Extreme star formation events in quasar hosts over 0.5 &lt;<i>z</i>&lt; 4

Pitchford, Lura K; Hatziminaoglou, E.; Feltre, Anna; Farrah, D.; Clarke, Charlotte; Harris, Kathryn A.; Hurley, P. D.; Oliver, Seb; Page, M. J.; Wang, L.

doi:10.1093/mnras/stw1840

Cited by 52 publications

(59 citation statements)

References 142 publications

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“…Once a substantial burst of star formation is triggered, the rapid formation of massive stars and supernovae, and associated negative feedback on gas feeding, will mask any correlation between the AGN fueling process -and associated nuclear star formation -and high rates of star formation on larger scales (Pitchford et al 2016), in part also because of the different duty cycles associated with these phenomena. The best indication of magnetically elevated accretion may well be relic stellar disks that persist after the activity has subsided, as in the GC.…”

Section: Discussionmentioning

confidence: 99%

Magnetically elevated accretion discs in active galactic nuclei: broad emission-line regions and associated star formation

Begelman

Silk

2016

Mon. Not. R. Astron. Soc.

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We propose that the accretion disks fueling active galactic nuclei are supported vertically against gravity by a strong toroidal (φ−direction) magnetic field that develops naturally as the result of an accretion disk dynamo. The magnetic pressure elevates most of the gas carrying the accretion flow at R to large heights z ∼ > 0.1R and low densities, while leaving a thin dense layer containing most of the mass -but contributing very little accretion -around the equator. We show that such a disk model leads naturally to the formation of a broad emission line region through thermal instability. Extrapolating to larger radii, we demonstrate that local gravitational instability and associated star formation are strongly suppressed compared to standard disk models for AGN, although star formation in the equatorial zone is predicted for sufficiently high mass supply rates. This new class of accretion disk models thus appears capable of resolving two longstanding puzzles in the theory of AGN fueling: the formation of broad emission line regions and the suppression of fragmentation thought to inhibit accretion at the required rates. We show that the disk of stars that formed in the Galactic Center a few million years ago could have resulted from an episode of magnetically elevated accretion at ∼ > 0.1 of the Eddington limit.

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Section: Discussionmentioning

confidence: 99%

Magnetically elevated accretion discs in active galactic nuclei: broad emission-line regions and associated star formation

Begelman

Silk

2016

Mon. Not. R. Astron. Soc.

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“…Pitchford et al (2016) document 513 luminous type 1 quasars with extreme star formation rates and find that for a given redshift, the SFR does not vary with AGN luminosity, black hole mass, or Eddington Ratios. They find that star formation in (HiBal's) is not impacted by outflows and conclude that for 0 ¡ z ¡ 3 star bursts in quasars typically evolve as the would without the presence of the AGN.…”

Section: Observationsmentioning

confidence: 99%

Feedback by AGN Jets and Wide-angle Winds on a Galactic Scale

Dugan

Gaibler

Silk

2017

ApJ

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To investigate the differences in mechanical feedback from radio-loud and radio-quiet Active Galactic Nuclei (AGN) on the host galaxy, we perform 3D AMR hydrodynamic simulations of wide angle, radioquiet winds with different inclinations on a single, massive, gas-rich disk galaxy at a redshift of 2-3. We compare our results to hydrodynamic simulations of the same galaxy but with a jet. The jet has an inclination of 0• (perpendicular to the galactic plane), and the winds have inclinations of 0 • , 45• , and 90• . We analyze the impact on the host's gas, star formation, and circum-galactic medium. We find that jet feedback is energy-driven and wind feedback is momentum-driven. In all the simulations, the jet or wind creates a cavity mostly devoid of dense gas in the nuclear region where star formation is then quenched, but we find strong positive feedback in all the simulations at radii greater than 3 kpc. All four simulations have similar SFRs and stellar velocities with large radial and vertical components. However, the wind at an inclination of 90• creates the highest density regions through ram pressure and generates the highest rates of star formation due to its ongoing strong interaction with the dense gas of the galactic plane. With increased wind inclination, we find greater asymmetry in gas distribution and resulting star formation. Our model generates an expanding ring of triggered star formation with typical velocity of order 1/3 of the circular velocity, superimposed on the older stellar population. This should result in a potentially detectable blue asymmetry in stellar absorption features at kpc scales.

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“…However, when the QSOs are selected to be FIR luminous, the mean SFR shows a flat trend with the bolometric AGN luminosity (e.g. Pitchford et al 2016).…”

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confidence: 99%

The mean star formation rates of unobscured QSOs: searching for evidence of suppressed or enhanced star formation

Stanley

Alexander

Harrison

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We investigate the mean star formation rates (SFRs) in the host galaxies of ∼3000 optically selected QSOs from the SDSS survey within the Herschel-ATLAS fields, and a radio-luminous sub-sample, covering the redshift range of z =0.2-2.5. Using WISE & Herschel photometry (12 -500µm) we construct composite SEDs in bins of redshift and AGN luminosity. We perform SED fitting to measure the mean infrared luminosity due to star formation, removing the contamination from AGN emission. We find that the mean SFRs show a weak positive trend with increasing AGN luminosity. However, we demonstrate that the observed trend could be due to an increase in black hole (BH) mass (and a consequent increase of inferred stellar mass) with increasing AGN luminosity. We compare to a sample of X-ray selected AGN and find that the two populations have consistent mean SFRs when matched in AGN luminosity and redshift. On the basis of the available virial BH masses, and the evolving BH mass to stellar mass relationship, we find that the mean SFRs of our QSO sample are consistent with those of main sequence star-forming galaxies. Similarly the radio-luminous QSOs have mean SFRs that are consistent with both the overall QSO sample and with star-forming galaxies on the main sequence. In conclusion, on average QSOs reside on the main sequence of star-forming galaxies, and the observed positive trend between the mean SFRs and AGN luminosity can be attributed to BH mass and redshift dependencies.

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Extreme star formation events in quasar hosts over 0.5 <z< 4

Cited by 52 publications

References 142 publications

Magnetically elevated accretion discs in active galactic nuclei: broad emission-line regions and associated star formation

Magnetically elevated accretion discs in active galactic nuclei: broad emission-line regions and associated star formation

Feedback by AGN Jets and Wide-angle Winds on a Galactic Scale

The mean star formation rates of unobscured QSOs: searching for evidence of suppressed or enhanced star formation

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