Dr. Zhen-Yi CAI （蔡振翼，Zin-Iak CUA）

Here are supplementary materials for “The Composite Spectral Energy Distribution of Quasars is Surprisingly Universal since Cosmic Noon” by Zhenyi Cai (2024, Universe, 10, 431). 

Do not hesitate to contact me if anything presented here is unclear or you need something else.

• • Quasar samples

A particular quasar sample containing 107,504 sources was constructed from the SDSS DR14Q catalog, by requiring SDSS quasars 

1) have positive flux densities and errors in all five SDSS bands, 

2) are covered by the GALEX imaging tiles with FUV exposure times longer than 1000 second, and

3) are within the central 0.5 degree radius of the field of view (FOV) of any one GALEX tile.

This particular quasar sample, supplemented with the GALEX counterparts within an SDSS/GALEX offset of < 2.6 arcsec, is available at “SDSS_DR14Q_GALEX_tFUV1000s_FOV0p5deg_os2p6as.fits”. There are 101,745 quasars at z < 3.

Out of this particular quasar sample, a unique bright quasar sample containing 23,256 sources, 

1) selected to have both high SDSS sample completeness and high GALEX detection fractions, and 

2) used to construct the mean/median composite SED for quasars at z < 3, 

is available at “SDSS_DR14Q_GALEX_tFUV1000s_FOV0p5deg_os2p6as_zmax3_unique_bright.fits”. 

See “entries_of_fits.pdf” for a detailed description of each entry in the above two fits files.

• • A universal intrinsic mean/median composite quasar SED

After taking the GALEX non-detections into account and correcting for the absorption of the intergalactic medium (IGM), the intrinsic mean quasar SED is available at “SED_UV_EMG_composite_mean_corrected_FG20.txt”, while the intrinsic median quasar SED is available at “SED_UV_EMG_composite_median_corrected_FG20.txt”.

A smoothly broken power law was fit to the mean/median composite quasar SED in several line-free windows:

the fit to the intrinsic mean quasar SED is available at “SED_UV_EMG_composite_mean_corrected_FG20_fit.txt”, while

the fit to the intrinsic median quasar SED is available at “SED_UV_EMG_composite_median_corrected_FG20_fit.txt”.

• • Correction factors for broadband IGM transmissions

Here are the filter-weighted broadband mean and median IGM transmissions for four broad bands.

• ◦ Mean correction factors for

• ▫ GALEX FUV: igm_transmission_broadband_correction_factors_FUV_mean.txt
• ▫ GALEX NUV: igm_transmission_broadband_correction_factors_NUV_mean.txt
• ▫ SDSS u: igm_transmission_broadband_correction_factors_u_mean.txt
• ▫ SDSS g: igm_transmission_broadband_correction_factors_g_mean.txt

• ▪ Median correction factors for

• ▫ GALEX FUV: igm_transmission_broadband_correction_factors_FUV_median.txt
• ▫ GALEX NUV: igm_transmission_broadband_correction_factors_NUV_median.txt
• ▫ SDSS u: igm_transmission_broadband_correction_factors_u_median.txt
• ▫ SDSS g: igm_transmission_broadband_correction_factors_g_median.txt

Note that the 1σ uncertainties in the above tables are associated with 1000 sources at each redshift. If there are more (less) sources at a redshift, the corresponding 1σ uncertainty should be smaller (larger).