We test the impact of gravitational lensing on the lifetime estimates of seven high-redshift quasars at redshift z 3 6. The targeted quasars are identified by their small observed proximity zone sizes, which indicate extremely short quasar lifetimes (t Q 2 105yr). However, these estimates of quasar lifetimes rely on the assumption that the observed luminosities of the quasars are intrinsic and not magnified by gravitational lensing, which would bias the lifetime estimates toward younger ages. In order to test the possible effects of gravitational lensing, we obtain high-resolution images of the seven quasars with the Hubble Space Telescope and look for signs of strong lensing. We do not find any evidence of strong lensing, i.e., all quasars are well described by point sources, and no foreground lensing galaxy is detected. We estimate that the strong-lensing probabilities for these quasars are extremely small ( 1/41.4 × 10-5) and show that weak lensing changes the estimated quasar lifetimes by only 20.2 dex. We thus confirm that the short lifetimes of these quasars are intrinsic. The existence of young quasars indicates a high obscured fraction, radiatively inefficient accretion, and/or flickering lightcurves for high-redshift quasars. We further discuss the impact of lensing magnification on measurements of black hole masses and Eddington ratios of quasars.

Yue M., Eilers A.-C., Simcoe R.A., Belli S., Davies F.B., Depalma D., et al. (2023). Detecting and Characterizing Young Quasars. III. the Impact of Gravitational Lensing Magnification. THE ASTROPHYSICAL JOURNAL, 950(2), 1-11 [10.3847/1538-4357/accf20].

Detecting and Characterizing Young Quasars. III. the Impact of Gravitational Lensing Magnification

Belli S.;
2023

Abstract

We test the impact of gravitational lensing on the lifetime estimates of seven high-redshift quasars at redshift z 3 6. The targeted quasars are identified by their small observed proximity zone sizes, which indicate extremely short quasar lifetimes (t Q 2 105yr). However, these estimates of quasar lifetimes rely on the assumption that the observed luminosities of the quasars are intrinsic and not magnified by gravitational lensing, which would bias the lifetime estimates toward younger ages. In order to test the possible effects of gravitational lensing, we obtain high-resolution images of the seven quasars with the Hubble Space Telescope and look for signs of strong lensing. We do not find any evidence of strong lensing, i.e., all quasars are well described by point sources, and no foreground lensing galaxy is detected. We estimate that the strong-lensing probabilities for these quasars are extremely small ( 1/41.4 × 10-5) and show that weak lensing changes the estimated quasar lifetimes by only 20.2 dex. We thus confirm that the short lifetimes of these quasars are intrinsic. The existence of young quasars indicates a high obscured fraction, radiatively inefficient accretion, and/or flickering lightcurves for high-redshift quasars. We further discuss the impact of lensing magnification on measurements of black hole masses and Eddington ratios of quasars.
2023
Yue M., Eilers A.-C., Simcoe R.A., Belli S., Davies F.B., Depalma D., et al. (2023). Detecting and Characterizing Young Quasars. III. the Impact of Gravitational Lensing Magnification. THE ASTROPHYSICAL JOURNAL, 950(2), 1-11 [10.3847/1538-4357/accf20].
Yue M.; Eilers A.-C.; Simcoe R.A.; Belli S.; Davies F.B.; Depalma D.; Hennawi J.F.; Mason C.A.; Munoz J.B.; Nelson E.J.; Tacchella S.
File in questo prodotto:
File Dimensione Formato  
Yue_2023_ApJ_950_105.pdf

accesso aperto

Tipo: Versione (PDF) editoriale
Licenza: Creative commons
Dimensione 1.16 MB
Formato Adobe PDF
1.16 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/953120
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 0
  • ???jsp.display-item.citation.isi??? 0
social impact