The Atacama Large Millimeter/Submillimeter Array

Wootten, Alwyn; Thompson, Alexander

doi:10.1109/jproc.2009.2020572

Cited by 430 publications

(277 citation statements)

References 16 publications

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“…A significant step forward in constraining the SED and understanding the YSO status could be made, for example, by using observations from the Atacama Large Millimeter/submillimeter Array (ALMA, Wootten & Thompson 2009). …”

Section: Discussionmentioning

confidence: 99%

Results from DROXO

Pizzocaro

Stelzer

Paladini

et al. 2016

A&A

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X-ray emission from young stellar objects (YSOs) is a key ingredient in understanding star formation. For the early, protostellar (Class I) phase, a very limited (and controversial) quantity of X-ray results is available to date. Within the EXTraS (Exploring the X-ray Transient and variable Sky) project, we have discovered transient X-ray emission from a source whose counterpart is ISO-Oph 85, a strongly embedded YSO in the ρ Ophiuchi star-forming region. We extract an X-ray light curve for the flaring state, and determine the spectral parameters for the flare from XMM-Newton/EPIC data with a method based upon quantile analysis. We combine photometry from infrared to millimeter wavelengths from the literature with mid-IR Spitzer and unpublished submm Herschel photometry that we analysed for this work, and we describe the resulting spectral energy distribution (SED) with a set of precomputed models. The X-ray flare of ISO-Oph 85 lasted ∼2500 s and is consistent with a highly-absorbed one-component thermal model (N H = 1.0 +1.2 −0.5 × 10 23 cm −2 and kT = 1.15 +2.35 −0.65 keV). The X-ray luminosity during the flare is log L X [erg/s] = 31.1 +2.0 −1.2 ; during quiescence we set an upper limit of log L X [erg/s] < 29.5. We do not detect other flares from this source. The submillimeter fluxes suggest that the object is a Class I protostar. We caution, however, that the offset between the Herschel and optical/infrared position is larger than that for other YSOs in the region, leaving some doubt on this association. To the best of our knowledge, this is the first X-ray flare from a YSO that has been recognised as a candidate Class I protostar via the analysis of its complete SED, including the submm bands that are crucial for detecting the protostellar envelope. This work shows how the analysis of the whole SED is fundamental to the classification of YSOs, and how the X-ray source detection techniques we have developed can open a new era in time-resolved analysis of the X-ray emission from stars.

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Section: Discussionmentioning

confidence: 99%

Results from DROXO

Pizzocaro

Stelzer

Paladini

et al. 2016

A&A

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“…The Atacama Large Millimeter/submillimeter Array (ALMA) is the largest millimeter and sub-millimeter astronomical facility ever built (Wootten & Thompson 2009). When fully operational, it will consist of 66 movable antennas (54 with a 12-m dish and 12 with a 7-m dish).…”

Section: Introductionmentioning

confidence: 99%

The ALMA Band 9 receiver

Baryshev

Hesper

Mena

et al. 2015

A&A

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Aims. We describe the design, construction, and characterization of the Band 9 heterodyne receivers (600-720 GHz) for the Atacama Large Millimeter/submillimeter Array (ALMA). First-light Band 9 data, obtained during ALMA commissioning and science verification phases, are presented as well. Methods. The ALMA Band 9 receiver units (so-called "cartridges"), which are installed in the telescope's front end, have been designed to detect and down-convert two orthogonal linear polarization components of the light collected by the ALMA antennas. The light entering the front end is refocused with a compact arrangement of mirrors, which is fully contained within the cartridge. The arrangement contains a grid to separate the polarizations and two beam splitters to combine each resulting beam with a local oscillator signal. The combined beams are fed into independent double-sideband mixers, each with a corrugated feedhorn coupling the radiation by way of a waveguide with backshort cavity into an impedance-tuned superconductor-insulator-superconductor (SIS) junction that performs the heterodyne down-conversion. Finally, the generated intermediate frequency (IF) signals are amplified by cryogenic and room-temperature HEMT amplifiers and exported to the telescope's IF back end for further processing and, finally, correlation. Results. The receivers have been constructed and tested in the laboratory and they show an excellent performance, complying with ALMA requirements. Performance statistics on all 73 Band 9 receivers are reported. Importantly, two different tunnel-barrier technologies (necessitating different tuning circuits) for the SIS junctions have been used, namely conventional AlO x barriers and the more recent high-current-density AlN barriers. On-sky characterization and tests of the performance of the Band 9 cartridges are presented using commissioning data. Continuum and line images of the low-mass protobinary IRAS 16293-2422 are presented which were obtained as part of the ALMA science verification program. An 8 GHz wide Band 9 spectrum extracted over a 0.3 × 0.3 region near source B, containing more than 100 emission lines, illustrates the quality of the data.

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“…This same quasar host galaxy also shows strong Lyman-α (Lyα) emission , indicating enhanced star formation or elevated ionization from the quasar flux. Recent observations with the Atacama Large Millimeter/submillimeter Array (ALMA; Wootten & Thompson 2009) of [C ii] line emission in the BR120-0725 host galaxy suggest an outflow of gas ionized by the quasar (Wagg et al 2012). At this early epoch, quasar hosts have both vigorous star formation and central black holes that accrete at the Eddington limit (Wang et al 2013a).…”

Section: Introductionmentioning

confidence: 99%

A glance at the host galaxy of high-redshift quasars using strong damped Lyman-αsystems as coronagraphs

Finley

Petitjean

Pâris

et al. 2013

A&A

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We searched quasar spectra from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) for the rare occurrences where a strong damped Lyman-α absorber (DLA) blocks the Broad Line Region emission from the quasar and acts as a natural coronagraph to reveal narrow Lyα emission from the host galaxy. We define a statistical sample of 31 DLAs in Data Release 9 (DR9) with log N(H i) ≥ 21.3 cm −2 located at less than 1500 km s −1 from the quasar redshift. In 25% (8) of these DLAs, a strong narrow Lyα emission line is observed with flux ∼25 × 10 −17 erg s −1 cm −2 on average. For DLAs without this feature in their troughs, the average 3-σ upper limit is <0.8 × 10 −17 erg s −1 cm −2 . Our statistical sample is nearly 2.5 times larger than the anticipated number of intervening DLAs in DR9 within 1 500 km s −1 of the quasar redshift. We also define a sample of 26 DLAs from DR9 and DR10 with narrow Lyα emission detected and no limit on the H i column density to better characterize properties of the host galaxy emission. Analyzing the statistical sample, we do not find substantial differences in the kinematics, metals, or reddening for the two populations with and without emission detected. The highly symmetric narrow Lyα emission line profile centered in the HI trough indicates that the emitting region is separate from the absorber. The luminosity of the narrow Lyα emission peaks is intermediate between that of Lyα emitters and radio galaxies, implying that the Lyα emission is predominantly due to ionizing radiation from the AGN. Galaxies neighboring the quasar host are likely responsible for the majority (>75%) of these DLAs, with only a minority (<25%) arising from H i clouds located in the AGN host galaxy.

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The Atacama Large Millimeter/Submillimeter Array

Cited by 430 publications

References 16 publications

Results from DROXO

Results from DROXO

The ALMA Band 9 receiver

A glance at the host galaxy of high-redshift quasars using strong damped Lyman-αsystems as coronagraphs

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