Chandra Follow-up Observations of Swift-BAT-selected AGNs II

Abstract

We present the combined Chandra and Swift-BAT spectral analysis of nine low-redshift (z ≤ 0.10), candidate heavily obscured active galactic nuclei (AGN) selected from the Swift-BAT 150 month catalog. We located soft (1−10 keV) X-ray counterparts to these BAT sources and joint fit their spectra with physically motivated models. The spectral analysis in the 1−150 keV energy band determined that all sources are obscured, with a line-of-sight column density N H ≥ 1022 cm−2 at a 90% confidence level. Four of these sources show significant obscuration with N H ≥ 1023 cm−2 and two additional sources are candidate Compton-thick Active Galactic Nuclei (CT-AGNs) with N H ≥ 1024 cm−2. These two sources, 2MASX J02051994–0233055 and IRAS 11058−1131, are the latest addition to the previous 3 CT-AGN candidates found using our strategy for soft X-ray follow-up of BAT sources. Here we present the results of our methodology so far, and analyze the effectiveness of applying different selection criteria to discover CT-AGN in the local Universe. Our selection criteria has an ∼20% success rate of discovering heavily obscured AGN whose CT nature is confirmed by follow-up NuSTAR observations. This is much higher than the ∼5% found in blind surveys.

2FHL J1745.1–3035: A Newly Discovered, Powerful Pulsar Wind Nebula Candidate

“…To quantitatively search for extended emission in 2FHL J1745.1-3035, we perform a comparison between the 2-7 keV surface brightness radial distribution and the one obtained from a simulated PSF in the same band, computed using the ChaRT and MARX 5.5.1 tools (see e.g., Fabbiano et al 2017;Jones et al 2020;Ma et al 2020;Traina et al 2021;Silver et al 2022, for a detailed description of this same approach in nearby active galactic nuclei). We report in Figure 9, bottom left panel, the 2-7 keV surface brightness radial profile of 2FHL J1745.1-3035, which we computed from a set of 11 annuli, where the two radii increase by 0 5 in each consecutive annulus, and the maximum external radius is 6 5, and the corresponding expected PSF profile which one would observe for a point-like source.…”

A New Mid-Infrared and X-ray Machine Learning Algorithm to Discover Compton-thick AGN

“…Observing and analyzing spectra of AGN in the X-rays and infrared to identify strong CT candidates is a time and resource intensive endeavor (see, e.g., Marchesi et al 2017;Andonie et al 2022;Silver et al 2022). The Burst Alert Telescope (BAT) on board Swift (Gehrels et al 2004) detected 1390 sources in its 150-month catalog 1 , almost 500 more than its predecessor, the 100-month catalog.…”