Welcome to Astronomer in Shanghai! Thank you for following my blog and for your interest in my life and adventures in Shanghai! As covid-19 persists in the US and around the world, and you are (hopefully) continuing to remain vigilant, avoiding large gatherings, and social distancing, I hope that you are all staying safe and healthy and that my blog highlights what the world looks like once recovery begins. As things improve, I hope that you enjoy small gatherings with friends and family and other outdoor activities. I’m sure you’ll find these interactions meaningful and enjoyable as I have.
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Life in Shanghai
I hope that this latest update continues to find all of you safe, healthy, and fully vaccinated. Even if you’re vaccinated, I hope that you are continuing to maintain social distancing practices and are generally staying safe. Moreover, as summer begins, I hope that all of you are able to do some fun things with your loved ones outside.
I’m sure some of you have seen the reports about the covid-19 situation in Guangzhou and the surrounding areas in Southern China. The cases continue to rise in this part of Southern China (near Hong Kong). In response to this outbreak (I believe of the delta variant), much of this area (stretching to Shenzhen) has been put into lockdown and requires people coming and going to quarantine for 14 days. There are currently 194 reported cases in Guangdong province, so China is taking prevention incredibly seriously. Thankfully the outbreak has been relatively localized and hasn’t impacted my life in Shanghai. In terms of cases, there are currently just 71 cases in Shanghai (all imported from people returning to China) and the recovery rate is at 96.38%. In Beijing, there are only 13 cases and the recovery rate is at 97.94%. For China as a whole there are 11,892 cases (~ 11,300 in Taiwan) and the recovery rate is at 85.23%.
In terms of Astronomy this was a productive week! I finally finished all the revisions that the Final Reviewer asked for for my DES paper on the evolution of the Stellar Mass – Halo Mass Relation, so hopefully I’ll hear back some positive news soon (and get to submit the paper for publication). On top of that, I spent a lot of my time doing research for DESI, the Dark Energy Spectroscopic Instrument. There’s a virtual collaboration meeting this week and I’ll be presenting my research on the spectroscopic completeness of Brightest Central Galaxies (what fraction will have a spectrum used to measure distance and chemical composition). Lastly, I finally figured out some of the bugs in my Luminosity Function mock catalog! I’m just running some final tests, but I think I’ve solved the discrepancy between the input function and my measurements! So, this week, I hope to finalize that the mock is working!
Last week, I began a series of deep dives into my research. This week, I’ll be talking about the Luminosity Function, since it’s the main project that I’m working on at SJTU. First, a Luminosity Function is simply a mathematical function that describes the number of galaxies at a given brightness/luminosity/absolute magnitude (all three essentially mean the same thing) within a cluster environment. To measure this, you simply count the number of galaxies within a radial region centered on the cluster center (often the BCG). However, because there are foreground and background galaxies, you also need to estimate how much contamination there is in your measurement. To measure a background Luminosity function, you can do the same thing either centered on a random point or measured at larger radial distances from the center of the cluster. Once you have both the inner region measured and the background, you subtract the two and are left with a signal that is the Luminosity Function.
Now that you understand what a Luminosity Function is from a measurement sense, what do you do with it. The Luminosity Function is important because it can tell us how galaxies populate dark matter halos. While the stellar mass – halo mass relation can tell us about the amount of either of these components, the Luminosity Function actually tells us more about the overall cluster population and allows us to determine how many faint galaxies there should be in the cluster environment. Moreover, we can compare Luminosity Functions at different halo masses to determine how halo mass impacts cluster population. If we study the Luminosity Function at higher redshifts, we can search for evolution and growth in different parts of the cluster population. We will also aim to determine whether the magnitude gap can be used to identify differences in the galaxy populations.
For the last few months, I’ve been working on a mock catalog for this analysis. Mock catalogs are simply catalogs of galaxies generated based on an input Luminosity Function (measured by someone else) and positions within a 3D dark matter only (no galaxies) simulation. This is an important tool, because it allows us to determine whether certain signals that we see in the Luminosity Function measurement are predicted by certain luminosity functions or result as a function of our observational measurements. Moreover, using mocks allows us to test the fundamental physics that is input into the Universe. We’ve been working on a mock in order to understand the impact of different background measurements.
I hope that this explanation clarifies what I’ve been working on here in Shanghai. Let me know if you have any questions!
Outside of Astronomy, we’re now in Plum Rain Season, a few weeks long period where it essentially rains every day. Much to my chagrin, even when it doesn’t rain, it’s incredibly humid, so running has not really been something I can comfortably do. As I noted the last few weeks, I’ve continue to go to the F45 HIIT classes for my exercise, which I’m really enjoying!
Even though I didn’t spend a ton of time outside, I still saw some lovely flowers and cool sculptures I wanted to share with you!
I also saw a lot of very cute cats!
As I said in the title for this week’s post, it’s the Dragon Boat Festival this weekend. So, Monday (today) was a holiday. As I noted last week, I unfortunately missed the Dragon Boat races (the main celebratory part of the holiday). Sadly, the traditional treat for Dragon Boat Festival, Zongzi, sticky rice balls with a filling are often filled with meat, so I didn’t get to enjoy those either. However, SJTU does give us gifts for the Dragon Boat Festival. Instead of just giving us snacks (most of which I can’t eat), this year they let us pick presents including household and cooking items. So, I decided to get a cleaning robot!
So far, it’s been pretty useful at getting the hair and dust in hard to reach places, which is great! I’m still figuring out what I’ll name it, but suggestions are welcome!
The main fun activity for me for this weekend was that on Sunday night, my friend Hannah Maia had a birthday orchestra concert and party! The concert was in the Shanghai Concert Hall, which is near People’s Square. When I lived in Xintiandi, I would run by it often and was always curious what it looked like inside. It’s a lovely concert hall, very much in the style of fancy concert halls I’ve seen in the US (even down to the seats not giving me enough leg room). More importantly, the music in the concert was great! While I’m not familiar enough with classical music to have been able to identify the pieces listening to the music (though I was later told that one of them was from Swan Lake), listening to orchestral music was a really nice way to spend an evening. I don’t think I’ve been to an orchestra concert since I was in college, so it was nice to get to go to one.
Food in Shanghai
On Tuesday, Tacolicious hosted a guest chef who was cooking vegan Filipino food! I don’t think I’d ever had Filipino food before, but when I saw that it was all vegan I knew I had to go. While unfortunately, I arrived too late to try the Jackfruit tacos, I got a Lumpia Burrito with smoked tofu, rice noodles, peanut brittle, and roasted vegetables and Sisig fries, fries topped with plant-based meat, picked onions, vegan cheese, and salsa! The side ginataang, coconut stewed taro leaves and mung beans.
The food was fantastic! I’m always excited to try different vegan food and this certainly did not disappoint. I really loved all the different textures in the burrito! I hope that I can try more exciting vegan fare over the summer!
Jewish Life in Shanghai
On Friday night, for Shabbat, Kehilat Shanghai hosted the first of our now monthly community Shabbats. We aren’t able to do them at the Ohel Moishe Synagogue/Jewish Refuge Museum, so we’ll be doing them either in different community spaces or restaurants. For this month, I led the service, which I really enjoyed. Even though we had a small turnout (due to the Dragon Boat festival holiday), it was really lovely to gather together for Shabbat, light the candles, and go through a Shabbat service! It was also really nice to see and hear how much everyone appreciated me leading the service!
Afterwards, we enjoyed a lovely dinner with conversations ranging on topics from sports, to the visa process of getting into China, to teaching in China.
Overall, this was another research focused week. This upcoming week will be pretty busy with the DESI collaboration meeting occupying a lot of my time in addition to other research that I’m working on. However, I know I’ll have some fun things to share with you (including some Dragon Boat themed trivia!).
I hope that you enjoyed hearing about what I’ve been working on, seeing pictures of Shanghai, and hearing about our Community Shabbat! I hope that you all have a safe and healthy week.
In peace,
Jesse
Hi Jesse,
I’m glad to hear you’re doing well and that China appears to have things under control with COVID. I hope the recent series of lockdowns in the South helps. That the numbers are creeping up is still a bit scary. I’m glad that everything is going well with your research. Fingers crossed about your paper! I hope the reviewer agrees with all of your changes. Also, I’m glad that you’ve got everything working with the mock catalogue! I know how hard you worked on that! I think you did a great job describing your research here! I’m sorry it’s so rainy and humid in Shanghai. We had a couple of hot days here, but it’s cooled off back into the 70s. I loved seeing all of the cats and fun statues. I’m glad the orchestra concert was fun! The concert hall looks marvelous! I am definitely envious of your vegan Filipino food. That looks amazing! What is the liquid next to the burrito. I’m glad that you had a nice Shabbat, even if it was smaller. I hope your DES concert goes well. I will be attending the Galaxy Cluster Formation 2021 conference this week, so lots of conferences for us. I hope you have another great and productive week! Stay safe and healthy!
Love,
Emmet
Thanks Emmet! I hope the situation in Guangzhou resolves itself soon. It’s definitely worrisome that these minor outbreaks keep happening, but hopefully as China strongly emphasizes getting vaccinated, things will improve.
I also hope that everything goes well with the Final Reviewer. I’ll keep you in the loop about that. And I’ll definitely let you know how the mock is going. It’s been a long process, but I’m happy to have figured a lot out. Glad you enjoyed my research description.
The concert hall was really cool! And the Filipino food was great. The liquid was the ginataang, stewed coconut with taro leaves and mung beans. It was also very good.
I hope that the Galaxy Cluster Formation Conference is Interesting and that your talk is well received! I’m not going to a ton of the DESI collaboration meeting talks because many start at 11pm or later, but I’ll go to a few. Hope you also have a safe, healthy, and productive week!
Another very full blog, Jesse.
Thinking about your vacuum cleaner and thinking about the names of similar models in the US I wonder if Foxtrot or Tango might be an appropriate name. A) because the machines presumably do a dance of a sort to avoid obstacles and yet manoeuvre themselves across every centimeter of the surface. and B) Foxtrot and Tango are? were? words used in radio communication when you are spelling out a word and so avoiding confusion between letters that sound similar when there is a lot of noise B,D, V or M, N etc.
Ok I sorta kinda get the luminosity function but assuming you are able to determine the actual reading in a galaxy what in fact does this tell you? The number of very large or very small stars ? and even if you know that what does knowledge of that explain about the difference or similarity among different galaxies that then tells you something else about the universe that depends on those findings?
Do you know what the vaccination rate is among all of China? I just learned that Vermont reached 81 % and as of tonight or tomorrow they intend to re-open everything unless explicitly prohibited by the feds. NY is still not much above 50% fully vaccinated with another 10% (I think having received one dose).
Lisa just bought a good (not great but good) vegan cook book called Isa Does It. The recipes are better than good (30 minute cook time for many with 10 minute intensive work time for almost all) but the graphics and layout, in my opinion, don’t make the recipes intuitively easy to follow. Moreover, she has recipes for seitan dishes for which she does not in fact include the recipe for the seitan earlier in the book so you need to hunt and peck for some of the items a recipe uses AND she uses store bought vegetable stock concentrate rather than offers a recipe for something that 90% of her dishes use. BUT those criticisms aside the book is good. (it’s about $35 here).
Stay safe.
Thanks Bernard! Tango and Foxtrot are very good and apt suggestions! I’ll let you know what I decide on! 🙂
So, for further clarification, a Luminosity Function is applied to a cluster of galaxies. It describes the number of galaxies at a given brightness, so it’s not just for an individual galaxy. That being said, measuring the luminosity or total stellar brightness in a galaxy can give you the mass of the galaxy and depending on the distribution of that light can tell you about how that galaxy is growing over time.
If you have the luminosity of the galaxy, you can estimate how many stars there are based on that brightness. From there, you can look at the color of the galaxy to get an estimate of what type of stars (and how recent the star formation is) exist within the galaxy. Red stars are old, blue stars are young. Understanding the differences in the stellar population of a galaxy can tell you a lot about how recently it’s formed and whether there’s been any recent mergers, which can often result in new stars being formed. Additionally, you can look at features such as a bulge or spiral arms to gain some of this about the galaxy’s formation.
In terms of the vaccination rate in China, I don’t have that number. However, I do know that China has administered about 890 million doses of covid-19 vaccines. They’re making it very easy to get covid-19 vaccinations here, which is great. I don’t know how many have gotten 2 doses, though. That being said, reopening was quite different because covid-19 was contained and restricted do to the strict quarantines. However, I can definitely understand how stressful the situation must be in New York, where things appear to be reopening a little early.
Thanks for the vegan cook book recommendation! I’ll have to look it up. I get a lot of my recipes online, so I’m always interested to try new ones!
Hope you and Lisa continue to stay safe and healthy.
Thanks for the overview of the significance of luminosity of galaxies. I feel much more comfortable now as I read about what your research entails and what it enables you to understand about galaxies in our observable universe.
Hi, Jesse.
I enjoyed reading your post as usual and seeing the sites of Shanghai. I am excited that you are participating in the DESI meetings and that you are on the home stretch of the DES paper. I trust the last reviewer is satisfied, and then you can send the article to the journal. After all those eyes in the collaboration, I wonder how they will find a reviewer! Keep up all the hard work on your mock galaxy, too. And thank you for these clear explanations of your work. Neil deGrasse Tyson, move over!
It is lovely to see so many cats roaming Shanghai. I was taken by the orange and orange and white cats, but it was fun, too, to see a cat in a store. I am so glad that the Chinese are so cat friendly. And the concert hall is so beautiful. Please wish Hannah Maia a happy birthday for me.
The rising cases is a tad worrisome, but I am glad you are safe and vaccinated. I wish more people would get vaccinated in New York State! I like Bernard’s proposed names for the vacuum cleaner, but given your love of Batman growing up, I also suggest Alfred, Bruce Wayne’s beloved butler!
To update you on life here, I went strawberry picking and mentioned the variety you have of white strawberries. The Ariels did not know about them. I got lovely big and juicy berries. And our porch upstairs is fixed, so I put in the new window box Dave Brown made me. I also got a new rose bush in honor of our anniversary, and our peach tree and raspberries and currants and rhubarb are thriving. I also put in a few tomatoes and potatoes. I am midway through my article on The Little Lame Prince and illustration and enjoying it, too.
I miss you and love you, Jesse.
Mom
THanks Mom! I hope the last reviewer is satisfied as well. I’m sure finding a reviewer will be a little tougher this time, but I’m not the first DES paper (and some have more authors). I’m glad that you enjoyed seeing the cats! There are a ton of cats in Shanghai, so I see them a lot. 🙂 I’m glad you enjoyed seeing the concert hall as well!
I really like the suggestion of naming it Alfred! That’s a great idea!
I’m glad that you were able to go strawberry picking! I miss doing that. And that’s great that you were able to do some minor home repairs. I hope that you get peaches and currants soon! Let me know.
I love and miss you as well. Have a safe and healthy week!