In the show this time, we talk to Prof. Subir Sarkar about galactic foregorunds and the BICEP2 result from earlier this year, Dr. Matias Vidal tells us about polarized radio foregrounds in this month's JodBite, and your astronomy questions are answered by Dr. Iain McDonald in Ask an Astronomer.
JodBite with Dr. Matias Vidal
Dr. Matias Vidal, a postdoctoral researcher at the Jodrell Bank Centre for Astrophysics who spoke to us in a previous JodBite, is the lead author of a recent paper on magnetic 'radio loops' in the Milky Way Galaxy. These arcs have been seen in radio maps for decades, but the new study uses polarisation measurements to show more of them and in greater detail than ever before. As Matias explains, the loops emit synchrotron radiation, but their origins, distances and sizes are uncertain. They may come from ancient supernovae, activity in the black hole at the Galactic centre, or something else entirely. Matias also discusses the relevance of his findings to studies of the cosmic microwave background, which must subtract emission from our Galaxy in order to infer the characteristics of the early Universe from the much fainter background radiation.
Interview with Prof. Subir Sarkar
Prof. Subir Sarkar, from Oxford University, gives us his views on the BICEP2 result that was reported in March this year, namely: a claimed detection of B-modes in the Cosmic MIcrowave Background, a sort of curl in the direction of the polarized CMB that would be an indicator of gravitational waves coming from the earliest moments of the universe, and which would imply that the theory of Inflation is correct. Prof. Sarkar briefly explains the reasons inflation was propsed in the first place, to explain discrepancies between cosmological observations and theory, and what a detection of evidence for inflation would mean for the cosmological community and physics as a whole. Prof. Sarkar also looks at the argument against the BICEP2 detection, that foreground polarised dust is introducing a spurious B-mode signal, concluding that it is the most likely explanation for the BICEP2 result. [Producer's note: this interview was recorded in April, and in the meantime Planck has confirmed that the result was due to foreground dust unaccounted for in the BICEP2 data.]
Ask an Astronomer
Dr. Iain McDonald answers your astronomical questions:
- John Brooks asks: "The 1970 Reader Digest Atlas of the Universe states that the Milky Way Galaxy contains 100,000 million stars. Today with our advanced technology the figures range vastly from 100 billion to 400 billion stars. So which is it? Surely now 44 years later we would have a much more accurate figure than to just still say 'between 100 and 400 billion stars'."
- Andre Joubert asks: What percentage of inner rocky planets will survive a Hot-Jupiter on its inward journey? Does this not reduce the estimates of habitable planets in the Milky Way?"
- Jorgen Nilssen and Peter Ellinger have a few related questions. Jorgen asks: "What is wrong with this argument: A lot of the Universe is moving away from us at speeds higher than C. When an object moves at C, its mass is infinite. Therefore, we are surrounded by a Black hole." Peter's question is: At the moment of the Big Bang, how come it went "bang"? Surely with everything in the universe being so close together, it would effectively be the biggest black hole ever and therefore have an impossibly high escape velocity. Surely this would have resulted in no bang whatsoever?
Odds and Ends
The ISS is getting upgraded to high-speed internet: a new instrument is being tested on the International Space Station that could drastically increase the speed of data transmission to and from orbit. OPALS (Optical Payload for Lasercomm Science) is a laser link that the station can use to communicate with the ground. Several large files, including videos, have already been sucessfully transmitted, but two main obstacles remain: daytime transmissions and adverse weather conditions.
The naming rights to the largest unnamed crater on Mars have been auctioned on eBay by Uwingu. The winning bid was $2,020.00. Profits from the auction will go to support space exploration, research and education grants. For more info, click here.
To celebrate the first test flight of NASA's Orion spacecraft, a team of interns at the Johnson Space Center put together a video parody of Meghan Trainor's "All About That Bass". The video, titled "All About That Space", shows the interns dancing, acting and lip synching along to their own space-adapted lyrics not only to entertain, but to show some examples of NASA's work. The original video can be viewed here.
|JodBite:||Matias Vidal and Mark Purver|
|Interview:||Prof. Subir Sarkar and Indy Leclercq|
|Ask An Astronomer:||Dr. Iain McDonald and Indy Leclercq|
|Presenters:||Josie Peters, Indy Leclercq and Hannah Stacey|
|Editors:||Christina Smith, Sally Cooper, Mark Purver and Charlie Walker|
|Segment Voice:||Tess Jaffe|
|Website:||Indy Leclercq and Stuart Lowe|
|Cover art:||A polarized radio filament as seen in WMAP data, taken from Dr. Vidal's paper. CREDIT: M. Vidal et al. (2014)|