Atacama Large Millimeter submillimeter Array

Santiago, Chile

Atacama Large Millimeter submillimeter Array

Santiago, Chile

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Da Cunha E.,Max Planck Institute for Astronomy | Da Cunha E.,Swinburne University of Technology | Walter F.,Max Planck Institute for Astronomy | Smail I.R.,Durham University | And 16 more authors.
Astrophysical Journal | Year: 2015

The ALESS survey has followed up on a sample of 122 sub-millimeter sources in the Extended Chandra Deep Field South at 870 μm with the Atacama Large Millimeter Array (ALMA), allowing us to pinpoint the positions of sub-millimeter galaxies (SMGs) to ∼0.3 arcsec and to find their precise counterparts at different wavelengths. This enabled the first compilation of the multi-wavelength spectral energy distributions (SEDs) of a statistically reliable survey of SMGs. In this paper, we present a new calibration of the magphys SED modeling code that is optimized to fit these ultraviolet-to-radio SEDs of star-forming galaxies using an energy balance technique to connect the emission from stellar populations, dust attenuation, and dust emission in a physically consistent way. We derive statistically and physically robust estimates of the photometric redshifts and physical parameters (such as stellar masses, dust attenuation, star formation rates (SFRs), and dust masses) for the ALESS SMGs. We find that the ALESS SMGs have median stellar mass , median SFR , median overall V-band dust attenuation mag, median dust mass , and median average dust temperature K. We find that the average intrinsic SED of the ALESS SMGs resembles that of local ultra-luminous infrared galaxies in the infrared range, but the stellar emission of our average SMG is brighter and bluer, indicating lower dust attenuation, possibly because they are more extended. We explore how the average SEDs vary with different parameters (redshift, sub-millimeter flux, dust attenuation, and total infrared luminosity), and we provide a new set of SMG templates that can be used to interpret other SMG observations. To put the ALESS SMGs into context, we compare their stellar masses and SFRs with those of less actively star-forming galaxies at the same redshifts. We find that at , about half of the SMGs lie above the star-forming main sequence (with SFRs three times larger than normal galaxies of the same stellar mass), while half are consistent with being at the high-mass end of the main sequence. At higher redshifts (), the SMGs tend to have higher SFRs and stellar masses, but the fraction of SMGs that lie significantly above the main sequence decreases to less than a third. © 2015. The American Astronomical Society. All rights reserved.


Glendenning B.E.,U.S. National Radio Astronomy Observatory | Ibsen J.,Atacama Large Millimeter Submillimeter Array | Kosugi G.,Japan National Astronomical Observatory | Raffi G.,European Southern Observatory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

The ALMA Software (~ 80% completed) is in daily use at the ALMA Observatory and has been developed as an end-toend system including: proposal preparation, dynamic scheduling, instrument control, data handling and formatting, data archiving and retrieval, automatic and manual data processing, and support for observatory operations. This presentation will expand on some software management aspects, procedures for releases, integrated system testing and deployment in Chile. The need for a realistic validation environment, now achieved with a two antenna interferometer at the observatory, and the balance between incremental development and stability of the software (a challenge at the moment) will be explained. © 2010 SPIE.


Cernicharo J.,CSIC - National Institute of Aerospace Technology | Goicoechea J.R.,CSIC - National Institute of Aerospace Technology | Daniel F.,CSIC - National Institute of Aerospace Technology | Agundez M.,CSIC - National Institute of Aerospace Technology | And 9 more authors.
Astronomy and Astrophysics | Year: 2010

We report on the detection with the HIFI instrument on board the Herschel satellite of the two hydrogen chloride isotopologues, H35Cl and H37Cl, towards the massive star-forming region W3 A. The J = 1-0 line of both species was observed with receiver 1b of the HIFI instrument at ∼625.9 and ∼624.9 GHz. The different hyperfine components were resolved. The observations were modeled with a non-local, non-LTE radiative transfer model that includes hyperfine line overlap and radiative pumping by dust. Both effects are found to play an important role in the emerging intensity from the different hyperfine components. The inferred H35Cl column density (a few times ∼1014 cm-2), and fractional abundance relative to H nuclei (∼7.5 × 10-10), supports an upper limit to the gas phase chlorine depletion of ≈ 200. Our best-fit model estimate of the H35Cl/H37Cl abundance ratio is ≈ 2.1 ± 0.5, slightly lower, but still compatible with the solar isotopic abundance ratio (≈ 3.1). Since both species were observed simultaneously, this is the first accurate estimation of the [35Cl]/[37Cl] isotopic ratio in molecular clouds. Our models indicate that even for large line opacities and possible hyperfine intensity anomalies, the H35Cl and H37Cl J = 1-0 integrated line-intensity ratio provides a good estimate of the 35Cl/37Cl isotopic abundance ratio. © 2010 ESO.


Weiss A.,Max Planck Institute for Radio Astronomy | Requena-Torres M.A.,Max Planck Institute for Radio Astronomy | Gusten R.,Max Planck Institute for Radio Astronomy | Garcia-Burillo S.,Observatorio Astronomico Nacional OAN | And 22 more authors.
Astronomy and Astrophysics | Year: 2010

We present observations of the rotational ortho-water ground transition, the two lowest para-water transitions, and the ground transition of ionised ortho-water in the archetypal starburst galaxy M 82, performed with the HIFI instrument on the Herschel Space Observatory. These observations are the first detections of the para-H2O(111-000) (1113 GHz) and ortho-H2O+(111-000) (1115 GHz) lines in an extragalactic source. All three water lines show different spectral line profiles, underlining the need for high spectral resolution in interpreting line formation processes. Using the line shape of the para-H 2O(111-000) and ortho-H2O +(111-000) absorption profile in conjunction with high spatial resolution CO observations, we show that the (ionised) water absorption arises from a ∼2000 pc2 region within the HIFI beam located about ∼50 pc east of the dynamical centre of the galaxy. This region does not coincide with any of the known line emission peaks that have been identified in other molecular tracers, with the exception of HCO. Our data suggest that water and ionised water within this region have high (up to 75%) area-covering factors of the underlying continuum. This indicates that water is not associated with small, dense cores within the ISM of M 82 but arises from a more widespread diffuse gas component. © 2010 ESO.


Gil J.P.,Atacama Large Millimeter submillimeter Array | Tejeda A.,U.S. National Radio Astronomy Observatory | Shen T.-C.,Atacama Large Millimeter submillimeter Array | Saez N.,Atacama Large Millimeter submillimeter Array
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

ALMA Software is a complex distributed system installed in more than one hundred of computers, which interacts with more than one thousand of hardware device components. A normal observation follows a flow that interacts with almost that entire infrastructure in a coordinated way. The Software Operation Support team (SOFTOPS) comprises specialized engineers, which analyze the generated software log messages in daily basis to detect bugs, failures and predict eventual failures. These log message can reach up to 30 GB per day. We describe a decoupled and non-intrusive log analysis framework and implemented tools to identify well known problems, measure times taken by specific tasks and detect abnormal behaviors in the system in order to alert the engineers to take corrective actions. The main advantage of this approach among others is that the analysis itself does not interfere with the performance of the production system, allowing to run multiple analyzers in parallel. In this paper we'll describe the selected framework and show the result of some of the implemented tools. © 2014 SPIE.


Hoff B.D.,Atacama Large Millimeter Submillimeter Array | Puga J.P.,Atacama Large Millimeter Submillimeter Array
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

The Atacama Large Millimeter/Submillimeter Array (ALMA) is a joint project between astronomical organizations in Europe, North America, and East Asia, in collaboration with the Republic of Chile. ALMA will consist of at least 54 twelve-meter antennas operating in the millimeter and sub-millimeter wavelength range. It will be located at an altitude above 5000m in the Chajnantor Plateau in northern Chile. There are 192 antenna foundations under construction at ALMA's Array Operations Site (AOS). Interchangeability between foundations will permit a variety of array configurations. Foundations provide the physical interface to the bedrock, as well as to the underground signal and power cable conduits. To achieve ALMA's precision requirements, the antenna pointing angular error budget is strict with anticipated non-repeatable error on the order of a few arc seconds. This level of precision imposes rigorous requirements on antenna foundations. The objective of this study is to demonstrate the methodology of precision tilt measurements combined with finite element simulation predictions to portray the qualitative nature of the antenna foundation surface deformation. Characteristics of foundation surface tilt have been examined in detail. Although the actual foundation has demonstrated much less resistance to tilt than the finite element representation, the simulation has predicted some key characteristics of the tilt pattern. The large deviations from the ideal have incited speculations into the compliance of materials, ambiguities in the construction, thermal effects and several other aspects described herein. This research has served as groundwork to characterize ALMA's foundation surface behavior on a micro-degree level and to identify subsequent studies to pursue. This in turn has contributed to the diagnosis of antenna pointing anomalies. © 2010 SPIE.


Rabanus D.,Atacama Large Millimeter submillimeter Array
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

Current large observatories, both in operation and projects in development or construction, face the challenge to find skilled personnel for integration and operation. Typical locations of these observatories are found to be remote, mainly due to electromagnetic pollution prevention, which in many if not all cases reduces the attractiveness of the work posts. Additional budgetary limitations restrict the recruitment radius for certain positions to the local labor market. This paper outlines these staffing constraints in more detail and elaborates on the need for training programs on various levels, which can be costly. This, in turn, drives the need for creative retention efforts. Therefore, financial modeling, contingency, risk and quality management, and the reliability, availability, and maintainability of an observatory are directly coupled to the local embedding in the labor market of the host country. © 2012 SPIE.


Shen T.-C.,Atacama Large Millimeter submillimeter Array | Soto R.,Atacama Large Millimeter submillimeter Array | Merino P.,Atacama Large Millimeter submillimeter Array | Pena L.,Atacama Large Millimeter submillimeter Array | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

The Atacama Large Millimeter/submillimeter Array (ALMA) will be a unique research instrument composed of at least 66 reconfigurable high-precision antennas, located at the Chajnantor plain in the Chilean andes at an elevation of 5000 m. This paper describes the experience gained after several years working with the monitoring system, which has a strong requirement of collecting and storing up to 150K variables with a highest sampling rate of 20.8 kHz. The original design was built on top of a cluster of relational database server and network attached storage with fiber channel interface. As the number of monitoring points increases with the number of antennas included in the array, the current monitoring system demonstrated to be able to handle the increased data rate in the collection and storage area (only one month of data), but the data query interface showed serious performance degradation. A solution based on no-SQL platform was explored as an alternative to the current long-term storage system. Among several alternatives, mongoDB has been selected. In the data flow, intermediate cache servers based on Redis were introduced to allow faster streaming of the most recently acquired data to web based charts and applications for online data analysis. © 2014 SPIE.


Lopez B.,Atacama Large Millimeter submillimeter Array | Jager R.,Atacama Large Millimeter submillimeter Array | Whyborn N.D.,Atacama Large Millimeter submillimeter Array | Knee L.B.G.,Atacama Large Millimeter submillimeter Array | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

The Atacama Large Millimeter/submillimeter Array (ALMA) is a joint project between astronomical organizations in Europe, North America, and East Asia, in collaboration with the Republic of Chile. ALMA will consist of at least 54 twelve-meter antennas and 12 seven-meter antennas operating as an aperture synthesis array in the (sub)millimeter wavelength range. It is the responsibility of ALMA AIV to deliver the fully assembled, integrated, and verified antennas (array elements) to the telescope array. After an initial phase of infrastructure setup AIV activities began when the first ALMA antenna and subsystems became available in mid 2008. During the second semester of 2009 a project-wide effort was made to put in operation a first 3-antenna interferometer at the Array Operations Site (AOS). In 2010 the AIV focus was the transition from event-driven activities towards routine series production. Also, due to the ramp-up of operations activities, AIV underwent an organizational change from an autonomous department into a project within a strong matrix management structure. When the subsystem deliveries stabilized in early 2011, steady-state series processing could be achieved in an efficient and reliable manner. The challenge today is to maintain this production pace until completion towards the end of 2013. This paper describes the way ALMA AIV evolved successfully from the initial phase to the present steady-state of array element series processing. It elaborates on the different project phases and their relationships, presents processing statistics, illustrates the lessons learned and relevant best practices, and concludes with an outlook of the path towards completion. © 2012 SPIE.


Lopez B.,Atacama Large Millimeter submillimeter Array | McMullin J.P.,Atacama Large Millimeter submillimeter Array | Whyborn N.D.,Atacama Large Millimeter submillimeter Array | Duvall E.,Atacama Large Millimeter submillimeter Array
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

The Atacama Large Millimeter/submillimeter Array (ALMA) is a joint project between astronomical organizations in Europe, North America, and East Asia, in collaboration with the Republic of Chile. ALMA will consist of at least 54 twelve-meter antennas and 12 seven-meter antennas operating as an interferometer in the millimeter and sub-millimeter wavelength range. It will be located at an altitude above 5000m in the Chilean Atacama desert. As part of the ALMA construction phase the Assembly, Verification and Integration (AIV) team receives antennas and instrumentation from Integrated Product Teams (IPTs), verifies that the sub-systems perform as expected, performs the assembly and integration of the scientific instrumentation and verifies that functional and performance requirements are met. This paper aims to describe those aspects related to the AIV Engineering team, its role within the 4-station AIV process, the different phases the group underwent, lessons learned and potential space for improvement. AIV Engineering initially focused on the preparation of the necessary site infrastructure for AIV activities, on the purchase of tools and equipment and on the first ALMA system installations. With the first antennas arriving on site the team started to gather experience with AIV Station 1 beacon holography measurements for the assessment of the overall antenna surface quality, and with optical pointing to confirm the antenna pointing and tracking capabilities. With the arrival of the first receiver AIV Station 2 was developed which focuses on the installation of electrical and cryogenic systems and incrementally establishes the full connectivity of the antenna as an observing platform. Further antenna deliveries then allowed to refine the related procedures, develop staff expertise and to transition towards a more routine production process. Stations 3 and 4 deal with verification of the antenna with integrated electronics by the AIV Science Team and is not covered directly in this paper. It is believed that both continuous improvement and the clear definition of the AIV 4-station model were key factors in achieving the goal of bringing the antennas into a state that is well enough characterized in order to smoothly start commissioning activities. © 2010 SPIE.

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