A complete hard X-ray selected sample of local, luminous AGNs

(1)

LLAMA and obscuration

Local Luminous AGN with Matched Analogs

Leonard Burtscher, Ric Davies, Ming-yi Lin,

Gilles Orban de Xivry, David Rosario et al.

Max-Planck-Institut für extraterrestrische Physik

Garching

ESO AGN workshop 27 June 2016

(2)

LLAMA and obscuration

Local Luminous AGN with Matched Analogs

Leonard Burtscher, Ric Davies, Ming-yi Lin,

Gilles Orban de Xivry, David Rosario et al.

Max-Planck-Institut für extraterrestrische Physik

Garching

ESO AGN workshop 27 June 2016

(3)

Sample and rationale

A complete, hard X-ray selected local sample

(4)

Sample and rationale

A complete, hard X-ray selected local sample

hard X-ray selected

(14-195 keV)

CT fraction in local universe ~ 30%; we have 3/20 = 15%,

i.e. miss ~ 3 sources

(5)

Sample and rationale

A complete, hard X-ray selected local sample

The most luminous

local sources: AGN

activity is more than

just „weather“

hard X-ray selected

(14-195 keV)

(6)

Sample and rationale

A complete, hard X-ray selected local sample

Local AGNs: we can

resolve the

circum-nuclear star cluster

The most luminous

local sources: AGN

activity is more than

just „weather“

hard X-ray selected

(14-195 keV)

(7)

Sample and rationale

A complete, hard X-ray selected local sample

Local AGNs: we can

resolve the

circum-nuclear star cluster

The most luminous

local sources: AGN

activity is more than

just „weather“

hard X-ray selected

(14-195 keV)

Davies, LB + 2015

optically obscured; only three are just X-ray absorbed. These

exceptions are “minor” since they are all close to the boundary

between the regimes. The X-ray absorbed AGN NGC 1365 is

optically classiﬁed as Sy 1.8 and, although in many studies is

taken to be a Sy 2, here we adopt a strict deﬁnition and so

classify it as Sy 1. Similarly MCG-05-23-016 is X-ray absorbed

and has only weak broad Hα, hence its previous classiﬁcation

as a Sy 2 which we have revised to Sy 1.9. The Sy 1.8

NGC 2992 has a column only marginally above our X-ray

absorption threshold and so is on the borderline in both

classiﬁcations. It would be classiﬁed as X-ray unabsorbed

according to other deﬁnitions that set the threshold at 10

22

cm

−2

(Panessa & Bassani

2002

). As such, there could be two more

optically obscured and one less X-ray absorbed AGN than

found using the strict deﬁnitions we apply in Figure

6 . This is

reﬂected by the ranges shown in Figure

7 .

The joint optical/X-ray classiﬁcations are summarized in

Figure

6 where we adopt the terminology of Merloni et al.

(

2014

_{) in which the ﬁrst/second digit of the classiﬁcation}

denotes the optical/X-ray type. This leads to the following

types:

type 11: optically unobscured and X-ray unabsorbed;

type 22: optically classiﬁed as Sy 2 and X-ray absorbed;

type 21: optically classiﬁed as Sy 2 but X-ray unabsorbed;

type 12: optically unobscured but X-ray absorbed.

Thus, with reference to the curves in Figure

7 adapted from

Merloni et al.

(

2014

) to the 14–195 keV luminosity scale, we

also have:

type 22+12: all X-ray absorbed AGNs

(regardless of their

optical classiﬁcation);

type 22+21: all AGNs optically classiﬁed as Sy 2

(indepen-dent of whether they are X-ray absorbed

).

Comparing the AGNs in our sample to the left edge of

Figure

7 immediately highlights a discrepancy. Above, we

noted that 50%–60% of our complete sample are optically

obscured and classed as Sy 2s, a fraction similar to that

estimated by Lawrence & Elvis

(

2010

). However, Merloni

et al.

(

2014

) class

∼90% of their AGNs in an overlapping

luminosity range

log

L

_{14 195}₋

∼

43 –

43.5 as Sy 2s. The

differ-ence is due to the large fraction of AGNs classiﬁed by these

authors as type 21, that is X-ray unabsorbed Sy 2 galaxies

(Pappa et al.

2001

; Panessa & Bassani

2002

; Brightman &

Nandra

2008

; Bianchi et al.

2012

).

4.2. How Common are X-Ray Unabsorbed Seyfert 2s?

X-ray unabsorbed Sy 2s are believed to be galaxies with a

direct view to the AGNs but in which there is no BLR

(such

objects are also known as pure or true Sy 2s

). This view is

supported by, for example, the six objects identiﬁed by

Hawkins

(

2004

) as having optical spectra typical of Sy 2s

(HβFWHM

< 1000 km s

−1

and

[O

III

]/Hβ

> 3) but large

amplitude variations typical of Sy 1s. Subsequent X-ray

observations of three by Gliozzi et al.

(

2007

_{) conﬁrmed that}

these do not have signiﬁcant absorption in the 0.3–8 keV band.

These authors also showed that these AGNs are relatively

luminous

(intrinsic

log

L

_{0.5 8}₋

>

43.2 ). Thus, despite their

rather low Eddington ratios

L

bol

L

Edd

<

0.01 (Gliozzi

et al.

2007

), the absence of a BLR cannot be explained by

low luminosities and/or accretion rates either being unable to

sustain a disk wind

(Nicastro

2000

; Elitzur & Ho

2009

) or

meaning that high dispersion prevents BLR clouds from

surviving

(Laor

2003

). At present, the reason that they may not

have a BLR is still open.

These objects may be related to the Sy 2s for which

spectropolarimetry shows no evidence of a hidden BLR. There

have been many studies of polarized emission from hidden

BLRs. The largest indicate that Sy 2s in which a hidden BLR

has not been detected have less luminous AGNs than other

Sy 2s but are not more optically obscured

(Tran

2001

,

2003

;

Gu & Huang

2002

)—qualitatively, but not necessarily

quantitatively, consistent with the idea that BLR may not form

in low luminosity AGNs. It also suggests that a BLR is

completely absent in at least 50% of Sy 2s. However, this

fraction is difﬁcult to put in perspective because of

complica-tions due to the impact of detection limits as well as the

expected scattering efﬁciency. The latter issue was addressed

by Heisler et al.

(

1997

) who showed that the ability to detect

polarized emission was related to the far-infrared colors in a

way that suggested the scattering particles were in the throat of

the torus, and so even they would be hidden at high

inclinations. Following on from work of Ramos Almeida

et al.

(

2011

) which shows that the intrinsic properties (rather

than just the inclination

) of the tori in Sy 1s and Sy 2s are

different, Ichikawa et al.

(

2015

_{) have ﬁtted torus models to}

Sy 2s with and without polarized emission. Their results again

Figure 3. Comparison of several host galaxy properties between the hard X-ray selected AGNs (orange; solid lines or plusses), and the matched inactive sample (dark green; dashed lines or crosses): H-band luminosity as a proxy for stellar mass (far left), axis ratio (center left), Hubble type (center right), and H-band luminosity vs. distance (far right). There is no obvious relation between host galaxy luminosity and distance; and as expected by design, the distributions of the inactive sample properties match those of the AGNs very well. The biggest discrepancy is in distance, and this results from our preference to select closer, rather than more distant, inactive galaxies when possible.

7

The Astrophysical Journal, 806:127 (14pp), 2015 June 10 Davies et al.

AGNs

inactive

(8)

Leonard Burtscher: Infrared Interferometry of AGNs

The torus: more than obscuration

A starburst-AGN connection?

(9)

Leonard Burtscher: Infrared Interferometry of AGNs

The torus: more than obscuration

A starburst-AGN connection?

Davies+ 2007

powerful AGN

activity only in

post-starburst

nuclei?

(10)

Li

n+

(in

pr

ep)

• SINFONI IFU

cubes to analyze

gas inflow /

outflow

The next steps

A complete, hard X-ray selected local sample

Nuclear Stellar Kinematics of Hard X-ray Selected AGNs with Matched Inactive Galaxies

Abstract

In a matched sample of local, 14–195 keV selected active galactic nuclei (AGN) and inactive galaxies, we investigate the spatially resolved stellar kinematics and distributions on the scale of 10-300 pc. Here we present first results on part of the sample. We extract the observed stellar velocity fields and stellar velocity dispersion field of both AGNs and inactive galaxies. With larger scale 2MASS Ks band image, the disk, bar, and bulge have been decomposed. We find that there is a flux excess above the fitted bulge Sérsic profile in the innermost region. In the next step, we will search for evidence of dynamically cold nuclear stellar populations distinct from the bulge, and study the nuclear M/L_K ratios. The key goal of this project is to understand the role of nuclear star formation in the AGN fueling process.

.

Sample Selection – Local Luminous AGN with Matched Analogs (LLAMA)

Extracting the Kinematic Map of CO(2-0) 2.29µm Stellar Absorption and Measuring Position Angle (PA)

Ming-Yi Lin

1,2

_,

Richard Davies

1

_,

Leonard Burtscher

1

_{, David Rosario}

1,3

1 – Max-Planck-Institut für extraterrestrische Physik, Gießenbachstr.1, 85748 Garching,

2 – Department of Physics, Ludwig-Maximilians-Universität München

3 – Department of Physics, Durham University, South Road, Durham DH1 3LE, UK

Decomposition and Nuclear Excess Flux

(Fig. 1) A complete volume-limited sample, selected from Swift/BAT 58 month all-sky catalogue. This is generally accepted as the least biased way to select AGN purely on their intrinsic luminosity. The criteria are: X-ray luminosity > 1042.5_{; z < 0.01; declination <15° (Davies et al. 2015).}

(Tab. 1) First half VLT SINFONI H+K band 100mas (FOV 3”×3”) observations of the LLAMA sample. All targets have been extracted 2D kinematics maps of CO(2-0) 2.29µm stellar absorption. The detailed disk/bar/bulge decomposition has been studied with Pair 6 & Pair 8 (labeled as red).

Table 1

PA~155°

PA~55°

Method:

_Results:

The kinematic PA measured from SINFONI is roughly consistent with the photometric PA derived from 2MASS image.

★  The stellar

velocity and

velocity dispersion

map of

Pair 5

:

Active galaxy

(Top: NGC 7582)

and

Inactive galaxy

(Bottom: NGC

4224).

★  The dashed line is

the fitted

kinematic PA.

★  Both galaxies

show a clear

stellar rotation.

Using Penalized Pixel-Fitting

(pPXF; Cappellari & Emsellem 2004):

Gemini spectral templates have been convolved to SINFONI H+K spectral resolution, we used it as stellar library.

Radius (arcsec) Radius (arcsec)

Bulge Bar Disk No excess flux Bulge

Disk Nuclear_excess

flux

(GALFIT)

Method:

_Results:

In order to look at whether there is an excess flux in the nucleus, we use larger scale 2MASS Ks band images to constrain the bulge Sérsic index(n_bulge) and effective

radius(Re_bulge). In our fitting procedure, n_disk is fixed to 1, Re_disk, n_bulge, Re_bulge are free parameters. If a bar has been identified in the host galaxy, then we add a bar component.

★  We present the 2MASS GALFIT result and SINFONI 1D stellar continuum radial profile of

Pair 8

: Active galaxy (Top: NGC 6814) and Inactive galaxy (Bottom: NGC 4254).

★  We have analyzed

Pair 6 & Pair 8

.

Except NGC 6814 (Seyfert 1.5), other 3 galaxies show

clear excess flux above the Sérsic fit to bulge in the innermost region, which can be

explained as an additional inner component.

Bulge

Cappellari et al. (2007) & Krajnovic et al. (2006)

Cappellari et al. 2007, MNRAS, 379, 418

Cappellari et al. 2010, AIP Conf. Proc. ,1240,211 Cappellari & Emsellem 2004, PASP, 16, 138

Davies et al. 2015, ApJ, 806, 127

Krajnovic et al. 2006, MNRAS, 366, 787 Peng et al. 2002, AJ, 124, 266

This project is a work in progress; we plan to combine the flux profile and dispersion profile to simultaneously

assess the evidence for a photometrically and kinematically distinct stellar population in the central tens of parsecs. With the observed velocity field, we can look for whether there is non-circular motion. We will also construct

dynamical models with Jeans Anisotropic Models method (Cappellari et al. 2010). The M/L_K ratio can help us to constrain the age of the stellar population and understand whether BH accretion is associated with nuclear star formation.

References

Summary of the Next Steps

Peng et al. 2002

(11)

Li

n+

(in

pr

ep)

• SINFONI IFU

cubes to analyze

gas inflow /

outflow

• X-SHOOTER

spectra to robustly

analyze the star

formation histories

The next steps

A complete, hard X-ray selected local sample

Nuclear Stellar Kinematics of Hard X-ray Selected AGNs with Matched Inactive Galaxies

Abstract

.

Sample Selection – Local Luminous AGN with Matched Analogs (LLAMA)

Extracting the Kinematic Map of CO(2-0) 2.29µm Stellar Absorption and Measuring Position Angle (PA)

Ming-Yi Lin

1,2

_,

Richard Davies

1

_,

Leonard Burtscher

1

_{, David Rosario}

1,3

1 – Max-Planck-Institut für extraterrestrische Physik, Gießenbachstr.1, 85748 Garching,

2 – Department of Physics, Ludwig-Maximilians-Universität München

3 – Department of Physics, Durham University, South Road, Durham DH1 3LE, UK

Decomposition and Nuclear Excess Flux

Table 1

PA~155°

PA~55°

Method:

_Results:

★  The stellar

velocity and

velocity dispersion

map of

Pair 5

:

Active galaxy

(Top: NGC 7582)

and

Inactive galaxy

(Bottom: NGC

4224).

★  The dashed line is

the fitted

kinematic PA.

★  Both galaxies

show a clear

stellar rotation.

flux

(GALFIT)

Method:

_Results:

★  We present the 2MASS GALFIT result and SINFONI 1D stellar continuum radial profile of

Pair 8

: Active galaxy (Top: NGC 6814) and Inactive galaxy (Bottom: NGC 4254).

★  We have analyzed

Pair 6 & Pair 8

.

Except NGC 6814 (Seyfert 1.5), other 3 galaxies show

clear excess flux above the Sérsic fit to bulge in the innermost region, which can be

explained as an additional inner component.

Bulge

Davies et al. 2015, ApJ, 806, 127

References

Summary of the Next Steps

Peng et al. 2002

see poster B9 by Ming-Yi Lin

Bur

ts

cher+

(in

pr

ep)

(12)

Li

n+

(in

pr

ep)

• SINFONI IFU

cubes to analyze

gas inflow /

outflow

• X-SHOOTER

spectra to robustly

analyze the star

formation histories

• APEX data to

probe molecular

inventory (+ trying

to get ALMA +

HST…)

The next steps

A complete, hard X-ray selected local sample

Nuclear Stellar Kinematics of Hard X-ray Selected AGNs with Matched Inactive Galaxies

Abstract

.

Sample Selection – Local Luminous AGN with Matched Analogs (LLAMA)

Extracting the Kinematic Map of CO(2-0) 2.29µm Stellar Absorption and Measuring Position Angle (PA)

Ming-Yi Lin

1,2

_,

Richard Davies

1

_,

Leonard Burtscher

1

_{, David Rosario}

1,3

1 – Max-Planck-Institut für extraterrestrische Physik, Gießenbachstr.1, 85748 Garching,

2 – Department of Physics, Ludwig-Maximilians-Universität München

3 – Department of Physics, Durham University, South Road, Durham DH1 3LE, UK

Decomposition and Nuclear Excess Flux

Table 1

PA~155°

PA~55°

Method:

_Results:

★  The stellar

velocity and

velocity dispersion

map of

Pair 5

:

Active galaxy

(Top: NGC 7582)

and

Inactive galaxy

(Bottom: NGC

4224).

★  The dashed line is

the fitted

kinematic PA.

★  Both galaxies

show a clear

stellar rotation.

flux

(GALFIT)

Method:

_Results:

★  We present the 2MASS GALFIT result and SINFONI 1D stellar continuum radial profile of

Pair 8

: Active galaxy (Top: NGC 6814) and Inactive galaxy (Bottom: NGC 4254).

★  We have analyzed

Pair 6 & Pair 8

.

Except NGC 6814 (Seyfert 1.5), other 3 galaxies show

clear excess flux above the Sérsic fit to bulge in the innermost region, which can be

explained as an additional inner component.

Bulge

Davies et al. 2015, ApJ, 806, 127

References

Summary of the Next Steps

Peng et al. 2002

see poster B9 by Ming-Yi Lin

Bur

ts

cher+

(in

pr

ep)

(13)

First results: BLR properties and obscuration

Schnorr-Müller+ 2016 (re-submitted)

Broad Line Region in local Seyferts

15

658 660 662 664 500 1000 1500 2000 Hα 658 660 662 664 λ (nm) 500 1000 1500 2000 flux (10 − 17 erg s − 1 Å − 1 ) MCG−06−30−015 Hβ 484 486 488 490 492 494 λ (nm) 100 200 300 400 500 flux (10 − 17 erg s − 1 Å − 1 ) Hγ 430 432 434 436 438 440 442 444 λ (nm) 100 150 200 250 flux (10 − 17 erg s − 1 Å − 1 ) [OIII] Paβ 1275 1280 1285 1290 1295 1300 1305 λ (nm) 150 200 250 300 350 flux (10 − 17 erg s − 1 Å − 1 ) Paγ 1070 1080 1090 1100 1110 1120 λ (nm) 200 250 300 350 400 flux (10 − 17 erg s − 1 Å − 1 ) HeI Paδ 995 1000 1005 1010 1015 1020 1025 1030 λ (nm) 200 250 300 350 flux (10 − 17 erg s − 1 Å − 1 )

Figure 8. Observed Hα, Hβ, Hγ, Paβ, Paγ and Paδ line profiles from an integrated spectrum of the inner 1.′′2 (black), fitted broad (blue) and broad plus narrow (red) profiles lines. On the Hγ panel, we show in grey a combination of the fitted Hγ profile and the spectrum of an inactive galaxy, in order to illustrate that most of the diﬀerences between the observed and fitted profiles are due to the shape of the underlying stellar continuum. On the Paγ panel, broad He I was subtracted from the spectrum.

650 655 660 665 670 100 200 300 400 500 600 Hα 650 655 660 665 670 λ (nm) 100 200 300 400 500 600 flux (10 − 17 erg s − 1 Å − 1 ) NGC1365 Hβ 480 482 484 486 488 490 492 494 λ (nm) 40 60 80 100 120 flux (10 − 17 erg s − 1 Å − 1 ) Hγ 432 434 436 438 440 442 λ (nm) 20 30 40 50 60 flux (10 − 17 erg s − 1 Å − 1 ) [OIII] Paβ 1270 1280 1290 1300 1310 λ (nm) 100 120 140 160 180 200 flux (10 − 17 erg s − 1 Å − 1 ) Paγ 1080 1085 1090 1095 1100 1105 1110 λ (nm) 100 110 120 130 140 150 160 flux (10 − 17 erg s − 1 Å − 1 ) HeI Paδ 1000 1005 1010 1015 1020 1025 λ (nm) 90 100 110 120 130 140 150 flux (10 − 17 erg s − 1 Å − 1 ) FeII HeII

Figure 9. Observed Hα, Hβ, Hγ, Paβ, Paγ and Paδ line profiles from an integrated spectrum of the inner 1.′′2 (black), fitted broad (blue) and broad plus narrow (red) profiles lines. On the Hγ panel, we show in grey a combination of the fitted Hγ profile and the spectrum of an inactive galaxy, in order to illustrate that most of the diﬀerences between the observed and fitted profiles are due to the shape of the underlying stellar continuum. On the Paγ panel, broad He I was subtracted from the spectrum.

(14)

First results: BLR properties and obscuration

Schnorr-Müller+ 2016 (re-submitted)

6 A. Schnorr-M¨

uller et al.

9 10 11 12 13 14 17.0 17.5 18.0 18.5 19.0 19.5 20.0 9 10 11 12 13 14 log (n [cm−3]) 17.0 17.5 18.0 18.5 19.0 19.5 20.0 log ( Φ [cm − 2 s − 1 ]) MCG0514 MCG0523 MCG0630 NGC1365 NGC2992 NGC3783 NGC4235 NGC4593 NGC6814

Figure 1. Ionising photon flux Φ_H versus hydrogen number den-sity n_H. The points show the location of best fit parameters Φ_H and n_H. These are defined as the median of grid points where the diﬀerence between each model and de-reddened observed line ratios is less than 20%. The extinction is optimised as a free pa-rameter independently at each grid point, and the resulting values are listed in Table 2. The contours delimit the regions correspond-ing to 1σ uncertainty on the derived parameters n_H and Φ_H. De-tails of the procedure are given in Section 3.3. Abbreviated name: MCG–05-14-012, MCG–05-23-16 and MCG–06-30-015.

as estimated from the He II lines for each object. The errors

in these estimates were derived assuming an uncertainty of

20% in the observed line ratios.

In the case of the H I lines, determining A

V

(NLR), is a

straightforward process since, as outlined in Section

3.1.3 , a

fixed set of intrinsic line ratios can be assumed. Deriving the

extinction A

V

(N LR) to the NLR was done during the step

of fitting and subtracting the narrow lines as described in

that Section. In Table

2 we list A

V

(NLR) as estimated from

the H I lines for each object. The errors in A

V

estimates were

derived assuming an uncertainty of 20% in the observed line

ratios.

The extinction to the BLR is derived in a diﬀerent way,

since the H I intrinsic line ratios are not known. To do so,

we followed these steps:

1) We compared the measured emission line ratios to

those derived from photoionisation calculations across

the entire density-flux plane. At each individual point

in the grid, we performed an independent

Levenberg-Marquardt least-squares minimisation to derive the best

fitting A

V

at that point. This results in a χ

2_red

map

show-ing how well the observations can be matched by

pho-toionisation calculations for a wide range of density and

incident flux.

2) As an estimate of the error in the broad line fluxes

mea-surements is diﬃcult to obtain, since it is dominated by

systematic eﬀects, we adopted an uncertainty of 20% for

each line ratio (corresponding to a fiducial 10%

uncer-tainty on each line flux). From the resulting χ

2_red

values,

we are able to draw in the standard way the region

cor-Object A_V (NLR) A_V (BLR) H I He II H I He II MCG0514 0.7+0.7_−0.7 0.2+0.3_−0.2 0.0_±0.2 0.0_±0.3 MCG0523 1.6+0.6_−0.8 1.3+0.3_−0.4 7.7_±1.3 4.2∗ MCG0630 2.4+0.7_−0.8 1.5+0.3_−0.3 2.8_±0.4 3.0∗ NGC1365 1.3+0.7_−0.7 2.2+0.4_−0.3 4.2_±0.5 4.4∗ NGC2992 2.8+0.7_−0.8 3.2+0.3_−0.3 4.7_±0.5 4.5∗ NGC3783 0.0+0.6_−0.0 - 0.1_±0.2 -NGC4235 2.5+0.7_−0.7 - 1.5_±0.5 -NGC4593 0.0+0.6_−0.0 - 0.0_±0.1 -NGC6814 1.4+0.6_−0.8 2.3+0.4_−0.3 0.4_±0.4 0.0_±0.3

Table 2. Extinction to the narrow line region, A_V (NLR), and ex-tinction to the broad line region, A_V (BLR), derived from Balmer and Paschen H I line ratios and the He II λ4686/He II λ10126.4 line ratio as described in Section 3.3. In objects where broad He II λ4686 is not detected a lower limit to A_V (BLR) was deter-mined from broad He II λ10126.4˚A. These lower limits are marked with an asterisk. Abbreviated name: 14-012, MCG–05-23-16 and MCG–06-30-015.

Object log(Φ_H) log(n_H) MCG0514 18.0_±0.2 11.7_±0.8 MCG0523 18.5_±0.5 11.8_±1.3 MCG0630 18.0_±0.3 11.5_±0.9 NGC1365 18.5_±0.7 11.2_±0.9 NGC2992 18.2_±0.6 11.2_±1.0 NGC3783 18.0_±0.3 11.7_±0.9 NGC4235 17.5_±0.3 11.0_±1.5 NGC4593 18.0_±0.2 13.7_±0.6 NGC6814 18.2_±0.8 11.9_±1.3

Table 3. Best fit parameters Φ_H and n_H. Abbreviated name: MCG–05-14-012, MCG–05-23-16 and MCG–06-30-015.

responding to 1σ uncertainty on the derived parameters

n

H

and Φ

H

as shown in Fig.

1 .

3) In order to further constrain the range of valid grid

points, we apply an additional constraint that the

cal-culated ratios must all individually diﬀer by less than

20% from the unreddened measured values. Grid points

that did not fulfil this criterion were discarded. If more

than one grid point fulfilled it, we calculated median

val-ues of n

H

, Φ

H

, A

V

(BLR) and line ratios. From here on

we refer to the median values of the valid grid point as

best fitting values. The best fitting values of n

H

and Φ

H

are shown in tables

3 . The best fitting A

V

(BLR) and

predicted line ratios values are listed in Table

4 . We note

that the median values of n

H

, Φ

H

and A

V

(BLR) are not

significantly aﬀected by increasing the selection

thresh-old to 30%. It is only when we allow the calculated and

unreddened measured ratios to diﬀer by 40% or more that

the diﬀerences become significant, because at that point

the density and photon flux become poorly constrained.

We also note that the grid points fulfilling our chosen

20% criterion cover a much smaller range in the n

H

-Φ

H

plane than the range covered by the 1σ uncertainty

con-tours shown in Fig.

1 . Except for MCG–05-23-16 and

(15)

First results: BLR properties and obscuration

Schnorr-Müller+ 2016 (re-submitted)

6 A. Schnorr-M¨

uller et al.

9 10 11 12 13 14 17.0 17.5 18.0 18.5 19.0 19.5 20.0 9 10 11 12 13 14 log (n [cm−3]) 17.0 17.5 18.0 18.5 19.0 19.5 20.0 log ( Φ [cm − 2 s − 1 ]) MCG0514 MCG0523 MCG0630 NGC1365 NGC2992 NGC3783 NGC4235 NGC4593 NGC6814

Figure 1. Ionising photon flux Φ_H versus hydrogen number den-sity n_H. The points show the location of best fit parameters Φ_H and n_H. These are defined as the median of grid points where the diﬀerence between each model and de-reddened observed line ratios is less than 20%. The extinction is optimised as a free pa-rameter independently at each grid point, and the resulting values are listed in Table 2. The contours delimit the regions correspond-ing to 1σ uncertainty on the derived parameters n_H and Φ_H. De-tails of the procedure are given in Section 3.3. Abbreviated name: MCG–05-14-012, MCG–05-23-16 and MCG–06-30-015.

as estimated from the He II lines for each object. The errors

in these estimates were derived assuming an uncertainty of

20% in the observed line ratios.

In the case of the H I lines, determining A

V

(NLR), is a

straightforward process since, as outlined in Section

3.1.3 , a

fixed set of intrinsic line ratios can be assumed. Deriving the

extinction A

V

(N LR) to the NLR was done during the step

of fitting and subtracting the narrow lines as described in

that Section. In Table

2 we list A

V

(NLR) as estimated from

the H I lines for each object. The errors in A

V

estimates were

derived assuming an uncertainty of 20% in the observed line

ratios.

The extinction to the BLR is derived in a diﬀerent way,

since the H I intrinsic line ratios are not known. To do so,

we followed these steps:

1) We compared the measured emission line ratios to

those derived from photoionisation calculations across

the entire density-flux plane. At each individual point

in the grid, we performed an independent

Levenberg-Marquardt least-squares minimisation to derive the best

fitting A

V

at that point. This results in a χ

2_red

map

show-ing how well the observations can be matched by

pho-toionisation calculations for a wide range of density and

incident flux.

2) As an estimate of the error in the broad line fluxes

mea-surements is diﬃcult to obtain, since it is dominated by

systematic eﬀects, we adopted an uncertainty of 20% for

each line ratio (corresponding to a fiducial 10%

uncer-tainty on each line flux). From the resulting χ

2_red

values,

we are able to draw in the standard way the region

cor-Object A_V (NLR) A_V (BLR) H I He II H I He II MCG0514 0.7+0.7_−0.7 0.2+0.3_−0.2 0.0_±0.2 0.0_±0.3 MCG0523 1.6+0.6_−0.8 1.3+0.3_−0.4 7.7_±1.3 4.2∗ MCG0630 2.4+0.7_−0.8 1.5+0.3_−0.3 2.8_±0.4 3.0∗ NGC1365 1.3+0.7_−0.7 2.2+0.4_−0.3 4.2_±0.5 4.4∗ NGC2992 2.8+0.7_−0.8 3.2+0.3_−0.3 4.7_±0.5 4.5∗ NGC3783 0.0+0.6_−0.0 - 0.1_±0.2 -NGC4235 2.5+0.7_−0.7 - 1.5_±0.5 -NGC4593 0.0+0.6_−0.0 - 0.0_±0.1 -NGC6814 1.4+0.6_−0.8 2.3+0.4_−0.3 0.4_±0.4 0.0_±0.3

Table 2. Extinction to the narrow line region, A_V (NLR), and ex-tinction to the broad line region, A_V (BLR), derived from Balmer and Paschen H I line ratios and the He II λ4686/He II λ10126.4 line ratio as described in Section 3.3. In objects where broad He II λ4686 is not detected a lower limit to A_V (BLR) was deter-mined from broad He II λ10126.4˚A. These lower limits are marked with an asterisk. Abbreviated name: 14-012, MCG–05-23-16 and MCG–06-30-015.

Object log(Φ_H) log(n_H) MCG0514 18.0_±0.2 11.7_±0.8 MCG0523 18.5_±0.5 11.8_±1.3 MCG0630 18.0_±0.3 11.5_±0.9 NGC1365 18.5_±0.7 11.2_±0.9 NGC2992 18.2_±0.6 11.2_±1.0 NGC3783 18.0_±0.3 11.7_±0.9 NGC4235 17.5_±0.3 11.0_±1.5 NGC4593 18.0_±0.2 13.7_±0.6 NGC6814 18.2_±0.8 11.9_±1.3

Table 3. Best fit parameters Φ_H and n_H. Abbreviated name: MCG–05-14-012, MCG–05-23-16 and MCG–06-30-015.

responding to 1σ uncertainty on the derived parameters

n

H

and Φ

H

as shown in Fig.

1 .

3) In order to further constrain the range of valid grid

points, we apply an additional constraint that the

cal-culated ratios must all individually diﬀer by less than

20% from the unreddened measured values. Grid points

that did not fulfil this criterion were discarded. If more

than one grid point fulfilled it, we calculated median

val-ues of n

H

, Φ

H

, A

V

(BLR) and line ratios. From here on

we refer to the median values of the valid grid point as

best fitting values. The best fitting values of n

H

and Φ

H

are shown in tables

3 . The best fitting A

V

(BLR) and

predicted line ratios values are listed in Table

4 . We note

that the median values of n

H

, Φ

H

and A

V

(BLR) are not

significantly aﬀected by increasing the selection

thresh-old to 30%. It is only when we allow the calculated and

unreddened measured ratios to diﬀer by 40% or more that

the diﬀerences become significant, because at that point

the density and photon flux become poorly constrained.

We also note that the grid points fulfilling our chosen

20% criterion cover a much smaller range in the n

H

-Φ

H

plane than the range covered by the 1σ uncertainty

con-tours shown in Fig.

1 . Except for MCG–05-23-16 and

MNRAS 000, 000–000 (0000)

Broad Line Region in local Seyferts

9 Object

r

_b

MCG–05-14-012

1.0 MCG–05-23-16

0.5 MCG–06-30-015

1.0 NGC1365

0.7 NGC2992

0.8 NGC3783

0.8 NGC4235

1.8 NGC4593

0.9 NGC6814

0.9 Table 5. Distance from the nucleus to the broad H I emitting

region in terms of the dust sublimation radius (see Section

4.1 for

details).

sionally suppressed at densities larger than 10

9.5

cm

−3

.

Re-verberation mapping studies of nearby AGN found that

both Hβ and C III] λ 1909˚

A have similar time lags,

im-plying they are produced at similar radii, in the outer

part of the BLR (

Onken & Peterson 2002

;

Trevese et al.

2014

), thus one might expect the H I emitting gas and

C III] λ 1909˚

A have similar densities. Regarding this issue,

we note that a broad range of densities is expected in a

sin-gle cloud with N

H

≈ 10

23

cm

−2

, so a density of 10

11

cm

−3

for Hβ and 10

9.5

cm

−3

for C III] λ 1909˚

A is consistent with

reverberation mapping results. For an additional discussion

on broad C III] λ 1909˚

A and Hβ, we refer to

Korista et al.

(

1997

) where maps of emission line equivalent widths in the

density–ionising photon flux plane are shown. There one can

see that the gas that is responsible for C III] λ 1909˚

A

con-tributes to Hβ at a typical fraction of

_{≈ 20–40% of that}

found in gas at densities > 10

11

cm

−3

, all else being equal

(see their Figs. 3e and 3g). Additionally, it is important to

consider that Hβ is emitted in most gas clouds that emit

C III] λ 1909˚

A, but the reverse is not true. So in this sense,

the present work is indicating that a majority fraction of the

optical and NIR H I emission lines are emitted in dense gas

(n >> 10

9.5

cm

−3

).

In the RPC models of

Baskin et al.

(

2014

), both Hβ and

C III] λ 1909˚

A are predominantly produced at radii close to

the dust sublimation radius, that is towards the outer part

of the BLR (see their Fig. 5). In their canonical model (for

which L

AGN

= 10

45

erg/s), C++ is found at column densities

through a cloud a little less than neutral hydrogen (see their

Fig. 3). For clouds in the outer part of the BLR, the range

of columns corresponds to a regime in which the volume

density drops rapidly from 10

11

cm

−3

(the density at which

the H I emission arises) to 10

9

cm

−3

(see their Fig. 2). Since

the critical density for C III] λ 1909˚

A is

_{≈ 10}

9.5

cm

−3

, the line

emission is collisionally suppressed. Thus the H I lines and

the C III] λ 1909˚

A line can arise in the same part of the BLR,

from gas that is at diﬀerent densities in the same clouds.

The RPC model predicts, without any free parameters,

not only that the density of the gas where H I lines are

pro-duced most strongly is

_{∼ 10}

11

cm

−3

, but that the clouds

with suitable conditions are located predominantly halfway

to the dust sublimation radius.

We can test this prediction using the photon fluxes

listed in table

3 . These are relatively well constrained to lie

in the range 10

17.5

-10

18.5

cm

−2

s

−1

, comparable to the

val-ues found by

Ruﬀ et al.

(

2012

) for their four QSOs. Since

we know the 14–195 keV luminosities for all our targets (list

in Table

1 ) we can calculate the distance from the AGN

at which the ionising photon flux matches those derived

from the line ratios, for a given spectral energy

distribu-tion (SED). The adopted SED is important since it

deter-mines the extrapolation of the photon rate from 14 keV down

to 13.6 eV. When calculating the photoionisation models,

Korista & Goad

(

2004

) used an SED comprising a power

law with an additional UV bump as shown in Fig. 1 of

Korista et al.

(

1997

). We prefer to adopt the SED derived for

NGC 1068 by

Pier et al.

(

1994

), since this object is

compa-rable to the AGN we have analysed here. However, we note

that it leads to lower extrapolated photon fluxes, and hence

small radii, than the SED used by

Korista et al.

(

1997

).

Fi-nally, in order to scale the results to the dust sublimation

radius R

dust

, we adopt R

dust

∼ 0.2 pc for an AGN

bolo-metric luminosity of 10

45

erg s

−1

as given by

Netzer

(

2015

)

for graphite grains. However, as

Netzer

(

2015

) notes, this

distance depends on the size and type of grain as well as

the anisotropy of the central radiation source, and therefore

R

dust

should not be considered too strictly as being at a

fixed location.

The resulting distances are listed in Table

5 . With the

exception of MCG–05-23-16, for which the photon flux is

poorly constrained as it was estimated based on only three

line ratios, and NGC 4235, which have the lowest photon flux

in the sample, the H I emitting region is close to (or even at)

the dust sublimation. This matches the expectations of the

RPC model, and is also in agreement with other theoretical

studies which suggested broad Paschen and Balmer lines in

large part come from the outer BLR, near or at the dust

sublimation radius (

Zhu et al. 2009

;

Czerny & Hryniewicz

2011

;

Mor & Netzer 2012

).

4.2 Predicted Line Ratios

Here we compare the predicted broad line ratios for the

objects in our study with measured line ratios in Seyfert

1/QSO samples in previous studies.

Dong et al.

(

2008

) measured the broad Hα/Hβ line

ra-tio on a sample of 446 nearby Seyfert 1 and quasi-stellar

objects that have blue continua (in order to minimise the

eﬀects of dust extinction). The measured broad Hα/Hβ line

ratios range from 2.3 to 4.2, skewed towards the large ratio

end. This distribution is well described by a log-Gaussian

with a peak of 3.06 and a standard deviation of 0.03 dex.

La Mura et al.

(

2007

) measured the Hα/Hβ in 90 nearby

(z

! 0.368) type 1 AGNs and they obtained a median of

3.45 _{± 0.65, while the measured ratios ranged from 1.56 to}

4.87. Zhou et al.

(

2006

) measured the broad Hα/Hβ line

ratio in a sample of 2000 narrow-line Seyfert 1s and they

obtained an average ratio of Hα/Hβ = 3.03 with a

disper-sion of

_{≈ 0.36. In a sample of broad line AGN with low}

starlight contamination,

Greene & Ho

(

2005

) found a mean

total (narrow and broad) Hα/Hβ ratio of 3.5

The line ratios we observe for the unreddened Seyfert 1s

MGC-05–14–012, NGC 3783 and NGC 4593 are in good

agreement with these other observational studies; as is the

predicted line ratio for NGC 6814, MCG–06–30–015 and

MCG-05–23–16, the latter based on the best fit to the Hα

and Pa lines, and for which we derived a substantial

ex-tinction of A

V

(BLR) = 7.7 mag. In contrast, the

dered-dened line ratios for NGC 1365, NGC 2992, NGC 4235 are

MNRAS 000, 000–000 (0000)

Hydrogen emitting

clouds are ~ at

sublimation radius

(16)

A near-IR

high-resolution atlas

of local AGNs

Bur

ts

cher+

2015

Dilution of stellar light

by the AGN continuum

(17)

Leonard Burtscher: What causes AGN activity?

Spectral decomposition

NGC 1386 (Sy 2)

9

Burtscher+ 2015

2.05 2.10 2.15 2.20 2.25 2.30 2.35 rest wavelength µm 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 F lu x den si ty Br H2 (1-0) S(1) H2 (1-0) S(0) [CaVIII] NaI CaI 12 CO (2-0) 12 CO (3-1) H2 (2-1) S(1) H eI 2.155 2.160 2.165 2.170 2.175 2.180 0.98 1.00 1.02 1.04 1.06 1.08 1.10 FWHM 1 = 298 km/s FWHM 2 = 325 km/s

Stars

Hot dust

(18)

A robust way to estimate

the obscuration

4

6

8

10

400

600

800 1000

1200

1400

1600

4

6

8

10 K−N

400

600

800 1000

1200

1400

1600

K band color temperature

ESO548 M87 MCG523 NGC1365 NGC1566 NGC2110 NGC2992 NGC3227 NGC3783 NGC4051 NGC4593 NGC5506 NGC6814 NGC7469 NGC7582 Circinus IC5063 NGC1068 NGC1386 NGC3081 NGC3281 NGC4388 NGC5128 NGC5135 NGC6300 NGC7172 NGC1052 NGC4579 Seyfert 1 Seyfert 1i Seyfert 2 LINER

Burtscher+ 2015

(19)

A robust way to estimate

the obscuration

4

6

8

10

400

600

800 1000

1200

1400

1600

4

6

8

10 K−N

400

600

800 1000

1200

1400

1600

K band color temperature

5 mag

(A

V

)

Burtscher+ 2015

• color

temperature

consistent with

optical

appearance →

obscuration

(20)

A robust way to estimate

the obscuration

4

6

8

10

400

600

800 1000

1200

1400

1600

4

6

8

10 K−N

400

600

800 1000

1200

1400

1600

K band color temperature

5 mag

(A

V

)

Burtscher+ 2015

✓ r1500K r_300K ◆2

• color

temperature

consistent with

optical

appearance →

obscuration

• normalization

consistent with

observed radii

of hot/warm

dust

(21)

Obscuration: Torus vs. BLR

Burtscher+ 2016

Torus obscuration A

V

[mag]

X

-ra

y

co

lum

n

[lo

g

N

_H

/

cm

^-2]

(22)

Obscuration: Torus vs. BLR

Burtscher+ 2016

Torus obscuration A

V

[mag]

X

-ra

y

co

lum

n

[lo

g

N

_H

/

cm

^-2]

(23)

Obscuration: Torus vs. BLR

Maiolino+2010

Burtscher+ 2016

Torus obscuration A

V

[mag]

X

-ra

y

co

lum

n

[lo

g

N

_H

/

cm

^-2]

(24)

Obscuration: Torus vs. BLR

Maiolino+2010

Burtscher+ 2016

Torus obscuration A

V

[mag]

X

-ra

y

co

lum

n

[lo

g

N

_H

/

cm

^-2]

Absorption in the dusty torus

Absorption in the dust-free BLR

(25)

Obscuration: Torus vs. BLR

Broad Line Region in local Seyferts

11 and so in this section we discuss whether that is necessarily

the case.

In Fig.

3 we compare the extinction to the NLR to the

extinction to the BLR. In three sources where the BLR is

un-obscured, there is also no obscuration to the NLR, which is

expected. Three sources have A

V

(BLR)

≃ A

V

(NLR) within

errors, which implies in these cases an obscuring structure

at larger scales than the NLR. In the Seyfert 1.8/1.9s in our

sample, the extinction to the NLR is substantially smaller:

1.9 mag in NGC 2992, 2.9 mag in NGC 1365 and 6.1 mag in

MGC –05-23-16. This implies that the extinction to the BLR

is due to dusty structures that are more compact than the

NLR. This could be the torus, and, in fact, previous

stud-ies of the spectral variation in the broad lines and

contin-uum of Seyfert 1.8/1.9s (

Goodrich 1989

;

Tran et al. 1992

;

Goodrich 1995

) showed that, in some of these objects, the

variations were consistent with changes in reddening, and

the time scales involved pointed to the obscuring source

be-ing close to the BLR, i.e., the torus. On the other hand,

dusty nuclear spirals and filaments are also a possibility: in

a recent study,

Prieto et al.

(

2014

) found that dusty nuclear

spirals and filaments on scales of tens of parsecs to a

hun-dred parsecs can cause moderate extinction to the nucleus,

in the range A

V

= 3–6 mag.

Such structures can in principle account for the

extinc-tion to the BLR in NGC 1365 and NGC 2992, but they

can-not account for the extinction to the BLR in MCG–05-23-16.

This latter object was one of those observed by

Prieto et al.

(

2014

), who found the filament crossing the nucleus causes

only a small amount of extinction, A

V

≈ 1 mag. This

im-plies the extinction to the BLR of MCG–05-23-16 occurs on

a much smaller scale.The mid-IR emission in AGNs tracing

the warm dust is typically located on scales < 50 pc for the

AGNs in our luminosity range, and specifically in the case of

MCG–05-23-016, the half-light radius of the mid-IR emission

is

_{≈2 pc as found by interferometry (}

Burtscher et al. 2013

).

Thus, in the case of MCG–05-23-16, considering the large

diﬀerence between the extinction to the NLR and BLR, the

fact that high spatial resolution observations showed that

the dust filament crossing its nucleus causes only a small

amount of extinction (

Prieto et al. 2014

) and the size of the

half-light radius of the mid-IR emission (

Burtscher et al.

2013

), we argue the torus is the structure obscuring the

BLR.

4.5 X-ray absorption and optical extinction

A quantitative comparison between extinction and

X-ray absorbing column has recently been presented by

Burtscher et al.

(

2016

) – and we refer to these authors for

a discussion of other results in the literature on this topic.

They showed that when one takes into account the

variabil-ity in the X-ray absorbing column, its lower limit is

con-sistent with the measured optical extinction for the

Galac-tic gas-to-dust ratio; and they argued that deviations from

this can be explained as absorption by dust-free neutral gas

within the BLR. The extinction used by these authors was

derived using the ‘dust colour’ method of

Burtscher et al.

(

2015

), and is a measure of the extinction to the hot (

_∼

1500 K) dust.

Because this probes nearly all the way to the BLR, it

can be used as a proxy for the extinction to the BLR. But

0 2 4 6 8 10 19 20 21 22 23 0 2 4 6 8 10 A_V to the BLR (mag) 19 20 21 22 23 log(N H [cm − 2 ]) MCG−05−14−012 MCG−05−23−16 NGC1365 NGC2992 NGC3783 NGC4593 MCG−06−30−015 NGC4235 NGC6814

Figure 4. A

_V

to the broad line region versus X-ray absorbing

column N

_H

, adapted from a similar figure by

Burtscher et al.

(

2016

). The vertical dashed lines denote the range of absorbing

columns in the literature, which indicates the minimum variability

for each object. The N

_H

value for MCG –05-14-012 is an upper

limit. The thick grey line represents the Galactic standard

gas-to-dust ratio (

Predehl & Schmitt 1995

;

Nowak et al. 2012

).

also because of that, we re-visit this issue here and look at

whether their conclusion is upheld when using the extinction

derived directly from the broad lines themselves.

We plot A

V

(BLR) versus the X-ray absorbing columns

in Fig.

4 . The thick grey curve gives the range of relations

us-ing the Galactic gas-to-dust ratio (N

H

/A

V

)

Galactic

= (1.79–

2.69)

_×10

21

cm

−2

(

Predehl & Schmitt 1995

;

Nowak et al.

2012

). The observed range of N

H

for each object,

trac-ing variations in X-ray absorbtrac-ing column, are indicated by

dashed lines. When N

H

variation is taken into account,

all objects in this study show that the lower end of their

range of N

H

/A

V

ratios is consistent with the Galactic

gas-to-dust ratio. In particular, we have 6 objects in common

with

Burtscher et al.

(

2016

), and the A

V

derived here from

the broad lines measurements is consistent with – and more

precise than – that derived with the dust colour method

presented by

Burtscher et al.

(

2016

). As such, our analysis

confirms their result.

4.6 Seyfert sub-type and Extinction to the Broad

Line Region

Finally, we also look at the relation between Seyfert

sub-type (as discussed in Section

3.4 ) and the extinction to the

BLR, which are plotted in Fig.

5 . There is a clear separation

between Seyfert 1-1.2s and Seyfert 1.8-1.9s: Seyfert 1-1.2s

are either unabsorbed objects or mildly absorbed objects,

while Seyfert 1.8-1.9s are aﬀected by substantial

obscura-tion to the BLR, in the range 4–8 mag. Our result is

con-sistent with earlier studies that suggested that these

inter-mediate AGN categories are comprised mostly of partially

obscured Seyfert 1s (

Goodrich 1989

,

1995

;

Dong et al. 2005

),

the remaining being objects with low AGN continuum flux

(

Rudy et al. 1988

;

Trippe et al. 2010

). And it supports the

MNRAS 000, 000–000 (0000)

Schno

rr

-M

ül

ler+

2016

(r

e-submi

tted

)

X

-ra

y

co

lum

n

[lo

g

N

_H

/

cm

^-2]

BLR obscuration A

V

[mag]

(26)

Obscuration: Torus vs. BLR

Bur

ts

cher+

2016

Schno

rr

-M

ül

ler+

2016

(r

e-submi

tted

)

H

ot

d

us

t

ob

sc

ura

tio

n

A

V

[mag]

BLR obscuration A

V

[mag]

Hot dust obscuration:

Uncertainties (<~ 5 mag)

due to intrinsic temperature

of hot dust

(27)

Resolving AGN tori

Outlook

(28)

Outlook

• GRAVITY; MATISSE: 2

nd

_{generation VLTI instrument offering phases}

(imaging), higher resolution (L band, and N) and more efficiency (4 beams)

(29)

Outlook

• GRAVITY; MATISSE: 2

nd

_{generation VLTI instrument offering phases}

(imaging), higher resolution (L band, and N) and more efficiency (4 beams)

• E-ELT/METIS

(30)

Outlook

• GRAVITY; MATISSE: 2

nd

_{generation VLTI instrument offering phases}

(imaging), higher resolution (L band, and N) and more efficiency (4 beams)

• E-ELT/METIS

• resolve large-scale „torus“ component found with MIDI: determine

the kinematics of the wind launching region

(31)

Outlook

• GRAVITY; MATISSE: 2

nd

_{generation VLTI instrument offering phases}

(imaging), higher resolution (L band, and N) and more efficiency (4 beams)

• E-ELT/METIS

• resolve large-scale „torus“ component found with MIDI: determine

the kinematics of the wind launching region

• resolve stellar populations very close to nearby AGNs

(32)

AGN NIR luminosity relations

Burtscher+ 2015

(33)

Leonard Burtscher: Where is the torus? Black hole and accretion disk

OB

late-type

stars

(1) inflow + starburst

(2) supernovae + turbulence

(34)

OB

late-type

stars

(1) inflow + starburst

(2) supernovae + turbulence

(35)

OB

late-type

stars

(1) inflow + starburst

(2) supernovae + turbulence

(36)

Leonard Burtscher: Where is the torus?

Physical torus models

(37)

Leonard Burtscher: Where is the torus?

Physical torus models

Schartmann+ 2009

Andreas Burkert:

ISM-SPP Proposal

S

TATE OF THE

A

RT AND PRELIMINARY WORK

Figure 2: Density distribution of our effort to model the stellar mass loss from the nuclear star cluster

in the nearby Seyfert galaxy NGC 1068 after an evolution time of (a) 7 · 10

4

yr and (b) 6 · 10

5

yr. Panel

(c) shows the corresponding temperature distribution of the large scale component, whereas panel

(d) displays a zoom-in into the central 2 pc region, where a dense disc builds up. Figure adapted from

*Schartmann et al. (2010).

disc theory) and compare its properties to available observations. The comparison of the mass

inflow rate as well as structural parameters with observations and previous modelling is done

to assess that this model accounts for both the obscuration and feeding of supermassive black

holes. This shows that our model is able to approximately account for the disc size as inferred

from interferometric observations in the mid-infrared and compares well to the extent and mass

of a rotating disc structure as inferred from water maser observations in NGC 1068. The results

summarised here have been published recently in (*Schartmann et al. 2010).

④ Radiation feedback on dusty clouds during Seyfert activity

As described above, our scenario of the evolution from a nuclear star cluster towards the

for-mation of discs and tori in nearby Seyfert galaxies leads to a clumpy or filamentary infall of gas

towards the centre during the pre-active phase. A hot inner accretion disc will form and the

central activity will start, while matter still gets accreted towards the central region. So far, we

only concentrated on the pre-active phase. As soon as the illumination starts, radiation

pres-sure forces can become of similar magnitude as gravitational forces. To investigate these

pro-cesses in great detail, we performed two-dimensional high-resolution radiation-hydrodynamical

simulations of idealised, dusty clouds, illuminated by a typical AGN spectrum and subject to

gravitational forces due to the central black hole and nuclear star cluster. To this end, we have

implemented a one-dimensional multi-wavelength, approximative equilibrium radiative transfer

algorithm into the PLUTO code, which comes at moderate costs and reasonable accuracy. We

find three distinct phases of the evolution of an infalling gas clump that experiences the

radia-tion pressure force of the central engine: (i) formaradia-tion of a lenticular shape with dense inner rim

caused by the interaction of gravity and radiation pressure (the lense phase), (ii) formation of a

clumpy sickle-shaped structure as the result of a converging flow (the clumpy sickle phase) and

(iii) a filamentary phase caused by a rapidly varying optical depth along the sickle (see Fig. 3).

Depending on its column density, the clump will either be completely pushed outwards or its

central (highest column density) parts move inwards, while its diffuse outer regions are pushed

outwards by radiation pressure effects. A stationary state cannot be found. The general

dynam-ical evolution of the cloud can approximately be described by a simple analytdynam-ical model. The

corresponding paper has recently been submitted to MNRAS (Schartmann, Krause & Burkert

2011).