ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope O O O O O O O O O O O O O O O O O B-Telescope O O O O O O O O O O B-Telescope O O O O O O O O O O O O O O O B-Telescope O O O B-Observatory O O O O O O O B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O O B-Observatory O O O O O O O O O B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope O B-Telescope O O O O O O O O B-Wavelength O O B-CelestialObject I-CelestialObject O O O O O O B-Telescope O B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength O O O O O O O O B-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O B-Telescope O O O O B-Wavelength I-Wavelength O O O O O O O O O O O O B-Telescope O B-Telescope O O O O O O O O O O O O O O O O O O O O O B-Telescope O O O O O O O O O O O B-Wavelength O O B-CelestialObject I-CelestialObject O O O O O O B-Telescope O O B-Wavelength O O O O O O O O O B-Wavelength O O B-Wavelength I-Wavelength O O O B-CelestialObject I-CelestialObject O O O O B-Wavelength O B-Wavelength O O B-Survey O O B-Telescope I-Telescope I-Telescope I-Telescope O O O O O O O O O O O O O O O B-Wavelength I-Wavelength O B-CelestialObject I-CelestialObject O O O O O B-Wavelength B-Wavelength B-Wavelength I-Wavelength O B-Wavelength O O O O O O O O O O O O O B-Wavelength O O O O O O O O B-Survey B-Wavelength I-Wavelength O B-Wavelength B-Wavelength I-Wavelength B-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O O B-Wavelength B-Wavelength I-Wavelength O O B-Survey O O B-Wavelength B-Wavelength I-Wavelength O B-Wavelength I-Wavelength O O B-Telescope O O O B-Wavelength I-Wavelength O O O O B-Wavelength I-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength O O O O
tokens: more warm absorption or reflection modeling. We then fit all the spectra with an absorbed power-law model. The required additional absorption at a redshift of the source in Chandra spectra modeling is moderate with a fitted absorption of . The value of the inferred absorption in Suzaku is consistent with that within uncertainties (Table 2 ). The Chandra spectra are harder with a photon index of , compared to the value of in Suzaku . The two Swift spectra are even harder than that of Chandra , while the value of the photon index cannot be well constrained due to low S/N and degeneracy with absorption. Thus in the fitting of Swift spectra we tied all the parameters to those of Chandra except the normalization. The fitted parameters are shown in Table 2 , and the spectra with the fitted power-law model are shown in Figure 3 . In Figure 3 we also show the joint contours of the photon index Γ and column density N H . It is clear that the changes of photon index between Suzaku and Chandra are significant at 99% confidence. Figure 3. Unfolded X-ray spectra of SDSS J155258+273728 with absorbed power-law model fits for Suzaku and Chandra observations. Inset: contours give the joint 68%, 90%, 99% confidence for the two interesting variables, photon index Γ, and the intrinsic absorption N H . Table 2 Parameters of X-Ray Spectra Fits a Notes. a Unabsorbed flux in 2–10 keV. b The values are fixed in the fitting. There is more than a factor of 2 brightening in Chandra observation with an unabsorbed 2–10 keV flux of erg s −1 cm −2 , compared to those in Suzaku and Swift -2014 with values of erg s −1 cm −2 and erg s −1 cm −2 , respectively. The inferred flux of Swift -2018 is erg s −1 cm −2 , indicating that the X-ray emission of SDSS J155258+273728 fades back to the level of Swift -2014. 3.1. IR–Optical–X-Ray Photometry and Variability In Figure 4 we show the X-ray and broad H α line variations of SDSS J155258+273728 on a decade. The optical and mid-IR photometry from CRTS and the Wide-field Infrared Survey Explorer survey are also shown. It is clear that accompanied by the significant enhancement of broad H α emission, SDSS J155258+273728 presents increased emission in hard X-ray, optical V -band, and mid-IR. The variation timescale of this broadband brightening is ∼4 yr, in which the X-ray varied more than a factor of 2, and CRTS V -band and mid-IR W 1, W 2 bands varied with amplitudes of 0.18 ± 0.12, 0.32 ± 0.02, and 0.43 ± 0.03, respectively. Figure 4. Light curves showing the multiwavelength changes observed in SDSS J155258+273728 in the optical V -band data from CRTS (top panel), mid-IR W 1 and W 2 bands from WISE (middle panel), and hard X-ray flux along with broad H α emission (bottom panel). In the top and bottom panels, we also present the median values of each season epoch. The dotted–dashed lines mark the start/end of the significant variation timescale. 4. Discussion 4.1. Reddening Measurement from Optical Spectra The detected moderate