First Measurements of Black Hole Accretion and Radio-jet Timescales in a Young Quasar at the Edge of Reionization
We present the first study dedicated to measuring the timescales for black hole accretion and jet launching in a quasar at the edge of reionization, PSO J352.4034–15.3373 at z = 5.832 ± 0.001. Previous work presented evidence of the strong radio synchrotron emission from the jet affecting the host g...
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| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/adc4df |
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| Summary: | We present the first study dedicated to measuring the timescales for black hole accretion and jet launching in a quasar at the edge of reionization, PSO J352.4034–15.3373 at z = 5.832 ± 0.001. Previous work presented evidence of the strong radio synchrotron emission from the jet affecting the host galaxy's dust-dominated continuum emission at ν _rest = 683 GHz ( ν _obs = 100 GHz), implying a break in the synchrotron spectrum. In this work, we present quasi-simultaneous observations at 1.5 GHz–42 GHz with the Karl G. Jansky Very Large Array, and derive a frequency break at ${\nu }_{{\rm{rest}}}^{{\rm{break}}}=196.46$ GHz ( ${\nu }_{{\rm{obs}}}^{{\rm{break}}}=28.76$ GHz). Modeling these observations, we calculate the jet spectral aging from the cooling of electrons to be t _spec ∼ 580 yr. From this measurement, we approximate the dynamical age t _dyn to be ∼2000 yr, implying a recent jet ejection. We compare the jet timescale to the quasar’s lifetime ( t _Q ) that indicates the duration of the latest black hole accretion event and is derived from the proximity zone size in the rest-UV/optical spectrum. However, a ghostly damped Ly α system affects this measurement yielding an upper limit of t _Q ≲ 10 ^4 yr, consistent with the jet lifetime and indicative of a young quasar. This suggests that the triggering of a UV-bright quasar phase may occur within comparable timescales as the launch of a relativistic radio jet. Therefore, we may be witnessing an early stage of black hole and jet interactions in a quasar during the first billion years of the Universe. |
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| ISSN: | 1538-4357 |