Well we have had cold and cloudy weather here in Orange County, but there is plenty of astronomical news appearing this week, including new indications that the universe is not flat and maybe there is not dark energy. So, let's begin with "A day in the Life of an Oxford Astrophysicist; Dr. Becky"
I follow Dr. Becky (on Twitter, not like I'm a stalker) and this week she offers "A Day in the Life of an Astrophysicist" which shows what she goes through on a typical day. You get to see a typical day, in and around Oxford, with her at work at her desk and attending lectures and seminars and discussing her research with colleagues. Wow, she has so much energy; I guess that is why she is a real astrophysicist and I am just an astrophysicist wannabe! Anyway if you are not following on Twitter, you can check out the episode on YouTube at: https://www.youtube.com/watch?v=XW_qIqLhPkI. Thanks for sharing (and putting the rest of us wannabes to shame), Dr. Becky!
|A Day in the Life of an Astrophysicist, Dr. Becky (Source: https://www.youtube.com/watch?v=XW_qIqLhPkI)|
Ok, as long as we are confessing about following people, you should also consider following Dr. Sabine Hossenfelder, who usually also has interesting astronomical news. This time, she really blows the top off of everything by drawing attention to a recent paper presenting new observational evidence that might lead us to get rid of the need for dark energy. Wow, now that is a mind blowing announcement. Hmm, when you look at the title of the paper, the mind blowing nature of the new analysis doesn't seem to be much, but that is just the way scientific papers present their findings. I followed up on the original referenced paper, but you can see the rest of her review at: https://www.youtube.com/watch?v=oqgKXQM8FpU. Thanks for bringing that to our attention, Sabine!
|Maybe dark energy doesn't exist at all (Source: https://www.youtube.com/watch?v=oqgKXQM8FpU)|
Well, after watching the Sabine Hosenfelder YouTube, I looked up the published paper that she referenced. So can can see here how the title of the paper just seems to announce some new evidence without much mentioning the mind blowing implication of the finding.
|Evidence for Anisotropy of cosmic expansion (Source: J. Colon, et al, arXiv:1808.04597v3)|
How do you get an estimate of the bulk flow of supernovas around us? You need a wide enough collection of observations to make sure we are not located in some peculiar location. The paper argues that the original supernova data that was originally used to determine the acceleration, not just the continuing expansion, of the universe was not wide enough to take into account the bulk flow of galaxies around us. You can check out the other details in the arXiv paper. I don't quite get all of the details, but it seems like there is a chance that this work could be Nobel prize type stuff, that could overturn the finding of the previous Nobel prize describing the acceleration of the universe, attributed to the unknown dark energy. Time will tell!
|Further analysis for wider sample of supernovas shows unexpected bulk flow (Source: J. Colon, et al, arXiv:1808.04597v3)|
Now if it is not enough to even think that maybe there is no dark energy, another just released paper finds that maybe the universe geometry is not flat after all. The latest analysis of Planck measurements of the Cosmic Microwave Background (CMB) seems to indicate that the geometry of the universe is not as flat as initially thought. When you go through the Einstein general relativity equations, the term Lamda K is used to indicate the flatness of the universe. Previous estimates showed that the universe was mostly flat, that is that Euclidean geometry could be used to describe and measure astronomical parameters. Lamda K was considered to be zero, or at least very close to zero. Now, this new study finds that the value might be closer to -0.04, not 0.0. If confirmed, this finding will call for new review of other cosmological parameters, including Hubble constant. This is just one more possible way to resolve the "tension" in the two widely used estimates of Hubble constant. Stay tuned! We all got used to thinking that the original "blue" curve represented our universe, but it seems that, if confirmed, the other colored curves are closer to reality.
|Latest Planck analysis shows non-flat universe? (Source: Silk, et al, arXiv:1911.02087v1)|
Another bit of astrophysics news was the discovery of a star - black hole binary system, where the black hole partner was of out of the ordinary expected size of 68 solar masses. This was much larger than expected by current theory. The results were published in the November 29 2019 issue of Nature, as brought to our attention by a Sky and Telescope tweet. The Nature article shows the following plot of radial velocity measurements for the binary system. The star's radial velocity is shown in purple and the black hole in yellow. You can see the light weight star experiences the wider range of radial velocity in its orbit around the black hole, and yet the black hole is also impacted by the star's orbit. I also learned that the difference in measured spectra identify which binary object is the star and which is the black hole, where we see not the black hole, but the accretion disk around the black hole. You can check out the other details in the original article.
|Wide star - Black Hole Binary system parameters from radial velocity (Source: J. Liu, et al, Nature, 27 Nov 2019)|
Ok, that is enough of good news and/or bad news from the astrophysics community, we can now sit back and enjoy the snow as seen on our local Saddleback Mountain. Yes, we often are used to seeing snow on our local Mt. Baldy, but snow on Saddleback is less common. This iPhone image shows the local snow capped peaks. Hmm, this might not look like Searching for Gravity Waves, Dr. Gary, sees from his Colorado home, but at least we do on occasion see some local snow!
|iPhone image of Saddleback Mountains from Orange County location (Source: Palmia Observatory)|
So, it was so unusual to see snow capped mountains, and since nighttime observing was mostly clouded out, it was time to break out the DSLR and tripod to get another shot at Saddleback. This is a little wider view of the snow capped mountains in Southern California. I used the radio antennas on top of the mountain peaks to focus the image until oncoming auto traffic forced me out of the ideal on street observation point!
|Seldom snow capped Saddleback Mountains, DSLR , 120 mm, Orange County view (Source: Palmia Observatory)|
Until next time,