Speaker
Description
Identifying intermediate-mass black holes (IMBHs) is crucial for understanding the co-evolution of galaxies and the seeds of supermassive black holes. We present a comprehensive multi-wavelength analysis of IC 1633 X-4 (2CXO J010952.3-455526), a hyperluminous X-ray source projected at the outskirts of the galaxy IC 1633 (z $\approx$ 0.024). By combining optical photometry from HST/WFPC2 with multi-epoch X-ray observations from Chandra, XMM-Newton, and Swift/XRT, along with UV coverage from Swift/UVOT to GALEX, we constructed a detailed broadband spectral energy distribution (SED).
We studied the interaction between the accretion disk and the X-ray corona using an irradiated disk model that incorporates both Galactic and intrinsic reddening. Our SED fitting yields a bolometric luminosity of $L_{bol} \approx 3.54 \times 10^{42}$ erg s$^{-1}$ and $\log(f_X/f_{opt}) = -0.25$. These results are remarkably consistent with the properties of standard active galactic nuclei (AGN), suggesting that the source operates in a similar accretion regime.
Most notably, the best-fit model reveals a low disk temperature of $kT_{bb} \approx 41$eV and an X-ray photon index of $\Gamma \approx 2$. Combined with the measured $L_{bol}$, it provides evidence for a black hole mass in the range of $10^4 - 10^6 M_\odot$, assuming sub-Eddington to near-Eddington accretion rates. Our findings indicate that IC 1633 X-4 is either a viable IMBH candidate, exhibiting AGN-like physics scaled down to the intermediate-mass regime, or a low-mass SMBH operating at a relatively low accretion rate.
| Participate the oral/poster presentation award competition | Yes |
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