TEMA 3. Host Galaxies & Environment

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1 TEMA 3. Host Galaxies & Environment AGN Dr. Juan Pablo Torres-Papaqui Departamento de Astronomía Universidad de Guanajuato DA-UG (México) División de Ciencias Naturales y Exactas, Campus Guanajuato, Sede Valenciana Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 1 / 36

2 Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 2 / 36

3 Give a general overview of different types of AGN hosts and a bit on their environment Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 3 / 36

4 Why is the host galaxy important What fuels the AGN/SMBH for 10 8 years? How is the SMBH fueled (ang. momentum loss). Gravitational interaction of galaxies? What does the host tell us about e.g. unification Two important questions: 1) What galaxies harbor AGN? 2) What influence does the environment have on the presence or absence of an AGN? Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 4 / 36

5 Studying AGN Host Galaxies Methods: Imaging: Detect the host and study its properties, morphology and environment. Spectroscopy: e.g. Study the stellar populations of the host galaxy. Difficulties: 1) AGN can be much bright (or fainter) than the host galaxy 2) Poor imaging resolution (from e.g. the ground) Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 5 / 36

6 Example of 3C273 Notice the difficulty in AGN subtraction Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 6 / 36

Variety of AGN Host Galaxies SB, MS 0801.

7 Variety of AGN Host Galaxies SB, MS S, PG E, Q S?, PG Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 7 / 36

8 General Findings on Host-Galaxy Types Low AGN Activity: Mostly Spirals (Sa-c) and in some E/S0 s with disturbed morphology (also in HI). High AGN Activity: Mostly in E/S0 s and some Spirals Radio-Loud AGN: Only in Massive Ellipticals! Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 8 / 36

9 However, open question! Why some galaxies host an active nucleus while others do not? Presence or absence of a black hole? Observational evidence that the majority (if not all) of the galaxies contain a Black Hole (Kormedy & Gebhardt 2001) Presence or absence of fueling material? Examine the central morphology. Any localized excess or deficit will be indicative of the presence of gas and dust, or merging. Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 9 / 36

10 The importance of SMBH masses and fueling, and the connection with the host galaxy. Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 10 / 36

11 Narrow-Line AGN activity BPT diagram (Baldwin et al. 1981) ( objects!) SDSS Sample: 2537 Seyferts and LINERs Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 11 / 36

12 Narrow-Line AGN activity AGN activity correlates with stellar mass and concentration (Kauffmann et al. 2003) Weak AGN: log L[OIII] < 7.0 Strong AGN: log L[OIII] > 7.0 Tracer of the strength of activity in the nucleus. Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 12 / 36

13 Narrow-Line AGN activity Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 13 / 36

14 Narrow-Line AGN activity The spectra of SLOAN narrow-line AGN show that they preferentially reside in giant galaxies with signs of recent star formation, as revealed by the λ4000å break measurements (D n index). The more active the galaxy is (as measured by the [OIII] λ5007å flux), the more massive and young the associated stellar population seems to be (Heckman & Kauffmann 2003). But are these young populations associated with the nucleus or with the host galaxy? - Fiber φ = 3 Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 14 / 36

15 Correlation between BH & Stellar Mass AGN Activity increases with increasing stellar mass and increasing central concentrations The BH mass buried in quiescent galaxies can be estimated through the Magorrian relationship between BH mass and bulge luminosity. ( M BH σ M 200 km/s (Gebhardt 2000, Ferrarese & Merrit 2000) log M BH = 0.36 M B (Magorrian et al. 1998, Ferrarese & Merrit 2000) ) 3.75 Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 15 / 36

16 Correlation between BH & Stellar Mass Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 16 / 36

17 Correlation BH Mass and AGN Activity? It seems that larger (spheroidal) stellar masses imply larger BH masses, measured through (future lecture): Reverberation technique Photo-ionization modeling Larger stellar mass also correlates with stronger nuclear (AGN) activity measure through OIII. The implication (although not proven directly) could be that the SMBH mass correlates with the AGN activity. Hence BIGGER galaxies have stronger AGN activity. Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 17 / 36

18 SMBH Mass Density Disregarding possible morphological type differences, the LF of local E/S0. Φ(L)dL = Φ 0 (L/L ) α exp( L/L )dl/l can be transformed into the local SMBH density through the Magorrian relationship, in general terms L = AM k Ψ(M BH )dm BH = Ψ 0 (M BH /M ) k(α+1) 1 exp( (M BH /M ) k )dm BH /M (I.3.1) adopting a bulge-luminosity to galaxy-luminosity ratio. The mass density of SMBHs in local galaxies is (4-5) 10 5 M Mpc 3. This implies that all giant galaxies have probably experienced a QSO phase in the past (Woltjer 1955,... Ferrarese 2002). Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 18 / 36

19 SMBH Mass Density Homework #4: Using the relation L = AM k, show the equation I.3.1 Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 19 / 36

20 Interactions of Quasar Host Galaxies Elliptical galaxies; often merging / interacting galaxies Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 20 / 36

material: Galactic bar Companions/Mergers Host

21 Host Galaxies & Environment Asymmetries of Quasar Host Galaxies Fueling the AGN Ways to transport the material: Galactic bar Companions/Mergers Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 21 / 36

22 Host Galaxies & Environment Asymmetries of Quasar Host Galaxies Early-type AGN Host Galaxies & Environment: AGN non-agn J.P. Torres-Papaqui Physics of AGN 22 / 36

23 Host Galaxies & Environment Asymmetries of Quasar Host Galaxies Late-type AGN Host Galaxies & Environment: AGN non-agn J.P. Torres-Papaqui Physics of AGN 23 / 36

24 Morphology of AGN Hosts All AGNs show significant structure in their inner 100 pc and 1 kpc regions Presence of significant amount of gas/dust Early-type galaxies: Non-AGN galaxies show no structure at all. AGN host show structure, consistent with early-type galaxies hosting a SMBH that only shows activity if sufficiently fueled. Late-type galaxies: Both AGN and non-agn show significant structure in their central region. Why? Not all of them host a Black Hole Material is not transported to the SMBH Large amount of dust/gas hides the AGNs from our sight Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 24 / 36

25 The optical continuum of Radio Galaxies Usually the old stellar population is the dominant - as usual in elliptical galaxies - but in some cases a young stellar population component is observed (typical ages between 0.5 and 2 Gyr). Consistent with the merger hypothesis for the triggering of the radio activity. But not a single type of merger AGN appears late after the merger Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 25 / 36

26 The optical continuum of Radio Galaxies Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 26 / 36

27 The optical continuum of Radio Galaxies The young stellar component may come from a recent merger We can use the age of the stars to date when this merger occurred To be compared with e.g. the age of the radio source (correlate?) Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 27 / 36

28 Some Conclusions on Hosts and Environments Most quasars, NLRGs/BLRGs, blazars are E/S0 hosts (some early type spirals for radio quiet quasars) Seyferts/LINERs are typically spirals The mass of the black-hole correlates with the bulge mass (Ferrerese et al. 2000) - larger bulge/ greater mass BH Bars appear to be no more common in Seyferts than normal galaxies (Mulchaey & Regan 1997). Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 28 / 36

29 Some Conclusions on Hosts and Environments Conflicting evidence regarding whether or not Seyferts are found in more interacting systems than normal galaxies (Dahari et al. 1984; DeRobertis & Yee 1988). May be that minor mergers are more important than major mergers for instigating AGN. Generally, luminous AGN tend to be in denser than average environments and low-luminosity AGN in normal/slightly dense environments. Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 29 / 36

30 How does this all fit together? Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 30 / 36

31 The basic scenario: AGN - Host connection AGNs are triggered by mergers. The merger hypothesis provides a mechanism by which matter can be accreted by the BH. It explains why AGNs are found in groups. AGN activity may be intermittent. Predicts that powerful AGN activity must have been more prevalent in the past (more merging!). More massive galaxies have more massive BH, hence stronger AGN activity for similar accretion rates Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 31 / 36

32 The basic scenario: AGN - Host connection Quasars were more common in the past - during the epoch of galaxy formation What s the connection? Black Holes form in the centers of young Galaxies. Black Holes shine as Active Galaxies (Quasars) until the fuel (infalling gas) is used up. Most Quasars are now gone, but the Black Holes remain. Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 32 / 36

33 The basic scenario: AGN - Host connection Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 33 / 36

34 The basic scenario: AGN - Host connection As small galaxies merge to form larger ones, black-holes may form at the nucleus. With plenty of fuel available early on, the galaxy light is dominated by emission of the black-hole (Quasar). Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 34 / 36

35 The basic scenario: AGN - Host connection Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 35 / 36

36 Host Galaxies & Environment But, but,... AGN appears to have been ejected from the host through a merger, or have no host at all?! Host Galaxies & Environment: AGN J.P. Torres-Papaqui Physics of AGN 36 / 36

TEMA 6. Continuum Emission

TEMA 6. Continuum Emission AGN Dr. Juan Pablo Torres-Papaqui Departamento de Astronomía Universidad de Guanajuato DA-UG (México) papaqui@astro.ugto.mx División de Ciencias Naturales y Exactas, Campus Guanajuato,