High cadence optical polarimetry for time domain astronomy on the Liverpool Telescope

Arnold, D. M.

doi:10.24377/ljmu.t.00006687

Cited by 3 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…After RINGO3 polaroid, the light is split by two dichroic mirrors in three beams that are simultaneously recorded by three EMCCD cameras (Arnold et al 2012). In Figure 2, we derive the photonic response function of RINGO3 instrument which accounts for at-mospheric extinction (King 1985), telescope optics 4 , instrument dichroics 5 , lenses (Arnold 2017), filters 67 transmission and the quantum efficiency of the EMC-CDs (Arnold 2017). The total throughput results in three broad bandpasses with the following mean photonic wavelengths λ 0, {BV,R,I} = 5385 Å, 7030 Å, 8245 Å and full-widths-at-half-maximum FWHM {BV,R,I} = 2232 Å, 1130 Å, 835 Å.…”

Section: Ringo3 Bandpasses Standarizationmentioning

confidence: 99%

Lowly Polarized Light from a Highly Magnetized Jet of GRB 190114C

Jordana-Mitjans

Mundell

Kobayashi

et al. 2020

ApJ

View full text Add to dashboard Cite

We report multi-color optical imaging and polarimetry observations of the afterglow of the first TeVdetected gamma-ray burst, GRB 190114C, using the RINGO3 polarimeter on the 2-m autonomous robotic Liverpool Telescope. Observations begin 201 s after the onset of the GRB and continue until ∼ 7000 s post-burst. High temporal resolution (∆t 2.3 − 4.6 s) and dense sampling of the RINGO3 light curves reveal a chromatic break at t ∼ 400 − 500 s -with initial temporal decay α ∼ 1.5 flattening to α ∼ 1 post-break -which we model as a combination of reverse and forward-shock components, with magnetization parameter R B ∼ 40. The observed polarization degree P ∼ 2 − 4% remains steady throughout the first ∼ 2000-s observation window, with a constant position angle. Broadband spectral energy distribution modeling of the afterglow confirms GRB 190114C is highly obscured (A v,HG = 1.49 ± 0.12 mag; N H,HG = (9.0 ± 0.03) × 10 22 cm −2 ). The measured polarization is therefore dominated by dust scattering and the intrinsic polarization is low -in contrast to P > 10% measured previously for other GRB reverse shocks. We test whether 1st and higher-order inverse Compton scattering in a magnetized reverse shock can explain the low optical polarization and the sub-TeV emission but conclude neither is explained in the reverse shock Inverse Compton model. Instead, the unexpectedly low intrinsic polarization degree in GRB 190114C can be explained if largescale jet magnetic fields are distorted on timescales prior to reverse shock emission.

show abstract

Section: Ringo3 Bandpasses Standarizationmentioning

confidence: 99%

Lowly Polarized Light from a Highly Magnetized Jet of GRB 190114C

Jordana-Mitjans

Mundell

Kobayashi

et al. 2020

ApJ

View full text Add to dashboard Cite

show abstract

“…We estimate RINGO3 depolarizing factor 5 (𝐷) during the T 0 ± 80 days period using the ∼ 485 observations of the 𝑃 = 4.5% − 9 % polarized standard stars and ∼ 95 observations of the 𝑃 ∼ 50% polarized planetary nebula of CRL 2688 (Shawl & Tarenghi 1976). After q-u ellipticity corrections (Arnold 2017), RINGO3 depolarizing effect is negligible in the BV band (𝐷 BV = 1.00±0.01) and small in the R/I bands (𝐷 {R,I } = 0.98 ± 0.01, 0.94 ± 0.01). Because R/I band polarization measurements are dominated by noise (resulting in upper limits), this correction is not applied to the polarization measurements of Table 2.…”

Section: Calibration Of Optical Polarizationmentioning

confidence: 99%

Coherence scale of magnetic fields generated in early-time forward shocks of GRBs

Jordana-Mitjans,

Mundell,

Smith

et al. 2021

Preprint

View full text Add to dashboard Cite

We report the earliest-ever detection of optical polarization from a GRB forward shock (GRB 141220A), measured 129.5 − 204.3 s after the burst using the multi-colour RINGO3 optical polarimeter on the 2-m fully autonomous robotic Liverpool Telescope. The temporal decay gradient of the optical light curves from 86 s to ∼ 2200 s post-burst is typical of classical forward shocks with 𝛼 = 1.091 ± 0.008. The low optical polarization 𝑃 𝐵𝑉 = 2.8 +2.0 −1.6 % (2𝜎) at mean time ∼ 168 s post-burst is compatible with being induced by the host galaxy dust (𝐴 𝑉 ,HG = 0.71 ± 0.15 mag), leaving low polarization intrinsic to the GRB emission itself -as theoretically predicted for forward shocks and consistent with previous detections of low degrees of optical polarization in GRB afterglows observed hours to days after the burst. The current sample of early-time polarization data from forward shocks suggests polarization from (a) the Galactic and host galaxy dust properties (i.e. 𝑃 ∼ 1% − 3%), (b) contribution from a polarized reverse shock (GRB deceleration time, jet magnetization) or (c) forward shock intrinsic polarization (i.e. 𝑃 ≤ 2%), which depends on the magnetic field coherence length scale and the size of the observable emitting region (burst energetics, circumburst density).

show abstract

Coherence scale of magnetic fields generated in early-time forward shocks of GRBs

Jordana-Mitjans

Mundell

Smith

et al. 2021

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We report the earliest-ever detection of optical polarization from a GRB forward shock (GRB 141220A), measured 129.5 − 204.3 s after the burst using the multi-colour RINGO3 optical polarimeter on the 2-m fully autonomous robotic Liverpool Telescope. The temporal decay gradient of the optical light curves from 86 s to ∼2200 s post-burst is typical of classical forward shocks with α = 1.091 ± 0.008. The low optical polarization $P_{BV} = 2.8 _{- 1.6} ^{+ 2.0} \, \%$ (2σ) at mean time ∼168 s post-burst is compatible with being induced by the host galaxy dust (AV, HG = 0.71 ± 0.15 mag), leaving low polarization intrinsic to the GRB emission itself —as theoretically predicted for forward shocks and consistent with previous detections of low degrees of optical polarization in GRB afterglows observed hours to days after the burst. The current sample of early-time polarization data from forward shocks suggests polarization from (a) the Galactic and host galaxy dust properties (i.e. $P \sim 1\%-3\%$), (b) contribution from a polarized reverse shock (GRB deceleration time, jet magnetization) or (c) forward shock intrinsic polarization (i.e. $P \le 2\%$), which depends on the magnetic field coherence length scale and the size of the observable emitting region (burst energetics, circumburst density).

show abstract

High cadence optical polarimetry for time domain astronomy on the Liverpool Telescope

Cited by 3 publications

References 0 publications

Lowly Polarized Light from a Highly Magnetized Jet of GRB 190114C

Lowly Polarized Light from a Highly Magnetized Jet of GRB 190114C

Coherence scale of magnetic fields generated in early-time forward shocks of GRBs

Coherence scale of magnetic fields generated in early-time forward shocks of GRBs

Contact Info

Product

Resources

About