Archives de la catégorie : Rapports de Comités

By / par Martine and Pamela Freeman, with input from the CASCA Sustainability Committee (The CASCA Sustainability Committee, The CASCA Equity & Inclusivity Committee)
(Cassiopeia – Spring / printemps 2021)

The CASCA Sustainability Committee is a group of astronomers concerned about our field’s contributions to environmental damage. This article is the second of a 2-part series in Cassiopeia which aims to bring more awareness within the astronomical community to the connections between race and the environment. It is also part of our committee’s effort to center perspectives often neglected in predominantly-white environmental groups.

Part 2: Astronomy Activities at Home and Abroad

In our previous article (1), we summarized the growing body of evidence demonstrating that the fallout from climate change will disproportionately impact people of color and Indigenous populations both globally and within Canada. Astronomers have been coming to grips with the excessive carbon emissions associated with professional astronomy (2,3), as well as with the manifestations of systemic racism in our field (4,5). These inequities must be recognized and sustainable practices must be proposed in ways that center racial (and other forms of) equity. In this article, we briefly review how the history of Western astronomy led to systemic racism and Eurocentrist practices within the field today. We next discuss how our field’s environmental impacts play into broader global patterns, and follow with a discussion of the combined environmental and cultural impact at observatories located on Indigenous territory. We propose rough guidelines to move us toward a more equitable and sustainable future.

Much of modern astronomy in Canada was made possible by settler colonialism (the formation of a governance system through the invasion of outsiders with the aim of assimilating or erasing Indigenous peoples, 6). Some of the oldest examples include renowned observations during European expeditions to the Caribbean (7) as well as the important role astronomy played in building Canada through government-sponsored mandates for timekeeping and mapmaking (8,9). As with most institutions in Canada today, a great deal of our astronomy resources — such as observatories (10,11), university buildings (12,13), and funds (14,15) — were facilitated by colonization. The benefits from these resources have gone primarily to Europeans and Euro-descendants. In the university setting today, astronomers’ participation in the settler colonialist framework is reflected by the severe underrepresentation of Black and Indigenous faculty as well as the exclusion and devaluation of Indigenous and non-Western knowledge within academic circles (16). Systemic racism in professional astronomy is, in part, a legacy of our profession’s historic and ongoing ties with colonialism.

As in the past, astronomy today benefits from environmental damage which is particularly damaging to Indigenous, Black, and other people of color. Although our field is not on the same level as the most egregious perpetrators of environmental racism (e.g. the oil industry and chemical plants), our impacts are non-negligible and we have a responsibility to do better. Our per-capita emissions from work alone, mostly from air travel, are typically well-beyond the average working person’s total emissions (2,3). As a predominantly white institution, therefore, Canadian astronomy is part of a North American pattern in which white people produce a much higher percentage of pollution than people of color, while a higher percentage of non-white people suffer the related health effects (17). Our emissions also contribute to a global pattern where the Global South bears the brunt of a climate crisis mostly perpetrated by the Global North (see part 1 and links therein). In addition, many of our observatories are situated on unceded or contested Indigenous lands both within Canada and internationally, where they impact the local environment and contribute to the global climate crisis. In Canada, the Dominion Radio Astrophysical Observatory (DRAO), including the Canadian Hydrogen Intensity Mapping Experiment (CHIME), is situated on the unceded lands of the Syilx/Okanagan (18) as well as the Nlaka’pamux people (19). In addition, the Algonquin Radio Observatory (ARO) is on the unceded land of the Omàwinini (Algonquin) people, which is part of the largest land claim being negotiated in Ontario today (20,21).

Of all the Canada-affiliated observatories, those on Maunakea on Hawai’i Island are the most well-publicized example where environmental and cultural concerns intersect. Kānaka Maoli (Native Hawaiian) views on the present and future of Maunakea Observatories (e.g. TMT) are diverse, ranging from strong support to strong opposition (22) with a variety of reasoning (see 23 for a Native Hawaiian-led overview of the issues). However, an oft-cited concern among the kia’i (protectors) is the environmental degradation of the mountain, considered sacred to many people (23, 24, 25). Many Hawaiians cite the concept of aloha ‘āina when discussing Maunakea, which translates to ‘love of the land’ and describes a deep relationship to nature (26, 27). Some TMT opponents are concerned about impacts to the water, destruction of rare species on the mountain, and hazardous spills (26, 28). Although mountain management plans are attempting to mitigate such impacts (29), these concerns stem from the previous damage that astronomy’s presence has had on the mountain (23,28). Canadian astronomy also benefits from other observatories on Indigenous territory both at home and abroad. Generally, increased activity in these lands (observers’ flights, frequent truck transport, occasional waste spills, etc.) and telescopes’ electricity usage add up to a high environmental footprint (30,31,32). Environmental impacts are coupled with impacts on culture, health, and well-being for Indigenous communities (32, 33, 34).

We encourage readers to think about steps that will move our field towards an equitable and sustainable future. The Sustainability Committee is working in partnership with the Equity and Inclusivity Committee to address some of the concerns put forth in this article. While we (the authors) lack the expertise to make direct recommendations for telescopes, we suggest that existing observatories regularly assess their environmental impacts in partnership with local Indigenous representatives and in doing so, center Indigenous methods. Indigenous-led recommendations for telescope consultation (e.g. 23, 35) should be followed in the consideration of new facilities and the re-consideration of existing facilities; environmental improvements cannot be a band-aid for unethically established observatories. Progress is possible: ALMA, for example, has programs for scientists to learn from, teach, and help preserve the culture of the local Likan Antai community (10). Meanwhile, recent developments at various ESO observatories (30, 36) and Gemini (37) have reduced environmental impacts.

Beyond telescopes, we encourage readers to consider the intersection of sustainability and equity in topics such as conferences, observing, computing resources, university spaces, and the perceived correlation of success with travel (see 38 for further discussion). As a field, steps that we make to reduce our carbon footprint should also prioritize racial (and other forms of) equity. Sustainability and equity must go hand-in-hand: sustainability can help address the increasing power and wealth gaps in the world, while equitable approaches are necessary for successful sustainability efforts.

References

1. https://casca.ca/?p=14580
2. https://www.nature.com/articles/s41550-020-1202-4
3. https://arxiv.org/pdf/1912.05834.pdf
4. https://astrobites.org/2020/06/12/blackinastro-black-representation-in-astro-physics-and-the-impact-of-discrimination/
5. https://www.particlesforjustice.org/
6. https://www.oxfordbibliographies.com/view/document/obo-9780190221911/obo-9780190221911-0029.xml
7. https://arxiv.org/pdf/2001.00674.pdf
8. http://articles.adsabs.harvard.edu//full/1938JRASC..32..381H/0000384.000.html
9. https://astro-canada.ca/index-eng
10. https://astrobites.org/2019/09/10/astronomical-observatories-and-indigenous-communities-in-chile/
11. https://astrobites.org/2019/08/02/maunakea-western-astronomy-and-hawaii/
12. https://uwaterloo.ca/arts/about-territorial-acknowledgement#Haldimand
13. https://www.mcgilldaily.com/2018/09/mcgill-a-colonial-institution/
14. https://www.dunlap.utoronto.ca/about/history/
15. https://en.wikipedia.org/wiki/Hollinger_Mines
16. https://arxiv.org/pdf/1910.02976.pdf
17. https://www.sciencedaily.com/releases/2019/03/190311152735.htm
18. https://www.syilx.org/about-us/
19. https://native-land.ca/
20. https://www.ontario.ca/page/algonquin-land-claim
21. https://www.tanakiwin.com/our-treaty-negotiations/overview-of-treaty-negotiations/
22. http://envisionmaunakea.org/wp-content/uploads/2018/03/Electronic-2018-03-23-March-Date-Report-of-the-Hui-Hoolohe.pdf
23. https://arxiv.org/pdf/2001.00970.pdf
24. https://guides.westoahu.hawaii.edu/c.php?g=977248&p=7065789
25. https://sacredmaunakea.wordpress.com/2015/04/25/speech-lanakila-mangauil-on-the-tmt-from-the-hawaii-independent-4252015/
26. https://www.civilbeat.org/connections/solution-to-tmt-conflict-aloha-aina/
27. https://www.vox.com/identities/2019/7/24/20706930/mauna-kea-hawaii
28. https://www.civilbeat.org/2015/04/does-the-thirty-meter-telescope-pose-environmental-risks/#:~:text=Another%20concern%20is%20the%20telescope’s,an%20endangered%20species%20until%202011.
29. http://www.malamamaunakea.org/uploads/management/plans/CMP_2009.PDF
30. https://www.eso.org/public/blog/environmental-footprint/
31. https://www.nature.com/articles/s41550-020-1190-4
32. https://doi.org/10.6084/m9.figshare.11522208.v1
33. http://www.afn.ca/honoring-earth/
34. https://journals.sagepub.com/doi/full/10.1177/1757975919831262
35. https://arxiv.org/abs/1910.03665
36. https://www.eso.org/public/about-eso/green/
37. https://www.gemini.edu/node/12420
38. https://arxiv.org/abs/1910.01272

About the authors: Martine and Pamela are both white settlers on Turtle Island (North America). Martine is a graduate student at the University of Toronto, on the traditional lands of the Huron-Wendat, the Seneca, and the Mississaugas of the Credit River. Pamela is a graduate student at the University of Calgary located on the traditional lands of the Blackfoot Confederacy, the Stoney Nakoda, and the Tsuut’ina First Nation, and the homeland of the Métis Nation of Alberta, Region 3. We acknowledge our settler and white privileges and will continue learning and working towards greater equity in astronomy.

By / par Michael Balogh (CATAC Chair)
(Cassiopeia – Spring / printemps 2021)

In our last article we provided some detail and references on the state of the TMT project, the informal NSF outreach process, US ELTP activity, and other relevant processes and discussions happening on Hawaii around land use and the issue of consent. These activities continue. As detailed in that report, the next major milestone will be the release of the US Astro2020 recommendations, in mid-2021. A top ranking in this report is essential for NSF engagement (expected to be at the level of at least 25%) and the viability of the project. Should the NSF accept the ELTP proposal, NSF will conduct an in-depth Preliminary Design Review, likely in late 2021. Acceptance will also trigger a federal Environmental Impact Statement that will take about three years to complete. In the meantime we have only a few updates:

• Following the retirement of Gary Sanders, Fengchuan Liu has been appointed Acting Project Manager. Fengchuan has been the Deputy Project Manager at TMT since 2015; prior to that he was a Project Manager at NASA’s Jet Propulsion Laboratories (JPL). He brings a lot of experience and talent to this role and is already having a positive impact.
• At the end of 2020, the independent evaluation of the Maunakea Comprehensive Management Plan (CMP) was released. You can access the full report here. The report was prepared for the Department of Land and Natural Resources by Ku`iwalu and includes both a self-assessment by the Office of Maunakea Management (OMKM) and a public assessment based on input to the review process. This evaluation found that the OMKM has made significant progress in several areas, and in particular is, in many regards, “effectively managing the activities and uses on Mauna Kea to better protect the natural and cultural resources''. However, they also found that OMKM has not effectively implemented the CMP in three major areas: timely adoption of administrative rules; consultation with members of the Native Hawaiian community on matters related to cultural and resources issues; and engagement with the community on education and outreach efforts. On February 4, House Speaker Scott Saiki announced that he would like to see a new management structure of Mauna Kea to replace UH. UH issued a strong response, defending their commitment to improving stewardship of Maunakea. On March 4, the Hawaii State House of Representatives passed two resolutions to form a working group which will develop recommendations for the future governance of Maunakea. We expect more key developments regarding management of these lands as the year progresses.
• The Caltech Submillimeter Observatory recently became the first telescope on Mauna Kea to submit its site decommissioning plan for approval. The draft was approved by OMKM, and the aim is for deconstruction and site restoration work to begin in summer 2022.

Finally, we remind you that the next TMT Science forum will take place June 26-29, 2022 at UBC in Vancouver.

CATAC membership:

Michael Balogh (University of Waterloo), Chair, mbalogh@uwaterloo.ca
Bob Abraham (University of Toronto; TIO SAC)
Stefi Baum (University of Manitoba)
Laura Ferrarese (NRC)
David Lafrenière (Université de Montréal)
Harvey Richer (UBC)
Kristine Spekkens (Royal Military College of Canada)
Luc Simard (Director General of NRC-HAA, non-voting, ex-officio)
Don Brooks (Executive Director of ACURA, non-voting, ex-officio)
Sara Ellison (CASCA President, non-voting, ex-officio)
Kim Venn (TIO Governing Board, non-voting, ex-officio)
Stan Metchev (TIO SAC, non-voting, ex-officio)
Tim Davidge (TIO SAC Canadian co-chair; NRC, observer)
Greg Fahlman (NRC, observer)

par Michael Balogh (CATAC Chair)
(Cassiopeia – hivers 2020)

The recently published Canadian LRP2020 recommends, as its top priority for large ground-based facilities, “that Canada participate in a very large optical telescope (VLOT), and that this participation be at a level that provides compelling opportunities for Canadian leadership in science, technology and instrumentation”. The report notes further that this access is best implemented through “continued participation in TMT, either at the currently proposed Maunakea site or at the scientifically acceptable alternative of Observatorio del Roque de los Muchachos”. This is consistent with past recommendations and reaffirms the importance of VLOT access for the Canadian optical/infrared astronomy community in the coming decades. The leadership opportunities provided by TMT (or any VLOT) depend to some degree on the final share, governance model and construction timeline. CATAC expects that there will be more certainty about those factors over the next year, but with the information available today we agree that participation in TMT (at either site) represents the best route to fulfill the goals of the LRP.

LRP2020 also recommends developing and adopting “a comprehensive set of guiding principles for the locations of astronomy facilities and associated infrastructure in which Canada participates. These principles should “be centred on consent from the Indigenous Peoples and traditional title holders who would be affected by any astronomy project”. CATAC is aware that many Canadians are very concerned about how TMT construction in Hawai’i can be consistent with these principles, and that there has been important discussion within Canada about this. CATAC has raised these concerns with the Board. Our recommendation for continued support of TMT is based in part on the following considerations:

• First and foremost, CATAC reaffirms our position that the decision about whether or not TMT is built in Hawaii should be entirely in the hands of the Hawaiian community, and that they are the only ones who should be responsible for defining what consent means within their own constituency.
• CATAC awaits the full development of the guiding principles recommended by the LRP, which we hope and expect will be consistent with the previous point.
• Recent developments have led to an opportunity for renewed dialogue within Hawai’i, that CATAC believes is consistent with the views expressed in our LRP, and the white papers on Indigeneous rights submitted to that process. These discussions are taking place among diverse groups, and involve not only TMT but all astronomy on Maunakea, as well as many broader issues of Hawaiian society. We describe some of these developments below, and note there are more details in our recent report to the CASCA Board, which is available on our website. It is vitally important to give these discussions the time and space they need. They are connected to concerns that are much broader than TMT, or astronomy.

Telescope Site, Partnership and Construction Timeline

On August 13, in response to the initial planning proposal for the US Extremely Large Telescope Program (ELTP), the US National Science Foundation (NSF) announced the initiation of an informal outreach process to engage people and groups interested in the Thirty Meter Telescope (TMT) project. Hawai’i House Speaker Saiki issued a press release about this on Aug 18. This outreach is a precursor to an NSF decision about whether or not to accept the ELTP proposal and formally join the project.

This engagement on the part of the NSF is welcomed by the TMT International Observatory (TIO) Partners, and brings a new opportunity for a Hawaiian consultation process and formal review, led by a widely respected body. It also establishes a timeline of events that will take place over the next 12-18 months, each of which will provide increasing clarity over the future viability of TMT:

• The US Astro2020 process is anticipated to release their public report in mid-2021. A top ranking in this report is essential for NSF engagement and the viability of the project. The report may make other recommendations relevant to TMT.
• Should the NSF accept the ELTP proposal, this will trigger a federal Environmental Impact Statement (EIS), which will take about three years to complete. Included as part of this review would be the important Section 106 process of the National Historical Protection Act. This would have the significant effect of leading to a federally recognized record of the importance of Maunakea to Hawaiians. Information from the public consultation phase of this process will shed further light on the situation as the review progresses. We note that a federal EIS may also be required at La Palma if the NSF is a partner.
• Upon acceptance of the proposal, NSF will also conduct an in-depth Preliminary Design Review, likely in late 2021. This is a comprehensive review of all aspects of the project, including operations and a detailed costing.

Assuming TMT construction cannot begin until the EIS has completed (which may not be the case), construction might not start before 2023. An estimate of seven years construction and three years commissioning would mean first science in 2033 or later. The main competition for TMT is the ESO Extremely Large Telescope (ELT) project. The ELT is currently under construction, and current planning anticipates technical first light (TFL ) by the end of 2025, though the COVID-19 pandemic may add some delay. It is planned that all four first-light instruments would be commissioned within two to three years after TFL. Assuming no delays to that project, the gap to TMT science could be six years. But, at this point, there is enough uncertainty in the timeline of both projects that the gap could be larger, or smaller.

In parallel with these NSF-led consultations, there are several other important discussions and activities underway in Hawaii. These include:

• In May, 2020, the Department of Land and Natural Resources (DLNR) launched an independent review of the University of Hawaii (UH) management of Maunakea as part of the Master Lease renewal process. The independent Hawaiian consultation group Ku`iwalu, has been engaged to evaluate the effectiveness of the UH and the OMKM in its implementation of the Comprehensive Management Plan (CMP). Some information about the process underway is available at their website. At the time of launch, the review was expected to conclude by the end of 2020, though this may be delayed.
• An important part of Governor Ige’s proposed path forward for TMT on Maunakea is the decommissioning of “as many telescopes as possible”. This process is underway, through the OMKM. Decommissioning is a lengthy process, as it involves its own Environmental Assessment and DLNR permit preceding the physical removal of the facility and complete restoration of the site. Decommissioning of the UH-Hilo teaching telescope, Hoku Kea is expected to be completed in 2023. The Caltech Submillimeter Observatory decommissioning is anticipated to be completed in 2022.
• Multiple groups in Hawaii are meeting to discuss broad issues such as housing, education and land ownership, including the role of astronomy. Among these groups are the Hawai’i Executive Collaborative and the ‘Aina Aloha Economic Futures. Participants in these meetings include TMT opponents. Canadians associated with TMT have also been invited to participate in some of these discussions, though the travel restrictions associated with the pandemic have significantly affected this effort.

Instrumentation Update

The TMT Exoplanet Roadmap Committee is considering the prioritization of desired exoplanet capabilities for planned second-generation TMT instruments: PSI, MICHI and HROS. The prioritization would be a function of the various instrument modes (imaging, spectroscopy, polarimetry) and their implementation (resolution, IFU, choice of wavelengths/bands). Input from the Canadian community is welcome, before mid-January. A short summary of proposed capabilities together with an Excel template for feedback are available on the CATAC web page.

Project Office Update

Dr. Gary Sanders, who has led the TMT Project as Project Manager with distinction since its inception, will retire at the start of 2021. Deputy Project Manager Fengchuan Liu, who has worked closely with Gary and co-directed the project for the last five years, will assume the Project Manager (acting) position while TMT searches for a permanent project manager.

From Pauline Barmby, Bryan Gaensler (LRP2020 co-chairs PLT2020)
(Cassiopeia – Winter / hivers 2020)

Au nom de Matt Dobbs, Jeremy Heyl, Natasha Ivanova, David Lafrenière, Brenda Matthews et Alice Shapley, nous sommes heureux de présenter le rapport final du Plan à long terme 2020 de la CASCA pour l’astronomie canadienne (PLT2020). La version non formatée du rapport est désormais disponible sur le site Web de CASCA. Une version conçue par des professionnels et une traduction en français sont en cours et devraient être disponibles au début de 2021.

Nous remercions tous ceux qui ont contribué à ces recommandations en rédigeant un livre blanc, en assistant à une discussion communautaire, en participant à des consultations ou en répondant à nos nombreuses demandes d’informations. Nous voudrions particulièrement souligner le travail très dur des membres du panel PLT2020 au cours des vingt derniers mois. Nous remercions également les agences dont le soutien financier a permis le processus PLT2020, et le conseil d’administration de la CASCA de nous avoir confié la direction de cet exercice.

Ce sera notre dernière mise à jour Cassiopeia. La section PLT2020 sur le site Web de la CASCA contient des liens vers tous les livres blancs et rapports soumis ainsi qu’un résumé du processus. Les versions conçues et traduites du rapport y seront disponibles quand fini.

chairs@lrp2020.groups.io

By Carter Rhea (Chair, CASCA Graduate Student Committee)
(Cassiopeia – Winter / hivers 2020)

Mainak Singha — Université du Manitoba

La recherche de Mainak portent sur la façon dont la faible accrétion des « noyaux galactiques actifs » (AGN) peut stimuler les processus d’évolution des galaxies. La plupart des modèles d’évolution des galaxies qui réussissent nécessitent que l’AGN lance des flux à l’échelle galactique pour diriger les processus d’évolution des galaxies. Afin de retracer les signes de ces flux, il utilise les données spectroscopiques (spectres) du SDSS (Sloan Digital Sky Survey). Les raies d’émission de ces spectres mettent en évidence l’ionisation causée par les photons des disques d’accrétion de l’AGN ou les chocs de l’AGN. Toute asymétrie dans les profils des lignes d’émission indique que le gaz se rapproche ou s’éloigne de nous, ce qui est la signature de flux sortants.

Figure 1: Diagramme standard BPT du SDSS DR7. La radiogalaxie J142041+025930 se trouve dans la région LINER (Low Ionization Nuclear Emission Line Region) de la partie suggérant qu’il s’agit d’une radiogalaxie à faible excitation (LERG).

Vivian Tan — Université York

Les recherches de Vivian se concentrent sur les galaxies qui résident au sein des amas de galaxies à des décalages vers le rouge de 0.25 < z < 0.6, dans les Hubble Frontier Fields. Les amas sont des environnements dynamiques où les galaxies interagissent et s’éteignent, ce qui signifie le passage de la formation d'étoiles à la phase de repos. Les processus d'éteignant modifient la morphologie d'une galaxie, dont nous voulons mesurer non seulement par leurs profils de lumière, mais aussi par leur distribution de masse stellaire. La cartographie de la masse stellaire d'une galaxie est généralement difficile à z > 0, mais les Frontier Fields disposent d’une photométrie Hubble multibande profonde. Cela signifie que des cartes de masse stellaire résolues sont possibles même pour des galaxies aussi petites que 108 masses solaires. Les galaxies ayant des masses stellaires aussi faibles n’ont pas été étudiées de manière résolue à z > 0. Comme nous pouvons analyser la morphologie avec des cartes de masse stellaire résolues, nous avons constaté que les galaxies quiescentes qui sont moins massives que 109.5 masses solaires sont plus susceptibles d’être dominées par un disque (indice de Sersic ~ 1 à 2), mais les galaxies quiescentes sont dominées par un bulbe au-dessus de cette limite de masse (indice de Sersic de 4 ou plus). Ce phénomène n’a été constaté que dans les amas, mais pas dans les environnements « de champ » moins denses. Cela signifie que différents processus d’extinction ont dû se produire pour transformer ces galaxies, et ces processus d’extinction dépendent à la fois de la masse des galaxies et de leur environnement.

La figure 2 montre le processus de création des cartes de masse stellaire résolues par un processus appelé « SED-fitting ». La galaxie est divisée en compartiments spatiaux, et un SED est ajusté au flux photométrique de plusieurs bandes dans chacun des compartiments. La SED ajustée peut révéler la masse stellaire de cette région de la galaxie et, en rassemblant tous ces éléments, on obtient une carte de masse stellaire résolue. Les mesures de l’indice Sersic de la masse stellaire sont obtenues par ajustement paramétrique d’un profil Sersic 2D directement sur la carte de la masse stellaire à l’aide de GALFIT.

Jessica Campbell — Université de Toronto

Les recherches de Jessica se concentrent sur la nature multiphasique du champ magnétique de notre Galaxie et sur la façon dont il se connecte entre les différentes phases du milieu interstellaire (ISM). Que ce soit le milieu ionisé chaud turbulent (WIM) qui remplit une grande partie de la Galaxie ou le milieu neutre froid (CNM) que l’on trouve souvent dans les feuilles et les filaments, ce milieu ISM complexe est imprégné de rayons cosmiques et de champs magnétiques de haute énergie. Lorsqu’ils sont accélérés par le champ magnétique, ces rayons cosmiques émettent un rayonnement radio synchrotron fortement polarisé linéairement. Lorsque cette émission polarisée passe à travers l’ISM de premier plan, les électrons thermiques et les champs magnétiques de l’ISM font tourner le plan de polarisation, un effet appelé rotation de Faraday. Ces rayons cosmiques peuvent également pénétrer et ioniser les régions les plus denses de l’ISM, ce qui fait que même le milieu essentiellement neutre est couplé au champ magnétique par des structures HI linéaires de 21 cm appelées « fibres HI ». Malgré la richesse des informations sur le champ magnétique de l’ISM et du CNM, on sait très peu de choses sur leurs relations mutuelles. Les milieux diffus ionisés et froids en touffes partagent-ils un champ magnétique commun ? Si oui, à quelle fréquence et dans quelles circonstances cela se produit-il ? Telles sont les questions qui motivent les recherches de Jessica.

La figure 3 montre l’émission de poussière de Planck à 353 GHz, où l’image en couleur représente l’intensité totale (non polarisée) et les lignes texturées indiquent l’orientation du champ magnétique. L’émission de poussière contient clairement les mêmes morphologies de genou et de fourche, et l’orientation du champ global est à peu près parallèle aux filaments polarisés F1 et F3.

Robert Bickley — Université de Victoria

La recherche de Robert se concentre sur l’interaction entre l’astronomie observationnelle et l’apprentissage automatique. Il utilise les techniques visuelles pour identifier les galaxies qui ont subies récemment les fusions avec une autre galaxie. Ces fusions ont une signature distincte – elles créent des morphologies bizarres et déplacent les étoiles qui appartiennent aux galaxies. Pour identifier les fusions en utilisant l’apprentissage automatique, il entraîne les réseaux au neurones convolutifs sur les fusions (et non-fusions) prises de la simulation bien connue: IllustrisTNG. Il les utilise d’entraîner, valider, et tester les réseaux.

La figure 4 démontre l’habileté du réseau à identifier les fusions comme une fonction de leur environnement. Si une galaxie a une voisine proche, sa valeur de r_1 va être petite; par contre, s’il n’y a pas de voisine, la valeur de r_1 va être tellement grande. Le panneau en haut démontre le nombre total de fusions et les contrôles (bleue et orange). De plus, il catégorise les classifications comme correcte ou incorrecte (fp, brun: contrôle classifié comme un fusion; tn, violet: contrôles bien-classifiées; fn, rouge: les fusions classifiées comme des contrôles; tp, verte: fusions bien-classifiées). Le panneau en bas montre la fraction de fusions et galaxies de contrôle qui sont identifiées correctement par le réseau.