Parameter estimation in X-ray astronomy using maximum likelihood

Wachter, Keri; Leach, R. A.; Kellogg, E.

doi:10.1086/157084

Cited by 132 publications

(112 citation statements)

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“…The instrumental background-subtracted spectra were modeled with xspec 25 v12.8.2 (Arnaud 1996). The Chandraspectra were binned to a minimum of 1 count/bin, and modeled using the extended C-statistic (Cash 1979;Wachter et al 1979). The spectra were fitted in the energy band 0.5-7 keV.…”

Section: Chandra Background Modelingmentioning

confidence: 99%

Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

Weeren

Ogrean

Jones

et al. 2017

ApJ

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To investigate the relationship between thermal and non-thermal components in merger galaxy clusters, we present deep JVLA and Chandraobservations of the HST Frontier Fields cluster MACSJ0717.5+3745. The Chandraimage shows a complex merger event, with at least four components belonging to different merging subclusters. Northwestof the cluster, ∼0.7 Mpc from the center, there is a ram-pressure-stripped core that appears to have traversed the densest parts of the cluster after entering the intracluster medium (ICM) from the direction of a galaxy filament to the southeast. We detect a density discontinuity north-northeastof this core, which we speculate is associated with a cold front. Our radio images reveal new details for the complex radio relic and radio halo in this cluster. In addition, we discover several new filamentary radio sources with sizes of 100-300kpc. A few of these seem to be connected to the main radio relic, while others are either embedded within the radio halo or projected onto it. A narrow-angled-tailed (NAT) radio galaxy, a cluster member, is located at the center of the radio relic. The steep spectrum tails of this active galactic nucleuslead into the large radio relic where the radio spectrum flattens again. This morphological connection between the NAT radio galaxy and relic provides evidence for reacceleration (revival) of fossil electrons. The presence of hot 20 keV ICM gas detected by Chandranear the relic location provides additional support for this re-acceleration scenario.

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Section: Chandra Background Modelingmentioning

confidence: 99%

Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

Weeren

Ogrean

Jones

et al. 2017

ApJ

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“…We grouped the spectral data to >1 counts bin −1 using GRPPHA and then fitted the data in the 0.3-7 keV range applying W-statistics (i.e. Cashstatistics with background subtraction; Wachter et al 1979). …”

Section: Chandra Quiescence Observation In 2016mentioning

confidence: 99%

A cold neutron star in the transient low-mass X-ray binary HETE J1900.1–2455 after 10 yr of active accretion

Degenaar

Ootes

Reynolds

et al. 2016

Monthly Notices of the Royal Astronomical Society: Letters

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The neutron star low-mass X-ray binary and intermittent millisecond X-ray pulsar HETE J1900.1-2455 returned to quiescence in late 2015, after a prolonged accretion outburst of 10 yr. Using a Chandra observation taken 180 d into quiescence we detect the source at a luminosity of 4.5 × 10 31 (D/4.7 kpc) 2 erg s −1 (0.5-10 keV). The X-ray spectrum can be described by a neutron star atmosphere model with a temperature of 54 eV for an observer at infinity. We perform thermal evolution calculations based on the 2016 quiescent data and a 98 eV temperature upper limit inferred from a Swift observation taken during an unusually brief ( 2 weeks) quiescent episode in 2007. We find no evidence in the present data that the thermal properties of the crust, such as the heating rate and thermal conductivity, are different than those of non-pulsating neutron stars. Finding this neutron star so cold after its long outburst imposes interesting constraints on the heat capacity of the stellar core; these become even stronger if further cooling were to occur.

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“…The spectra were grouped to have at least 1 count per bin, and the fit was done using the extended C-statistic 25 (Cash 1979;Wachter et al 1979). 4.…”

Section: X-ray Foreground and Background Modelingmentioning

confidence: 99%

FRONTIER FIELDS CLUSTERS:CHANDRAAND JVLA VIEW OF THE PRE-MERGING CLUSTER MACS J0416.1-2403

Ogrean

Weeren

Jones

et al. 2015

ApJ

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Merging galaxy clusters leave long-lasting signatures on the baryonic and non-baryonic cluster constituents, including shock fronts, cold fronts, X-ray substructure, radio halos, and offsets between the dark matter (DM) and the gas components. Using observations from Chandra, the Jansky Very Large Array, the Giant Metrewave Radio Telescope, and the Hubble Space Telescope, we present a multiwavelength analysis of the merging Frontier Fields cluster MACS J0416.1-2403 (z = 0.396), which consists of NE and SW subclusters whose cores are separated on the sky by ∼250 kpc. We find that the NE subcluster has a compact core and hosts an X-ray cavity, yet it is not a cool core. Approximately 450 kpc south-southwest of the SW subcluster, we detect a density discontinuity that corresponds to a compression factor of ∼1.5. The discontinuity was most likely caused by the interaction of the SW subcluster with a less massive structure detected in the lensing maps SW of the subclusterʼs center. For both the NE and the SW subclusters, the DM and the gas components are well-aligned, suggesting that MACS J0416.1-2403 is a pre-merging system. The cluster also hosts a radio halo, which is unusual for a pre-merging system. The halo has a 1.4 GHz power of (1.3 ± 0.3) × 10 24 W Hz −1 , which is somewhat lower than expected based on the X-ray luminosity of the cluster if the spectrum of the halo is not ultra-steep. We suggest that we are either witnessing the birth of a radio halo, or have discovered a rare ultra-steep spectrum halo.

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Parameter estimation in X-ray astronomy using maximum likelihood

Cited by 132 publications

References 0 publications

Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

Chandra and JVLA Observations of HST Frontier Fields Cluster MACS J0717.5+3745

A cold neutron star in the transient low-mass X-ray binary HETE J1900.1–2455 after 10 yr of active accretion

FRONTIER FIELDS CLUSTERS:CHANDRAAND JVLA VIEW OF THE PRE-MERGING CLUSTER MACS J0416.1-2403

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