A similar to 3.8 hr PERIODICITY FROM AN ULTRASOFT ACTIVE GALACTIC NUCLEUS CANDIDATE

作者：Lin Dacheng^*; Irwin Jimmy A; Godet Olivier; Webb Natalie A; Barret Didier

来源：Astrophysical Journal Letters, 2013, 776(1): L10.

DOI：10.1088/2041-8205/776/1/L10

• accretion
• accretion disks
• black hole physics
• X-rays: galaxies
• X-rays: individual (2XMM J123103.2+110648)

Very few galactic nuclei are found to show significant X-ray quasi-periodic oscillations (QPOs). After carefully modeling the noise continuum, we find that the similar to 3.8 hr QPO in the ultrasoft active galactic nucleus candidate 2XMM J123103.2 + 110648 was significantly detected (similar to 5 sigma) in two XMM-Newton observations in 2005, but not in the one in 2003. The QPO root mean square (rms) is very high and increases from similar to 25% in 0.2-0.5 keV to similar to 50% in 1-2 keV. The QPO probably corresponds to the low-frequency type in Galactic black hole X-ray binaries, considering its large rms and the probably low mass (similar to 105M(circle dot)) of the black hole in the nucleus. We also fit the soft X-ray spectra from the three XMM-Newton observations and find that they can be described with either pure thermal disk emission or optically thick low-temperature Comptonization. We see no clear X-ray emission from the two Swift observations in 2013, indicating lower source fluxes than those in XMM-Newton observations.

• 出版日期2013-10-10