Monte Carlo processes for including Chandra instrument response uncertainties in parameter estimation studies

Drake, J. J.; Ratzlaff, Peter W.; Kashyap, Vinay; Edgar, R. J.; Izem, Rima; Jerius, D.; Siemiginowska, Aneta; Vikhlinin, A.

doi:10.1117/12.672226

Cited by 18 publications

(10 citation statements)

References 8 publications

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“…Table 3 lists the total number of Chandra counts in the combined observations in each of these features in order to give an indication of the significance at which they are detected and the degree of certainty with which we can discuss their properties. It should be noted that the number of counts obtained for some components of the system (> 10 4 ) puts us in the regime, discussed by Drake et al (2006), in which calibration uncertainties are likely to dominate over statistical ones. Methods to include calibration uncertainties in the analysis of Chandra data have been discussed by, e.g., Lee et al (2011) and Xu et al (2014).…”

Section: Discussionmentioning

confidence: 97%

DeepChandraobservations of Pictor A

Hardcastle

Lenc

Birkinshaw

et al. 2015

Mon. Not. R. Astron. Soc.

116

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We report on deep Chandra observations of the nearby broad-line radio galaxy Pictor A, which we combine with new Australia Telescope Compact Array (ATCA) observations. The new X-ray data have a factor 4 more exposure than observations previously presented and span a 15-year time baseline, allowing a detailed study of the spatial, temporal and spectral properties of the AGN, jet, hotspot and lobes. We present evidence for further time variation of the jet, though the flare that we reported in previous work remains the most significantly detected time-varying feature. We also confirm previous tentative evidence for a faint counterjet. Based on the radio through X-ray spectrum of the jet and its detailed spatial structure, and on the properties of the counterjet, we argue that inverse-Compton models can be conclusively rejected, and propose that the X-ray emission from the jet is synchrotron emission from particles accelerated in the boundary layer of a relativistic jet. For the first time, we find evidence that the bright western hotspot is also time-varying in X-rays, and we connect this to the small-scale structure in the hotspot seen in high-resolution radio observations. The new data allow us to confirm that the spectrum of the lobes is in good agreement with the predictions of an inverse-Compton model and we show that the data favour models in which the filaments seen in the radio images are predominantly the result of spatial variation of magnetic fields in the presence of a relatively uniform electron distribution.

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Section: Discussionmentioning

confidence: 97%

DeepChandraobservations of Pictor A

Hardcastle

Lenc

Birkinshaw

et al. 2015

Mon. Not. R. Astron. Soc.

116

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“…We note that an in-depth evaluation of Chandra calibration uncertainties in the context of qLMXB NS M-R measurements based on the prescriptions by Drake et al (2006), Lee et al (2011), and Xu et al (2014) will be presented in a subsequent publication.…”

Section: Instrument Calibration Uncertaintiesmentioning

confidence: 99%

“…Following Guillot et al (2013), we adopt a 3% systematic error to account for the instrument response uncertainties. We note that an in-depth evaluation of Chandra calibration uncertainties in the context of qLMXB NS M − R measurements based on the prescriptions by Drake et al (2006), Lee et al (2011), andXu et al (2014) will be presented in a subsequent publication.…”

Section: Instrument Calibration Uncertaintiesmentioning

confidence: 99%

Neutron Star Mass–radius Constraints of the Quiescent Low-Mass X-Ray Binaries X7 and X5 in the Globular Cluster 47 Tuc

Bogdanov

Heinke

Özel

et al. 2016

ApJ

113

141

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We present Chandra/ACIS-S subarray observations of the quiescent neutron star (NS) low-mass X-ray binaries X7 and X5 in the globular cluster 47Tuc. The large reduction in photon pile-up compared to previous deep exposures enables a substantial improvement in the spectroscopic determination of the NS radius and mass of these NSs. Modeling the thermal emission from the NS surface with a non-magnetized hydrogen atmosphere and accounting for numerous sources of uncertainties, we obtain for the NS in X7 a radius of = -+ R 11.1 0.7 0.8 km for an assumed stellar mass of M=1.4 M e (68% confidence level). We argue, based on astrophysical grounds, that the presence of a He atmosphere is unlikely for this source. Due to the excision of data affected by eclipses and variable absorption, the quiescent low-mass X-ray binary X5 provides less stringent constraints, leading to a radius of = -+ R 9.6 1.1 0.9 km, assuming a hydrogen atmosphere and a mass of M=1.4 M e . When combined with all existing spectroscopic radius measurements from other quiescent low-mass X-ray binaries and Type I X-ray bursts, these measurements strongly favor radii in the 9.9-11.2 km range for a ∼1.5 M e NS and point to a dense matter equation of state that is somewhat softer than the nucleonic ones that are consistent with laboratory experiments at low densities.

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“…We can obtain a first estimate of the effect of calibration expected from pure Poisson statistics by assuming that the "true" ARF is an unknown member of the library of ARFs. Following Drake et al (2006), one can then proceed by (i) either simulating a single spectrum with the nominal ARF and fitting it across all ARFs in the library, (ii) or by generating a single spectrum per ARF in the library and subsequently fitting it with the nominal ARF. Following Section 5 of Barret & Cappi (2019), we use the former method as it is able to capture more closely the perturbative nature of detector miscalibration in the recovery of best-fit parameter values; and we refer to Cucchetti et al (2018) for an implementation of the latter method.…”

Section: Overview Of the Effects Of A Nonoptimal Calibrationmentioning

confidence: 99%

Physics Beyond the Standard Model with Future X-Ray Observatories: Projected Constraints on Very-light Axion-like Particles with Athena and AXIS

Júlia

Reynolds

Parker

et al. 2023

ApJ

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Axion-like particles (ALPs) are well-motivated extensions of the Standard Model of Particle Physics and a generic prediction of some string theories. X-ray observations of bright active galactic nuclei (AGNs) hosted by rich clusters of galaxies are excellent probes of very-light ALPs, with masses log ( m a / eV ) < − 12.0 . We evaluate the potential of future X-ray observatories, particularly Athena and the proposed AXIS, to constrain ALPs via observations of cluster-hosted AGNs, taking NGC 1275 in the Perseus cluster as our exemplar. Assuming perfect knowledge of the instrument calibration, we show that a modest exposure (200 ks) of NGC 1275 by Athena permits us to exclude all photon–ALP couplings g aγ > 6.3 × 10−14 GeV−1 at the 95% confidence level, as previously shown by Conlon et al., representing a factor of 10 improvement over current limits. We then proceed to assess the impact of realistic calibration uncertainties on the Athena projection by applying a standard Cash likelihood procedure, showing the projected constraints on g aγ weaken by a factor of 10 (back to the current most sensitive constraints). However, we show how the use of a deep neural network can disentangle the energy-dependent features induced by instrumental miscalibration and those induced by photon–ALP mixing, allowing us to recover most of the sensitivity to the ALP physics. In our explicit demonstration, the machine learning applied allows us to exclude g aγ > 2.0 × 10−13 GeV−1, complementing the projected constraints of next-generation ALP dark matter birefringent cavity searches for very-light ALPs. Finally, we show that a 200 ks AXIS/on-axis observation of NGC 1275 will tighten the current best constraints on very-light ALPs by a factor of 3.

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Monte Carlo processes for including Chandra instrument response uncertainties in parameter estimation studies

Cited by 18 publications

References 8 publications

DeepChandraobservations of Pictor A

DeepChandraobservations of Pictor A

Neutron Star Mass–radius Constraints of the Quiescent Low-Mass X-Ray Binaries X7 and X5 in the Globular Cluster 47 Tuc

Physics Beyond the Standard Model with Future X-Ray Observatories: Projected Constraints on Very-light Axion-like Particles with Athena and AXIS

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