Iram Institute Of Radio Astronomie Millimetrique

Saint-Martin-Vésubie, France

Iram Institute Of Radio Astronomie Millimetrique

Saint-Martin-Vésubie, France

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Yang Y.,Max Planck Institute for Astronomy | Decarli R.,Max Planck Institute for Astronomy | Dannerbauer H.,CEA Saclay Nuclear Research Center | Dannerbauer H.,University of Vienna | And 14 more authors.
Astrophysical Journal | Year: 2012

In order to constrain the bolometric luminosities, dust properties, and molecular gas content of giant Lyα nebulae, the so-called Lyα blobs, we have carried out a study of dust continuum and CO line emission in two well-studied representatives of this population at z ∼ 3: an Lyα blob discovered by its strong Spitzer Multiband Infrared Photometer 24 μm detection (LABd05) and the Steidel blob 1 (SSA22-LAB01). We find that the spectral energy distribution of LABd05 is well described by an active-galactic-nucleus-starburst composite template with L FIR = (4.0 0.5) × 1012 L, comparable to high-z submillimeter galaxies and ultraluminous infrared galaxies. New Large APEX Bolometer Camera 870 μm measurements rule out the reported Submillimeter Common-User Bolometer Array detection of the SSA22-LAB01 (S 850 μm = 16.8mJy) at the >4σ level. Consistent with this, ultradeep Plateau de Bure Interferometer observations with 2″ spatial resolution also fail to detect any 1.2mm continuum source down to 0.45mJy beam-1 (3σ). Combined with the existing (sub)millimeter observations in the literature, we conclude that the FIR luminosity of SSA22-LAB01 remains uncertain. No CO line is detected in either case down to integrated flux limits of S νΔV ≲ 0.25-1.0Jykms-1, indicating a modest molecular gas reservoir, M(H2) < (1-3) × 1010M. The non-detections exclude, with high significance (12σ), the previous tentative detection of a CO J=4-3 line in the SSA22-LAB01. The increased sensitivity afforded by the Atacama Large Millimeter/submillimeter Array will be critical in studying molecular gas and dust in these interesting systems. © 2012 The American Astronomical Society. All rights reserved.


Combes F.,Paris Observatory | Boquien M.,French National Center for Scientific Research | Kramer C.,Instituto Radioastronomia Milimetrica | Xilouris E.M.,National institute for astrophysics | And 17 more authors.
Astronomy and Astrophysics | Year: 2012

Power spectra of deprojected images of late-type galaxies in gas or dust emission are very useful diagnostics of the dynamics and stability of their interstellar medium. Previous studies have shown that the power spectra can be approximated as two power laws, a shallow one on large scales (larger than 500 pc) and a steeper one on small scales, with the break between the two corresponding to the line-of-sight thickness of the galaxy disk. The break separates the 3D behavior of the interstellar medium on small scales, controlled by star formation and feedback, from the 2D behavior on large scales, driven by density waves in the disk. The break between these two regimes depends on the thickness of the plane, which is determined by the natural self-gravitating scale of the interstellar medium. We present a thorough analysis of the power spectra of the dust and gas emission at several wavelengths in the nearby galaxy M 33. In particular, we use the recently obtained images at five wavelengths by PACS and SPIRE onboard Herschel. The wide dynamical range (2-3 dex in scale) of most images allows us to clearly determine the change in slopes from -1.5 to -4, with some variations with wavelength. The break scale increases with wavelength from 100 pc at 24 and 100 μm to 350 pc at 500 μm, suggesting that the cool dust lies in a thicker disk than the warm dust, perhaps because of star formation that is more confined to the plane. The slope on small scales tends to be steeper at longer wavelength, meaning that the warmer dust is more concentrated in clumps. Numerical simulations of an isolated late-type galaxy, rich in gas and with no bulge, such as M 33, are carried out to better interpret these observed results. Varying the star formation and feedback parameters, it is possible to obtain a range of power spectra, with two power-law slopes and breaks, that nicelybracket the data. The small-scale power-law does indeed reflect the 3D behavior of the gas layer, steepening strongly while the feedback smoothes the structures by increasing the gas turbulence. M 33 appears to correspond to a fiducial model with an SFR of ~ 0.7 Mo/yr, with 10% supernovae energy coupled to the gas kinematics. © ESO, 2012.


Casasola V.,National institute for astrophysics | Hunt L.K.,National institute for astrophysics | Combes F.,Paris Observatory | Garcia-Burillo S.,Observatorio Astronomico Nacional OAN | Neri R.,Iram Institute Of Radio Astronomie Millimetrique
Astronomy and Astrophysics | Year: 2011

We present 12CO(1-0) and 12CO(2-1) maps of the interacting barred LINER/Seyfert 2 galaxy NGC 3627 obtained with the IRAM interferometer at resolutions of 2.″ × 1.″ and 0.″ × 0.″6, respectively. We also present single-dish IRAM 30m 12CO(1-0) and 12CO(2-1) observations used to compute short spacings and complete interferometric measurements. These observations are complemented by IRAM 30 m measurements of HCN(1-0) emission detected in the center of NGC 3627. The molecular gas emission shows a nuclear peak, an elongated bar-like structure of ∼18″ (∼900 pc) diameter in both 12CO maps and, in 12CO(1-0), a two-arm spiral feature from r ∼ 9″ (∼450 pc) to r ∼ 16″ (∼800 pc). The inner ∼18″ bar-like structure, with a north/south orientation (PA = 14°), forms two peaks at the extremes of this elongated emission region. The kinematics of the inner molecular gas shows signatures of non-circular motions associated both with the 18″ bar-like structure and the spiral feature detected beyond it. The 1.6 μm H-band 2MASS image of NGC 3627 shows a stellar bar with a PA = - 21°, different from the PA (= 14°) of the 12CO bar-like structure, indicating that the gas is leading the stellar bar. The far-infrared Spitzer-MIPS 70 and 160 μm images of NGC 3627 show that the dust emission is intensified at the nucleus and at the ansae at the ends of the bar, coinciding with the 12CO peaks. The GALEX far-ultraviolet (FUV) morphology of NGC 3627 displays an inner elongated (north/south) ring delimiting a hole around the nucleus, and the 12CO bar-like structure is contained in the hole observed in the FUV. The torques computed with the HST-NICMOS F160W image and our PdBI maps are negative down to the resolution limit of our images, ∼60 pc in 12CO(2-1). If the bar ends at ∼3 kpc, coincident with corotation (CR), the torques are negative between the CR of the bar and the nucleus, down to the resolution limit of our observations. This scenario is compatible with a recently-formed rapidly rotating bar which has had insufficient time to slow down because of secular evolution, and thus has not yet formed an inner Lindblad resonance (ILR). The presence of molecular gas inside the CR of the primary bar, where we expect that the ILR will form, makes NGC 3627 a potential smoking gun of inner gas inflow. The gas is fueling the central region, and in a second step could fuel directly the active nucleus. © 2011 ESO.


Casasola V.,National institute for astrophysics | Hunt L.K.,National institute for astrophysics | Combes F.,Paris Observatory | Garcia-Burillo S.,Observatorio Astronomico Nacional OAN | And 4 more authors.
Astronomy and Astrophysics | Year: 2010

We present 12CO(1-0) and 12CO(2-1) maps of the interacting Seyfert 2/LINER galaxy NGC5953 obtained with the IRAM interferometer at resolutions of 2″.1 × 1″.4 and 1″.1 × 0″.7, respectively. We also present single-dish IRAM 30m observations of the central region of NGC5953 for the 12CO(1-0), 12CO(2-1) , and HCN(1-0) transitions at resolutions of 22″, 12″, and 29″, respectively. The CO emission is distributed over a disk of diameter ∼16″(∼2.2 kpc), within which are several, randomly distributed peaks. The strongest peak does not coincide with the nucleus, but is instead offset from the center, ∼2-3″ (∼340 pc) toward the west/southwest. The kinematics of the molecular component are quite regular, as is typical of a rotating disk. We also compared the 12CO distribution of NGC5953 with observations at other wavelengths in order to study correlations between different tracers of the interstellar medium. The HST/F606W WFPC2 images show flocculent spiral structures and an "S-shape" feature ≳60 pc in radius, possibly associated with a nuclear bar or with the radio jet. A two-dimensional bulge/disk decomposition of the H-band (HST/F160W) and 3.6 μm (Spitzer/IRAC) images reveals a circumnuclear "ring" ∼10-14″ in diameter, roughly coincident in size with the CO disk and with a star-forming ring previously identified in ionized gas. This ring is not present in the near-infrared (NIR) J - K color image, nor is it present in the "dust-only" image constructed from the 8 μm IRAC map. The implication is that the excess residual ring is stellar, with colors similar to the surrounding disk. We interpret this ring, visible in ionized gas, which appears as stars in the NIR, and with no sign of hot dust, as due to a red super giant population at least 10-15 Myr old. However, star formation is still ongoing in the disk and in the ring itself. Using NIR images, we computed the gravity torques exerted by the stellar potential on the gas. The torques are predominantly positive in both 12CO(1-0) and 12CO(2-1), suggesting that gas is not flowing into the center, and less than 5% of the gas angular momentum is exchanged in each rotation. This comes from the regular and almost axisymmetric total mass and gas distributions in the center of the galaxy. In NGC 5953, the AGN is apparently not being actively fueled in the current epoch. © 2010 ESO.


Lis D.C.,California Institute of Technology | Neufeld D.A.,Johns Hopkins University | Phillips T.G.,California Institute of Technology | Gerin M.,Ecole Normale Superieure de Paris | Neri R.,Iram Institute Of Radio Astronomie Millimetrique
Astrophysical Journal Letters | Year: 2011

We report a detection of the excited 220-211 rotational transition of para-H2O in APM 08279+5255 using the IRAM Plateau de Bure Interferometer. At z = 3.91, this is the highest-redshift detection of interstellar water to date. From large velocity gradient modeling, we conclude that this transition is predominantly radiatively pumped and on its own does not provide a good estimate of the water abundance. However, additional water transitions are predicted to be detectable in this source, which would lead to an improved excitation model. We also present a sensitive upper limit for the hydrogen fluoride (HF) J = 1-0 absorption toward APM 08279+5255. While the face-on geometry of this source is not favorable for absorption studies, the lack of HF absorption is still puzzling and may be indicative of a lower fluorine abundance at z = 3.91 compared with the Galactic interstellar medium. © 2011. The American Astronomical Society. All rights reserved.


Navarrini A.,Iram Institute Of Radio Astronomie Millimetrique | Groppi C.,Arizona State University | Lin R.,Jet Propulsion Laboratory | Chattopadhyay G.,Jet Propulsion Laboratory
22nd International Symposium on Space Terahertz Technology 2011, ISSTT 2011 | Year: 2011

We report on the construction and test results of a waveguide Orthomode Transducer (OMT) for the 385-500 GHz band. The OMT is based on a symmetric reversecoupling structure and consists of two copper alloy blocks in split-block configuration fabricated using numerically controlled (CNC) milling machining. Test results of a first prototype OMT employing standard UG387 flanges at all ports were described at the previous ISSTT Symposium. Here, we report on experimental results of a second OMT version utilizing custom made mini-flanges and much shorter input and output waveguides. This second OMT version is tolerant to misalignment errors of the block halves, has improved performance over the first prototype, and covers a wider band than initially specified. From 325 to 500 GHz the measured input reflection coefficient of the second prototype OMT was less than -10 dB, the transmission was ≈-1 dB, and the isolation was less than -30 dB at room temperature for both polarization channels.


Ladu A.,National institute for astrophysics | Pisanu T.,National institute for astrophysics | Navarrini A.,Iram Institute Of Radio Astronomie Millimetrique | Marongiu P.,National institute for astrophysics | Valente G.,National institute for astrophysics
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

We present the optical and mechanical design of a 3mm band SIS receiver for the Gregorian focus of the Sardinia Radio Telescope (SRT). The receiver, was designed and built at IRAM and deployed on the IRAM for the Plateau de Bure Interferometer antennas until 2006. Following its decommissioning the receiver was purchased by the INAFAstronomical Observatory of Cagliari with the aim to adapt its optics for test of the performance of the new 64-m diameter Sardinia Radio Telescope (SRT) in the 3 mm band (84-116 GHz). The instrument will be installed in the rotating turret inside of the Gregorian focal room of SRT. The dimensions of the focal room, the horn position in the lower side of the cryostat and the vessel for the liquid helium impose very hard constraints to the optical and mechanical mounting structure of the receiver inside the cabin. We present the receiver configuration and how we plan to install it on SRT. © 2014 SPIE.


Navarrini A.,Iram Institute Of Radio Astronomie Millimetrique | Fontana A.L.,Iram Institute Of Radio Astronomie Millimetrique | Maier D.,Iram Institute Of Radio Astronomie Millimetrique | Serres P.,Iram Institute Of Radio Astronomie Millimetrique | Billon-Pierron D.,Iram Institute Of Radio Astronomie Millimetrique
Journal of Infrared, Millimeter, and Terahertz Waves | Year: 2014

We present the design, construction and performance of backshort-tuned Single Side Band (SSB) and of fixed-tuned Double Side Band (DSB) Superconductor-Insulator-Superconductor (SIS) mixers covering the frequency range of 129-174 GHz (2 mm band). Receivers employing these SSB mixers have been continuously operated for astronomical observations on the six antennas of the IRAM Plateau de Bure Intereferometer (PdBI) since 2007 and on the IRAM 30 m Pico Veleta (PV) radio telescope since 2009. The DSB version of the mixer was employed in a prototype of a four-element focal plane array that was tested on the IRAM 30 m radio telescope. Both SSB and DSB mixers employ the same chip and are based on a wideband single ended probe transition from WR6 full-height waveguide to thin-film microstrip line and on a series array of two Nb/Al-AlOx/Nb junctions. The measured receiver noise for the four-element DSB mixer array pumped by a Gunn oscillator cascaded with a frequency doubler was in the range 25-35 K across the 135-168 GHz LO band. The PdBI and PV receivers equipped with the SSB mixers have measured noise temperatures in the range of 30 K to 60 K and an image sideband rejection below -10 dB over the 129-174 GHz RF band. The measurement results agree well with the predictions obtained through detailed simulations of the SIS receivers based on the standard theory of quantum mixing. © 2014 Springer Science+Business Media New York.


Stil I.,Iram Institute Of Radio Astronomie Millimetrique | Fontana A.L.,Iram Institute Of Radio Astronomie Millimetrique | Lefranc B.,Iram Institute Of Radio Astronomie Millimetrique | Navarrini A.,Iram Institute Of Radio Astronomie Millimetrique | And 2 more authors.
23rd International Symposium on Space Terahertz Technology 2012, ISSTT 2012 | Year: 2012

The losses of ∼1.2 m long WR10 (2.54×1.27 mm2) rectangular waveguides were measured at room temperature across the 70-116 GHz band. Ten different waveguide modules were machined in two different materials (Aluminum alloy and Brass) using different surface roughness (Ra) and different split-block waveguide geometries (E-plane and b-edge) as to establish the dependency of the losses on the various parameters. The measurements of the various units were performed with the IRAM mm-wave Vector Network Analyzer (MVNA) across the 70-116 GHz single-mode band of the WR10 waveguide.


Serres P.,Iram Institute Of Radio Astronomie Millimetrique | Garnier O.,Iram Institute Of Radio Astronomie Millimetrique | Bortolotti Y.,Iram Institute Of Radio Astronomie Millimetrique | Navarro S.,Iram Institute Of Radio Astronomie Millimetrique | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

We present the design, construction and test results of a prototype MMIC receiver for the 3 mm band (84-116 GHz). The receiver cryogenic module consists of a single corrugated feed horn cascaded with an Ortho Mode Traducer (OMT) that splits the two incoming linear polarized signals in two independent single-mode rectangular waveguides. Low noise MMIC HEMT amplification modules, attached to the OMT WR10 waveguide outputs, amplify the signal of each polarization channel. Outside the dewar, each signal is filtered, down-converted, and further amplified to provide a final 8 GHz IF bandwidth across 4-12 GHz. The receiver was installed on the Pico Veleta 30 m telescope in August 2010 where it was used to perform spectral line surveys of astronomical sources. The measured receiver noise temperature was below 75 K with an average value of ∼55 K for both polarization channels across 84-116 GHz. © 2012 SPIE.

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