Reverberation Measurements of the Inner Radius of the Dust Torus in Nearby Seyfert 1 GalaxiesMasahiro Suganuma( National Astronomical Observatory of Japan )Y. Yoshii, T. Minezaki, H. Tomita, T. Aoki, S. Koshida(University of Tokyo)Y. Kobayashi (National Astronomical Observatory of Japan)K. Enya(Japan Aerospace Exploration Agency)B. A. Peterson(Australian National University) with MAGNUM (Multicolor Active Galactic NUclei Monitoring) group:

Introduction: What determine the inner radius of the dust torus ?

Where is the inner border of the dust torus located being compared with other regions of AGNs ?

Principles of dust reverberation method

Monitoring observations and results Simultaneous photometric monitoring in Opt. / NIR Clear lag time detections between V-band var. and K-band var. Discussion

Outline:

Main FocusUrry & Padovani (1995)2. Where is the border located being compared with other regions?1. What determine the inner radius?Sublimation temperature of grains (graphite) = const.-> The radius should to be proportional to L0.5UV Unified scheme of AGNs expect it to be outside of BLR Thermal dust reverberation can resolve the inner border of dust torus by means of differences of flux variations between optical and near-infrared.

Thermal dust reverberation of AGNs.

Monitoring Observation of AGNsLos2-m optical / infrared robotic telescope (since Aug. 2000)Maui IslandTop of Mt. Haleakala (3050m)

First ResultMinezaki et al. (2004) ApJL, 600, 35NGC 4151 Vnuc=15.4mag1242 km/s (3KCMB)

Succeeding resultsDSS R-band image

NGC 4051Vnuc=15.2mag924 km/s (3KCMB)DSS Bj-band image

NGC 3227Vnuc=14.4mag1480 km/s (3KCMB)DSS Bj-band image

NGC 7469Vnuc=14.5mag4521 km/s (3KCMB)DSS R-band image

Lag time vs. Optical LuminosityBefore MAGNUMAfter this work Minezaki et al. (2004) and references therein(nucleus)

Lag time vs. Optical Luminosity with BLR lagsBroad Emission LineNIR(K-band) Broad-emission line lags for objects that also have infrared lags Including Hi & Lo ionization lines)(nucleus)F9: Clavel et al. (+89) Rodriguez-Pascual et al. (+97) Peterson et al. (04)N3783: Reichert et al. (+94) N7469: Wanders et al. (+97) Kriss et al. (00) Collier et al. (+98)N5548: Peterson et al. (02) Krolik et al. (1991) Peterson & Wandel. (+99) Dietrich et al. (+93) Korista et al. (+95)N4151: Clavel et al. (+90) Maoz et al. (+91) Kaspi et al. (+96)N3227: Winge et al. (+95) Onken et al. (03) Shemmer et al. (04)

Supported Picture of Central sub-parsec of Seyfert 1 GalaxiesWithin inner border of dust torusBLR : Dust torus :

SummaryInner radius of the dust torus is determined as being proportional to square root of its central luminosity. Inner border of the dust torus is located near outer border of broad-emission line region (BLR).Lag time measurements between flux variation of V-band and K-band for nearby Seyfert 1 galaxies with MAGNUM telescope cleared that There is tight correlation between optical luminosity and near-infrared lag with t L0.5opt . Near-infrared lags are located on near the upper border of broad-emission line lags on L- t plane.( Suganuma et al. 2006, ApJ 639, 46 )In other words, it could be say that

LUV4r2 4QT4 1500K (UV/ )

(UV/m)

10m

The optical and NIR monitoring observation since Jan. 200183 target objects of Seyfert 1 galaxies and radio-quiet quasars2DF10322-0233, 2DF1138-0131, 2DF12203-0119, 2DF12254-0101, 2DF12474+0025, 2DF13451-0231, 2DF14382-0116, 2QZ1013+0028, 3C120, Akn120, EDR17174+5932, EDR17183+5313, IRAS03450+0055, IRASF21256+0219, KUV08217+4235, L107-351, LBQS00262+0244, LBQS10245-0021, LBQS1029-0047, LBQS13421+0155, MOA2001BLG5, MOA201BLG5, MS02448+1928, MS03574+1046, Mrk110, Mrk335, Mrk509, Mrk590, Mrk744, Mrk79, Mrk817, NGC2403_ulx, NGC3031, NGC3227, NGC4051, NGC4151, NGC4395, NGC4395d1, NGC4395d2, NGC4395d3, NGC4395d4, NGC4639, NGC5548, NGC7469, PG0844p349, PG0953+414, PG1613p658, PHL1070, Q2237+030, RXJ17591p6635, RXJ17595p6645, RXJ17597p6629, RXJ18003+6624, RXJ18003p6615, RXJ18006p6641, RXJ18009p6622, RXJ18012+6624, RXJ18012+6631, RXJ18012p6631, RXJ18015p6632, RXJ2138.2+0112, RXJ2156.7+1426, RXSJ11240+3110, RXSJ13129+2628, S0254+0101, S0257m0027, SDSS13091-0015, SDSS17205+6128, SDSS17230+5400, SDSS17244+6036, SDSS23264-0030, SDSSJ0007-0054, SDSSJ0207-0048, SDSSJ0315+0012, SDSSJ0943-0043, SDSSJ0957-0023, SDSSJ1004p4112, SDSSJ1024-0021, SDSSJ1044+0003, SDSSpJ1204m0021, TON730, mcg08-11-0112005Observation continues until present. 2006

0.01mag

AGN

(U)BV HK NGC 5548

(U)BV HK NGC 4051

(U)BV HK NGC 3227

(U)BV HK NGC 7469

-SED1m

B-V0.0-0.1V vs. B flux vs. flux diagram in the optical

H-K0.9-1.2Black body 1500-1800KK vs. H flux vs. flux diagram in the near-infrared

V,K CCF()

() () Maoz & Netzer 1989; White & Peterson 1994 Peterson et al. 1998

Structure Function SF

Structure Function (SF)SF: Power SpectrumSF +SF

- Ill be talking about recent results of our dust reverberation study for nearby Seyfert1 Galaxies. ~~~~~~~~~~~~~~- This study was collaborated with these members of MAGNUM group.

- This presentation is divided into these four parts. ~~~~~~~~~~~~~~~~~~~~~~~- First for an introduction, Id like to clear our focus of this study.- Second, I will explain the principle of dust reverberation method of observation.- Then, I will present our observations and results.- Finally, Ill discuss about our results from these two points of view.- On this first slide, I will describe our focus of this study. ~~~~~~~~~~~~~~~~~~~~~~~~- This is a schematic viewgraph of AGNs we generally believe.- There seems to exist a dust region with a donuts-like shape around the central engine and broad-emission line region.- However, we havent seen this by spatially resolved images!!

- We break down our focus into two questions. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~- The first question is What determine the inner radius?- And second question is Where is the inner border located being compared with other regions?

- For the first question, if sublimation temperature of dust grains are constant, the inner radius of the torus should be proportional to square-root of UV luminosity of the central engine.- For the second question, unified scheme of AGNs expect it to be outside of the broad-line region.

- To answer for these questions, we use a thermal reverberation technique of observation. ~~~~~~~~~~~~~~~~~~~~~~

- On this second slide, I will explain the principle of thermal dust reverberation of AGNs. ~~~~~~~~~~~~~~~~- This figure shows a typical spectrum shape of type 1 AGNs in optical to near-infrared. ~~~~~~~~~~~~~~- The optical emission, the longer wavelength tail of power-law component, comes from the central engine. - On the other hand, near-infrared emission is thought to be thermally originated from hot dust surrounding the central engine.- The dust grains are irradiated by the central engine up to near their sublimation temperature of about a thousand and hundreds of Kelvin.

- So, if we monitor an AGN in optical and near-infrared simultaneously, we will observe lag time between the variation of them. ~~~~~~~~~~~~- The lag time should correspond to the light-travel time of the inner radius of the dust torus.

- Next, I will briefly present our MAGNUM observatory. ~~~~~~~~~~~~~~~~~- In Hawaiian island of Maui, on the top of Mt. Haleakala, three thousand meters high, we prepared a 2-m optical and infrared robotic telescope that doesnt have any operators or engineers staying in Hawaii. ~~~~~~~~~~~~~- We only watch from Tokyo how the observations are carried out.- We started monitoring observations for several AGNs in two-thousand one.- Now, Ill show you the first result of our observations. ~~~~~~~~~~~~~- This is NGC forty-one fifty-one, a nearby bright Seyfert 1 galaxy.

- This graph shows the observed light curves for V-band and for K-band. ~~~~~~~~~~~~~- The shapes of these two curves are similar, but K-band one delays after V-band one.

- Our cross-correlation analysis measured the lag time to be about forty-eight days. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~- Moving on to the next slide, I will show you the succeeding results for other several objects. ~~~~~~~~~~~~~~~~~~~~~~~~~~- This is NGC fifty-five forty-eight.

- This next graph shows the observed light curves for this object. ~~~~~~~~~~~~~~~~~- If we shift K light curve ahead by about fifty days, these peaks and valleys of two curves coincide with each others. - Next slide is NGC 40 51. ~~~~~~~~~- And these are observed light curves. ~~~~~~~~~~~~~~~~~~~~~~~- We measured the lag time to be ten or twenty days.

- Next is NGC 32 27. ~~~~~~~~~- And these are observed light curves. ~~~~~~~~~~~- We measured the lag time to be about twenty days.

- The final is NGC 74 69. ~~~~~~~~~- And these are observed light curves. ~~~~~~~~~~~- We measured the lag times to be seventy or ninety days.- From here, I will discuss about what our results mean. ~~~~~~~~~~~~~~~~~~~- I will plot our lag time measurements on luminosity vs. lag time diagram. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~- These are lag time measurements reported before our observation. - Before our observation, there have been a few measurements.- Now, I plot our results here.

- There is a tight correlation between lag time and luminosity for a wide luminosity range of Seyfert 1 galaxies. ~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~- The next point we should examine is how large the infrared lags are compared with broad-emission line lags. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~- This is the same diagram with the last slide.- Here, these are lag times for broad emission lines reported for the objects- And I again plot the infrared lags on this diagram.- As you can see, the infrared lags are located on near upper border of broad-emission line lags!- Next, let me describe last two discussions on this schematic viewgraph. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~- Irradiated by the central engine, the inner radius of the dust torus of AGN is determined as being proportional to square-root of its central luminosity.- And, broad-emission line region is within inner border of dust torus- So, to summarize, our dust reverberation observations for nearby type 1 AGNs using MAGNUM telescope cleared these two things. ~~~~~~~~~~~~~- First, there is a tight correlation between optical luminosity and near-infrared lag, with delta t proportional to square root of optical luminosity.- Second, these lags are located on near the ceiling of those of broad-emission lines.

- In other words, we can say these things.

- Please see our recent publication here for details.- Thank you very much. ~~~~~~~~~~~~~~~~summary