%0 Generic %1 khrykin2021first %A Khrykin, Ilya S. %A Hennawi, Joseph F. %A Worseck, Gabor %A Davies, Frederick B. %D 2021 %K library %T The first measurement of the quasar lifetime distribution %U http://arxiv.org/abs/2102.04477 %X Understanding the growth of the supermassive black holes powering luminous quasars, their co-evolution with host galaxies, and impact on the surrounding intergalactic medium depends sensitively on the duration of quasar accretion episodes. Unfortunately, this time-scale, known as the quasar lifetime, $t_\rm Q$, is still uncertain by orders of magnitude ($t_Q0.01~\rm Myr-1~Gyr$). However, the extent of the He II Ly$\alpha$ proximity zones in the absorption spectra of $z_qso\sim3-4$ quasars constitutes a unique probe, providing sensitivity to lifetimes up to $30$ Myr. Our recent analysis of $22$ archival He II proximity zone spectra reveals a surprisingly broad range of emission timescales, indicating that some quasars turned on $1$ Myr ago, whereas others have been shining for $30$ Myr. Determining the underlying quasar lifetime distribution (QLD) from proximity zone measurements is a challenging task owing to: 1) the limited sensitivity of individual measurements; 2) random sampling of the quasar light curves; 3) density fluctuations in the quasar environment; and 4) the inhomogeneous ionization state of He II in a reionizing IGM. We combine a semi-numerical He II reionization model, hydrodynamical simulations post-processed with ionizing radiative transfer, and a novel statistical framework to infer the QLD from an ensemble of proximity zone measurements. Assuming a log-normal QLD, we infer a mean $log_10łeft(t_Q/\rm Myr\right)\rangle=0.22^+0.22_-0.25$ and standard deviation $\sigma_\rm log_10t_Q=0.80^+0.37_-0.27$. Our results allow us to estimate the probability of detecting young quasars with $t_Qłeq0.1$ Myr from their proximity zone sizes yielding $płeft(0.1~\rm Myr\right)=0.19^+0.11_-0.09$, which is broadly consistent with recent determination at $z6$.

@misc{khrykin2021first, abstract = {Understanding the growth of the supermassive black holes powering luminous quasars, their co-evolution with host galaxies, and impact on the surrounding intergalactic medium depends sensitively on the duration of quasar accretion episodes. Unfortunately, this time-scale, known as the quasar lifetime, $t_{\rm Q}$, is still uncertain by orders of magnitude ($t_{\rm Q}\simeq 0.01~{\rm Myr}-1~{\rm Gyr}$). However, the extent of the He II Ly$\alpha$ proximity zones in the absorption spectra of $z_{\rm qso}\sim3-4$ quasars constitutes a unique probe, providing sensitivity to lifetimes up to $\sim 30$ Myr. Our recent analysis of $22$ archival He II proximity zone spectra reveals a surprisingly broad range of emission timescales, indicating that some quasars turned on $\lesssim 1$ Myr ago, whereas others have been shining for $\gtrsim 30$ Myr. Determining the underlying quasar lifetime distribution (QLD) from proximity zone measurements is a challenging task owing to: 1) the limited sensitivity of individual measurements; 2) random sampling of the quasar light curves; 3) density fluctuations in the quasar environment; and 4) the inhomogeneous ionization state of He II in a reionizing IGM. We combine a semi-numerical He II reionization model, hydrodynamical simulations post-processed with ionizing radiative transfer, and a novel statistical framework to infer the QLD from an ensemble of proximity zone measurements. Assuming a log-normal QLD, we infer a mean $\langle {\rm log}_{10}\left(t_{\rm Q}/{\rm Myr}\right)\rangle=0.22^{+0.22}_{-0.25}$ and standard deviation $\sigma_{{\rm log}_{10}t_{\rm Q}}=0.80^{+0.37}_{-0.27}$. Our results allow us to estimate the probability of detecting young quasars with $t_{\rm Q}\leq0.1$ Myr from their proximity zone sizes yielding $p\left(\leq 0.1~{\rm Myr}\right)=0.19^{+0.11}_{-0.09}$, which is broadly consistent with recent determination at $z\sim 6$.}, added-at = {2021-02-10T12:12:53.000+0100}, author = {Khrykin, Ilya S. and Hennawi, Joseph F. and Worseck, Gabor and Davies, Frederick B.}, biburl = {https://www.bibsonomy.org/bibtex/21e2026fc869d0c4a6c896571b83673d0/gpkulkarni}, description = {The first measurement of the quasar lifetime distribution}, interhash = {a67fb4c057641882bf48889a85775cb4}, intrahash = {1e2026fc869d0c4a6c896571b83673d0}, keywords = {library}, note = {cite arxiv:2102.04477Comment: 14 pages, 10 figures, submitted to MNRAS}, timestamp = {2021-02-10T12:12:53.000+0100}, title = {The first measurement of the quasar lifetime distribution}, url = {http://arxiv.org/abs/2102.04477}, year = 2021 }