Lecture: 20 January “Mapping the Missing Matter in Our Universe” by Sunil Simha, UCSC

20 January 2021, Wednesday, Live-streamed via Zoom, YouTube and Facebook

“Mapping the Missing Matter in Our Universe”


Sunil Simha, UC Santa Cruz

Fast Radio Bursts (FRBs) are mysterious events that were discovered only in the last decade by astronomers. They last a few milliseconds at most but are extremely bright sources of radio waves. They are so bright that we can spot them from distant galaxies. Although we are not fully certain how they are produced, we already have some ideas about how we can use them to study the universe.

According to simulations, matter in the universe is distributed along filamentous structures which make up the “cosmic web”. Unfortunately, most of this matter is fully ionized and therefore invisible to optical telescopes. This is where FRBs come in. Just like a prism dispersing the individual colors of sunlight, the ionized matter disperses FRBs and the amount of dispersion depends on how much matter is between the source and the Earth.

In our most recent work, we have tried to leverage the observed dispersion of FRB 19068, an event detected by the Australian Square Kilometer Array Pathfinder, to study the matter between us the source. Augmenting it with data from the Sloan Digital Sky Survey and our own optical observations, we showed that it is possible to map out the ionized matter to a considerable extent. Our study represents a proof of concept and we expect astronomers to routinely use similar but more refined techniques to make inferences of the cosmic web.

Brief Bio

Sunil Simha obtained his BS-MS degrees in Physics from The Indian Institute of Technology Madras (IITM) in Chennai, India.  He was inspired to pursue astronomy and physics when he qualified to attend an Astronomy Olympiad training workshop in the 12th grade.

In college, he participated actively in the university’s astronomy club, organizing and giving talks and also conducting public observing sessions. After working on a research project on Quasar absorption line studies during a summer at IUCAA (Pune, India) under Prof. R. Srianand, he decided to pursue further studies in astronomy.

Following an opportunity to work with Prof. Xavier Prochaska at UCSC during a summer internship abroad, he applied to UCSC’s PhD program in 2018. Since then, he’s been working on using Fast Radio Bursts as cosmological probes, under Prof. Prochaska’s guidance, as part of the CRAFT and F^4 teams. He is also involved in the red-side detector upgrade of LRIS on board the Keck telescope at Mauna Kea under the leadership of Prof. Constance Rockosi, UCSC.

How to Attend

To attend the virtual meeting “live” with the opportunity to ask questions:

Connect by 7:30pm on Wednesday, January 20th by clicking this Zoom meeting link: https://zoom.us/j/95830904603?pwd=UDNKdm16US9wK1EremdJeGptdjNNdz09

Clicking the link may prompt you to install the Zoom virtual meeting app. Once installed, you will be able to join the meeting.   If the app is already installed on your device, simply enter the meeting number 958 3090 4603 and password 116064 to join the meeting.

Once joined, you can test your audio and video, and greet other members.

Board members will join the meeting early to help troubleshoot any problems with audio or video. 

Club and welcome announcements will begin at 7:45pm and the lecture will start promptly at 8:00pm.

Alternatively, please visit the following channels to attend the live stream:

SFAA YouTube channel: https://www.youtube.com/channel/UChuBJGp_iJYZ11q_ayA-q3A

SFAA Facebook: https://www.facebook.com/groups/152754481404310

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