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Andrea Gokus @agokus.bsky.social · 14/08/2024

As Markus already said, because the meeting is hybrid - people participate online or in person - printouts don't work for poster sessions as usual. Sustainability is one of the main pillars of this IAU meeting, which is why a lot of effort was spent on the virtual access to the meeting.

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Andrea Gokus @agokus.bsky.social · 04/06/2024

POV: You're an astronomer in the US who wishes for organizers to make meetings more sustainable.

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Andrea Gokus @agokus.bsky.social · 30/04/2024

For more details, check out the paper, published under open access in PNAS Nexus (doi.org/10.1093/pnas...). We hope that our article encourages more conversation about the meeting culture in academia and are very interested in constructive discussion 💚

doi.org

Astronomy’s climate emissions: Global travel to scientific meetings in 2019

Abstract. Travel to academic conferences—where international flights are the norm—is responsible for a sizeable fraction of the greenhouse gas (GHG) emissi

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Andrea Gokus @agokus.bsky.social · 30/04/2024

To assess the emissions for all meetings, we used the Travel Carbon footprint calculator programmed by Didier Barret (travel-footprint-calculator.irap.omp.eu), which can also be used to find an emission-minimized meeting location.

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Andrea Gokus @agokus.bsky.social · 30/04/2024

One important aspect, however: In order to create more sustainable and more inclusive meetings, it is necessary that our community works together to reach this goal and that we don’t let perfectionism be the enemy of progress!

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Andrea Gokus @agokus.bsky.social · 30/04/2024

Because networking is one key element at meetings, opportunities and space must be created for people to network naturally – passively listening to talks online is not the same as engaging in lively discussions.

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Andrea Gokus @agokus.bsky.social · 30/04/2024

What do we conclude from this? Making meetings more sustainable can make them also more inclusive, because if we make meetings at least hybrid, or even fully virtual, many barriers fall away. However, virtual attendees must not be treated as second class participants!

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Andrea Gokus @agokus.bsky.social · 30/04/2024

But more importantly, who does not get to travel much, or at all? → Scientists at less wealthy institutes or in less wealthy countries; those having to deal with lengthy/complicated visa processes; those with care-taking responsibilities; and those with disabilities.

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Andrea Gokus @agokus.bsky.social · 30/04/2024

Most astronomy meetings are ≤ 100 attendees in size, but depending on the meeting venue, average emissions can be very high if most people have to fly medium to long distance. For large meetings, average emissions scatter around the average value of 1t CO2e per person.

Scatter plot of the meeting size versus the average emissions per participant. Most meetings have a size of 30 to less than 200 participants. No clear correlation is visible.

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Andrea Gokus @agokus.bsky.social · 30/04/2024

Not a big surprise, but the higher the amount of local (< 100 km from venue) participation, the smaller the average emissions. However, even meetings with few local attendees can have travel emissions below the average.

$Scatter plot of the percentage of local participants versus the average emissions per participant. The average greenhouse gas emissions per meeting participant decreases with increasing fraction of local attendees.$

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Andrea Gokus @agokus.bsky.social · 30/04/2024

The distributions of the average CO2-equivalent emissions/person/meeting, here split for conferences and schools (since they pursue different goals for participation), show how widespread travel-related emissions are, depending on the meeting.

Histograms showing the distribution of average carbon emissions per participant and meeting. Different colors indicate the continent on which the meeting took place. The left figure shows the numbers for conferences, which peak at 1 t of CO2-equivalent emissions and ranges up to 4t of average emissions. The right figure shows the data for schools, which peaks at slightly less emissions of 0.6 t of CO2e, ranging above 1.5 t.

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Andrea Gokus @agokus.bsky.social · 30/04/2024

#Astronomy is a very internationally collaborative field, but as can be seen from the map, the majority of meetings tend to take place in Europe and North America. Meetings in remote places cause more flights → more emissions. Our estimation is at least 42,500 tCO2e in total.

World map showing where meetings, both conferences (circles) and schools (squares), took place. A color scale indicates the average emission per participant per conference and the size of the symbols reveals the total emissions. Meetings are heavily clustered in Europe and on the east and west coast of the United states. There is very few meetings on the African and South American continent. Meetings in Oceania as well as in Hawai'i have the highest carbon footprint per participant.

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Andrea Gokus @agokus.bsky.social · 30/04/2024

How much did astronomers actually travel in terms of distance in 2019 in total? More than 300 times to the moon and back! Or, to put it in astronomical units: more than 1.5 AU! doi.org/10.1093/pnas... A🧵summarizing our paper, written together with members of Astronomers for Planet Earth:

Screenshot of the header from the published paper in the journal PNAS Nexus. The title of the paper is "Astronomy's climate emissions: Global travel to scientific meetings in 2019". The authors are, in the order of the author list: Andrea Gokus, Knud Jahnke, Paul M. Woods, Vanessa A. Moss, Volker Ossenkopf-Okada, Elena Sacchi, Adam R. H. Stevens, Leonard Burtscher, Cenk Kayhan, Hannah Dalgleish, Victoria Grinberg, Travis Rector, Jan Rybizki, and Jacob White.

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Andrea Gokus @agokus.bsky.social · 05/04/2024

The US Congress is in the process of largely defunding the #Chandra X-ray mission and we need to #saveChandra! youtube.com/shorts/sE-RU...

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Andrea Gokus @agokus.bsky.social · 02/04/2024

I am very proud that the paper is finally published and that I contribute a small puzzle piece to increase our knowledge about blazars, and Mrk 421 in particular, which has been studied by so many people before me!

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Andrea Gokus @agokus.bsky.social · 02/04/2024

Several models exist to explain blazar flares & rapid variability during such; based on our X-ray data we find the most plausible one for this flare to be a scenario where plasmoids undergo magnetic reconnection in a spine layer embedded in the jet (Petropoulou+16, Christie+19).

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Andrea Gokus @agokus.bsky.social · 02/04/2024

These time scale can be translated to the size of the region where the X-rays are emitted. The rapid variability indicates processes occurring in a very compact region in the jet, while the steady increase hints at the flare being produced at ~ 1 pc from the central engine.

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Andrea Gokus @agokus.bsky.social · 02/04/2024

Using the Timing mode data taken by XMM-Newton, I created a PSD capable of tracing the shortest variability time scales. Most of the PSD is dominated by Poisson noise (as expected), but we also detect variability as short as 1000s, while the overall flux increase took ~16 hours.

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Andrea Gokus @agokus.bsky.social · 02/04/2024

With Mrk 421 being so bright in the X-rays, I was able to look at time-resolved spectra and analyse how they change during the flare. The blazar shows a 'harder-when-brighter' behaviour and a loop in the hysteresis curve indicates that particle cooling dominates the emission.

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Andrea Gokus @agokus.bsky.social · 02/04/2024

While the gamma-ray flare was not too exceptional (barely reaching 2 Crab Units overall - Mrk 421 has shown gamma-ray flares with the flux being larger than 3 Crab Units), the X-ray flux of Mrk 421 increased immensely within a day, which we were able to track with XMM-Newton.

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Andrea Gokus @agokus.bsky.social · 02/04/2024

The multi-wavelength campaign is described in detail in an earlier proceedings publication (pos.sissa.it/395/869). In the publication that just came out only the X-ray data from XMM-Newton are discussed as they yielded the most interesting insights into the jet physics.

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Andrea Gokus @agokus.bsky.social · 02/04/2024

The FACT collaboration monitors bright blazars at TeV energies and alerts the astro community whenever they see a gamma-ray flare. Together, we set up a campaign involving several telescopes covering different wavelengths of the spectrum - and then had to wait for a bright flare.

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Andrea Gokus @agokus.bsky.social · 02/04/2024

While this wasn't the 1st time Mrk 421 showed such a bright X-ray flux, it's the brightest state that we have ever been able to study the source with XMM-Newton, with which we looked at the blazar continuously for more than one day. This observation wasn't chance-coincidence, though!

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Andrea Gokus @agokus.bsky.social · 02/04/2024

... that allowed us to probe the compact regions of the jet. To emphasize how extraordinarily bright this X-ray flare was: for a few hours, Mrk 421 was as bright as Galactic X-ray binaries (e.g., Cyg X-1), while being more than 400 million light years away from us! 🤯

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Andrea Gokus @agokus.bsky.social · 02/04/2024

What makes this study special, as Mrk 421 has been studied multiple times with many different instruments for more than 2 decades? We were able to catch the source during an extremely bright flare in the X-rays with XMM-Newton & obtained high-resolution timing & spectral data...

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Andrea Gokus @agokus.bsky.social · 02/04/2024

#PaperDay! My analysis of the #blazar Markarian 421 during an extremely bright X-ray flare in 2019 is published - technically overdue since I already worked on the data during my PhD 😅 Here's my brief synopsis, full publication at doi.org/10.1093/mnra... by MNRAS

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