Constraining the ellipticity of strongly magnetized neutron stars powering superluminous supernovae

Moriya, Takashi J.; Tauris, T. M.

doi:10.1093/mnrasl/slw072

Cited by 18 publications

(18 citation statements)

References 40 publications

(54 reference statements)

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“…We assume that all of the rotational energy goes into electromagnetic spin-down, instead of gravitational wave radiation (e.g. Moriya & Tauris 2016;Ho 2016).…”

Section: Magnetar Misalignment: Powering Both Jet and Snmentioning

confidence: 99%

The GRB–SLSN connection: misaligned magnetars, weak jet emergence, and observational signatures

Margalit

Metzger

Thompson

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Multiple observational lines of evidence support a connection between hydrogen-poor superluminous supernovae (SLSNe) and long duration gamma-ray bursts (GRBs). Both events require a powerful central energy source, usually attributed to a millisecond magnetar or an accreting black hole. The GRB-SLSN link raises several theoretical questions: What distinguishes the engines responsible for these different phenomena? Can a single engine power both a GRB and a luminous SN in the same event? We propose a new unifying model for magnetar thermalization and jet formation: misalignment between the rotation (Ω) and magnetic dipole (µ) axes thermalizes a fraction of the spindown power by reconnection in the striped equatorial wind, providing a guaranteed source of "thermal" emission to power the supernova. The remaining un-thermalized power energizes a relativistic jet. In this picture, the GRB-SLSN dichotomy is directly linked to Ω · µ through the misalignment angle α, such that the thermal fraction is 1.025α/ 0.636 + α 4 1/4 . We extend earlier work to show that even weak relativistic jets of luminosity ∼ 10 46 erg s −1 can escape the expanding SN ejecta hours after the explosion -whether driven by a magnetar or black hole accretionimplying that escaping relativistic jets may accompany many SLSNe regardless of the details of their driving mechanism. We calculate the observational signature of these jets. We show that they may produce transient UV cocoon emission lasting a few hours when the jet breaks out of the ejecta surface. A longer-lived optical/UV signal may originate from a mildly-relativistic wind driven from the interface between the jet and the ejecta walls. This provides a new explanation for the secondary early-time maximum observed in some SLSNe light curves, such as LSQ14bdq. This scenario also predicts a population of GRB from on-axis jets with extremely long durations, potentially similar to the population of "jetted tidal disruption events", in coincidence with a small subset of SLSNe.

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“…We assume that all of the rotational energy goes into electromagnetic spin-down, instead of gravitational wave radiation (e.g. Moriya & Tauris 2016;Ho 2016).…”

Section: Magnetar Misalignment: Powering Both Jet and Snmentioning

confidence: 99%

The GRB–SLSN connection: misaligned magnetars, weak jet emergence, and observational signatures

Margalit

Metzger

Thompson

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…The fiducial millisecond magnetar model relates the evolution of the star's spin frequency W( ) t to the X-ray light curve (Zhang & Mészáros 2001;Metzger et al 2011). The original model assumes that the rapidly rotating star loses angular momentum through a combination of gravitational waves and electromagnetic radiation, although the amount of energy lost to gravitational-wave emission is small compared to electromagnetic losses (Ho 2016;Lasky & Glampedakis 2016;Moriya & Tauris 2016). In general, the spin-down of a neutron star can be described by the torque equation…”

Section: Introductionmentioning

confidence: 99%

The Braking Index of Millisecond Magnetars

Lasky

Leris

Rowlinson

et al. 2017

ApJL

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We make the first measurement of the braking index n of two putative millisecond magnetars born in short gammaray bursts. We measure =  n 2.9 0.1 and =  n 2.6 0.1 for millisecond magnetars born in GRB 130603B and GRB 140903A, respectively. The neutron star born in GRB 130603B has the only known a braking index consistent with the fiducial n=3 value. This value is ruled out with 99.95% confidence for GRB 140903A. We discuss possible causes of < n 3 braking indices in millisecond magnetars, showing that several models can account for the measurement of the braking index in GRB 140903A, while it is more difficult to account for a braking index consistent with n=3.

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“…A strong internal toroidal magnetic field component (B t ) could cause a NS distortion, producing an ellipticity ǫ = 1.6 × 10 −6 (B t /10 15 G) 2 [57]. Therefore, the ellipticity of the new born millisecond magnetars can reach an order of magnitude of 10 −3 [58,59]. However, the MSPs forming in the recycling channel are NSs with weak magnetic field.…”

Section: Discussionmentioning

confidence: 99%

Ultra-compact binary pulsars as continuous dual-line gravitational wave sources

Chen

2021

Preprint

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Binary millisecond pulsars (MSPs) are detached binary systems consisting of a MSP and a He white dwarf. If the initial orbital periods of binary MSPs are less than 0.3 day, they would evolve toward ultra-compact binary pulsars due to the rapid orbital shrinkage by the gravitational wave (GW) radiation. During the orbital decay, the MSP with an ellipticity would spin down by the GW radiation and the magnetic dipole radiation. Our calculations indicate that the angular momentum loss is dominated by the GW radiation when the ellipticities of the neutron stars (NSs) are in the range of (1−50)×10 −7 , and the frequencies of high-frequency GW signals from the rotating NSs are 10 − 100 Hz when the binary pulsars can be visible as low-frequency GW sources. These high-frequency GW signals are possible to be detected by the aLIGO and the third-generation GW detectors such as Einstein Telescope, depending on the frequencies and the distances. Therefore, some ultra-compact binary pulsars have an opportunity to become intriguing dual-line GW sources. By detecting the low-frequency GW signals, the NS mass can be accurately derived. A dual-line detection of two band GW signals could provide a constraint on the moment of inertia and the ellipticity of the NS. Thus the dual-line GW sources can be potentially applied to constrain the equation of state of the NS.

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Constraining the ellipticity of strongly magnetized neutron stars powering superluminous supernovae

Cited by 18 publications

References 40 publications

The GRB–SLSN connection: misaligned magnetars, weak jet emergence, and observational signatures

The GRB–SLSN connection: misaligned magnetars, weak jet emergence, and observational signatures

The Braking Index of Millisecond Magnetars

Ultra-compact binary pulsars as continuous dual-line gravitational wave sources

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