Table 1 3σ X-ray fluence and X-ray energy upper limits from FRB 20200120E at the times of bursts B4 and B9, derived from NICER and XMM-Newton observations

From: Multiwavelength constraints on the origin of a nearby repeating fast radio burst source in a globular cluster

Timescale (Δt)

\({N}_{{\rm{obs}}}^{{\rm{a}}}\) (Counts)

Absorbed 0.5–10 keV

Fluence limit

(Model 1b:

Γ = 1.5, Ecut = 85 keV)

(\({{\mathcal{F}}}_{{\rm{X}}}\), 10−10 erg cm−2)

Absorbed 0.5–10 keV

Fluence limit

(Model 2c:

kT = 10 keV)

(\({{\mathcal{F}}}_{{\rm{X}}}\), 10−10 erg cm−2)

Absorbed 0.5–10 keV

Fluence limit

(Model 3d:

Γ = −0.5, Ecut = 500 keV)

(\({{\mathcal{F}}}_{{\rm{X}}}\), 10−10 erg cm−2)

Unabsorbed 0.5–10 keV

Energy limite

(EX, 1041 erg)

NICER upper limits at the time of burst B4

10 s

7

<0.4

<3

<3

<0.5–5

1 s

1

<0.3

<2

<2

<0.3–3

100 ns to 100 msf

0

<0.2

<1

<1

<0.3–2

XMM-Newton upper limits at the time of burst B9

100 s

1

<0.4

<1

<1

<0.6–2

100 ms to 10 sg

0

<0.3

<1

<1

<0.5–2

  1. X-ray fluence and X-ray energy upper limits are derived from Poisson 3σ (99.73%) confidence intervals, calculated using the Bayesian method described in ref. 89. The background measurements in Extended Data Table 4 were used to obtain confidence intervals for NICER.
  2. aThe number of photons detected with NICER or XMM-Newton in the 0.5–10 keV energy band within ±Δt/2 of the barycentric, infinite frequency peak time of burst B4 (\({t}_{{\rm{peak}}}^{{\rm{B4}}}\)) or burst B9 (\({t}_{{\rm{peak}}}^{{\rm{B9}}}\)). The number of photons reported for XMM-Newton are within the PSF of the EPIC/pn camera, which was centred on FRB 20200120E’s position from VLBI17.
  3. bModel 1 corresponds to an exponentially cut-off power-law spectrum, similar to the X-ray counterpart of the FRB-like radio burst from SGR 1935+2154 (refs. 11,12,13,14).
  4. cModel 2 corresponds to a typical blackbody spectrum observed from magnetar hard X-ray bursts119,120.
  5. dModel 3 corresponds to an exponentially cut-off power-law spectrum, similar to the spectrum measured from the SGR 1806–20 giant flare31,121.
  6. eThe unabsorbed energy limits were calculated assuming a distance of 3.63 ± 0.34 Mpc (ref. 122) to FRB 20200120E. The range indicates the minimum and maximum values obtained using the unabsorbed fluence limits from models 1, 2 and 3.
  7. fThe absorbed fluence and unabsorbed energy limits were calculated on timescales of 100 ns, 1 μs, 10 μs, 100 μs, 1 ms, 10 ms and 100 ms. Identical values were obtained for these timescales.
  8. gThe absorbed fluence and unabsorbed energy limits were calculated on timescales of 100 ms, 1 s and 10 s. Identical values were obtained for these timescales.
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