2024-01-11 NASA
◆NGC 4945は活動的な銀河で、その中心のブラックホールによるパーティクルジェットが銀河の進化に影響を与えている可能性があります。これにより、星の形成フェーズがいかに抑制されるかを理解する手がかりが得られました。
＜関連情報＞
- https://science.nasa.gov/centers-and-facilities/goddard/nasa-scientists-discover-a-novel-galactic-fossil/
- https://iopscience.iop.org/article/10.3847/1538-4357/acd18a/meta
Swift/XRTが偶然発見した超大光度X線源の新しいサンプル A New Sample of Transient Ultraluminous X-Ray Sources Serendipitously Discovered by Swift/XRT
Murray Brightman, Jean-Marie Hameury, Jean-Pierre Lasota, Ranieri D. Baldi, Gabriele Bruni, Jenna M. Cann, Hannah Earnshaw, Felix Fürst, Marianne Heida, Amruta Jaodand, Margaret Lazzarini, Matthew J. Middleton, Dominic J. Walton, and Kimberly A. Weaver
The Astrophysical Journal Published 2023 July 3
DOI:10.3847/1538-4357/acd18a
Abstract
Ultraluminous X-ray sources (ULXs) are our best laboratories for studying extreme super-Eddington accretion. Most studies of these objects are of relatively persistent sources; however, there is growing evidence to suggest a large fraction of these sources are transient. Here we present a sample of five newly reported transient ULXs in the galaxies NGC 4945, NGC 7793, and M81 serendipitously discovered in Swift/XRT observations. Swift monitoring of these sources have provided well-sampled lightcurves, allowing for us to model the lightcurves with the disk-instability model of Hameury & Lasota, which implies durations of 60–400 days and that the mass-accretion rate through the disk is close to or greater than the Eddington rate. Of the three source regions with prior Hubble Space Telescope imaging, color–magnitude diagrams of the potential stellar counterparts show varying ages of the possible stellar counterparts. Our estimation of the rates of these sources in these three galaxies is 0.4–1.3 yr−1. We find that, while persistent ULXs dominate the high end of galaxy luminosity functions, the number of systems that produce ULX luminosities are likely dominated by transient sources.
