Comparison of the characteristics of magnetars born in death of massive stars and merger of compact objects with swift gamma-ray burst data

Abstract

Assuming that the shallow-decaying phase in the early X-ray lightcurves of gamma-ray bursts (GRBs) is attributed to the dipole radiations (DRs) of a newborn magnetar, we present a comparative analysis for the magnetars born in death of massive stars and merger of compact binaries with long and short GRB (lGRB and sGRB) data observed with the Swift mission. We show that the typical braking index (n) of the magnetars is ∼3 in the sGRB sample, and it is ∼4 for the magnetars in the lGRB sample. Selecting a sub-sample of the magnetars whose spin-down is dominated by DRs (n ≲ 3) and adopting a universal radiation efficiency of 0.3, we find that the typical magnetic field strength (Bp) is 1016 G versus 1015 G and the typical initial period (P0) is ∼20 ms versus 2 ms for the magnetars in the sGRBs versus lGRBs. They follow the same relation between P0 and the isotropic GRB energy as $P_0\propto E_{\rm jet}^{-0.4}$. We also extend our comparison analysis to superluminous supernovae (SLSNe) and stable pulsars. Our results show that a magnetar born in merger of compact stars tends to have a stronger Bp and a longer P0 by about one order of magnitude than that born in collapse of massive stars. Its spin-down is dominated by the magnetic DRs as old pulsars, being due to its strong magnetic field strength, whereas the early spin-down of magnetars born in massive star collapse is governed by both the DRs and gravitational wave (GW) emission. A magnetar with a faster rotation speed should power a more energetic jet, being independent of its formation approach.

Tale of GRB 171010A/SN 2017htp and GRB 171205A/SN 2017iuk: Magnetar origin?

“…Overall, magnetars as the central engine powering sources can explain the different types of light-curve properties with diverse sets of physical parameters like (10 14 -10 15 gauss) and (a few ms), see Duncan & Thompson (1992). Hence, and values of a newborn magnetar can govern the energy of the resulting GRB and SN, e.g., a fast-rotating magnetar may produce a more energetic GRB (Zou et al, 2019(Zou et al, , 2021. The difference in properties of magnetars originated from the core-collapse of a massive star and the merger of compact objects are presented by Zou et al (2021).…”

“…Hence, and values of a newborn magnetar can govern the energy of the resulting GRB and SN, e.g., a fast-rotating magnetar may produce a more energetic GRB (Zou et al, 2019(Zou et al, , 2021. The difference in properties of magnetars originated from the core-collapse of a massive star and the merger of compact objects are presented by Zou et al (2021). They found that the magnetars associated with the core-collapse of massive stars exhibit weaker and a shorter , nearly one to two orders of magnitude compared to those generated from the binary compact mergers.…”

“…The physical processes that power underlying SN arise via thermal heating from radioactive material trapped in the ejecta. Although, apart from the conventional SN power-source models (e.g., radioactive decay of 56 Ni and circumstellar interaction), a central engine based powering source (a black hole/collapsar model; Woosley 1993 or a millisecond magnetar; Usov 1992) can also explain observed properties of GRB-SNe (MacFadyen & Woosley, 1999;Wheeler et al, 2000;Woosley & Bloom, 2006;Cano et al, 2016;Dessart et al, 2017;Obergaulinger & Aloy, 2020;Roy, 2021;Zou et al, 2021). The millisecond magnetars with initial spin periods of ∼1-10 ms and magnetic fields of ∼10 14−15 gauss are believed to induce relativistic Poynting-flux jets (Bucciantini et al, 2008), relevant mechanism to explain such energetic stellar explosions.…”

Constraining the Ellipticity of the Newborn Magnetar with the Observational Data of Long Gamma-Ray Bursts

“…Lasky et al (2017) has constrained the braking indices of the magnetars by using the observed X-ray light curves. Lü et al (2019) and Zou et al (2021) systematically calculated the distribution of the braking indices of magnetars in short and long GRBs, the results show that the braking indices of a number of GRBs are between three and five, implying GW emission already existed in the process of magnetars' spin-down.…”

Where are the magnetar binary companions? Candidates from a comparison with binary population synthesis predictions

“…Owing to their large energy reservoirs, magnetars have also been invoked as the central engines in a variety of transients, from compact object mergers, which produce short gamma-ray bursts (GRBs, Bucciantini et al 2012;Gompertz et al 2013;Rowlinson et al 2013;Gompertz et al 2014;Metzger & Piro 2014;Zou et al 2021), corecollapse long GRBs (Wheeler et al 2000;Komissarov & Barkov 2007;Metzger et al 2011), superluminous supernovae (Kasen & Bildsten 2010;Woosley 2010;Metzger et al 2015) and fast blue optical transients (Prentice et al 2018;Mohan et al 2020). Many fast radio burst models also implicate magnetars (e.g.…”