing the total number of detected (sub)millimeter selected galaxies (SMGs) in this field to 14. Using radio images from the Very Large Array (VLA) and Spitzer mid-infrared (mid-IR) data, we find statistically robust radio and/or 24-micron counterparts to eight of the 14 SMGs in the field around 4C41.17. Follow-up spectroscopy with Keck/LRIS has yielded redshifts for three of the eight robustly identified SMGs, placing them in the redshift range 0.5 < z < 2.7, i.e. well below that of 4C41.17. We infer photometric redshifts for a further four sources using their 1.6-micron (rest-frame) stellar feature as probed by the IRAC bands; only one of them is likely to be at the same redshift as 4C41.17. Thus at least four, and as many as seven, of the SMGs within the 4C41.17 field are physically unrelated to the radio galaxy. With the redshift information at hand we are able to constrain the observed over-densities of SMGs within radial bins stretching to R=50 and 100" (~ 0.4 and ~ 0.8Mpc at z ~ 3.8) from the radio galaxy to ~ 5x and ~ 2x that of the field, dropping off to the background value at R=150". [Abridged]Comment: 20 pages, 9 figures, accepted for publication in MNRA

Generation of Porous Structures Using Fused Deposition

The Fused Deposition Modeling process uses hardware and software machine-level language that are very similar to that of a pen-plotter. Consequently, the·use of patterns with poly-lines as basic geometric features, instead of the current method based on filled polygons (monolithic models), can increase its efficiency. In the current study, various toolpath planning methods have been developed to fabricate porous structures. Computational domain decomposition methods can be applied to the physical or to slice-level domains to generate structured and unstructured grids. Also, textures can be created using periodic tiling of the layer with unit cells (squares, honeycombs, etc). Methods 'based on curves include fractal space filling curves and.change of effective road width Within a layer or within a continuous curve. Individual phases can also be placed in binary compositions. In present investigation, a custom software has been developed and implemented to generate build files (SML) and slice files (SSL) for the above-mentioned structures, demonstrating the efficient control ofthe size, shape, and distribution ofporosity.Mechanical Engineerin

Quasars in the MAMBO blank field survey

Our MAMBO 1.2 mm blank field imaging survey of ~0.75 sqd has uncovered four unusually bright sources, with flux densities between 10 and 90 mJy, all located in the Abell 2125 field. The three brightest are flat spectrum radio sources with bright optical and X-ray counterparts. Their mm and radio flux densities are variable on timescales of months. Their X-ray luminosities classify them as quasars. The faintest of the four mm bright sources appears to be a bright, radio-quiet starburst at z~3, similar to the sources seen at lower flux densities in the MAMBO and SCUBA surveys. It may also host a mildly obscured AGN of quasar-like X-ray luminosity. The three non-thermal mm sources imply an areal density of flat spectrum radio sources higher by at least 7 compared with that expected from an extrapolation of the lower frequency radio number counts.Comment: 8 pages, 7 figures. Accepted for publication by A&

First detection of [CII]158um at high redshift: vigorous star formation in the early universe

We report the detection of the 2P_3/2 -> 2P_1/2 fine-structure line of C+ at 157.74 micron in SDSSJ114816.64+525150.3 (hereafter J1148+5251), the most distant known quasar, at z=6.42, using the IRAM 30-meter telescope. This is the first detection of the [CII] line at high redshift, and also the first detection in a Hyperluminous Infrared Galaxy (L_FIR > 10^13 Lsun). The [CII] line is detected at a significance level of 8 sigma and has a luminosity of 4.4 x 10^9 Lsun. The L_[CII]/L_FIR ratio is 2 x 10^-4, about an order of magnitude smaller than observed in local normal galaxies and similar to the ratio observed in local Ultraluminous Infrared Galaxies. The [CII] line luminosity indicates that the host galaxy of this quasar is undergoing an intense burst of star formation with an estimated rate of ~3000 Msun/yr. The detection of C+ in SDSS J1148+5251 suggests a significant enrichment of metals at z ~ 6 (age of the universe ~870 Myr), although the data are consistent with a reduced carbon to oxygen ratio as expected from chemical evolutionary models of the early phases of galaxy formation.Comment: 5 pages, 2 figures, accepted by A&A Letter

Confirmation of the VeLLO L1148-IRS: Star Formation at very low (Column) Density

We report the detection of a compact (of order 5 arcsec; about 1800 AU projected size) CO outflow from L1148-IRS. This confirms that this Spitzer source is physically associated with the nearby (about 325 pc) L1148 dense core. Radiative transfer modeling suggests an internal luminosity of 0.08 to 0.13 L_sun. This validates L1148-IRS as a Very Low Luminosity Object (VeLLO; L < 0.1 L_sun). The L1148 dense core has unusually low densities and column densities for a star-forming core. It is difficult to understand how L1148-IRS might have formed under these conditions. Independent of the exact final mass of this VeLLO (which is likely < 0.24 M_sun), L1148-IRS and similar VeLLOs might hold some clues about the isolated formation of brown dwarfs.Comment: accepted to MNRAS; Figure 1 degraded to permit submissio

Properties of mm galaxies: Constraints from K-band blank fields

We have used the IRAM Plateau de Bure mm interferometer to locate with subarcsecond accuracy the dust emission of three of the brightest 1.2mm sources in the NTT Deep Field (NDF) selected from our 1.2mm MAMBO survey at the IRAM 30m telescope. We combine these results with deep B to K imaging and VLA interferometry. Strikingly, none of the three accurately located mm galaxies MMJ120546-0741.5, MMJ120539-0745.4, and MMJ120517-0743.1 has a K-band counterpart down to the faint limit of K>21.9. This implies that these three galaxies are either extremely obscured and/or are at very high redshifts (z>~4). We combine our results with literature data for 11 more (sub)mm galaxies that are identified with similar reliability. In terms of their K-band properties, the sample divides into three roughly equal groups: (i) undetected to K~22, (ii) detected in the near-infrared but not the optical and (iii) detected in the optical with the possibility of optical follow-up spectroscopy. We find a trend in this sample between near-infrared to submm and submm to radio spectral indices, which in comparison to spectral energy distributions (SEDs) of low redshift infrared luminous galaxies suggests that the most plausible primary factor causing the extreme near-infrared faintness of our objects is their high redshift. We show that the near-infrared to radio SEDs of the sample are inconsistent with SEDs that resemble local far-infrared cool galaxies with moderate luminosities, which were proposed in some models of the submm sky. We briefly discuss the implications of the results for our understanding of galaxy formation.Comment: aastex, 5 figures. Accepted by Ap

Radio and millimeter properties of z∼5.7z \sim 5.7 Lyα\alpha emitters in the COSMOS field: limits on radio AGN, submm galaxies, and dust obscuration

We present observations at 1.4 and 250 GHz of the $z\sim 5.7$ Ly$\alpha$ emitters (LAE) in the COSMOS field found by Murayama et al.. At 1.4 GHz there are 99 LAEs in the lower noise regions of the radio field. We do not detect any individual source down to 3$\sigma$ limits of $\sim 30\mu$Jy beam$^{-1}$ at 1.4 GHz, nor do we detect a source in a stacking analysis, to a 2$\sigma$ limit of $2.5\mu$Jy beam$^{-1}$. At 250 GHz we do not detect any of the 10 LAEs that are located within the central regions of the COSMOS field covered by MAMBO ($20' \times 20'$) to a typical 2$\sigma$ limit of $S_{250} < 2$mJy. The radio data imply that there are no low luminosity radio AGN with $L_{1.4} > 6\times 10^{24}$ W Hz$^{-1}$ in the LAE sample. The radio and millimeter observations also rule out any highly obscured, extreme starbursts in the sample, ie. any galaxies with massive star formation rates $> 1500$ M$_\odot$ year$^{-1}$ in the full sample (based on the radio data), or 500 M$_\odot$ year$^{-1}$ for the 10% of the LAE sample that fall in the central MAMBO field. The stacking analysis implies an upper limit to the mean massive star formation rate of $\sim 100$ M$_\odot$ year$^{-1}$.Comment: 11 pages AAStex format 3 figures. ApJ COSMOS Special Issue. Changes: Added 'Note added in proof' to reflect nine new sources in the LAE sampl