Daniel AsmusPoshak Gandhi

Sebastian F. HönigAlain Smette

Wolfgang J. Duschl

Santiago 2012

MID-INFRARED PROPERTIESOF LOCAL

ACTIVE GALACTIC NUCLEI

Types of nuclear activity

B. Keel

Types of nuclear activity

B. Keel

NASA

Type 1 AGN

Type 2 AGN

AGN in the mid-infrared

VISIR manual

AGN N-band SED

Spitzer/IRS (~0.8m) Hernán-Caballero & Hatziminaoglou (2011)

Aver. Sy 1 Aver. Sy 2

AGN N-band SED

Spitzer/IRS (~0.8m) Hernán-Caballero & Hatziminaoglou (2011)

PAH silicate PAH [NeII] PAH silicate PAH [NeII]

Aver. Sy 1 Aver. Sy 2

Importance of angular resolution in the MIR

Spitzer/IRS (~0.8m) versus VLT/VISIR (~8m)Hernán-Caballero & Hatziminaoglou (2011) and Hönig et al. (2010)

PAH silicate PAH [NeII] PAH silicate PAH [NeII]

Aver. Sy 1 Aver. Sy 2

“continuum”

The MIR--X-ray luminosity correlation● Strong correlation

– (e.g. Gandhi et al. 2009)

● No noticeable dependence on object type!

Gandhi et al. 2009

LINERType 1 AGN (other)Type 2 AGN (other)

absorption-corr. X-ray luminosity

obse

rve d

MIR

lum

inos

ity

Open issues

● Sample not uniform or complete in any sense→ extend study to such a sample

● Possible trend of MIR excess for log L2-10keV < 41.5

→ real?→ enlarge coverage at lowest luminosities

Gandhi et al. 2009

Structure of the talk

Low-luminosity AGN BAT AGN

High-res.Photometry

High-res.Photometry

Non-AGN Contamination

MIR SED

M 87

NGC 4261NGC 1097

M 104 Sombrero

Low-luminosity AGN

MIR emission sources in LLAGN

The LLAGN programme● Goals:

– Investigate existence of obscuring tori around LLAGN– Test apparent deviation of MIR--X-ray relation at low L

● Estimate contamination by star-formation

The LLAGN programme● Goals:

– Investigate existence of obscuring tori around LLAGN– Test apparent deviation of MIR--X-ray relation at low L

● Estimate contamination by star-formation

● Method: photometry at highest available angular resolution – in 2 narrow-band filters (12μm continuum and PAH at 11.3μm)

● Samples: <D> ~ 20 Mpc, <r0> ~ 40 pc, <log L

X> ~ 40.8

– Southern hemisphere - VLT/VISIR ● Observed in 2009● 11 new LLAGN

(+7 with additional data) ● Mixed properties

The LLAGN programme● Goals:

– Investigate existence of obscuring tori around LLAGN– Test apparent deviation of MIR--X-ray relation at low L

● Estimate contamination by star-formation

● Method: photometry at highest available angular resolution – in 2 narrow-band filters (12μm continuum and PAH at 11.3μm)

● Samples: <D> ~ 20 Mpc, <r0> ~ 40 pc, <log L

X> ~ 40.8

– Southern hemisphere - VLT/VISIR ● Observed in 2009● 11 new LLAGN

(+7 with additional data) ● Mixed properties

– Northern hemisphere - Gemini/Michelle● Observed in 2010● 15 LL-Seyferts from Palomar Sample

(Ho et al. 1997)● 13 observed (but not all in both filters)

Results: Photometry

● 18 detections (out of 31)

– Point-like – No evidence for

extended emission

● 13 non-detections– One reason:

high uncertainty in L

X

● Add 7 objects from the archive

→ total of 25 detected LLAGN

smoothed

DE

C o

f fse

t [“

]

Ra offset [“]

PAH continuum PAH continuumGemini/Michelle VLT/VISIR

Comparison to Spitzer/IRS

Solid line: Spitzer/IRS Red points: VISIR photometry

Comparison to Spitzer/IRS

Solid line: Spitzer/IRS Red points: VISIR photometry

For LLAGN: 0.4” ≠ 4”-scale

Maximum SF contamination

Spitzer/IRS VISIR photometry maximum SF contribution

● Scale the SF template by the PAH 11.3μm from the IRS of the LLAGN→ maximum of SF contribution (to 12μm)

>75%(4)

>75%(4)

50 - 75%(6)

50 - 75%(6)

25 - 50%(4)

25 - 50%(4)

<25%(10)

<25%(10)

Maximum SF contamination

Spitzer/IRS VISIR photometry maximum SF contribution

● Scale the SF template by the PAH 11.3μm from the IRS of the LLAGN→ maximum of SF contribution (to 12μm)

● For the 24 detected LLAGN with IRS:

>75%(4)

>75%(4)

50 - 75%(6)

50 - 75%(6)

25 - 50%(4)

25 - 50%(4)

<25%(10)

<25%(10)

Maximum SF contamination

Spitzer/IRS VISIR photometry maximum SF contribution

● Scale the SF template by the PAH 11.3μm from the IRS of the LLAGN→ maximum of SF contribution (to 12μm)

● For the 24 detected LLAGN with IRS:

→ Star formation is weak at 0.4”-scale in most LLAGN

(if PAH remains a valid tracer...)

Structure of the talk

Low-luminosity AGN BAT AGN

High-res.Photometry

High-res.Photometry

Non-AGN Contamination

MIR SED

BAT AGN

The “BAT AGN”

Credit: NASA

Swift/BAT AGN observations● Swift

– Launched 2004– Gamma-ray burst hunter– 3 instruments:

● UVOT (UV & optical, 170-650 nm)● XRT (X-ray, 0.2-10keV) ● BAT (gamma-ray, 14-195 keV)

● Hardest X-rays (>20keV) are absorbed only in the Compton-thick case

→ BAT is well-suited for unbiased AGN searches

Credit: NASA

Swift/BAT AGN observations● Swift

– Launched 2004– Gamma-ray burst hunter– 3 instruments:

● UVOT (UV & optical, 170-650 nm)● XRT (X-ray, 0.2-10keV) ● BAT (gamma-ray, 14-195 keV)

● Hardest X-rays (>20keV) are absorbed only in the Compton-thick case

→ BAT is well-suited for unbiased AGN searches

Credit: NASA

Unbiased, flux-limited, complete, all-sky sample of 104 AGN (Tueller et al. 2008, Winter et al. 2009)

Swift/BAT AGN observations● Swift

– Launched 2004– Gamma-ray burst hunter– 3 instruments:

● UVOT (UV & optical, 170-650 nm)● XRT (X-ray, 0.2-10keV) ● BAT (gamma-ray, 14-195 keV)

● Hardest X-rays (>20keV) are absorbed only in the Compton-thick case

→ BAT is well-suited for unbiased AGN searches

Credit: NASA

We observed 77 of the 104 BAT AGN (high-res MIR photometry)

Unbiased, flux-limited, complete, all-sky sample of 104 AGN (Tueller et al. 2008, Winter et al. 2009)

Results: MIR imaging

● 75 of 77 detected – Point-like – mostly no evidence for extended

emission (except NGC 6240)

● Star formation (PAH) weak in majority of BAT AGN at 0.4”-scale

silicate PAH continuum

Results: average MIR SED

Type 1Type 2

Silicate in emission in type 1 & in absorption for type 2 AGN

Results: average MIR SED

Comparison to:- - - clumpy torus models (Hönig &

Kishimoto 2010)

Type 1Type 2

Silicate in emission in type 1 & in absorption for type 2 AGN

Structure of the talk

Low-luminosity AGN BAT AGN

High-res.Photometry

High-res.Photometry

Non-AGN Contamination

MIR SED

12μm – 2-10keV correlation

(absorption-corrected)

Correlation from Gandhi et al. 09...

● Objects: 42● Spearman Rank:

ρ = 0.88 (log p = -17)

● Power-law fit: log L

MIR ~

(1.00 ±0.08) log LX

Power-law fit to:─── all AGN from G09

12μm – 2-10keV correlation

(absorption-corrected)

Adding the LLAGN...

● Objects: 77● Spearman Rank:

ρ = 0.94 (log p = -30)

● Power-law fit: log L

MIR ~

(1.05 ±0.05) log LX

Power-law fit to:─── all AGN from G09

12μm – 2-10keV correlation

Power-law fit to:─── all AGN from G09─── all AGN

(absorption-corrected)

Adding the BAT AGN...

● Objects: 134● Spearman Rank:

ρ = 0.90 (log p = -42)

● Power-law fit: log L

MIR ~

(1.00 ±0.04) log LX

● Fit depends somewhat on algorithm used

● Correlation dominated by X-ray uncertainties

12μm – 2-10keV correlation

Power-law fit to:─── all AGN from G09─── all AGN

(absorption-corrected)

Adding the BAT AGN...

● Objects: 134● Spearman Rank:

ρ = 0.90 (log p = -42)

● Power-law fit: log L

MIR ~

(1.00 ±0.04) log LX

● Fit depends somewhat on algorithm used

● Correlation dominated by X-ray uncertainties

Correlation applicable to all AGN

Conclusions● High-angular resolution mid-infrared imaging of ~120 local AGN

– Most objects show point-like MIR emission at ~0.4” resolution

● Comparison to Spitzer/IRS spectra– No correlation between MIR properties at 4” and 0.4” scale – Most AGN show weak or absent nuclear PAH emission

→ Nuclear MIR emission contribution due to star formation likely minor

● MIR--X-ray luminosity correlation– Strongest 12μm—2-10keV correlation for all AGN combined (slope ~1)

→ MIR--X-ray correlation valid for all AGN down to LX ~1040 erg/s!

→ fundamental physical connection → uniform structure in all AGN

● Origin of MIR emission in AGN– Results favor dusty obscuring torus...– LLAGN might have additional non-thermal component, e.g., jet...

Future work● Add radio data into the multiwavelength analysis

● For lowest accretion rate objects:– Assemble high spatial resolution IR SEDs and N-band spectroscopy – Model comparisons and SED fitting with various components– Complete Palomar LLAGN

● For all AGN:– Assess importance of CT AGN– Intrinsic indicator comparison– Obtain N-band spectra– Test AGN unification

● ...