Monthly Archives: June 2018

(Cassiopeia – Summer / été 2018)

by / par Simon Coudé
Thesis defended on February 19, 2018
Université de Montréal / University of Montréal
Thesis advisor: Dr. Pierre Bastien

The English version follows

Abstract
L’astronomie sous-millimétrique est une fenêtre unique pour l’étude des propriétés physiques d’une grande variété d’environnements interstellaires, des pouponnières d’étoiles de notre Galaxie aux jets relativistes issus de noyaux galactiques actifs. Grâce en particulier aux observations polarimétriques, il est même possible d’étudier les effets de l’interaction entre le magnétisme et la turbulence sur la dynamique de ces milieux. Cette thèse présente les résultats d’une étude sous-millimétrique dont l’objectif est de caractériser les propriétés physiques et la dynamique d’une sélection de régions de formation d’étoiles et de jets extragalactiques à partir d’observations continues, spectroscopiques et polarimétriques obtenues au télescope James-Clerk-Maxwell (JCMT).

Nous avons d’abord quantifié l’effet de la contamination moléculaire sur les observations du nuage moléculaire géant d’Orion A obtenues à 450 µm et 850 µm avec la caméra SCUBA-2. À l’aide de mesures spectroscopiques effectuées avec le spectromètre HARP de la raie moléculaire 12CO J=3-2, nous avons identifié un échantillon de 33 sources dont le flux à 850 µm est fortement contaminé par des flots moléculaires environnants. Nous avons finalement montré que cette contamination mène à une sous-estimation de l’indice spectral d’émissivité β obtenu à partir du ratio des flux mesurés à 450 µm et 850 µm.

Dans le cadre du programme BISTRO au JCMT, nous avons utilisé le polarimètre POL-2 afin de caractériser le champ magnétique dans la région de formation d’étoiles Barnard 1 du complexe moléculaire de Persée. Nous avons d’abord déterminé l’orientation sur le plan du ciel du champ magnétique à partir de la carte de polarisation linéaire obtenue à 850 µm. Nous avons aussi calculé une valeur de 1.05 ± 0.92 pour le rapport entre les composantes turbulentes et ordonnées de l’énergie magnétique. Grâce aux observations de la raie moléculaire C18O J=1-0 obtenues au FCRAO, nous avons enfin appliqué la technique de Davis-Chandrasekhar-Fermi afin d’évaluer l’amplitude du champ magnétique à ~20 µG.

Avec l’équipe de mise en marche de POL-2, nous avons détecté avec succès la polarisation à 850 µm dans le coeur protostellaire CB 68. Nous avons ainsi déterminé l’orientation dans le plan du ciel du champ magnétique à l’intérieur de cet objet, que nous avons ensuite comparé avec les données SCUPOL dans la littérature. Additionnellement, nous avons mesuré une diminution de la fraction de polarisation en fonction de l’intensité totale, ce qui pourrait être expliqué par des effets de dépolarisation le long de la ligne de visée.

Finalement, nous avons mené la première campagne avec POL-2 afin d’étudier la variabilité temporelle de la polarisation linéaire à 850 µm vers quatre noyaux galactiques actifs: 3C 84, 3C 273, 3C 279 et 3C 454.3. Nous avons mesuré une variation significative de la fraction et de l’angle de polarisation pour 3C 84, 3C 273 et 3C 279 sur une période de 9 mois. Cette variabilité supporte la présence de cellules turbulentes magnétisées à l’intérieur de chocs permanents le long des jets relativistes issus de l’accrétion de matière sur les trous noirs supermassifs au centre de ces galaxies.

Submillimetre astronomy is a unique window for the study of the physical properties of a large variety of interstellar environments, from the stellar nurseries of our Galaxy to the relativistic jets from active galactic nuclei. With polarimetric observations in particular, it is even possible to study the effects of the interaction between magnetism and turbulence on the dynamics of these environments. This thesis presents the results from a submillimetre study which goal was to characterise the physical and dynamical properties of a selection of star-forming regions and extragalactic jets using continuum, spectroscopic and polarimetric observations from the James Clerk Maxwell Telescope (JCMT).

We have first quantified the effect of molecular contamination on SCUBA-2 observations at 450 µm and 850 µm of the Orion A giant molecular cloud. With spectroscopic measurements using the HARP spectrometer of the 12CO J=3-2 molecular line, we have identified a sample of 33 sources for which the 850 µm flux is highly contaminated by nearby molecular outflows. Finally, we have shown that this contamination leads to an underestimation of the emissivity spectral index β derived from the 450 µm to 850 µm flux ratio.

As part of the BISTRO survey at the JCMT, we have used the POL-2 polarimeter in order to characterise the magnetic field in the Barnard 1 star-forming region in the Perseus molecular cloud complex. We have inferred the plane-of-sky orientation of the magnetic field from the linear polarisation map obtained at 850 µm. We have also calculated a value of 1.05 ± 0.92 for the turbulent-to-ordered magnetic energy ratio. With FCRAO observations of the C18O J=1-0 molecular line, we have also applied the Davis-Chandrasekhar-Fermi method in order to evaluate the amplitude of the magnetic field to be ~20 µG.

With the POL-2 commissioning team, we have successfully detected the 850 µm polarisation in the CB 68 protostellar core. We have then inferred the plane-of-sky orientation of the magnetic field within this cloud that we have then compared to previously published SCUPOL observations. Additionally, we have measured a diminution in the fraction of polarisation as a function of total intensity, which could be explained by depolarisation effects along the line-of-sight.

Finally, we have lead the first POL-2 campaign to study the temporal variability of the 850 µm linear polarisation towards four active galactic nuclei: 3C 84, 3C 273, 3C 279 and 3C 454.3. We report significant variability in the fraction and angle of polarisation for 3C 84, 3C 273 and 3C 279 over a period of 9 months. This variability supports the presence of magnetised turbulent cells within standing shocks along the relativistic jets originating from the accretion of matter on the central supermassive black holes of these galaxies.

By / par Patrick Côté (NRC Herzberg Astronomy & Astrophysics Research Centre)
(Cassiopeia – Summer / été 2018)

Background

The Cosmological Advanced Survey Telescope for Optical and ultraviolet Research (CASTOR) is a proposed Canadian-led space telescope that has been in detailed study by the Canadian Space Agency (CSA) since 2011. The mission concept was developed in response to LRP2010, which identified Canada’s top priorities in space astronomy as “…significant involvement in the next generation of dark energy missions — ESA`s Euclid, or the NASA WFIRST mission, or a Canadian-led mission, the Canadian Space Telescope.” A detailed concept study for CASTOR was completed in 2012. Subsequent CSA-sponsored technical studies, undertaken between 2013 and 2017, further developed the mission concept by retiring sources of technical risk. In 2015, the mid-term review of LRP2010 recommended that the CSA immediately launch a Phase 0 study for CASTOR.

Design

CASTOR is a 1-m telescope that uses a three-mirror-anastigmat design to deliver Hubble-like image quality (FWHM ~ 0.15”) over a wide field of view (0.5 deg x 0.5 deg) — nearly a hundred times larger than that of Hubble’s cameras. Complementing the Euclid and WFIRST missions, CASTOR would operate at UV/blue-optical wavelengths using dichroics to image simultaneously in three pass-bands that span the 0.15-0.55 micron region. CASTOR would also offer strong synergies with LSST by providing superior resolution and point-source sensitivity at blue-optical wavelengths, as well as direct access to the UV region. The latter will become a critical capability in the coming decade when HST will likely cease operations. In short, CASTOR would be a powerful vehicle for both surveys and Guest Observer programs, and would provide Canadian astronomers with a unique and strategic capability in the coming decade.

Status

In the fall of 2017, CSA commissioned an extended Science Maturation Study (SMS) for the CASTOR mission that began in January 2018. The 14-month study, which will conclude in March 2019, will revise and update the CASTOR concept with an emphasis on the science case. Eight science working groups have been formed to explore scientific opportunities across a broad range of fields, from the cosmology to the solar system, with an eye towards updating the scientific requirements and optimizing the observing plan. Technical work is addressing all aspects of the mission design, including mission architecture, opto-mechanical design (including a possible spectrographic capability), satellite bus and launch options, ground segment requirements, and mission implementation plan.

The study — which will lead to an improved understanding of mission cost, schedule and risk, and involve an exploration of possible international partnerships and collaborations — is being led by Honeywell Aerospace (Ottawa), in collaboration with ABB Engineering (Quebec) and Magellan Aerospace (Winnipeg). The science team that consists of nearly 60 researchers at 17 Canadian universities and institutes. The study also involves major international partners — currently the Jet Propulsion Laboratory (JPL) and the Indian Institute of Astrophysics, who have been our partners in Astrosat, and are responding to an ISRO call for Astrosat2 proposals.

For more information on the CASTOR mission, see the project website.

To get involved in CASTOR, please contact Patrick Côté (scientific) or Alan Scott (technical).

By / par Chris Wilson, McMaster University (JCMT Board member for Canada)
(Cassiopeia – Summer / été 2018)

The JCMT continues to produce exciting new science results, with many results from the Large Programs appearing in the past 6 months. I’d like to particularly highlight the amazing results from the Canadian built polarimeter POL2 on SCUBA-2, including the first observations of the magnetic field structure inside the “Pillars of Creation” from the BISTRO Large Program (see Pattle et al., 2018, ApJL, in press, ArXiv: 1805.11554 and Ward-Thompson et al., 2017, ApJ). Pierre Bastien (Montreal) also presented a poster on POL-2 results at the recent CASCA meeting. The first generation Gould Belt Survey with SCUBA-2 is being very productive and publishing lots of papers, with good Canadian participation and leadership. There is also a major Canadian role in the new transient large program with some exciting papers published recently.

Magnetic field vectors in the “Pillars of Creation” in the M16 nebula are shown overlaid on a 3-colour HST image from Hester et al. (1996). The data were obtained at 850 microns with the POL2 instrument mounted in front of SCUBA-2 on the JCMT. Figure from Pattle et al. (2018, ApJL, in press).

Canadian PI observing time on the JCMT continues to be very oversubscribed, although the oversubscription rate in the most recent semester (18B) was lower than previous semesters. This drop may reflect the uncertainty in future Canadian participation in the JCMT (see below), or simply proposer fatigue caused by the high oversubscription rate.

The East Asian Observatory (EAO) currently has a 5-year agreement to operate the JCMT that ends in February, 2020. Recently, the EAO Board decided that they wish to continue to operate the JCMT for a second 5-year term. They would welcome continued participation by their U.K. and Canadian partners, and are also looking for additional partners from Asia and beyond.

As a result of this extended commitment by the EAO, the observatory is planning for upgrades to the existing instrumentation. The current 230 GHz receiver will be replaced with a newer, more sensitive receiver within the next year. Active investigations are underway for replacements for both SCUBA-2 and the 345 GHz array receiver HARP-B. Assistant Director Jessica Dempsey gave a talk about the future instrumentation plans at the JCMT at the recent CASCA meeting in Victoria.

The current Canadian university funding runs out February 2019. We will be looking for options to continue to fund JCMT operations, but none are currently obvious. The NSERC RTI program that has funded the Canadian operations contribution from February 2017-February 2019 did not run a competition in 2017. It remains to be seen whether it will be resurrected for the 2018 competition this fall given the new infusion of money from the Federal Government to the granting councils. The CADC currently operates the archive for the JCMT and about half of our PI observing time is tied to this CADC contribution. Whether this situation will continue if university funding for the JCMT ends remains to be confirmed. Another opportunity we are exploring is whether a CFI proposal could fund a contribution to the new instruments on the JCMT in return for continued PI access by Canadian researchers.

If operational funding from Canada lapses completely, Canadian astronomers will continue to be members of and have access to the existing Large Programs on the JCMT. Whether this courtesy would be extended at the next large program call (likely sometime in 2020) remains to be seen.

From / de John Hutchings
(Cassiopeia – Summer / été 2018)

The LRPIC meets regularly to monitor LRP projects and priorities, and our recent reports to CASCA are posted on the website. There are now three major ground-based facilities approaching key points of their development: TMT, SKA, and MSE. TMT still awaits approval to build on the Mauna Kea site, and also at the alternative site at La Palma. Progress continues with design work and telescope hardware among the partners, while there is welcome news of NSF’s plan to support both TMT and GMT. SKA is moving to formalize its move to a treaty organisation, although Canada and some others await acceptance as associate members. The MSE project also is moving towards a more formal partnership as it begins final study work prior to construction funding. All three of these major facilities, in which Canada has long played a reading role, will require funding and approval to retain our share and future. The timing and process for these funds will require careful planning. LRPIC notes the successful commissioning of CHIME and the ongoing plans to be a partner in CCAT-prime.

As widely discussed at CASCA, the status of our LRP plans for space facilities is very unsatisfactory. The CSA budget and mandate have both declined in recent years, under more than one government, to being unable to support any significant space science program, and being directed in detail by the government. Consultation and lobbying continue, as CSA-funded studies proceed for mission opportunities that have no guaranteed future. The recent debacle over joining WFIRST is well-known as an example of how badly things have gone, and got some attention in the Globe and Mail. We are working with the Coalition for Astronomy (ACURA, CASCA, and industry) in lobbying on a broad front.

Meantime, JWST, funded when CSA space science was viable, remains as our only partnership in space for the next decade, with no new future facilities committed. Projects that are ready to move ahead include leadership in the wide-field-UV CASTOR telescope, significant participation in SPICA, and valuable smaller partnerships in LiteBIRD, XARM, Ultrasat, and others.

We remind you of the open discussion email list for LRP matters:

lrpic-discuss@lists.casca.ca

By / par Arielle Moullet
(Cassiopeia – Summer / été 2018)

The SOFIA project has released two calls for proposals (CfP) for observing time in the Cycle 7 period.

The regular call solicits proposals of any size and combination of instruments. A total of 400 hours of observing time and approximately $4 million of funding is available to support these programs.

A complementary call for proposals for “SOFIA Legacy Programs” (SLP) has also been released, soliciting large coherent programs aimed at high-impact science that also have a significant promise of valuable archival data sets. Programs up to 100 hours of observing time are solicited in this category. In addition to observing time, these programs are invited to deliver higher level data products (including supporting data, software and theory). Nominally, two SLP programs are expected to be selected per cycle, with observations carried out over two cycles, and a third year included for completion of the higher-level data processing and analysis. Up to $1 million per cycle is available for support of the SLPs.

The main parts of the Cycle 7 (April 27, 2019 – April 27, 2020) calendar are:

• CfP release: June 1, 2018
• CfP update: July 16, 2018
• Proposal Deadline: September 7, 2018 (9 p.m. PDT)
• Selections announced: November 2018

The Call for Proposals documents can be found here and here.

Any questions about the Cycle 7 Calls for Proposals can be directed to sofia_help@sofia.usra.edu.

From / de Gerald Schieven
(Cassiopeia – Summer / été 2018)

ARCADES, A New Facility for ALMA Data Reduction/Analysis

NRC’s Herzberg Astronomy and Astrophysics Research Centre is pleased to announce a new project which aims to make all aspects of ALMA data analysis easier. The ARCADES (ALMA Retrieval with the CANFAR Data System) project has several different components which we are starting to roll out. The first component is aimed primarily at astronomers who have some experience with ALMA’s data reduction software, CASA. For this component, we are making available one-click virtual machines on the CANFAR computing environment which have CASA pre-loaded and easy mechanisms to download raw ALMA data. These virtual machines will have ample computing power and storage space, and are fully interactive (e.g., for running CLEAN). We are looking for several beta testers for this system – please contact Helen Kirk if you are interested.

New Horizons in Planetary Systems 13-17 May 2019

Members of the Millimetre Astronomy Group at Herzberg and their counterparts at NRAO are jointly organizing (as part of their roles within the North American ALMA Science Centre) a science conference entitled “New Horizons in Planetary Systems” to be held from 13-17 May 2019 in downtown Victoria BC.

The meeting is planned to have a broad scope, including planetary systems in formation within protoplanetary disks, minor objects in the solar system, debris disks and exoplanets. Experts will be asked to provide insights from all these fields to enhance our understanding of how planets form and evolve. Although it is organized by the NAASC, the meeting is not ALMA-centric, with a strong focus on the impact of the New Horizons mission flyby of a KBO in January 2019, as well as experts from TESS and other facilities who will be asked to provide a multi-chromatic picture of the current understanding in their fields. Invited speakers have been asked to provide broadly accessible talks.

Confirmed invited speakers include:

• Brett Gladman (UBC): theory of planet formation
• Grant Kennedy (U Warwick): debris disk constraints on planet formation
• Heather Knutson (Caltech): exoplanet atmospheric composition
• Emmanuel Lellouch (Observatoire de Paris): solar system objects, constraints on formation
• Karin Öberg (Harvard U): protoplanetary disk composition and chemistry
• John Spencer (SWRI): New Horizons KBO flyby: first results

We will also host a public talk on New Horizons by Deputy Mission Scientist Kelsi Singer (SWRI).

For more information, contact LOC Chair Brenda Matthews. Pre-registration will open in July with registration and abstract submission in October 2018.

Cycle 6 Canadian Submission Statistics

A record 1839 proposals were submitted requesting over 33K hours of ALMA time in Cycle 6, corresponding to an oversubscription rate of 4.8. Canadian PIs also submitted a record 44 proposals, requesting nearly 1000 hours. Canadian astronomers have full access to the North American fraction of ALMA time (~33%). The results from the Cycle 6 proposal review process are expected to be released in late July. Cycle 6 runs October 2018 through September 2019.

ALMA Publications

Over 1000 refereed publications have now appeared using ALMA data. Of these, more than 13% have had authors or co-authors from Canadian institutions.