A Close Look at Star Formation around Active Galactic Nuclei

By Roger Davies, F. Sanchez, R. Genzel, L. Tacconi, E. Hicks, S. Friedrich, A. Sternberg. 2007

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We analyze star formation in the nuclei of nine Seyfert galaxies at spatial resolutions down to 0.085″, corresponding to length scales of order 10 pc in most objects. Our data were taken mostly with the near-infrared adaptive optics integral field spectrograph SINFONI. The stellar light profiles typically have size scales of a few tens of parsecs. In two cases there is unambiguous kinematic evidence for stellar disks on these scales. In the nuclear regions there appear to have been recent, but no longer active, starbursts in the last 10-300 Myr. The stellar luminosity is less than a few percent of the AGN in the central 10 pc, whereas on kiloparsec scales the luminosities are comparable. The surface stellar luminosity density follows a similar trend in all the objects, increasing steadily at smaller radii up to ~1013 L☉ kpc−2 in the central few parsecs, where the mass surface density exceeds 104 M☉ pc−2. The intense starbursts were probably Eddington limited and hence inevitably short lived, implying that the starbursts occur in multiple short bursts. The data hint at a delay of 50-100 Myr between the onset of star formation and subsequent fueling of the black hole. We discuss whether this may be a consequence of the role that stellar ejecta could play in fueling the black hole. While a significant mass is ejected by OB winds and supernovae, their high velocity means that very little of it can be accreted. On the other hand, winds from AGB stars ultimately dominate the total mass loss, and they can also be accreted very efficiently because of their slow speeds.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/7efadfb4811fa5dc4e513cd913ab62173a0ec1c2

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Citations in the corpus

• TORUS AND ACTIVE GALACTIC NUCLEUS PROPERTIES OF NEARBY SEYFERT GALAXIES: RESULTS FROM FITTING INFRARED SPECTRAL ENERGY DISTRIBUTIONS AND SPECTROSCOPY (2011, background): “There is strong nuclear (∼ 0.2′′ ∼ 65 pc) star formation in this galaxy, but it only contributes a small fraction of the Kband luminosity within 0.2′′ (see e.g., Davies et al. 2007 and references therein).”
• Revisiting the Unified Model of Active Galactic Nuclei (2015, methodology): “According to Davies et al. (2007) and Davies et al. (2014), the equivalent widths of the Brγ lines in the 15 AGNs studied by this group, practically rule out on-going SF and indicate post SF population.”
• An analytic model of angular momentum transport by gravitational torques: from galaxies to massive black holes (2010, background): “Davies et al. (2007) and Hicks et al. (2009) measure star formation in nuclear regions around AGN (∼ 1− 100pc), perhaps closest to the regions of interest here, and find results consistent with the scalings in Bouché et al. (2007).”
• The Coevolution of Galaxies and Supermassive Black Holes: Insights from Surveys of the Contemporary Universe (2014, methodology): “On much smaller scales (ten to hundred pc) and for a much smaller sample, Davies et al. (2007) also find evidence for a delay of-order 100 Myr between a starburst and powerful AGN activity.”
• An expanded Mbh–σ diagram, and a new calibration of active galactic nuclei masses (2010, background): “Schartmann et al. (2010), for example, describe how stellar mass loss from the nuclear star cluster (or nuclear disc; Davies et al. 2007) in NGC 1068 can feed the black hole of this active Seyfert galaxy.”
• Resolving the mid-infrared cores of local Seyferts (2009, background): “Furthermore, the instantaneous IR luminosity of a SB can vary by more than an order of magnitude (e.g. Cid Fernandes et al. 2004; Davies et al. 2007), depending on its size and age.”
• The green valley is a red herring: Galaxy Zoo reveals two evolutionary pathways towards quenching of star formation in early-and late-type galaxies (2014, methodology): “Perhaps a declining sSFR favours black hole growth: Davies et al. (2007) suggested that the absence of strong stellar feedback (core collapse supernovae, O-star winds) makes it easier to transport gas to the centre, and also that mass-loss from Asymptotic Giant Branch stars could easily fuel black…”
• FEEDBACK FROM CENTRAL BLACK HOLES IN ELLIPTICAL GALAXIES. III. MODELS WITH BOTH RADIATIVE AND MECHANICAL FEEDBACK (2010, result): “These findings are nicely supported by recent observations (e.g, see Lauer et al. 2005; Davies et al. 2007, 2009; Shapiro et al. 2010).”
• A diversity of dusty AGN tori - Data release for the VLTI/MIDI AGN Large Program and first results for 23 galaxies (2013, background): “…however whether nuclear star clusters would rather hinder or help accretion or if there is a time-delay between the onset of nuclear star-formation and powerful accretion onto the AGN (e.g. Davies et al., 2007; Vollmer et al., 2008; Schartmann et al., 2009; Wada et al., 2009; Davies et al., 2012).”
• SPITZER QUASAR AND ULIRG EVOLUTION STUDY (QUEST). IV. COMPARISON OF 1 Jy ULTRALUMINOUS INFRARED GALAXIES WITH PALOMAR-GREEN QUASARS (2009, background): “This random component of accretion is known to be important among local AGN (e.g., Davies et al. 2007).”
• Timing the starburst–AGN connection (2010, background): “As pointed out by Davies et al. (2007), the Galactic centre also fits into this picture, where the winds from nearby young OB stars are not being accreted as efficiently as expected (Baganoff et al. 2003; Paumard et al. 2006).”
• INSPIRALLING SUPERMASSIVE BLACK HOLES: A NEW SIGNPOST FOR GALAXY MERGERS (2008, background): “Galaxy mergers can also trigger starbursts, and after tens of Myr some stars evolve into asymptotic giant branch stars, whose winds might be accreted efficiently onto SMBHs to fuel AGNs (Davies et al. 2007).”
• GALAXY ZOO: THE FUNDAMENTALLY DIFFERENT CO-EVOLUTION OF SUPERMASSIVE BLACK HOLES AND THEIR EARLY- AND LATE-TYPE HOST GALAXIES (2010, background): “Other possibilities include mass loss from evolved stars (e.g., Davies et al. 2007; Ho 2008), the infall of a minor dwarf galaxy or the tidal disruption of a star by the black hole (e.g., Gezari et al. 2006) As we have discussed, it is unlikely that the late-type AGN hosts are involved in the same…”
• What drives the growth of black holes (2011, methodology): “Furthermore, given the gas-inflow times, there can be a significant delay between the initial triggering event and the onset of AGN activity (≈ 50–500 Myrs; e.g., Davies et al. 2007; Schawinski et al. 2009; Wild et al. 2010); see §2.1–2.2.”
• Adaptive Optics for Astronomy (2012, methodology): “A possible solution to this puzzle was proposed by (Davies et al. 2007, see also Wild et al. 2010).”