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Truth or Consequences, NM, United States

Lestrade J.-F.,Paris Observatory | Carilli C.L.,Pete menici Array Science Center | Thanjavur K.,Canada France Hawaii Telescope Corporation | Thanjavur K.,University of Victoria | And 5 more authors.
Astrophysical Journal Letters | Year: 2011

We present high-resolution imaging of the low-order (J = 1 and 2) CO line emission from the z = 3.93 submillimeter galaxy (SMG) MM18423+5938 using the Expanded Very Large Array, and optical and near-IR imaging using the Canada-France-Hawaii Telescope. This SMG with a spectroscopic redshift was thought to be gravitationally lensed given its enormous apparent brightness. We find that the CO emission is consistent with a complete Einstein ring with a major axis diameter of 14, indicative of lensing. We have also identified the lensing galaxy as a very red elliptical coincident with the geometric center of the ring and estimated its photometric redshift z 1.1. A first estimate of the lens magnification factor is m 12. The luminosity L′CO(1 - 0) of the CO(1-0) emission is 2.71 0.38 × 1011 m -1Kkms-1 pc2, and, adopting the commonly used conversion factor for ultraluminous infrared galaxies (ULIRGs), the molecular gas mass is M(H2) = 2.2 × 1011 m -1 M⊙, comparable to unlensed SMGs if corrected by m 12. Our revised estimate of the far-IR luminosity of MM18423+5938 is 2 × 10 13 m -1 < L FIR < 3 × 10 14 m -1 L⊙, comparable to that of ULIRGs. Further observations are required to quantify the star formation rate in MM18423+5938 and to constrain the mass model of the lens in more detail. © 2011. The American Astronomical Society. All rights reserved.

Decarli R.,Max Planck Institute for Astronomy | Walter F.,Max Planck Institute for Astronomy | Yang Y.,Max Planck Institute for Astronomy | Carilli C.L.,Pete menici Array Science Center | And 8 more authors.
Astrophysical Journal | Year: 2012

We search for extended Lyα emission around two z > 6 quasars, SDSS J1030+0524 (z = 6.309) and SDSS J1148+5251 (z = 6.419) using Wide Field Camera 3 narrowband filters on board the Hubble Space Telescope. For each quasar, we collected two deep, narrowband images, one sampling the Lyα line+continuum at the quasar redshifts and one of the continuum emission redward of the line. After carefully modeling the point-spread function, we find no evidence for extended Lyα emission. These observations set 2σ limits of L(Lyα, extended) <3.2 × 1044ergs-1 for J1030+0524 and L(Lyα, extended) <2.5 × 1044 ergs -1 for J1148+5251. Given the star formation rates typically inferred from (rest-frame) far-infrared measurements of z ∼ 6 quasars, these limits are well below the intrinsic bright Lyα emission expected from the recombination of gas photoionized by the quasars or by the star formation in the host galaxies, and point toward significant Lyα suppression or dust attenuation. However, small extinction values have been observed along the line of sight to the nuclei, thus reddening has to be coupled with other mechanisms for Lyα suppression (e.g., resonance scattering). No Lyα emitting companions are found, down to a 5σ sensitivity of ∼1 × 10 -17ergs-1cm-2 arcsec-2 (surface brightness) and ∼5 × 10-17ergs-1cm-2 (assuming point sources). © 2012. The American Astronomical Society. All rights reserved.

Decarli R.,Max Planck Institute for Astronomy | Walter F.,Max Planck Institute for Astronomy | Carilli C.,Pete menici Array Science Center | Riechers D.,Cornell University | And 20 more authors.
Astrophysical Journal | Year: 2014

We present a molecular line scan in the Hubble Deep Field North (HDF-N) that covers the entire 3 mm window (79-115 GHz) using the IRAM Plateau de Bure Interferometer. Our CO redshift coverage spans z ≲ 0.45, 1 ≲ z ≲ 1.9 and all z ≳ 2. We reach a CO detection limit that is deep enough to detect essentially all z > 1 CO lines reported in the literature so far. We have developed and applied different line-searching algorithms, resulting in the discovery of 17 line candidates. We estimate that the rate of false positive line detections is 2/17. We identify optical/NIR counterparts from the deep ancillary database of the HDF-N for seven of these candidates and investigate their available spectral energy distributions. Two secure CO detections in our scan are identified with star-forming galaxies at z = 1.784 and at z = 2.047. These galaxies have colors consistent with the "BzK" color selection and they show relatively bright CO emission compared with galaxies of similar dust continuum luminosity. We also detect two spectral lines in the submillimeter galaxy HDF 850.1 at z = 5.183. We consider an additional nine line candidates as high quality. Our observations also provide a deep 3 mm continuum map (1σ noise level = 8.6 μJy beam-1). Via a stacking approach, we find that optical/MIR bright galaxies contribute only to <50% of the star formation rate density at 1 < z < 3, unless high dust temperatures are invoked. The present study represents a first, fundamental step toward an unbiased census of molecular gas in "normal" galaxies at high-z, a crucial goal of extragalactic astronomy in the ALMA era. © 2014. The American Astronomical Society. All rights reserved..

Lentati L.,Astrophysics Group | Carilli C.,Astrophysics Group | Carilli C.,Pete menici Array Science Center | Alexander P.,Astrophysics Group | And 2 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2014

A new Bayesian method for performing an image domain search for line-emitting galaxies is presented. The method uses both spatial and spectral information to robustly determine the source properties, employing either simple Gaussian, or other physically motivated models whilst using the evidence to determine the probability that the source is real. In this paper, we describe the method, and its application to both a simulated data set, and a blind survey for cold molecular gas using observations of the Hubble Deep Field-North taken with the Plateau de Bure Interferometer. We make a total of six robust detections in the survey, five of which have counterparts in other observing bands. We identify the most secure detections found in a previous investigation, while finding one new probable line source with an optical ID not seen in the previous analysis. This study acts as a pilot application of Bayesian statistics to future searches to be carried out both for low-J CO transitions of high-redshift galaxies using the Jansky Very Large Array (JVLA), and at millimetre wavelengths with Atacama Large Millimeter/submillimeter Array (ALMA), enabling the inference of robust scientific conclusions about the history of the molecular gas properties of star-forming galaxies in the Universe through cosmic time. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Decarli R.,Max Planck Institute for Astronomy | Walter F.,Max Planck Institute for Astronomy | Carilli C.,Pete menici Array Science Center | Bertoldi F.,University of Bonn | And 7 more authors.
Astrophysical Journal Letters | Year: 2014

We study the properties of the interstellar medium in the interacting system BR1202-0725 at z = 4.7 via its [N II] and [C II] fine-structure line emission. This system consists of a QSO, a sub-mm galaxy (SMG), and two Lyα emitters (LAEs). Such a diversity in galaxy properties makes BR1202-0725 a unique laboratory of star formation and galaxy evolution at high redshift. We present ionized nitrogen ([N II] 205 μm) observations of this system, obtained with the IRAM Plateau de Bure Interferometer. We find no [N II] emission at the quasar location, but tentative [N II] line detections associated with the SMG and one of the LAEs. Together with available ionized carbon ([C II] 158 μm) Atacama Large Millimeter Array observations of this system, we find the following: the [C II]/[N II] luminosity ratio is >5.5 for the QSO and the SMG, but it is as low as ∼2 in the LAE, suggesting that, in this source, most of the [C II] emission is associated with the ionized medium (H II regions) rather than the neutral one (photon-dominated regions). This study demonstrates the importance of combined studies of multiple fine-structure lines in order to pin down the physical properties of the interstellar medium in distant galaxies. © 2014. The American Astronomical Society. All rights reserved.

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