2026/07/21 by Qin-Mei Li, Qi-Bin Sun, Sheng-Bang Qian +5
#astro-ph.HE #hep-ph
The Bp--P0 correlation serves as a critical probe of magnetar engine physics. Although this scaling relation has been firmly established for long gamma-ray bursts (lGRBs), systematic investigations for short GRBs (sGRBs) remain absent, leaving the physical differences between the two populations poorly constrained. Here we analyze 33 Swift sGRBs exhibiting prominent X-ray plateaus from newborn millisecond magnetar spin-down, and derive their initial spin period P0 and polar magnetic field Bp. sGRB magnetars span P0 ∈ [1.73, 18.28] ms and Bp ∈ [0.06, 2.82] × 1017 G (⟨ Bp ⟩ = 7.05 × 1016 G), significantly more magnetized than lGRB magnetars (Bp ∈ [0.39, 23.08] × 1015 G; ⟨ Bp ⟩ = 3.69 × 1015 G). For the first time, we derive consistent power-law Bp--P0 correlations for GRBs : the scaling for sGRBs is log Bp = (0.84±0.07)log P0 + (15.79±0.07), whose slope is highly consistent with that of lGRBs, log Bp = (0.83±0.09)log P0 + (14.92±0.06). The near-identical slopes imply a universal magnetar spin-down mechanism, while the vertical offset between intercepts traces divergent progenitor channels. This scaling relation thus offers a new diagnostic to disentangle the formation pathways of GRB. Within the framework of the standard spin-up model, the mass accretion rates of sGRBs (M ∼ 1 × 10-1 to 3 × 10-1 M_\odot s-1) are substantially higher than those of lGRBs (M ∼ 10-4 to 1 × 10-1 M_\odot s-1). Our work completes the missing Bp--P0 statistics for sGRBs, quantitatively unifies their magnetar physics with lGRBs, and provides new observational constraints on the origin diversity of relativistic transients.