ALMA observations of cold molecular gas in AGN hosts at z ∼ 1.5 – evidence of AGN feedback?

Kakkad, D.; Mainieri, V.; Brusa, M.; Padovani, P.; Carniani, Stefano; Feruglio, C.; Sargent, M.; Husemann, B.; Bongiorno, A.; Bonzini, M.; Piconcelli, E.; Silverman, John D.; Rujopakarn, W.

doi:10.1093/mnras/stx726

Cited by 66 publications

(82 citation statements)

References 93 publications

(155 reference statements)

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“…The inferred molecular masses (or upper limits) are clearly below what observed in main-sequence galaxies with similar redshift and SFR, while they are comparable to molecular masses observed in active galaxies (Figure 4). Indeed, the depletion timescale, which is the time required for the outflow to remove the gas from the galaxy (τ dep = M gas /SFR), estimated for each QSOs of our sample (τ dep < 800 Myr) is consistent to those observed in high-z submillimetre galaxies (SMGs) and obscured QSOs at z = 1.5 − 2.5 (Banerji et al, 2017;Kakkad et al, 2017).…”

Section: Molecular Gassupporting

confidence: 79%

Star Formation Quenching in Quasar Host Galaxies

Carniani

2017

Front. Astron. Space Sci.

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Galaxy evolution is likely to be shaped by negative feedback from active galactic nuclei (AGN). In the whole range of redshifts and luminosities studied so far, galaxies hosting an AGN frequently show fast and extended outflows consisting in both ionized and molecular gas. Such outflows could potentially quench the start formation within the host galaxy, but a clear evidence of negative feedback in action is still missing. Hereby I will analyse integral-field spectroscopic data for six quasars at z ∼ 2.4 obtained with SINFONI in the H-and K-band. All the quasars show [OIII]λ5007 line detection of fast, extended outflows. Also, the high signal-to-noise SINFONI observations allow the identification of faint narrow Hα emission (FWHM < 500 km/s), which is spatially extended and associated with star formation in the host galaxy. On paper fast outflows are spatially anti-correlated with star-formation powered emission, i.e., star formation is suppressed in the area affected by the outflow. Nonetheless as narrow, spatially-extended Hα emission, indicating star formation rates of at least 50-100 M ⊙ yr −1 , has been detected, either AGN feedback is not affecting the whole host galaxy, or star formation is completely quenched only by several feedback episodes. On the other hand, a positive feedback scenario, supported by narrow emission in Hα extending along the edges of the outflow cone, suggests that galaxy-wide outflows could also have a twofold role in the evolution of the host galaxy. Finally, I will present CO(3-2) ALMA data for three out of the six QSOs observed with SINFONI. Flux maps obtained for the CO(3-2) transition suggest that molecular gas within the host galaxy is swept away by fast winds. A negative-feedback scenario is supported by the inferred molecular gas mass in all three objects, which is significantly below what observed in non-active main-sequence galaxies at high-z.

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Section: Molecular Gassupporting

confidence: 79%

Star Formation Quenching in Quasar Host Galaxies

Carniani

2017

Front. Astron. Space Sci.

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“…This scenario is supported by the observation of low gas fraction in AGN host galaxies (e.g., Brusa et al 2015;Kakkad et al 2017), as well as the AGNdriven molecular gas outflow (Cicone et al 2014;Feruglio et al 2015). In addition, it has been reported that AGN hosts preferentially lie in the green valley or below the main sequence (Nandra et al 2007;Salim et al 2007;Silverman et al 2008;Ellison et al 2016;Smith et al 2016), suggesting that AGN could drive the transition from the star-forming to the quiescent phases.…”

Section: Discussionmentioning

confidence: 70%

SDSS-IV MaNGA-resolved Star Formation and Molecular Gas Properties of Green Valley Galaxies: A First Look with ALMA and MaNGA

Lin

Belfiore

Pan

et al. 2017

ApJ

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We study the role of cold gas in quenching star formation in the green valley by analyzing ALMA 12 CO (1-0) observations of three galaxies with resolved optical spectroscopy from the MaNGA survey. We present resolution-matched maps of the star formation rate and molecular gas mass. These data are used to calculate the star formation efficiency (SFE) and gas fraction ( f gas ) for these galaxies separately in the central "bulge" regions and outer disks. We find that, for the two galaxies whose global specific star formation rate (sSFR) deviates most from the star formation main sequence, the gas fraction in the bulges is significantly lower than that in their disks, supporting an "inside-out" model of galaxy quenching. For the two galaxies where SFE can be reliably determined in the central regions, the bulges and disks share similar SFEs. This suggests that a decline in f gas is the main driver of lowered sSFR in bulges compared to disks in green valley galaxies. Within the disks, there exist common correlations between the sSFR and SFE and between sSFR and f gas on kiloparsec scales-the local SFE or f gas in the disks declines with local sSFR. Our results support a picture in which the sSFR in bulges is primarily controlled by f gas , whereas both SFE and f gas play a role in lowering the sSFR in disks. A larger sample is required to confirm if the trend established in this work is representative of the green valley as a whole.

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“…Aird et al 2010), so there is much interest in unravelling the signatures of AGN feedback on molecular gas in these distant AGN hosts (e.g. Brusa et al 2015;Kakkad et al 2017).…”

Section: Comparisons To Agn Host Galaxies At High Redshiftmentioning

confidence: 99%

“…Recently, Kakkad et al (2017) reported lower t dep and molecular gas fractions from an ALMA survey of ten X-ray selected AGN at z ∼ 1.5. In the scenario of suppressive AGN feedback on star formation, their results are interpreted as widespread evidence for the prompt removal of star-forming molecular gas, possibly by an outflow, which depresses f gas .…”

Section: Comparisons To Agn Host Galaxies At High Redshiftmentioning

confidence: 99%

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LLAMA: normal star formation efficiencies of molecular gas in the centres of luminous Seyfert galaxies

Rosario

Burtscher

Davies

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Using new APEX and JCMT spectroscopy of the CO 2→1 line, we undertake a controlled study of cold molecular gas in moderately luminous (L bol = 10 43−44.5 erg s −1 ) Active Galactic Nuclei (AGN) and inactive galaxies from the Luminous Local AGN with Matched Analogs (LLAMA) survey. We use spatially resolved infrared photometry of the LLAMA galaxies from 2MASS, WISE, IRAS & Herschel, corrected for nuclear emission using multi-component spectral energy distribution (SED) fits, to examine the dust-reprocessed star-formation rates (SFRs), molecular gas fractions and star formation efficiencies (SFEs) over their central 1-3 kpc. We find that the gas fractions and central SFEs of both active and inactive galaxies are similar when controlling for host stellar mass and morphology (Hubble type). The equivalent central molecular gas depletion times are consistent with the disks of normal spiral galaxies in the local Universe. Despite energetic arguments that the AGN in LLAMA should be capable of disrupting the observable cold molecular gas in their central environments, our results indicate that nuclear radiation only couples weakly with this phase. We find a mild preference for obscured AGN to contain higher amounts of central molecular gas, which suggests a connection between AGN obscuration and the gaseous environment of the nucleus. Systems with depressed SFEs are not found among the LLAMA AGN. We speculate that the processes that sustain the collapse of molecular gas into dense pre-stellar cores may also be a prerequisite for the inflow of material on to AGN accretion disks.

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ALMA observations of cold molecular gas in AGN hosts at z ∼ 1.5 – evidence of AGN feedback?

Cited by 66 publications

References 93 publications

Star Formation Quenching in Quasar Host Galaxies

Star Formation Quenching in Quasar Host Galaxies

SDSS-IV MaNGA-resolved Star Formation and Molecular Gas Properties of Green Valley Galaxies: A First Look with ALMA and MaNGA

LLAMA: normal star formation efficiencies of molecular gas in the centres of luminous Seyfert galaxies

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