scholarly journals The impact of AGN on their host galaxies

2013 ◽  
Vol 9 (S304) ◽  
pp. 284-290
Author(s):  
C. M. Harrison

AbstractIn these proceedings I briefly: (1) review the impact (or “feedback”) that active galactic nuclei (AGN) are predicted to have on their host galaxies and larger scale environment, (2) review the observational evidence for or against these predictions and (3) present new results on ionised outflows in AGN. The observational support for the “maintenance mode” of feedback is strong (caveat the details); AGN at the centre of massive halos appear to be regulating the cooling of hot gas, which could in turn control the levels of future star formation (SF) and black hole growth. In contrast, direct observational support for more rapid forms of feedback, which dramatically impact on SF (i.e., the “quasar mode”), remains elusive. From a systematic study of the spectra of ≈24 000 AGN we find that extreme ionised gas kinematics are common, and are most prevalent in radio bright AGN (L1.4 GHz > 103 W Hz−1). Follow-up IFU observations have shown that these extreme gas kinematics are extended over kilo-parsec scales. However, the co-existence of high-levels of SF, luminous AGN activity and radio jets raises interesting questions on the primary drivers and impact of these outflows. Galaxy-wide, high-mass outflows are being observed in an increasing number of AGN and are a plausible mechanism for the depletion of gas; however, there is still much work to be done to determine the physical processes that drive these outflows and to measure the level of impact that they have on their host galaxies.

2019 ◽  
Vol 489 (4) ◽  
pp. 5225-5230
Author(s):  
W Ishibashi

ABSTRACT Growing observational evidence confirms the existence of massive black holes ($M_{\rm BH} \sim 10^9 \, \mathrm{M}_{\odot }$), accreting at rates close to the Eddington limit, at very high redshifts ($z \gtrsim 6\!-\!7$) in the early Universe. Recent observations indicate that the host galaxies of the first quasars are chemically evolved systems, containing unexpectedly large amounts of dust. Such a combination of high luminosities and large dust content should form favourable physical conditions for radiative dusty feedback. We explore the impact of the active galactic nucleus (AGN) feedback, driven by radiation pressure on dust, on the early growth of massive black holes. Assuming Eddington-limited exponential black hole growth, we find that the dynamics and energetics of the radiation pressure-driven outflows also follow exponential trends at late times. We obtain modest outflow energetics (with momentum flux $\dot{p} \lesssim L/c$ and kinetic power $\dot{E}_{\rm k} \lesssim 10^{-3} L$), comparable with available observations of quasar-driven outflows at very high redshifts, but significantly lower than typically observed in local quasars and predicted by wind energy-driven models. AGN radiative dusty feedback may thus play an important role in powering galactic outflows in the first quasars in the early Universe.


2019 ◽  
Vol 631 ◽  
pp. A132 ◽  
Author(s):  
S. J. Molyneux ◽  
C. M. Harrison ◽  
M. E. Jarvis

Using a sample of 2922 z <  0.2, spectroscopically identified active galactic nuclei (AGN), we explore the relationship between radio size and the prevalence of extreme ionised outflows, as traced using broad [O III] emission-line profiles in spectra obtained by the Sloan Digital Sky Survey (SDSS). To classify radio sources as compact or extended, we combined a machine-learning technique for morphological classification with size measurements from two-dimensional Gaussian models to data from all-sky radio surveys. We find that the two populations have statistically different [O III] emission-line profiles; the compact sources tend to have the most extreme gas kinematics. When the radio emission is confined within 3″ (i.e. within the spectroscopic fibre or ≲5 kpc at the median redshift), the chance of observing broad [O III] emission-line components, which are indicative of very high velocity outflows and have a full width at half-maximum > 1000 km s−1, is twice as high. This difference is greatest for the highest radio luminosity bin of log[L1.4 GHz/W Hz−1] = 23.5−24.5 where the AGN dominate the radio emission; specifically, > 1000 km s−1 components are almost four times as likely to occur when the radio emission is compact in this subsample. Our follow-up ≈0.3″–1″ resolution radio observations for a subset of targets in this luminosity range reveal that radio jets and lobes are prevalent, and suggest that compact jets might be responsible for the stronger outflows in the wider sample. Our results are limited by the available relatively shallow all-sky radio surveys, but forthcoming surveys will provide a more complete picture of the connection between radio emission and outflows. Overall, our results add to the growing body of evidence that ionised outflows and compact radio emission in highly accreting “radiative” AGN are closely connected, possibly as a result of young or weak radio jets.


2019 ◽  
Vol 15 (S352) ◽  
pp. 127-131
Author(s):  
Bram P. Venemans ◽  
Fabian Walter ◽  
Marcel Neeleman ◽  
Mladen Novak ◽  
Roberto Decarli

AbstractLuminous quasars are powered by accretion onto supermassive black holes. Such luminous quasars have been discovered up to the highest redshifts, z > 7. Here we discuss recent observations of the host galaxies of luminous quasars at z ≳ 6. We do not find a correlation between ongoing black hole growth and star-formation rate in the high redshift quasars, possibly indicating that black holes and their hosts do not co-evolve. We further show that even with high spatial resolution observations of the gas kinematics, dynamical mass estimates remain highly uncertain and should be used with caution.


2019 ◽  
Vol 489 (4) ◽  
pp. 4926-4943 ◽  
Author(s):  
M Glowacki ◽  
J R Allison ◽  
V A Moss ◽  
E K Mahony ◽  
E M Sadler ◽  
...  

ABSTRACT Obscuration of quasars by accreted gas and dust, or dusty intervening galaxies, can cause active galactic nuclei (AGN) to be missed in optically selected surveys. Radio observations can overcome this dust bias. In particular, radio surveys searching for H i absorption inform us on how the AGN can impact on the cold neutral gas medium within the host galaxy, or the population of intervening galaxies through the observed line of sight gas kinematics. We present the results of an H i absorption line survey at 0.4 &lt; z &lt; 1 towards 34 obscured quasars with the Australian SKA Pathfinder (ASKAP) commissioning array. We detect three H i absorption lines, with one of these systems previously unknown. Through optical follow-up for two sources, we find that in all detections the H i gas is associated with the AGN, and hence that these AGN are obscured by material within their host galaxies. Most of our sample are compact, and in addition, are either gigahertz peaked spectrum (GPS), or steep spectrum (CSS) sources, both thought to represent young or recently re-triggered radio AGN. The radio spectral energy distribution classifications for our sample agree with galaxy evolution models in which the obscured AGN has only recently become active. Our associated H i detection rate for GPS and compact SS sources matches those of other surveys towards such sources. We also find shallow and asymmetric H i absorption features, which agrees with previous findings that the cold neutral medium in compact radio galaxies is typically kinematically disturbed by the AGN.


2019 ◽  
Vol 15 (S359) ◽  
pp. 265-266
Author(s):  
Bruno Dall’Agnol de Oliveira ◽  
Thaisa Storchi-Bergmann

AbstractOften associated with the regulation of star formation in galaxies, active galactic nuclei (AGN) play a fundamental role in the evolution of galaxies through their feedback effects. To investigate the impact of these effects, we analysed the optical emission-line properties of 8 type II AGNs with bolometric luminosities LBol > 1045 erg s−1, using integral field spectroscopy (IFS) observations with Gemini Multi-Object Spectrograph (GMOS). The gas kinematics was obtained by fitting Gaussian components to the profiles of the emission lines of the ionized gas. Using only the broadest component – that we associate with the gas in outflow – we calculated the mass outflow rate (Ṁout), finding values of up to 10 M⊙ yr−1. The outflow kinetic power (Ėout reaches maximum values between 1041 and 1043 erg s−1, which correspond to feedback efficiencies of ∼0.001−0.1 % of Lbol. These values are below that required to quench the star formation during the evolution of galaxies in simulations and analytical models. We also investigated the effect of uncertainties on the values of the physical quantities used in the calculations – such as the electron density – on the final values of Ṁout and Ėout.


2009 ◽  
Vol 5 (S267) ◽  
pp. 266-266
Author(s):  
Andreas Schulze ◽  
Lutz Wisotzki

The observed relations between the black hole mass and the properties of the spheroidal galaxy component imply a close connection between the growth of supermassive black holes and the evolution of their host galaxies. An effective approach to study black hole growth is to measure black hole masses and Eddington ratios of well-defined type 1 AGN samples and determine the underlying distribution functions.


2011 ◽  
Vol 734 (2) ◽  
pp. 121 ◽  
Author(s):  
B. D. Simmons ◽  
J. Van Duyne ◽  
C. M. Urry ◽  
E. Treister ◽  
A. M. Koekemoer ◽  
...  

2019 ◽  
Vol 489 (1) ◽  
pp. 497-516 ◽  
Author(s):  
Nadia L Zakamska ◽  
Ai-Lei Sun ◽  
Michael A Strauss ◽  
Rachael M Alexandroff ◽  
W N Brandt ◽  
...  

Abstract We present Hubble Space Telescope 1.4–1.6 $\mu$m images of the hosts of 10 extremely red quasars (ERQs) and six type 2 quasar candidates at z = 2–3. ERQs, whose bolometric luminosities range between 1047 and 1048 erg s−1, show spectroscopic signs of powerful ionized winds, whereas type 2 quasar candidates are less luminous and show only mild outflows. After performing careful subtraction of the quasar light, we clearly detect almost all host galaxies. The median rest-frame B-band luminosity of the ERQ hosts in our sample is $10^{11.2}\, \mathrm{L}_{\odot }$, or ∼4L* at this redshift. Two of the 10 hosts of ERQs are in ongoing mergers. The hosts of the type 2 quasar candidates are 0.6 dex less luminous, with 2/6 in likely ongoing mergers. Intriguingly, despite some signs of interaction and presence of low-mass companions, our objects do not show nearly as much major merger activity as do high-redshift radio-loud galaxies and quasars. In the absence of an overt connection to major ongoing gas-rich merger activity, our observations are consistent with a model in which the near-Eddington accretion and strong feedback of ERQs are associated with relatively late stages of mergers resulting in early-type remnants. These results are in some tension with theoretical expectations of galaxy formation models, in which rapid black hole growth occurs within a short time of a major merger. Type 2 quasar candidates are less luminous, so they may instead be powered by internal galactic processes.


2017 ◽  
Vol 845 (2) ◽  
pp. 134 ◽  
Author(s):  
Anna K. Weigel ◽  
Kevin Schawinski ◽  
Neven Caplar ◽  
O. Ivy Wong ◽  
Ezequiel Treister ◽  
...  

2020 ◽  
Vol 500 (2) ◽  
pp. 2177-2187 ◽  
Author(s):  
A Cruz ◽  
A Pontzen ◽  
M Volonteri ◽  
T R Quinn ◽  
M Tremmel ◽  
...  

ABSTRACT Using cosmological hydrodynamic simulations with physically motivated models of supermassive black hole (SMBH) formation and growth, we compare the assembly of Milky Way-mass (Mvir ≈ 7 × 1011 M⊙ at z = 0) galaxies in cold dark matter (CDM) and self-interacting dark matter (SIDM) models. Our SIDM model adopts a constant cross-section of 1 cm2 g−1. We find that SMBH formation is suppressed in the early Universe due to SIDM interactions. SMBH–SMBH mergers are also suppressed in SIDM as a consequence of the lower number of SMBHs formed. Lack of initial merger-driven SMBH growth in turn delays SMBH growth by billions of years in SIDM compared to CDM. Further, we find that this delayed growth suppresses SMBH accretion in the largest progenitors of the main SIDM galaxies during the first 5 Gyr of their evolution. Nonetheless, by z = 0.8 the CDM and SIDM SMBH masses differ only by around 0.2 dex, so that both remain compatible with the MBH–M* relation. We show that the reduced accretion causes the SIDM SMBHs to less aggressively regulate star formation in their host galaxies than their CDM counterparts, resulting in a factor of 3 or more stars being produced over the lifetime of the SIDM galaxies compared to the CDM galaxies. Our results highlight a new way in which SIDM can affect the growth and merger history of SMBHs and ultimately give rise to very different galaxy evolution compared to the classic CDM model.


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