Digest
Subaru/PFS follow-up of a radio-loud, X-ray–detected UNVEIL source at z=1.715 (BBQSORS) reveals a broad Mg II line (FWHM ≳ 4000 km s−1) with narrow absorbers and a strongly curved, Λ-shaped UV continuum across 1500–3500 Å. The continuum is incompatible with simple dust reddening and is well matched by a T≈10^4 K blackbody; UV–MIR photometry is consistently fit by three blackbodies at ≈9700, 1500, and 80 K. A marginal GALEX NUV detection suggests a V-shaped SED break near 1400 Å—bluer than the 3000–4000 Å breaks seen in canonical LRDs—implying a hotter, thinning envelope around the SMBH. Together with the emerging X-ray and radio emission, the data point to a transitional LRD-to-quasar phase as the cocoon fragments and the nucleus becomes exposed.
Key figures to inspect
- Figure 1: Use the HSC+Spitzer cutouts with VLASS 3 GHz contours to confirm the radio core’s association with BBQSORS and look for a close companion/merger; in the PFS spectrum panels, inspect the Λ-shaped continuum and quantify the Mg II width, the narrow absorber that dips to the continuum, and accompanying Al III ab…
- Figure 2: Check the EPIC/pn 0.4–7.2 keV (rest 1–20 keV) detection and the ≈3.4σ significance; compare the best-fit spectral model and residuals to assess whether emerging hard X-rays are consistent with a dispersing envelope rather than heavy, Compton-thick obscuration.
- Figure 3: Examine the UV–MIR SED decomposition—blackbodies at ≈9700 K (envelope), ≈1500 K (torus), and ≈80 K (host dust)—and locate the V-shaped break near 1400 Å; contrast with the plotted LRD-like ≈5000 K component to see how a hotter envelope shifts the turnover.
- Figure 4: Compare BBQSORS to blue and dust-reddened quasar templates after de-reddening the PFS spectrum; note the persistent blue-end mismatch (<~2200 Å) arguing against dust-only explanations, and use the PFS vs SDSS/DESI overlay to gauge spectral-shape stability across epochs/instruments.