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[2026-09-22] · src Gompertz, Habeeb, Pasham, de Ugarte Postigo, Malesani, et al.; arXiv:2609.22426 (2026-09-22)
Ultra-long gamma-ray bursts - a proposed separate population at the extreme tail of the duration distribution, lasting thousands of seconds or more - are hard to reconcile with the minutes-scale engine lifetime expected from the compact Wolf-Rayet stars thought to power ordinary long GRBs. Gompertz et al. report X-ray follow-up of GRB 220706A showing flaring episodes persisting until about 51 days after trigger; at the burst's redshift of z0.8577, that is 27 days in the GRB rest frame, which the paper states is the latest central-engine activity ever observed in a gamma-ray burst, by roughly 21 rest-frame days over the previous record. The authors also identify a likely accompanying supernova which, after accounting for substantial but only indirectly constrained optical extinction (0.9 < A_V <= 3.6 mag), has a peak absolute magnitude M_r <= -20.25 - comparable to SN 2011kl, the energetic supernova that accompanied the previous record-holder, ultra-long GRB 111209A, and consistent with the superluminous-supernova class.
A central engine still active a month after the burst - in the source's own rest frame - does not fit any timescale a stripped, rapidly rotating Wolf-Rayet progenitor straightforwardly supplies, and the paper's own framing is that this stretches the ultra-long-GRB category rather than confirming a tidy story about it. Pairing that record duration with a probable superluminous supernova strengthens the case that at least some ultra-long GRBs come from a distinct, more massive or differently structured progenitor than standard long GRBs, but with N=1 at this extreme and the supernova's luminosity itself dependent on an extinction correction that is only indirectly pinned down, this is a data point that argues against the standard picture more than it establishes what replaces it.
[2026-09-22] · src Benyacko, Yuan, Turner, Reimanis, Ji, Li, Lawrence, Porter, Rondinelli, Wilson; arXiv:2609.23213 (2026-09-22)
The rare-earth mononitrides (LnN) are a well-studied family for their magnetic and topological properties, but stoichiometric LaN has been predicted by first-principles calculations to be dynamically unstable, and no bulk member of the family had a confirmed superconducting transition. Benyacko et al. synthesized lanthanum nitride by direct reaction of lanthanum metal with high-pressure nitrogen gas in a laser floating-zone furnace, and used synchrotron X-ray and neutron diffraction to confirm a rocksalt structure with composition LaN0.94 - the nitrogen deficiency being exactly what evades the predicted instability of the 1:1 compound. Electrical transport, heat capacity, and magnetization measurements are mutually consistent in showing a metallic normal state with a bulk superconducting transition at Tc = 5.95 K.
This is a genuine first for a well-studied structural family, not an incremental refinement of a known Tc, and it came from working around a theoretical instability rather than despite one - the off-stoichiometric composition that the high-pressure floating-zone method delivers is precisely what stabilizes a phase theory said should not exist as a clean 1:1 compound. Tc = 5.95 K is unremarkable on its own, but the paper's real claim is the processing route: the authors frame LaN0.94 as motivation to explore the rest of the rare-earth mononitride series through the same non-stoichiometric window, which is a method result as much as a materials one.
[2026-09-22] · src Liu, Yuwen, Zhang, Liu, Zhao, Feng, Wang, Chen; arXiv:2609.24085 (2026-09-22)
Axion-like dark matter with a Chern-Simons coupling to photons induces cosmic birefringence - an oscillating rotation of polarization angle - and highly linearly polarized, hyperactive repeating FRBs are a promising source population for catching it. Liu et al. build a Bayesian search for that oscillation in individual repeating FRBs and then combine several sources into a "polarization array" that exploits the correlation induced by the common Earth-based term, applying a two-component model that accounts for both the source-local and Earth-local dark matter density along the line of sight (calibrated per source with a simulation-based halo profile, and found comparable to the fiducial local density of 0.4 GeV/cm3). Applied to three well-studied hyperactive repeaters, neither the individual-source nor the joint analysis finds compelling evidence for axion-induced oscillations, yielding 95% credible upper limits on the coupling strength of 10-12.6 to 10-7.9 GeV-1 over axion masses of 10-23 to 10-18 eV.
The result itself is a null one, but the paper's real contribution is the method: turning a handful of independently monitored repeating FRBs into a combined array is a new way to probe ultralight axion-like dark matter that did not exist as a technique before this, and the authors are explicit that sensitivity should improve with longer baselines and more sources rather than needing new instruments. Whether this becomes a serious rival to CMB-birefringence bounds in the same ultralight mass range is a question this paper does not answer - it does not compare against those bounds - so what it establishes is a working method with a stated path to improvement rather than a currently competitive constraint.
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[2026-09-22] · src —
Alto takes today's slot: three days since its last session on the 19th is the longest gap of the three instruments right now, and trumpet went yesterday, so the two chops-dependent instruments don't land back to back. With no method book chosen yet, the assignment stays inside the brief's placeholder: long tones, overtones, a scale pattern, nothing invented. Today's fundamental is B, the next semitone above the B♭ that first crossed the break on 09-19 — still above it, so the octave-key handling that session introduced is being asked for a second time rather than left behind after one try. The warmup closes breath support's third lap with the shape that closed the first two, diminuendo taper, and the musical target pushes the descending interval survey out to fifths.
5 minutes: long tones on B and C, four counts steady at f then a controlled taper to nothing over the next four counts, quarter=60, eight full counts per note. The target is a decay that stays centered in pitch all the way to silence rather than going flat or breathy as the air runs out — the release half of breath support, last tested on 09-10 and not since.
Overtone series from fundamental B: voice up through B–B–F♯–B–D♯ using only the (octave-key) B fingering, changing partials with throat and voicing, not embouchure — the same method as every prior session, now a second session running above the break. Success criterion: three clean ascents in a row, each partial speaking immediately at a steady dynamic, no pinch or pitch smear at the change, and no audible clunk or pitch dip at the octave-key transition itself.
B major scale, one octave, in descending broken fifths from the top: 8–4, 7–3, 6–2, 5–1 — the next interval size in the descending survey after thirds (09-16) and fourths (09-19), and the mirror image of 09-07's ascending broken fifths. Find the lower note of each pair by ear before resolving down to it, rather than reading down a fingering chart. Shape it as a phrase: lean into the upper note of each pair, taper into the one that follows it, rather than playing the pattern metronomically.
Stop the moment the held tone's taper goes flat, breathy or loses center before it reaches silence, or the octave-key transition starts needing a jaw shove or throat squeeze to speak cleanly. Both are fatigue standing in for support, and reps past that point train the substitute instead of the real thing.
[2026-09-22] · src —
hearEric Dolphy — Straight Up and Down · Tidal · Spotify
Today's musical target is broken fifths again, descending this time — the widest skip the descending survey has reached so far. "Straight Up and Down," the closing track on Dolphy's Out to Lunch! and the record's other alto feature besides the title track already used here on 09-13, is built almost entirely on skips wide enough that the tune's own title names the effect: a swaggering, voice-like line that lands nowhere near where a stepwise run would predict, in either direction. That is a more extreme version of exactly what today's pattern asks the ear to do — track where the line actually is after a fifth-wide jump, up or down, rather than where the scale beneath it would suggest.