Dissertation: Behavior of Low-mass X-ray Binaries and their Formation in Globular Clusters

(Cassiopeia – Autumn/l’automne 2016)

by Arash Bahramian
Thesis defended on June 22, 2016
Department of Physics, University of Alberta
Thesis advisor: Dr. Craig O. Heinke

Abstract
Low mass X-ray binaries (LMXBs) are systems of compact stellar remnants accreting from a low mass companion star. These systems show various levels of mass transfer on various timescales. Many aspects of accretion in these systems are still not fully understood, specifically the emission processes involved in various states of mass transfer. The population of LMXBs has been found to be orders of magnitude higher (per unit mass) in globular clusters (GCs) compared to the Galactic field. This overabundance has been explained as due to the formation of LMXBs by stellar encounters in GCs. In this thesis, we study GC LMXB populations, and the details of accretion in these systems. First, we focus on the population of LMXBs and the role of stellar encounters in their formation in GCs. We calculate model-independent stellar encounter rates for 124 Galactic GCs, and show that core-collapsed clusters tend to have lower numbers of LMXBs compared to other clusters with similar values of the stellar encounter rate. Then, we focus on studying accretion in LMXBs in various classes of systems (quiescent, transient, ultra-compact and symbiotic). We provide evidence for the presence of low-level accretion in the rise and decay of outbursts in transient LMXBs, and the absence of low-level accretion in many quiescent neutron star LMXBs. Finally we study two peculiar LMXBs, and show that one is an ultra-compact X-ray binary, and another one is a symbiotic X-ray binary.

Dissertation: What Governs Star Formation in Galaxies? A Modern Statistical Approach

(Cassiopeia – Autumn/l’automne 2016)

By Sahar Rahmani
Thesis defended on August 23, 2016
Department of Physics and Astronomy, Western University
Thesis advisor: Dr. Pauline Barmby

Abstract
Understanding the process of star formation is one of the key steps in understanding the formation and evolution of galaxies. In this thesis, I address the empirical star formation laws, and study the properties of galaxies that can affect the star formation rate.

The Andromeda galaxy (M31) is the nearest large spiral galaxy, and therefore, high resolution images of this galaxy are available. These images provide data from various regions with different physical properties. Star formation rate and gas mass surface densities of M31 have been measured using three different methods, and have been used to compare different star formation laws over the whole galaxy and in spatially-resolved regions. Using hierarchical Bayesian regression analysis, I conclude that there is a correlation between surface density of star formation and the stellar mass surface density. A weak correlation between star formation rate, stellar mass and metallicity is also found.

To study the effect of other properties of a galaxy on the star formation rate, I utilize an unsupervised data mining method (specifically the self-organizing map) on measurements of both nearby and high-redshift galaxies.
Both observed data and derived quantities (e.g. star formation rate, stellar mass) of star-forming regions in M31 and the nearby spiral galaxy M101 are used as inputs to the self-organizing map. Clustering the M31 regions in the feature space reveals some (anti)-correlations between the properties of the galaxy, which are not apparent when considering data from all regions in the galaxy. The self-organizing map can be used to predict star formation rates for spatially-resolved regions in galaxies using other properties of those regions.

I also apply the self-organizing map method to spectral energy distributions of high-redshift galaxies. Template spectra made from galaxies with known morphological type are used to train self-organizing maps. The trained maps are used to classify a sample of galaxy spectral energy distributions derived from fitting models to photometry data of 142 high-redshift galaxies. The grouped properties of the classified galaxies are found to be more tightly correlated in mean values of age, specific star formation rate, stellar mass, and far-UV extinction than in previous studies.

Dissertation: X-ray Populations in The Local Group: Insights with Hubble and Chandra

(Cassiopeia – Autumn/l’automne 2016)

neven vulic

by Neven Vulic
Thesis defended on June 21, 2016
University of Maryland, College Park
Thesis advisors: Dr. Pauline Barmby and Dr. Sarah C. Gallagher

Abstract
X-ray observations provide a unique perspective on the most energetic processes in the Universe. In particular, Low-mass X-ray binaries (LMXBs) found in globular clusters have been shown to depend on the mass, radius, and metallicity of the cluster. This thesis focuses on the impact environmental parameters have on X-ray sources and the underlying physical explanations for them. I studied the X-ray binary population in M31 using 1 Ms of Chandra ACIS data and 6-filter photometry from the Panchromatic Hubble Andromeda Treasury Survey. From a sample of 83 star clusters we found the brightest and most compact star clusters preferentially hosted an X-ray source. An investigation of 1566 H II regions found that neither radius nor H-alpha luminosity was a predictor of an H II region hosting an X-ray source. To study the faintest X-ray sources a stacking analysis of star clusters and H II regions was completed. Non-detections throughout resulted in upper limits of ~10×1032 erg/s. I produced the most sensitive Chandra X-ray point source catalogue of M31, detecting 795 X-ray sources in an area of ~0.6 deg2, to a limiting unabsorbed 0.5-8.0 keV luminosity of ~10×1034 erg/s. The flatter completeness-corrected X-ray luminosity function of the bulge compared to the disk, consistent with previous work, indicated a lack of bright high-mass X-ray binaries in the disk and an aging population of LMXBs in the bulge. I also investigated the origin of the relationship between the metallicity of 109 Galactic globular clusters and LMXB formation by studying the number density of red giant branch (RGB) stars. A Spearman Rank test between the RGB star density and metallicity [Fe/H] confirmed the data could not have been drawn from a random distribution.

Dissertation: Monitoring Broad Absorption-line Quasar Variability

(Cassiopeia – Autumn/l’automne 2016)

jesse1
By Jesse Rogerson
Thesis defended on April 18, 2016
Department of Physics and Astronomy, York University
Thesis advisor: Dr. Patrick Hall

Abstract
Winds generated by an accreting super massive black hole may provide feedback to the host galaxy and offer an explanation for the co-evolution of galaxies with their super massive black holes that has been reported in the literature. Some outflows are manifested as broad absorption line (BAL) troughs in quasar spectra, and are measured at velocities as high as ~60,000 km s−1 at ultra-violet wavelengths. These BAL troughs have been observed to vary on both long (years) and short (weeks) rest-frame time-scales and can emerge in a quasar that had none, or disappear completely. By monitoring the variability of absorption in BAL quasars, constraints can be placed on outflow models and the structure of quasars in general.

In this study, we isolate a set of quasars that exhibit emergent CIV BALs in their spectra, by comparing archival data in the SDSS Data Release 7 to the BOSS Data Release 9 and 10. After visually defining a set of emergent BALs, follow-up observations were obtained with the Gemini Observatory for 105 quasars. BALs were formally detected in all but two of the quasars in the dataset, and we report 219 absorption complexes in the entire set. After a BAL has emerged, we find it is equally likely to continue increasing as it is to start decreasing in a subsequent observation. Based on the range of time between our observations, this indicates the coherence time-scale of BALs is less than 100 days. There is a strong signal of coordinated variability among two troughs in the same quasar. Further, coordination is stronger if the velocity separation between the two troughs is smaller. We conclude the variability is likely due to changes in the ionizing flux incident on the absorbing cloud, which agrees with the results of Filiz Ak et al. (2013).

In this work we also test two competing models of BAL variability (bulk motion and ionization changes) in the context of a case study of the quasar SDSS J023011.28+005913.6, which had two high-velocity emergent troughs. Both models yield plausible results.

Update from the Canadian Space Agency / Compte rendu de l’agence spatiale canadienne

From/de Denis Laurin, Senior Program Scientist/Scientifique principal de programme, Space astronomy, Space Exploration development/Développement d’exploration spatiale, CSA/ASC
(Cassiopeia – Autumn/l’automne 2016)

La version française suit

Canadian Space Exploration Workshop – CSEW 2016

The CSA will host a consultation workshop on November 24-25 in downtown Montreal to update the space sciences priorities, looking at opportunities for the next decade and beyond. This includes space astronomy, planetary exploration and space health disciplines. Ideas will be welcomed from the community (academia & industry) to help shape future of Canadian space activities. The workshop is a forum for the current space exploration Topical Teams (described in Cassiopeia March 2016) to present and discuss their interim results.

Participation by a broad representation of the community in space sciences is thus important to ensure that the set of objectives of the Canadian Exploration communities are being fully and accurately captured.

More details are presented on the CSEW webpage. There is no fee to participate, but registration is required. For any questions about the workshop please contact: asc.aces-csew.csa@canada.ca.

English above

Atelier canadien sur l’exploration spatiale – ACES 2016

L’ASC offrira un atelier de consultation le 24 et 25 novembre au centre-ville de Montréal afin de mettre à jour les priorités en sciences spatiales, revoir les opportunités pour la prochaine décennie et au-delà. Cela comprend l’astronomie spatiale, l’exploration planétaire et de la santé dans l’espace. Des idées seront échangées par la communauté (les universités, l’industrie) pour aider à façonner l’avenir des activités spatiales canadiennes. L’atelier est un forum pour les Équipes thématiques en exploration spatiale actuelles (tel que décrites dans le numéro Cassiopeia mars 2016) pour présenter et discuter leurs résultats intermédiaires.

La participation d’une large partie de la communauté directement concernée par les sciences spatiales est donc importante pour faire en sorte que leurs objectifs soient pleinement et correctement entendus.

Plus de détails sont présentés sur la page Web CSEW. Il n’y a pas de frais pour participer, mais l’inscription est obligatoire. Pour toutes questions concernant l’atelier, contacter: asc.aces-csew.csa@canada.ca.

Celebrating the History of Radio Astronomy in Canada

By/par Tim Robishaw, DRAO
(Cassiopeia – Autumn/l’automne 2016)

A workshop on the history of Canadian radio astronomy was held July 25 and 26 at the Dominion Radio Astrophysical Observatory (DRAO).

Workshop participants under the John A. Galt 26-m telescope.

Workshop participants under the John A. Galt 26-m telescope.

Workshop participants under the John A. Galt 26-m telescope.

Workshop participants under the John A. Galt 26-m telescope.

Nametags of workshop participants were customized with telescopes and observatories from their past.

Nametags of workshop participants were customized with telescopes and observatories from their past.

A major motivation for the event was the work of the late Richard Jarrell (York University), the author of “The Cold Light of Dawn: A History of Canadian Astronomy”. Richard collected an extensive archive on the history of Canadian radio astronomy, including many interviews with all the original players. Richard had just begun writing a book on this topic at the time of his passing in late 2013. A group of Canadian radio astronomers hopes to finish writing this book following the outline Richard provided and using his archival material. To this end, in addition to topics of worldwide importance to the history of radio astronomy, contributions were solicited on topics pertaining to the development of radio astronomy in Canada. Richard’s wife, Martha, attended the workshop and hand-delivered Richard’s archives and interviews to DRAO where they will be housed.

The workshop included 27 talks covering a breadth of stories about the development of radio astronomy at Canada’s universities and observatories. The nearly 50 attendees took part in a discussion about practicing history led by Woody Sullivan (University of Washington), Miller Goss (NRAO)—both active historians of radio astronomy—and NRAO Archivist, Ellen Bouton.

A website containing videos of the talks and photos from the workshop can be found here. And thanks to Joseph Fletcher (NRC, retired) and Bob Hayward (NRAO, retired), we now have video of a 1987 NRC workshop entitled “Radio Astronomy and Canada: Fifty Years of Progress”. These videos can also be found at the above website.
If you prefer to view the videos directly, the Youtube links to the workshop playlists are below:

Update from the Canadian Space Agency / Compte rendu de l’agence spatiale canadienne

From/de Denis Laurin, Senior Program Scientist, Space astronomy, Space Exploration development, CSA,
with contributions from/avec des contributions de Jean Dupuis, Senior mission scientist

(Cassiopeia – Summer/été 2016)

La version française suit

Congratulations to John Hutchings

Figure 1 - Left to right: Sylvain Laporte (CSA President); John Hutchings (NRC); David St-Jacques (CSA astronaut).

Figure 1 – Left to right: Sylvain Laporte (CSA President); John Hutchings (NRC); David St-Jacques (CSA astronaut).

In recognition of his exceptional contribution to the Canadian Space Program, Dr. John B. Hutchings was presented with the John H. Chapman Award of Excellence during a ceremony at the 17th Conference on Astronautics of the Canadian Aeronautics and Space Institute (CASI ASTRO 2016) in Ottawa, Ontario.

The Chapman Award is a tribute to the distinguished career and achievements of an extraordinary individual, whose vision and contributions have shaped Canada’s space program.

JAXA Hitomi

Despite the unfortunate premature end of the Hitomi X-ray observatory on March 26, JAXA did collect valuable scientific data (during the commissioning phase). A report published on the JAXA website describes the event (Hitomi report). The science team is analysing the available data (mainly SXS instrument) and significant science results will soon be published. Furthermore, the Canadian contribution of the laser metrology system (CAMS) built by Neptec demonstrated excellent performance.

ISRO ASTROSAT

Contributed by Jean Dupuis, Senior Mission Scientist, CSA

Figure 2 - UVIT FUV image of the central region (~3 arcmin) of the globular cluster NGC 1851 (FUV CaF2 filter, exposure time of 10 minutes, provided by John Hutchings, NRC-Herzberg)

Figure 2 – UVIT FUV image of the central region (~3 arcmin) of the globular cluster NGC 1851 (FUV CaF2 filter, exposure time of 10 minutes, provided by John Hutchings, NRC-Herzberg)

The first call for proposals for the ASTROSAT Canadian open time (5%) has been issued with a deadline of July 29th (see recent e-mail by John Hutchings to CASCA mailing list). Support to Canadian proposers is to be provided by Joe Postma of the University of Calgary (jpostma@ucalgary.ca). UVIT is reportedly performing well and commissioning activities are mostly completed and the observatory has initiated its science programme. The Figure below shows one such science verification image obtained with UVIT’s Far-UV channel of the globular cluster NGC 1851. This work is done in collaboration with the UVIT team at the Indian Institute of Astrophysics (IIA).

CSA MOST Archive

Described in more detail in the spring issue of e-Cass, the MOST mission data archive is essentially completed, thanks to the effort of Dr Vinothini Sangaralingam, Visiting Fellow (CSA / NSERC) in close collaboration with CADC (David Bohlender, for implementation and maintenance) and MOST science team members. For further information on the MOST mission and data availability, please contact the MOST Mission Scientist, Jaymie Matthews: matthews@astro.ubc.ca.

CSA JWST Science Support

Contributed by Jean Dupuis, Senior Mission Scientist, CSA

CSA is working on a plan to provide science support for data analysis during the JWST mission where 5% of the open observation time will be available to Canadian astronomers. We encourage the community to contact us and the Joint Committee on Space Astronomy (JCSA) with their ideas on how CSA could optimally support science activities during the JWST operations.

NASA WFIRST

CSA continues to define potential Canadian contributions to the WFIRST mission, a dark energy and exoplanet mission ranked high priority in the CASCA LRP for space astronomy. A Phase 0 contract was awarded in May to Honeywell Space (COMDEV) for a duration of 12 months. The result will provide information needed by CSA (technology assessment, feasibility, costs, and schedule for development phases) for decision towards the next phase.

CSA Topical Teams in Space Astronomy

CSA Topical Teams in Space Astronomy
The purpose, membership and support for Topical Teams were described in the spring issue of e-Cass. The teams held a lunch time session at CASCA in Winnipeg that was well attended. The teams’ goal is a set of draft reports to be discussed at the next CSA Space Exploration Workshop which is planned for mid-November 2016 in Montreal. (An announcement of the workshop will be sent to the communities once it is confirmed.)

Wishing everyone a great summer!
Denis Laurin



Félicitations à John Hutchings

Figure 1 - Gauche à droite: Sylvain Laporte (Président ASC); John Hutchings (CNRC); David St-Jacques (astronaute ASC).

Figure 1 – Gauche à droite: Sylvain Laporte (Président ASC); John Hutchings (CNRC); David St-Jacques (astronaute ASC).

En reconnaissance de sa contribution exceptionnelle au Programme spatial canadien, John B. Hutchings s’est vu remettre le prix d’excellence John H. Chapman au cours d’une cérémonie qui s’est déroulée à l’occasion de la 17e Conférence de l’Institut aéronautique et spatial du Canada sur l’astronautique à Ottawa, en Ontario.

Le prix Chapman souligne la carrière distinguée et les réalisations d’un individu extraordinaire dont la vision et le dévouement hors pair ont contribué à l’avancement du Programme spatial canadien.

JAXA Hitomi

Malgré la fin prématurée malheureuse de l’observatoire en rayons-X Hitomi le 26 mars, la JAXA a quand même recueilli des données scientifiques importantes (lors de la phase de mise en service). Un rapport publié sur le site de JAXA décrit la série d’évènements . L’équipe scientifique analyse les données disponibles (principalement de l’instrument SXS) et des résultats scientifiques significatifs seront bientôt publiés. En outre, la contribution canadienne du système de métrologie laser (CAMS) construite par Neptec, a démontré d’excellentes performances.

ISRO ASTROSAT

Contribué par Jean Dupuis, Scientifique principal de missions, ASC.

Figure 2 - Image UVIT FUV de la région centrale (environ 3 minutes d’arc) de l’amas globulaire  NGC 1851 (filtre FUV CaF2, temps d’exposition de 10 minutes;, fourni par John Hutchings, Herzberg-CNRC)

Figure 2 – Image UVIT FUV de la région centrale (environ 3 minutes d’arc) de l’amas globulaire NGC 1851 (filtre FUV CaF2, temps d’exposition de 10 minutes;, fourni par John Hutchings, Herzberg-CNRC)

La première demande propositions pour le temps ouvert canadien sur ASTROSAT (5%) a été émise avec une date limite du 29 juillet (voir le récent envoi de message par John Hutchings à la liste de diffusion de CASCA). Un soutien aux proposants canadiens sera fournis par Joe Postma à l’Université de Calgary (jpostma@ucalgary.ca). L’instrument UVIT démontre de bons résultats et les activités de mise en service sont pour la plupart terminées et l’observatoire a lancé son programme scientifique. L’image ci-dessous montre un exemple d’une telle image de vérification scientifique dans l’UV lointain par UVIT de l’amas globulaire NGC 1851. Ce travail est fait en collaboration avec l’équipe UVIT à l’Institut Indien d’Astrophysique.

ASC archive des données MOST

Décrit plus en détail dans le numéro du printemps de l’e-Cass, l’archive de données de la mission MOST est essentiellement complétée, grâce à l’effort du Dr Vinothini Sangaralingam, boursière postdoc (CSA / CRSNG) en étroite collaboration avec le CADC (David Bohlender, pour la mise en œuvre et la maintenance des pages web) et plusieurs membres de l’équipe scientifique. Pour de plus amples informations sur la mission MOST et la disponibilité des données, s’il vous plait contacter le scientifique de la mission MOST, Jaymie Matthews: matthews@astro.ubc.ca.

ASC JWST support scientifique

Contribué par Jean Dupuis, Scientifique principal de missions, ASC.

CSA prépare un plan de soutien scientifique pour les analyses de données au cours de la mission JWST où 5% du temps d’observation ouverte sera disponible aux astronomes canadiens. Nous encourageons la communauté à communiquer à l’ASC ou à notre Comité consultatif (JCSA) leurs idées sur la façon optimale de soutenir les activités scientifiques au cours des opérations JWST.

NASA WFIRST

L’ASC continue de déterminer les contributions potentielles du Canada à la mission WFIRST, une mission pour explorer l’énergie sombre et les exoplanètes; la mission demeure haute priorité dans le plan à long terme de la CASCA pour l’astronomie spatiale. Un contrat de phase 0 a été attribué en mai à Honeywell Space (COMDEV) pour une durée de 12 mois. Le résultat servira à fournir les informations nécessaires par l’ASC (tel que l’évaluation de la technologie, la faisabilité, les couts et le calendrier pour les phases de développement) pour la prise de décision vers la phase ultérieure.

En vous souhaitant à tous et à toutes un été agréable!
Denis Laurin

TMT Update: Site Physics, Permits, Parameters and Science

By/par Ray Carlberg
(Cassiopeia – Summer/été 2016)

Some of the background of the loss of the site permit in Hawaii was discussed in the Vernal Equinox edition of Cassiopeia. TMT has announced that it plans to resume construction in April 2018 or sooner, but of course it needs a site on which to build. Since the project was scientifically, technically and financially built around Hawaii we would all like to build there, and, it is not that easy to simply transport an entire multi-national project someplace else. Doubly so when significant decisions need to be made over the short time left this calendar year.

Hawaii continues to provide an impressive flow of news stories about TMT. There is a laudable local effort to create a more positive environment, but that is a long term effort that seems very unlikely to overcome a deeply entrenched opposition in a short time. The legal process required to grant a permit is itself clouded. It took about 5 months to appoint a hearing officer to oversee the process. The opponents pointed out at least one significant appearance of bias. Their case is strong enough that all parties, pro and con, have petitioned for a new hearing officer. In TMT’s case we do not want to go through a long permit process knowing that there is already a substantial basis for a court to rule the entire effort to be invalid. Somewhat astonishingly, Hawaii has recently reaffirmed the hearing officer’s appointment.

So, TMT is looking for an alternate site. the list of really good sites is not all that long. The physics of an astronomical site is interesting in itself and reasonably simple. The air needs to have as little turbulence as possible and be as dry as possible. Turbulence in the air has three components. Mountains are always windy and the aerodynamics of wind over the surface gives rise to a ground shear layer that becomes turbulent. Getting above the local ground layer is the reason that CFHT has a 44m high dome for a 3.57m telescope. TMT has a 60m high dome so gets a little further into good air. Ground heating of the air on the way to the mountain generates thermal convection between the ground and the cloud layer at around 3000m. The development of turbulent convection is minimized for steep mountains near coastlines, high enough to get above cumulus clouds. Good seeing needs to start with higher altitude airflow that is as laminar as possible, which occurs in the trade winds. These originate in the Hadley cell airflow in which the thermal energy of air near the equator causes it to rise high in the atmosphere, descending at +/- 20 degrees as extremely dry air with remarkably steady wind. It also generally means relatively cloud free skies (and often deserts on the ground). The outcome is that at a good site there is mainly a ground layer, which good design can minimize, and, a shear layer near the tropopause around 10km altitude, which airplane passengers frequently experience. The beauty of having a single dominant turbulent layer distorting light is that it means that relatively simple adaptive optics systems can focus (conjugate) on and provide remarkable correction, although better correction and wider fields of view does require 3D correction.

The other major factor in a good site is simply height. A higher mountain increases UV transparency and reduces the water in the atmosphere which has such a dense spectrum of lines that both reduce transparency and emit radiation. Chile has the advantage of a very cold current from Antarctica off the coast rather than the tropical water of Hawaii which leads to more water column at the same height. For some observations, water is simply a nuisance, but for those interested in exoplanets, water is an important molecule to detect. And of course physics of molecular lines means that lots of interesting molecules have their lines in the infrared and mid-infrared. A non-scientific issue is that costs tend to go up with height as well, but ALMA and other telescopes (including the ACT built by Empire Dynamic Structures) have greatly developed high altitude construction techniques. Another non-scientific factor is that people have been climbing mountains for a long time and nobody in TMT wants to go to another mountain with cultural artefacts and native population connections.

All that doesn’t leave a long list of viable mountains. The best are Mauna Kea in the north and in the south the mountains of the northern Atacama Desert of Chile. Polar sites are also very good, but have additional technical challenges and high costs. To help make a comparative scientific assessment manageable, TMT developed the “Nelson-Cohen” site merit function, with an estimate of the speed of acquiring a given scientific goal in the optical in natural seeing, near-infrared with AO and mid-infrared with AO. These are representative science uses, and specific ones will give somewhat different outcomes. The sites currently under consideration are Mauna Kea (13N at 4050m), Roque de los Muchachos Observatory (ORM) in the Canaries (2250m), San Pedro Martir (SPM) in Baja Mexico (2830m), Vicuna Mackenna (3100m) near Paranal and Honar (5400m) south of the ALMA site. For optical band natural seeing observations Mackenna is best with Honar, Mauna Kea and ORM being about 15-18% less desirable although transparency is a larger issue at ORM. SPM is about 28% less effective than Mackenna. In the NIR Honar is best with MK 13N and Mackenna down 14-18% and SPM, ORM down 34-42%. In the mid-IR Honar truly stands out, with MK13N and Mackenna down 40-43% and SPM and ORM down 53-56%. In the south, the choice between Honar and Mackenna depends on how important mid-IR is for your science. By any assessment AO assisted observations and NIR and mid-IR are becoming more important uses as both science interests move to redder bands and as IR technology improves. If only a small fraction of the time was required for mid-IR, a poor site does give that from time to time, which a queue system (not in the TMT baseline) could give. However, for time critical observations (such as planet transits and all sorts of LSST followup) a small queue fraction is not likely to be satisfactory.

The E-ELT is being built on a site essentially identical to Mackenna although Mackenna does have room for more telescopes in the future. Clearly TMT on Hawaii would give us a competitive telescope with complementary sky access. Other sites in the North would give us a smaller telescope on a worse site, which would be hard to justify. A high site in Chile would give us an advantage over E-ELT for a range of interesting science. Canadians are of course familiar with the advantages of dealing with the difficulties and long term payoff of pioneering a high, remote site, which Hawaii once was.

The TMT fund is not money that astronomers can move around at will which is true for all members of TMT, which is where the complications begin. The Canadian SAC members have so far mainly pointed out the increased scientific return of the Chilean sites, particular relevant to scientific observations (exoplanets) which are likely to become a major use of ELTs. It would be sad to leave the North but we may have no choice. We in Canada have built our case on the century of tradition of “second to none” which has important implications for the TMT site choice for Canadian astronomers.

Maunakea Spectroscopic Explorer (MSE) Update

By/par Michael Balogh, on behalf of Pat Hall, chair of the MSE Advisory Group
(Cassiopeia – Summer/été 2016)

Conceptual design work continues for the MSE! The call for bids for the telescope structure conceptual design has been issued, with a closing date of 5 July. Scientists and engineers from five Canadian universities, along with industry partners, are preparing a CFI application for construction of a prototype high-resolution spectrograph and design and development of integrated observational and operational databases and software.

Detailed Science Case on arXiv

The 210-page MSE Detailed Science Case has been finalized and published online here. A ten-page concise overview is also available here. Detailed Science Case white papers and other background science and technical documents are now posted here.
The Detailed Science Case illustrates the breadth of scientific areas in which MSE will have a transformative impact. To name just a few: the in-situ chemical tagging of the distant Galaxy using high-resolution (R~40,000) stellar spectra, measuring the dark matter density profiles of Milky Way dwarf galaxies using repeat spectra of thousands of stars in those galaxies, and reverberation mapping of supermassive black holes in quasars.

Engineering and Science Collaboration Meeting

More than 40 members of the MSE international science, and engineering, teams met for the first integrated Engineering and Science collaboration meeting, in Madrid on 27-29 April. The Univesidad Autonoma de Madrid (UAM) hosted a delightful event; one that provided a venue for a wholesome exchange over the science ambition versus the engineering realities of complex systems such as MSE. Spanish and Australian teams demonstrated unique fiber positioning robotic technology (the third team from NAIOT in China was unable to attend). MSE’s Project Manager comments: “It was a thoroughly successful meeting, fully achieving its objectives, and was very enjoyable as well!”

ALMA Matters

From/de Gerald Schieven
(Cassiopeia – Summer/été 2016)

ALMA Band 1 Goes into Production

Figure 1 - the prototype Band 1 (35-52 GHz (8.5-5.7 mm)) cartridge

Figure 1 – the prototype Band 1 (35-52 GHz (8.5-5.7 mm)) cartridge

Band 1 is the lowest frequency band for ALMA and covers the 35 to 52 GHz region of the millimetre-wave spectrum. Science drivers for this band include dust continuum studies of protoplanetary disks, red-shifted molecular lines from galaxies at high redshift, the Sunyaev-Zel’ovich effect, and much more (Di Francesco et al. 2013).

Band 1 development for ALMA is being led by ASIAA in Taiwan in collaboration with NAOJ, the University of Chile, NRAO, and NRC Herzberg. A successful Critical Design Review was held in Taipei in January 2016, and the ALMA Board has now approved the Band 1 project team to go into production of the 73 Band receiver cartridges needed to equip all ALMA antennas in Chile. The production schedule proposed by ASIAA would see all Band 1 cartridges delivered to the JAO by the end of 2019.

Figure 2 - the prototype orthomode transducer (OMT), designed and produced by NRC Herzberg

Figure 2 – the prototype orthomode transducer (OMT), designed and produced by NRC Herzberg

The NRC Herzberg technical contribution to Band 1 is the design, production, and testing of the orthomode transducers (OMTs), precision passive millimetre-wave devices which separate the incoming radiation into its two orthogonal linearly polarized components. This permits ALMA to make observations of the polarization of continuum and spectral line sources in Band 1. NRC Herzberg will be producing the production OMTs (one per receiver cartridge) in-house using the precision machining facilities provided by NRC’s Design and Fabrications Services workshop in Victoria, and will verify the performance of each unit through cryogenic testing in its millimetre-wave instrumentation laboratory.

Face-to-face Visits

If you wish to travel to Victoria for face-to-face assistance with ALMA data reduction and analysis, please contact Brenda Matthews.