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Return-Path: <atel@astronomerstelegram.org> Delivered-To: stefano@bicar.it Received: by mail.planetcloud-host.com (Postfix, from userid 1016) id CD4A014BF7; Sat, 29 Mar 2025 08:06:06 +0100 (CET) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on mail.planetcloud-host.com X-Spam-Level: X-Spam-Status: No, score=-0.0 required=7.0 tests=RCVD_IN_DNSWL_BLOCKED, RCVD_IN_VALIDITY_RPBL_BLOCKED,RCVD_IN_VALIDITY_SAFE_BLOCKED,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=disabled version=3.4.0 Received-SPF: Pass (sender SPF authorized) identity=mailfrom; client-ip=174.142.199.243; helo=server.astronomerstelegram.org; envelope-from=atel@astronomerstelegram.org; receiver=stefano@bicar.it Received: from server.astronomerstelegram.org (astronomerstelegram.org [174.142.199.243]) by mail.planetcloud-host.com (Postfix) with ESMTP id D13511449A for <stefano@bicar.it>; Sat, 29 Mar 2025 08:06:04 +0100 (CET) Received: from server.astronomerstelegram.org (localhost [127.0.0.1]) by server.astronomerstelegram.org (Postfix) with ESMTP id 45FF0288076A for <stefano@bicar.it>; Sat, 29 Mar 2025 03:06:03 -0400 (EDT) To: stefano@bicar.it From: atel@astronomerstelegram.org Subject: ATel 17117 Message-Id: <20250329070603.45FF0288076A@server.astronomerstelegram.org> Date: Sat, 29 Mar 2025 03:06:03 -0400 (EDT) ------------------------------------------------------------------------------ The Astronomer's Telegram is free to read, free to publish, free to use. Thanks to the support of our patrons, we can continue to keep it free. https://www.patreon.com/astronomerstel ------------------------------------------------------------------------------ The Astronomer's Telegram http://www.astronomerstelegram.org ------------------------------------------------------------------------------ Posted: Within the last 24 hours ============================================================================== ATEL #17117 ATEL #17117 Title: FRB 20250316A: X-ray Flux Upper Limits with NICER and Simultaneous Radio Observations with CHIME/Pulsar Author: Aaron B. Pearlman (McGill University; Trottier Space Institute at McGill University) on behalf of the CHIME/FRB Collaboration, and Keith C. Gendreau (NASA GSFC), Zaven Arzoumanian (NASA GSFC), Elizabeth C. Ferrara (University of Maryland; CRESST II; NASA GSFC), Joheen Chakraborty (MIT), Teruaki Enoto (Kyoto University; RIKEN), Tolga Guver (Istanbul University), Chin-Ping Hu (NCUE) Queries: aaron.b.pearlman@physics.mcgill.ca Posted: 28 Mar 2025; 16:39 UT Subjects:Radio, X-ray, Transient, Fast Radio Burst FRB 20250316A is a bright fast radio burst (FRB) discovered by the CHIME/FRB Collaboration (ATel #17081) and associated with the nearby galaxy NGC 4141, located at a distance of ~40 Mpc. Using the full CHIME/FRB Outriggers VLBI array, the FRB source was localized with sub-arcsecond precision (ATels #17086, #17114, #17115) to a region near a clump of extended optical emission (ATel #17116, GCN #39887). Observations with the Einstein Probe (EP) Follow-up X-ray Telescope (FXT) revealed a potentially variable X-ray source (ATel #17100) spatially coincident with FRB 20250316A (ATels #17100, #17114, #17115). We performed six target-of-opportunity (ToO) X-ray observations of FRB 20250316A using NICER, starting at 2025-03-18 00:44:27 UTC and ending on 2025-03-21 00:26:58 UTC, with a total exposure of 6.7 ks. We report 3σ upper limits on the persistent 0.5-10 keV X-ray flux (F<sub>x</sub>) of FRB 20250316A, assuming a fiducial absorbed power-law spectral model with a hydrogen column density of N<sub>H</sub> = 1.43 × 10<sup>20</sup> cm<sup>-2</sup> and a photon index of Γ = 2 (see Pearlman et al. 2025 for details). Observation Mid-Time (UTC) | 3σ Persistent X-ray Flux Upper Limit (erg cm<sup>-2</sup> s<sup>-1</sup>): 2025-03-18 00:53:49 | F<sub>x</sub> < 4 × 10<sup>-13</sup> 2025-03-18 08:33:33 | F<sub>x</sub> < 1 × 10<sup>-12</sup> 2025-03-19 00:12:49 | F<sub>x</sub> < 5 × 10<sup>-13</sup> 2025-03-19 07:53:49 | F<sub>x</sub> < 3 × 10<sup>-12</sup> 2025-03-20 08:25:23 | F<sub>x</sub> < 4 × 10<sup>-13</sup> 2025-03-21 00:13:11 | F<sub>x</sub> < 7 × 10<sup>-14</sup> These NICER X-ray flux upper limits are consistent with previous X-ray flux measurements of EP J120944.2+585060 obtained from EP/FXT and Swift/XRT observations (ATels #17100, #17101, #17109). Our deepest NICER X-ray flux upper limit corresponds to a 3σ upper limit of L<sub>x</sub> < 10<sup>40</sup> erg s<sup>-1</sup> on the persistent X-ray luminosity of FRB 20250316A in the 0.5-10 keV energy range, using a distance of 40 Mpc to FRB 20250316A (ATel #17081). We also carried out a search for X-ray bursts in the NICER data, with widths between 100 ns and 100 s, using a Bayesian Blocks algorithm (Scargle 1998; Pearlman et al. 2025). No astrophysical X-ray bursts were detected with a statistical significance above 3σ. Additionally, we performed a search for X-ray pulsations between 0.1 and 1000 Hz in the NICER data using the Rayleigh (Z<sub>1</sub><sup>2</sup>) statistic (Buccheri et al. 1983). We also conducted a PRESTO-based acceleration search with zmax = ± 200 Fourier bins (Ransom et al. 2002). These periodicity searches were conducted in the 0.5-2.0, 2.0-10.0, and 0.5-10.0 keV energy ranges using all of our NICER observations, as well as data from individual exposures. In each case, no significant evidence of X-ray pulsations was found above a 3σ detection threshold. NICER observations on 2025-03-18 and 2025-03-20 were scheduled during high time resolution follow-up radio observations of FRB 20250316A with CHIME/Pulsar (The CHIME/Pulsar Collaboration et al. 2021). We performed a coherent search for radio bursts with widths between 40.96 μs and 13 ms (see Pearlman et al. 2025 for details). No radio bursts were detected above a signal-to-noise ratio of 7 in the 400-800 MHz band during these CHIME/Pulsar observations. These NICER observations were performed under an approved NICER General Observer Cycle 7 ToO program focused on X-ray observations of nearby FRB sources (PI: A. B. Pearlman). NICER will continue to observe FRB 20250316A. NICER is a 0.2-12 keV X-ray telescope operating on the International Space Station. NICER is a non-imaging telescope with a field of view of ~30 arcmin<sup>2</sup>. The NICER mission and portions of the NICER science team activities are funded by NASA. ------------------------------------------------------------------------------ Password Certification: Aaron Pearlman (aaron.b.pearlman@physics.mcgill.ca) https://www.astronomerstelegram.org/?read=17117 ============================================================================== ============================================================================== This is an automatically-generated notice. You can remove yourself permanently from receiving both the Daily Email Digest and Instant Email Notices from The Astronomer's Telegram by following this link: https://www.astronomerstelegram.org?unsubscribe&confirmation=a803d34e7ea924f9a4142bac00763549&address=stefano@bicar.it
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