Yuxin (Vic) Dong

NSF Graduate Research Fellow

CIERA, Northwestern University

Email GitHub ORCID

Howdy! I'm a fifth-year PhD student at Northwestern University, working with Prof. Wen-fai Fong. I'm broadly interested in understanding the origin and evolution of cosmic transients and their environments.

My graduate studies focus on uncovering the physical origins of fast radio bursts using multi-wavelength observations of their local and global environments. I'm also an active member of scientific collaborations including the Fast and Fortunate for FRB Follow-up (F4) and CHIME/FRB.

Before coming to Northwestern, I earned my bachelor’s degree in Physics with minors in Mathematics and Astronomy from Purdue University.

When I'm not in the office, I enjoy running, hiking, exploring new coffee shops, and reading.

Research

FRBs

Fast radio bursts (FRBs) are incredibly bright, millisecond-long radio flashes with dispersion measures that imply an extragalactic origin. Only a small fraction (4%) of FRBs are known to repeat, while most appear as one-off events. Despite the rapidly growing sample of FRBs, the nature of their progenitors still remain enigmatic, especially when they are hard to localize and have no multi-wavelength counterparts.

FRB-Optical Transient Crossmatching

The leading progenitor model for FRBs involves magnetars, which are often born from the core-collapse of massive stars. If this connection holds true, some FRBs should be associated with supernovae (SNe). In my most recent work, I built a framework to systematically crossmatch all SNe and optical transients reported to the Transient Name Server (TNS) with the first sample of CHIME-KKO Outrigger FRBs to directly test this idea.

Although we did not find any significant spatial or redshift matches, we quantified the significance of future associations and explored the transparentcy timescale after which FRBs can escape their local dense plasma environments. Building on this, I am developing an automated system to identify potential optical counterparts to CHIME FRBs through the CHIME/FRB Slack alert network. This effort comes at a particularly exciting time, as the Rubin Observatory’s LSST will soon enable the discovery of optical transients at an unprecedented rate, bringing us closer than ever to identifying an FRB-SN connection!

Figure: A schematic overview of possible progenitors and timescales connecting SNe and FRBs. Different progenitor pathways, from accreting white dwarfs to massive stars, produce supernovae and other transients across long evolutionary timescales. Once a magnetar is formed, the surrounding material must thin over years to decades before the first FRB can escape its dense plasma environment.

Publication

Searching for FRB Radio Counterparts

The first repeating FRB 20121102A revealed a surprising compact, persistent radio source (PRS) counterpart in a dwarf galaxy, offset from its center. The leading explanation is that a compact neutron star powers a synchrotron nebula, producing the observed radio emission. Because the origins of both PRSs and FRBs are still uncertain, we set out to investigate whether PRSs could serve as signposts for FRBs. To date, five FRB-PRSs have been discovered, most reside in dwarf galaxies and all are repeating FRBs.

Using observations from VLA and EVN, we studied a sample of off-nuclear PRSs in nearby dwarf galaxies. Among them, we identified one source as the most promising FRB-PRS candidate, J1136+2643, distinguished by its compact size and galactocentric offset. While other sources may also be FRB-PRSs, some are likely background AGN. Comparing our data to models of neutron star wind nebulae and hypernebulae, we found that the radio properties of J1136+2643 are consistent with both scenarios.

This work highlights the diversity of PRSs in dwarf galaxies, the flexibility of current FRB progenitor models, and the observational challenges in distinguishing true FRB-associated PRSs from interlopers.

Figure: Radio spectral luminosities of the sample of PRS candidates (blue), including the most promising PRS candidate, J1136+2643 (bolded). The luminosities span several orders of magnitude and are generally lower than those of known FRB–PRSs, but are comparable to other types of radio transients.

Publication

The Superlative Environment of FRB 20201124A

FRB 20201124A is one of the most active repeaters ever observed, yet it sits in a region without any obvious optical signs of star formation. Using VLA and HST observations, we mapped the location and morphology of star formation throughout the host and searched for a PRS coincident with the FRB.

Our observations revealed dust-obscured star formaton extending to the FRB's location, suggesting a magnetar born in-situ from the explosion of a massive star as the central engine. Our observations reveal that this is the most dust-obscured FRB host discovered so far. More recently, it even has a tentative PRS association, making its environment truly unique. Cases like this show why looking across multiple wavelengths is so important for understanding where FRBs come from.

Figure: HST imaging of the FRB 20201124A host galaxy, with radio contours overlaid at 6 GHz (blue) and 22 GHz (magenta). The radio emission is clearly resolved and extends to the FRB position (red star), indicating the presence of star formation at the FRB’s location.

Publication

Ca-rich Transients

Calcium-rich (Ca-rich) transients are a quirky class of supernovae, known for their rapid evolution, modest brightness, and strong calcium emission lines. Despite these distinctive features, their progenitors are still debated. Interestingly, nearly half are found in the outskirts of mostly elliptical galaxies, hinting at a connection to older stellar populations rather than massive young stars.

As an undergraduate at Purdue, I worked with Prof. Dan Milisavljevic to get at the progenitor question through their environments. We compiled archival multi-wavelength observations for a sample of Ca-rich transients and used the stellar population modeling tool Prospector to study their host properties. For nine host galaxies, we were able to construct detailed star formation histories, which we used to determine supernova rates and assess whether each transient likely originated from a core-collapse or Type Ia-like explosion.

Our results suggest that Ca-rich transients don't exclusively come from core-collapse SNe. Instead, they likely arise either from white dwarfs or a mixed population including both white dwarfs and massive stars. I had a lot of fun (and growing pains) learning (spectral energy distribution) SED fitting and stellar population analysis through this project and was my first dive into the world of transients!

Figure: Broadband photometry of a Ca-rich transient host, spanning optical to FIR. Best-fit model spectra and model photometry (red line and squares) are shown for both a simple parametric model and a more sophisticated non-parametric model. The Prospector models capture the data well across all wavelengths, allowing robust estimates of the host galaxy’s properties.

Publication

sGRBs

The merger of binary neutron stars are cosmic collisions that produce gravitational waves and electromagnetic counterparts. Short-duration gamma-ray bursts (sGRBs) have long been linked to these events following GW/GRB 170817A. To better understand the formation and evolution of binary neutron star mergers, I worked with Wen-fai and Dr. Anya Nugent as an Illinois Space Grant Fellow in 2020 to study the host galaxies of a sample of sGRBs.

Leveraging my experience with Prospector, we analyzed key stellar population properties such as age, mass, and metallicity. It was an incredible experience to be part of the team and contribute to this project during my undergrad. All of our fits and final products were compiled into the BRIGHT (Broad-band Repository for Investigating Gamma-ray burst Host galaxies Traits) catalogue to facilitate future studies of sGRB environments.

Publication 1 Publication 2 Press Coverage

Outreach & Science Communication

Outside of research, I’m passionate about outreach and building a supportive, inclusive community. Here are a few ways I try to make that happen.

Astronomy on Tap Chicago

Making astronomy accessible in casual, fun environments

It's always fun bringing astronomy to folks over a few drinks of beer at local breweries. I started volunteering for AoT since 2021 and have been one of the main organizers ever since. I usually help with things like venue coordination, social media advertisement, speaker recruitment, and event setup on the day of. People always ask the best questions and know all the answers to the trivia questions!! There's never a dull moment when talking to people about astronomy. I mean, how could you!?

An AoT event at Five & Dime in Evanston near CIERA

I was a scorer at an AoT event at Begyle Brewery, our usual spot!

A flyer I made for the Pi day event. People loved pi and pie!

Another flyer I'm proud of, black holes are always a hit for the spooky season

Alexa gave an amazing talk about FRBs that day, I was in awe

What a typical AoT event looks like

Graduate Womxn in Physics

Building community and representation in physics and astronomy

I was thrilled to co-found GWIP with my friend, Rachel Zhang, now a Gates Cambridge Scholar. As the current president, I’m dedicated to fostering a supportive and inclusive community for womxn in physics at Northwestern. We use the term "womxn" to broadly include cisgender women, transgender people, non-binary individuals, and other gender-diverse members of our community.

Our organization is built around three main pillars: community and advocacy, mentorship, and professional development, all aimed at empowering members to thrive academically, personally, and professionally in physics. The slideshow highlights some of the events we have hosted. Some of my favorites are the bowl painting event, the coffee series which I co-established, and the cocoa and conversation event.

The Welcome Back Bash at the start of the 2024–2025 academic year, featuring fall-themed trivia

I was thrilled to co-found GWIP with my friend, Rachel Zhang, now a Gates Cambridge Scholar. As the current president, I'm dedicated to fostering a supportive and inclusive community for womxn in physics at Northwestern. We use the term "womxn" to broadly include cisgender women, transgender people, non-binary individuals, and other gender-diverse members of our community.

Everyone was so so creative with the mugs they painted at our community building event!!

Cocoa and conversations with festive gifts for the holidays

Some of us painting our mugs, I still use mine regularly :D

Interested in Collaborating?

If you'd like to chat, please feel free to contact me! I love getting involved in outreach, giving talks, and collaborating on various science projects (even if they are not directly related to FRBs). I'd love to hear from you, and thank you for vising my page :D

Get in Touch