Had a fantastic time in Leiden this week attending the Extreme Matter in Extreme Stars, hosted by the always-brilliant Lorentz Center. The meeting sought to bring together neutron star theorists and observers, with nuclear physics theorists and experimenters, as well as people interested in gravitational-wave sources involving neutron stars. Really nice program with only a few review talks but plenty of opportunity for discussion and short "pop-up" talks, and great attendance by ECRs. To put our money where our mouths are we were tasked with writing a "white paper" or similar intended to bridge the information/assumption gaps between these various communities. A week is only enough to really make a start and so our work will continue remotely; stay tuned!

Labels: 2024, meetings

GOTO team members Tom Killestein and Lisa Kelsey have done an incredible job developing and managing our "flagship" outreach program, Kilonova Seekers, launched with great fanfare back in 2023. The project provides candidate transients detected by GOTO and asks users to play "spot the difference" in distingushing genuine transients (or source variability) from various kinds of artifacts that crop up in our differencing procedure. Tom & Lisa wrote up their work for MNRAS and the paper has now been published. Accompanying the paper were press releases from Portsmouth, Turku, Leicester and even Monash, the latter also acknowledging the contribution of Monash PhD student Sergey Belkin. Although it was not possible to include all our contributing volunteer scientists in the author list, they are acknowledged in the paper's appendix A; all 4.5 pages of them! Keep up the great work

Labels: 2024, outreach

Brendan O'Brien runs the amazing Astrophiz series of podcasts, in which he interviews astrophysicists about their work. I met him briefly at the Transients Down Under meeting in January, and and he later arranged an interview which has now been published as Explosive Neutron Stars. If you prefer another source for your podcasts, try Audible, Soundcloud, Apple Podcasts or YouTube. Do yourself a favour — give it a listen!

Labels: 2024, outreach

Almost 20 years ago I made the first attempt to match thermonuclear bursts with the predictions of Andrew Cumming's "settle" code, for the well-known accretion-powered millisecond pulsar SAX J1808.4—3658. The code was written in IDL and kind of clunky, but worked (after a fashion).

Adelle Goodwin took up the reins for her undergrad, and later PhD work, updating both the settle code and translating my crusty IDL code into Python. Over that time we (with Tom Hilder and others) also attempted to apply the code to additional sources, but could never quite get it to work.

With the expert help of the ADACS team, via a project led by Adelle, we have made substantial corrections and improvements to the matching code, now known as beansp (the "p" is silent). In a new paper submitted to MNRAS, we have now successfully applied the code to a second system, IGR J17498—2921. This (also) 401 Hz pulsar went into outburst in 2011 and exhibited a series of bursts, which we matched with settle to infer a very low H-fraction and metallicity. We also constrain the system inclination and find suggestions for a massive (around twice the mass of our sun) neutron star.

Hopefully the code will be applied to additional systems in the near future!

Labels: 2024, thermonuclear bursts

This week I attended the Transients Down Under meeting hosted by Swinburne U.. Really nice program and a great bunch of old and new colleagues all interested in various kinds of transients. Testament to the growth of the community here in Australia over the last decade or so. Parallel sessions made it difficult to attend everything I wanted, and the lack of an online option was a little frustrating, as the original presenter for our GOTO talk couldn't make it back to Australia for the meeting.

The program featured a good showing from Monash including PhD student Sergey Belkin presenting his latest result on the first discovery of a GRB optical counterpart with GOTO.

Labels: 2024, meetings

Gamma-ray bursts, particularly poorly-localised ones, are a secondary science priority for our GOTO network of telescopes, after binary neutron-star mergers. While we've followed up many such events, up until late last year we'd been unsuccessful in actually discovering an optical counterpart.

This all changed with GRB230911A, detected last September, and for which Monash PhD student Sergey Belkin identified the optical afterglow (reported first in GCN #34681). This discovery was significant in several respects; it included observations from both our northern and southern instruments (the latter was deployed only a few months earlier), and was an emphatic demonstration of the effectiveness of our automated screening, with just one candidate left over for human review. Sergey reported the discovery in a research note, which has now been published by IOP.

Hopefully the first of many more!

Labels: 2024, transients