J-PLUS: Unveiling the brightest end of the Ly<i>α</i>luminosity function at 2.0 <<i>z</i>< 3.3 over 1000 deg<sup>2</sup>
D. Spinoso, A. Orsi, C. López-Sanjuan, S. Bonoli, K. Viironen, D. Izquierdo-Villalba, D. Sobral, S. Gurung-López, A. Hernán-Caballero, A. Ederoclite, J. Varela, R. Overzier, J. Miralda-Escudé, D. J. Muniesa, J. M. Vílchez, J. Alcaniz, R. E. Angulo, A. J. Cenarro, D. Cristóbal-Hornillos, R. A. Dupke, C. Hernández-Monteagudo, A. Marín-Franch, M. Moles, L. Sodré Jr, H. Vázquez-Ramió
Abstract
We present the photometric determination of the bright end of the Ly α luminosity function (LF; at L Ly α ≳ 10 43.3 erg s −1 ) within four redshift windows (Δ z < 0.16) in the interval 2.2 ≲ z ≲ 3.3. Our work is based on the Javalambre Photometric Local Universe Survey (J-PLUS) first data release, which provides multiple narrow-band measurements over ∼1000 deg 2 , with limiting magnitude r ∼ 22. The analysis of high- z Ly α -emitting sources over such a wide area is unprecedented and allows us to select approximately 14 500 hyper-bright ( L Ly α > 10 43.3 erg s −1 ) Ly α -emitting candidates. We test our selection with two spectroscopic programs at the GTC telescope, which confirm ∼89% of the targets as line-emitting sources, with ∼64% being genuine z ∼ 2.2 quasars (QSOs). We extend the 2.2 ≲ z ≲ 3.3 Ly α LF for the first time above L Ly α ∼ 10 44 erg s −1 and down to densities of ∼10 −8 Mpc −3 . Our results unveil the Schechter exponential decay of the brightest-end of the Ly α LF in great detail, complementing the power-law component of previous determinations at 43.3 ≲ Log 10 ( L Ly α /erg s −1 ) ≲ 44. We measure Φ * = (3.33 ± 0.19)×10 −6 , Log( L * ) = 44.65 ± 0.65, and α = −1.35 ± 0.84 as an average over the probed redshifts. These values are significantly different from the typical Schechter parameters measured for the Ly α LF of high- z star-forming Lyman- α emitters (LAEs). This implies that z > 2 AGNs/QSOs (likely dominant in our samples) are described by a structurally different LF from that used to describe z > 2 star-forming LAEs, namely L QSOs * ~ 100 L LAEs * and Φ QSOs * ~ 10 −3 Φ LAEs * , with the transition between the two LFs happening at L Ly α ∼ 10 43.5 erg s −1 . This supports the scenario in which Ly α -emitting AGNs/QSOs are the most abundant class of z ≳ 2 Ly α emitters at L Ly α ≳ 10 43.3 erg s −1 . Finally, we suggest that a significant number of these z ≳ 2 AGNs/QSOs (∼60% of our samples) are currently misclassified as stars based on their broad-band colours, but are identified for the first time as high- z line-emitters by our narrow-band-based selection.