PEARLS: NuSTAR and XMM-Newton Extragalactic Survey of the JWST North Ecliptic Pole Time-Domain Field IV: X-Ray Variability Analysis

Ross Silver; Francesca Civano; Xiurui Zhao; Samantha Creech; S. P. Willner; Christopher N. A. Willmer; Rogier A. Windhorst; Haojing Yan; Anton M. Koekemoer; Rosalia O'Brien; Rafael Ortiz III; Rolf A. Jansen; Gibson B. Bowling; Payaswini Saikia; W. Peter Maksym; Nico Cappelluti; Francesca Fornasini; Massimo Ricotti; Timothy Carleton; Seth H. Cohen; Rachel Honor; Jake Summers; Jordan C. J. D'Silva; Sibasish Laha; Dan Coe; Christopher J. Conselice; Jose M. Diego; Simon P. Driver; Brenda Frye; Norman A. Grogin; Madeline A. Marshall; Nor Pirzkal; Aaron Robotham; Russell E. Ryan Jr

arXiv · 2609.24963

PEARLS: NuSTAR and XMM-Newton Extragalactic Survey of the JWST North Ecliptic Pole Time-Domain Field IV: X-Ray Variability Analysis

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Abstract

NuSTAR and XMM-Newton have observed the James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-Domain Field (TDF) for almost five contiguous years starting in 2019. In that time, the NEP X-ray survey has accumulated 3.5 Ms and 228 ks of quasi-simultaneous NuSTAR and XMM-Newton observations, respectively. This paper presents variability results for the 112 NuSTAR and 453 XMM-Newton sources detected in this field, based solely on the X-ray photometric data. Four NuSTAR sources and 11 XMM-Newton sources varied in at least one band at >=99% confidence. The sources with redshift measurements show a relationship between luminosity and variability with 74% of variable sources brighter than 5x the sensitivity limit of the survey. This is supported by about 1/3 of sources with more than 400 counts detected being variable and only 4 sources with fewer counts showing variability. Variability timescales are not well determined, but variability amplitude tends to be larger on longer timescales.

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Ross Silver, Francesca Civano, Xiurui Zhao, Samantha Creech, S. P. Willner, Christopher N. A. Willmer, Rogier A. Windhorst, Haojing Yan, Anton M. Koekemoer, Rosalia O'Brien, Rafael Ortiz III, Rolf A. Jansen, Gibson B. Bowling, Payaswini Saikia, W. Peter Maksym, Nico Cappelluti, Francesca Fornasini, Massimo Ricotti, Timothy Carleton, Seth H. Cohen, Rachel Honor, Jake Summers, Jordan C. J. D'Silva, Sibasish Laha, Dan Coe, Christopher J. Conselice, Jose M. Diego, Simon P. Driver, Brenda Frye, Norman A. Grogin, Madeline A. Marshall, Nor Pirzkal, Aaron Robotham, Russell E. Ryan Jr. 2026-09-21. PEARLS: NuSTAR and XMM-Newton Extragalactic Survey of the JWST North Ecliptic Pole Time-Domain Field IV: X-Ray Variability Analysis. https://arxiv.org/abs/2609.24963

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