The first large sample of HI observations of fast radio burst hosts������
Marcin Glowacki
The first large sample of HI observations of fast radio burst hosts������(…and the 100s of discoveries lurking ‘nearby’)
Marcin Glowacki
Fast radio bursts (FRBs)
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Fast radio bursts: extremely luminous bursts of radio energy on millisecond timescales at cosmological distances. A few seen to repeat; most do not.
First discovered in 2007 (archival data), years before next discovery. Now have thousands (although only 100s published)
Characteristic sweep in frequency - dispersion measure (DM)
Thornton et al. 2013
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Fast radio bursts (FRBs)
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Shown that FRBs can probe the ‘missing baryons’
Relationship seen between DM and redshift of the FRB
FRBs also powerful tools for cosmological studies – and meanwhile we still are trying to learn what creates them!
Macquart et al. 2020
See Glowacki & Lee 2024 for a summary on other uses FRBs have on cosmology problems!
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Total ASKAP FRB sources: 99
50 localised to (sub-)arcsecond precision, most with redshifts
Image credit: Lachlan Marnoch
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First four FRB host galaxies detected in HI
All strongly asymmetric, all attributed to recent merger activity
Michałowski 2021
Kaur et al. 2022
Lee-Waddell et al. 2023
Lee-Waddell et al. 2023
Disturbed HI -> A fast FRB channel?
Galaxy merger events traced by HI
Disturbed HI -> A fast FRB channel?
Star formation, birth of massive stars which are relatively short-lived
Galaxy merger events traced by HI
Disturbed HI -> A fast FRB channel?
Neutron stars, magnetars; popular progenitor models for FRBs
Star formation, birth of massive stars which are relatively short-lived
Galaxy merger events traced by HI
Disturbed HI -> A fast FRB channel?
Neutron stars, magnetars; popular progenitor models for FRBs
Star formation, birth of massive stars which are relatively short-lived
FRBs and happy astronomers
Galaxy merger events traced by HI
Disturbed HI -> A fast FRB channel?
Neutron stars, magnetars; popular progenitor models for FRBs
NEED MORE STATISTICS!
Star formation, birth of massive stars which are relatively short-lived
FRBs and happy astronomers
Galaxy merger events traced by HI
FRB211127
The first commensal HI/FRB detection
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FRB20211127I: collaboration between CRAFT and WALLABY (Glowacki et al. 2023)
Only 5th (published) extragalactic FRB host with HI emission detected. Lower S/N but appeared less asymmetric…
Using HI for the redshift measurement
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Red = FRB host galaxy
Blue = Neighbour
Grey = Whole system
Green = Optical redshift obtained AFTER MeerKAT data
Using HI for the redshift measurement
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Red = FRB host galaxy
Blue = Neighbour
Grey = Whole system
Green = Optical redshift obtained AFTER MeerKAT data
Larger sample needed
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Every z < 0.1 FRB host to that point searched for in HI detected – but only 6 such hosts
Is this true of most ‘typical’ FRB host galaxies (generally star forming discs rather than dwarf or ‘red and dead’ galaxies)?
And do the majority have disturbed/strongly asymmetric HI?
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A larger sample!
MeerKAT: 10
GMRT: 5
FAST: 5
Other: 2
Hugh Roxburgh
MeerKAT
MeerKAT
GMRT
Hugh Roxburgh
MeerKAT
MeerKAT
GMRT
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Hugh Roxburgh - PhD Milestone 2
Transitioning to quiescence, so checks out!
The first commensal HI/FRB detection
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FRB20211127I: collaboration between CRAFT and WALLABY (Glowacki et al. 2023)
Only 5th (published) extragalactic FRB host with HI emission detected. Lower S/N but appeared less symmetric…
The first commensal HI/FRB detection
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FRB20211127I: collaboration between CRAFT and WALLABY (Glowacki et al. 2023)
Only 5th (published) extragalactic FRB host with HI emission detected. Lower S/N but appeared less symmetric…
MeerKAT
Key statistics
16/17 of these hosts detected in HI (21/22 in total)
Six are unambiguously settled, with one borderline case, and three that need deeper/targeted observations (ergo, 11:6 disturbed:settled)
No statistical excess of HI disturbance
Roxburgh, Glowacki & Bera et al. 2025
arxiv.org/abs/2507.06594
Now accepted to PASA
Hugh Roxburgh
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More to investigate…
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Red = one-off FRB hosts
Blue = repeating FRB hosts
Possible trend in hosts of repeating FRBs being less massive in both stellar and HI content, but more statistics needed here too (some weak support from other FRB host studies)
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Tspin limits via FRBs
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Given a well-localised, high S/N FRB in a HI-rich host, can impose upper limits on Tspin!
We have FRBs (e.g. the ‘WALLABY-FRB’) that can be used to demonstrate this idea – work underway!
Roxburgh et al. 2025
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Emission
Population occupancy for HI spin states
(tells us about gas state / phase)
*upper limits in this case
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A tangent…
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The power of MeerKAT…
Glowacki et al. 2024b
49 brand-new HI detections in a single 2.3 hr pointing with MeerKAT!
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Glowacki et al. 2024b
49 brand-new HI detections in a single 2.3 hr pointing with MeerKAT!
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Meet the 49ers: Interacting galaxies
Central galaxy is stripping gas from its companions
Part of a larger group of 9 galaxies
Now have deeper time on this field (2.3 hr -> 14 hr!)
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Video by Alexander Sivitilli
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Meet the 49ers: How likely?
Unlikely based on other studies thus far to find this many in such a short pointing – but likely to find some HI in any random MeerKAT pointing
Some luck with where we pointed - but still had to look in the data as well
MIGHTEE-HI and LADUMA pointings thus far has hundreds of galaxies
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Meet the 49ers: How likely?
Unlikely based on other studies thus far to find this many in such a short pointing
Some luck with where we pointed - but still had to look in the data as well
MIGHTEE-HI and LADUMA pointings thus far has hundreds of galaxies
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The power of MeerKAT
ICRAR Summer Student project by Jasmine White: searched three MeerKAT datasets on FRBs for further HI detections
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Jasmine White
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The power of MeerKAT
ICRAR Summer Student project by Jasmine White: searched three MeerKAT datasets on FRBs for further HI detections
85 HI detections total
70+ new (not in HIPASS nor ALFALFA)
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Jasmine White
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The power of MeerKAT
ICRAR Summer Student project by Jasmine White: searched three MeerKAT datasets on FRBs for further HI detections
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Jasmine White
Large(r) HI gas cloud found; no stars seen from Gemini follow up, yet we find that �MHI = 1.9×109 M☉
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The power of MeerKAT
ICRAR Summer Student project by Damon Clift: searched another MeerKAT datasets on an FRB (Galactic plane) for further HI detections
~20 more HI detections (so 100+ in total!)
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Damon Clift
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The power of MeerKAT
PhD project by Craig Smith (UWC) - 16(+?) sources
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Craig Smith
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The power of MeerKAT
PhD project by Craig Smith (UWC) - 16(+?) sources
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Craig Smith
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Another MeerKAT project (UHF band) targeting FLASH survey HI absorption detections for broad outflows (Mahony et al., in prep)
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HI absorption search!
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HI absorption search!
FLASH Target
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HI absorption search!
Brand new detections of HI absorption!
8 in total!
Glowacki et al. in prep
FLASH Target
PATCHwork survey
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PATCHwork survey
Providing Ancillary science Through Catalogues of HI-work survey
Compiling more gas-rich galaxies! Five other datasets already in hand not yet fully examined (some worked on by Craig and at least 1 future Honours student)
Also have deeper MeerKAT time on the 49ers! Name out of date…
Building towards a catalogue of HI-rich galaxies found in other MeerKAT Open Time datasets. Have any? Want a good student project? Let me know!
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Summary
Marcin Glowacki - marcin.glowacki@roe.ac.uk
The SKA pathfinder telescopes are great for HI studies (and fast radio transients discovery) already!
First large sample of FRB hosts in HI; almost all detected in HI, but not all FRB hosts have disturbed gas – Roxburgh et al. 2025
PATCHwork survey has 120+ HI detections already; do let me know if you are interested!
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Bonus slides
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Constraining the Hubble constant with FRBs
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James et al. 2022 - constrained the Hubble Constant using FRBs from ASKAP and Parkes (16 localised, 60 unlocalised)
Hubble Constant of 73 (+12, -8) km s-1 Mpc-1, and other constraints placed e.g. on DMhost and maximum FRB energy
~100 localised FRBs will measure H0 to an uncertainty of 2.5 km s-1 Mpc-1!
Clancy James
James et al. 2022, MNRAS, 516, 4, pp.4862-4881
See Glowacki & Lee 2024 for a summary on other uses FRBs have on cosmology problems!
A larger sample!