CIV wind properties of the SDSS-V X-ray selected quasars: strong optical-to-UV emission is key regardless of X-ray strength

CIV wind properties of the SDSS-V X-ray selected quasars: strong optical-to-UV emission is key regardless of X-ray strength
Amy L. Rankine, David Homan, James Aird, Pranavi Hiremath, Scott F. Anderson, Roberto J. Assef, Franz E. Bauer, W. N. Brandt, Marcella Brusa, Johannes Buchner, Maria Chira, Yaherlyn D’iaz, Patrick B. Hall, Anton M. Koekemoer, Mirko Krumpe, Georg Lamer, Teng Liu, Sean Morrison, Blessing Musiimenta, C. A. Negrete, Qingling Ni, Paola Rodr’iguez Hidalgo, Mara Salvato, Donald P. Schneider, Yue Shen, Matthew J. Temple, Dus’an Tub’in-Arenas, Dominika Wylezalek
arXiv:2603.15075v2 Announce Type: replace
Abstract: We present an investigation of the rest-frame optical/UV and X-ray properties for a sample of 3027 X-ray selected quasars between $1.5 leq z leq 3.5$ detected in the deepest Spectrum Roentgen Gamma/eROSITA data available and observed by the fifth iteration of the Sloan Digital Sky Survey (SDSS-V). We parametrize the CIV$lambda1549$ emission line to infer the strength of accretion disc winds and perform X-ray spectral fitting. The X-ray spectral properties — namely, the 2keV monochromatic luminosity (L$_text{2keV}$) and spectral slope — are not strongly correlated with wind strength. Despite this result, the X-ray selected sample is shifted towards lower CIV blueshifts and higher equivalent widths than the optically selected sample observed in previous SDSS surveys, and matching in optical luminosity, redshift, and Eddington ratio does not reduce these differences. We estimate the far-UV luminosity using the HeII$lambda1640$ line luminosity and define the slopes between this and the 2500A monochromatic luminosity ($L_{2500}$) and L$_text{2keV}$ ($alpha_text{ouv}$ and $alpha_text{uvx}$, respectively) in a similar manner to the familiar $alpha_text{ox}$ parameter, which tracks the spectral slope between $L_{2500}$ and L$_text{2keV}$. The quantity $alpha_text{ouv}$ is more strongly correlated with wind strength in our sample than $alpha_text{ox}$. We show that the correlation between $alpha_text{ox}$ and wind strength is driven by the relationship between the optical luminosity and wind strength. Our results are consistent with a radiation line-driven wind, whereby the ionising far-UV photons must not over-ionise the gas. The hard X-ray photons are few enough in number to have a negligible effect on the ionisation state of the material.arXiv:2603.15075v2 Announce Type: replace
Abstract: We present an investigation of the rest-frame optical/UV and X-ray properties for a sample of 3027 X-ray selected quasars between $1.5 leq z leq 3.5$ detected in the deepest Spectrum Roentgen Gamma/eROSITA data available and observed by the fifth iteration of the Sloan Digital Sky Survey (SDSS-V). We parametrize the CIV$lambda1549$ emission line to infer the strength of accretion disc winds and perform X-ray spectral fitting. The X-ray spectral properties — namely, the 2keV monochromatic luminosity (L$_text{2keV}$) and spectral slope — are not strongly correlated with wind strength. Despite this result, the X-ray selected sample is shifted towards lower CIV blueshifts and higher equivalent widths than the optically selected sample observed in previous SDSS surveys, and matching in optical luminosity, redshift, and Eddington ratio does not reduce these differences. We estimate the far-UV luminosity using the HeII$lambda1640$ line luminosity and define the slopes between this and the 2500A monochromatic luminosity ($L_{2500}$) and L$_text{2keV}$ ($alpha_text{ouv}$ and $alpha_text{uvx}$, respectively) in a similar manner to the familiar $alpha_text{ox}$ parameter, which tracks the spectral slope between $L_{2500}$ and L$_text{2keV}$. The quantity $alpha_text{ouv}$ is more strongly correlated with wind strength in our sample than $alpha_text{ox}$. We show that the correlation between $alpha_text{ox}$ and wind strength is driven by the relationship between the optical luminosity and wind strength. Our results are consistent with a radiation line-driven wind, whereby the ionising far-UV photons must not over-ionise the gas. The hard X-ray photons are few enough in number to have a negligible effect on the ionisation state of the material.