Constraints on the Duty Cycles of Quasars at z ∼ 6

Chen, Huanqing; Gnedin, Nickolay Y.

doi:10.3847/1538-4357/aae8e8

Cited by 15 publications

(16 citation statements)

References 45 publications

(45 reference statements)

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“…Given their low nuclear luminosities (hence mass accretion rate onto SMBHs) and SFRs, the low-luminosity quasars studied here will not move drastically in the M BH -M dyn plane even over the next ∼10 Myr (typical lifetime of high-redshift quasars expected with the transverse proximity effect; Borisova et al 2016), unless there is a rich supply of gas which infalls to the galaxy. This is particularly true if the quasar duty cycle is 10 −2 , as suggested for z ∼ 6 objects recently (Chen & Gnedin 2018). Note that Izumi et al (2018b) argued that the four HSC quasar hosts studied in ALMA Cycle 4 are on or even below the star formation main sequence at z ∼ 6 (e.g., Salmon et al 2015).…”

Section: Integrated Form: M Bh -M Dynmentioning

confidence: 75%

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). VIII. A less biased view of the early co-evolution of black holes and host galaxies

Izumi

Onoue

Matsuoka

et al. 2019

Publications of the Astronomical Society of Japan

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We present ALMA [C ii] line and far-infrared (FIR) continuum observations of three $z \gt 6$ low-luminosity quasars ($M_{\rm 1450} \gt -25$ mag) discovered by our Subaru Hyper Suprime-Cam (HSC) survey. The [C ii] line was detected in all three targets with luminosities of $(2.4\mbox{--}9.5) \times 10^8\, L_{\odot }$, about one order of magnitude smaller than optically luminous ($M_{\rm 1450} \lesssim -25$ mag) quasars. The FIR continuum luminosities range from $\lt 9 \times 10^{10}\, L_{\odot }$ (3 $\sigma$ limit) to ${\sim } 2 \times 10^{12}\, L_{\odot }$, indicating a wide range in star formation rates in these galaxies. Most of the HSC quasars studied thus far show [C ii]/ FIR luminosity ratios similar to local star-forming galaxies. Using the [C ii]-based dynamical mass ($M_{\rm dyn}$) as a surrogate for bulge stellar mass ($M_{\rm\, bulge}$), we find that a significant fraction of low-luminosity quasars are located on or even below the local $M_{\rm\, BH}$–$M_{\rm\, bulge}$ relation, particularly at the massive end of the galaxy mass distribution. In contrast, previous studies of optically luminous quasars have found that black holes are overmassive relative to the local relation. Given the low luminosities of our targets, we are exploring the nature of the early co-evolution of supermassive black holes and their hosts in a less biased way. Almost all of the quasars presented in this work are growing their black hole mass at a much higher pace at $z \sim 6$ than the parallel growth model, in which supermassive black holes and their hosts grow simultaneously to match the local $M_{\rm\, BH}$–$M_{\rm\, bulge}$ relation at all redshifts. As the low-luminosity quasars appear to realize the local co-evolutionary relation even at $z \sim 6$, they should have experienced vigorous starbursts prior to the currently observed quasar phase to catch up with the relation.

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Section: Integrated Form: M Bh -M Dynmentioning

confidence: 75%

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). VIII. A less biased view of the early co-evolution of black holes and host galaxies

Izumi

Onoue

Matsuoka

et al. 2019

Publications of the Astronomical Society of Japan

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“…Our results are in agreement with, and confirm, their assumptions. Interestingly, the constraints on the quasar lifetimes derived by Chen & Gnedin (2018) are extremely sensitive to the kinematics and distribution of cold gas in quasar hosts.…”

Section: Agn Duty-cyclementioning

confidence: 99%

Black hole obscuration and duty-cycles mediated by AGN feedback in high-redshift galaxies

Trebitsch

Volonteri

Dubois

2019

Monthly Notices of the Royal Astronomical Society

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Dense gas in the centre of galaxies feeds massive black holes, but can also become a source of obscuration and limit our ability to find faint Active Galactic Nuclei (AGN). We use a high resolution cosmological radiative hydrodynamics simulation to connect the properties of the gas in the central region (a few tens of parsecs) of a high redshift galaxy to the growth of a massive black hole during the first billion years of the Universe. We find that the feedback from the AGN efficiently controls the growth of the black hole and limits the duration of the high accretion episodes by emptying the gas reservoir. As the galaxy grows in mass, the production of metals results in the presence of dust-enriched gas in the galaxy centre that can obscure highly accreting black holes enough to strongly reduce their UV/optical visibility. We also find that the gas outside the very centre of the galaxy can contribute to the total column density and obscuration at a level at least comparable to the gas in the nuclear region. We suggest that this explains the different duty cycles required to explain the masses of high redshift quasars and the observed UV/optical luminosity functions: in our case, the AGN would be observed with an X-ray luminosity above L X = 10 42 erg s −1 around 30% of the time, but with UV magnitude brighter than M 1450 = −23 only 4% of the time.

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“…While local spiral galaxies have V rot /V circ ≃ 1.2-1.4, it is not clear whether high-z QSO host galaxies have also similarly high ratios; if they have such high ratios, our procedure will be overestimating M h by a factor of 1.2 3 -1.4 3 ≃ 2-3. On the other hand, Chen & Gnedin (2018) have shown V rot /V circ > 0.6 by imposing that the duty cycle defined as the ratio of the number density of z ∼ 6 QSOs to that of hosting dark halos has to be less than unity.…”

Section: Sample and Halo Mass Estimationmentioning

confidence: 99%

Black versus Dark: Rapid Growth of Supermassive Black Holes in Dark Matter Halos at z ∼ 6

Shimasaku

Izumi²

2019

ApJL

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We report on the relation between the mass of supermassive black holes (SMBHs; M BH ) and that of hosting dark matter halos (M h ) for 49 z ∼ 6 quasi-stellar objects (QSOs) with [C II]158µm velocitywidth measurements. Here, we estimate M h assuming that the rotation velocity from FWHM CII is equal to the circular velocity of the halo; we have tested this procedure using z ∼ 3 QSOs that also have clustering-based M h estimates. We find that a vast majority of the z ∼ 6 SMBHs are more massive than expected from the local M BH -M h relation, with one-third of the sample by factors 10 2 . The median mass ratio of the sample, M BH /M h = 6 × 10 −4 , means that 0.4% of the baryons in halos are locked up in SMBHs. The mass growth rates of our SMBHs amount to ∼ 10% of the star formation rates (SFRs), or ∼ 1% of the mean baryon accretion rates, of the hosting galaxies. A large fraction of the hosting galaxies are consistent with average galaxies in terms of SFR and perhaps of stellar mass and size. Our study indicates that the growth of SMBHs (M BH ∼ 10 8−10 M ⊙ ) in luminous z ∼ 6 QSOs greatly precedes that of hosting halos owing to efficient gas accretion even under normal star formation activities, although we cannot rule out the possibility that undetected SMBHs have local M BH /M h ratios. This preceding growth is in contrast to much milder evolution of the stellar-to-halo mass ratio.

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Constraints on the Duty Cycles of Quasars at z ∼ 6

Cited by 15 publications

References 45 publications

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). VIII. A less biased view of the early co-evolution of black holes and host galaxies

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). VIII. A less biased view of the early co-evolution of black holes and host galaxies

Black hole obscuration and duty-cycles mediated by AGN feedback in high-redshift galaxies

Black versus Dark: Rapid Growth of Supermassive Black Holes in Dark Matter Halos at z ∼ 6

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