G.GiovanniniDepartment of Physics and Astronomy – Bologna University

&IRA/INAF

with the collaboration of M. Giroletti, K. Hada and M. Orienti (IRA/INAF)

Astrophysics Multifrequency Programs:

AGN properties from gamma-ray & radio observations

66 high-confidence blazars (27 lower confidence)Radiogal.: CenA, 3C111

Now about 1000 gamma-ray AGNAGN -non BLAZARS include radio galaxies

FSRQISP Bl-LacHSP Bl-Lac

< 100 mJy > 100 mJy

BL Lacs FSRQs

8 GHz20 GHz30 GHz

Significant correlation between radio and gamma-ray (e.g., Ackermann et al. 2011, Ghirlanda et al. 2010, Lister et al. 2011, Lindford et al. 2011)

FSRQs on average brighter and apparently more luminous in radio than BL Lacs

(but severe redshift incompleteness)

FSRQs

BL Lacs

Y-ray color (purple) + optical

Background & point sources subtracted From Nils Odegard (GSFC)Abdo et al. 2010 Science, 328, 725

Over ½ of the total >100 MeV observed LAT flux in the lobes

LAT>200 MeV

WMAP20GHz

LAT 2FGL 68% and 95%confidence ellipses on radio images

IC/X-Ray lobes: B 0.4 microG NGC6251 Takeuchi etal.2012 B 1.5 microG in Fornax A Feigelson et al.

Better sensitivity is necessary

See e.g. Meng Su et al. 2012 IAU-GA, JD-6

low energy photon

gamma-ray photon

relativistic electron

Radio and gamma-ray emission in blazars

• synchrotron radio emission originates from relativistic electrons that can upscatter photons to high energy

– some connection between radio and gamma-ray properties is expected!

– observationally, all EGRET AGNs are radio loud, differently from most X-ray QSOs

• the blazar sequence was originally devised on the basis of the radio luminosity

• evidence or not of flux-flux, Lum-Lum correlations is a debated issue

– Stecker et al. (1993), Mücke et al. (1997), Bloom (2008), etc.

– bias, variability, number of sources, etc.

Donato et al. (2001)

Radio/gamma-ray connection in the Fermi era

• Big questions– is there a correlation between radio and gamma-ray flux in AGNs? YES– is it also significant? YES – does it depend on simultaneity? YES– does it depend on blazar type? May be– does it depend on energy band? May be

Many useful resources are available to study the connection between the Gamma-ray and radio emission

-VLBI for milliarcsecond scale resolution imaging, e.g. -through MOJAVE or dedicated monitoring experiment: https://www.physics.purdue.edu/astro/mojave/ - single dish studies, e.g. with the Medicina (5, 8, and 22 GHz) and Noto (43 GHz) radio telescopes

Blazar monitoring at Medicina/Noto● People involved: C. Raiteri, M. Villata, U. Bach, P. Leto, M. Giroletti, M. Orienti, M.

Rossini

● 34 blazars are monitored about once per month at four frequency (up to 43 GHz) since december 2004.

● The new Enhanced Single-dish Control System is in use since late 2011 in Medicina, granting improved sensitivity

● Comparison of radio vs gamma-ray light curve is possible, to assess correlation, time delays etc.

Radio at 4 frequencies – from www3.mpifr-bonn.mpg.de/staff/ubach/bmonit/

Radio (Medicina at 8 GHz) and gamma from 2012 – M. Rossini master thesis

1 mas5 mas

Krichbaum

43 GHz86 GHz

M87 – A well known friendGood resolution

Nearby: 16.7 Mpc

Large black hole mass: ~6X109 Msun

Scale 1 mas = 0.081pc = 140 Rs.

Well studied at all wavelengths from radio to TEV

Walker

core

HST-1

500 pc

A VHE у-ray emitting:

2003-2006 by HESS – variability on time scale of days in high statedata (Aharonian et al. 2006) promising possibility of TeV production it is the nucleus However HST-1: in the X-ray increased by more than a factor 50 2001-2006 with a major flare on 2005

Superluminal motions of radio features in HST-1 (Cheung et al. 2007)

Harris et al. 2009

Why HST-1 ??

Where is the “blazar emission zone” γ-detected AGN?M87 a confusing case:

2005 TeV flare with radio, X-Ray and optical flare of HST-1 Harris et al. 2009

in February 2008 M87 showed a strong VHE у-ray activity: multiple flares, short term variability.HST-1 was in a low state (in X-ray) , decreasing in radioCore in its highest state since 2000 (Acciari et al. 2009)

2010 Feb 10 high flux level at > 100 GeV: MAGIC ATel 2431 Apr. 9 strong flare VERITAS/MAGICNo activity in X-ray, optical, and radio in the Core and in HST-1

VLA A config15 GHz

March 1998

June 2003

23 mJy/beam

4 mJy/beam

HST-1 is detected at all epochsThe two outermost regions move at ~4 c. The motion of a third feature that is detected upstream is more difficult to characterize. The overall position angle of HST-1 has changed during the time of our observations from −65° to −90° (Giroletti et al. 2012).

Our results on the component’s evolution suggest that structural changes at the upstream edge of HST-1 can be related to the VHE events. Giovannini et al. (2011) noted a change in the velocity in HST-1 at the epoch ~2005.5, coincident with the TeV γ-ray activity

all the data are at 1.7GHzthe span is from 2005 Oct to 2009 Jul, every 2~4 months, 17epochs. linear interpolation is used between neighboring epochs (by K. Hada)

CORE LOCATION: approaching the SMBH

Hada et al. 2012, observedM87 at different frequencieswith VLBA. They estimated the core shift because ofdifferent optical depths.

The SMBH is at 14-23 Rs fromthe 43GHz core

Large scale jet direction

New observations with VLBAand the GBT have been obtainedbut not yet scheduled to observeat 86 GHz and to obtain images in the accretion region

INNER JET PROPERTIES: jet launching region

To understand the mechanisms of jet formation it is crucial toknow the jet collimation structure.

Jet: -- conical structure above about 105 Rs (Asada & Nakamura 2012) -- a parabolic collimation z(r) = Kr0.58±0.02 between a few 100s Rs and 105 Rs from the coreNote: HST-1 is at 2 x 105 Rs

Now we are reaching the stage to explore z(r) within ~ 100 Rs

Using Hada et al. data we can investigate the region < 100 Rs (we know the ‘core’ position):

-- Conical shape r0.76 < 100 Rs

INNER JET PROPERTIES: jet launching region

R 0.56±0.03

parabolic

Conical shapeR0.76

Non spinningMax spinning

+

+ 230 GHz VLBIDoeleman et al.2012, circular Gaussian core

conical

Alma+mmVLBI + millimetron & Radioastron VLBI satellite

Thanks to space VLBI with Radioastron

and in the near future to a mm VLBI including ALMA (and millimetron)

we will be able to obtain images likethese but to do real physics we willneed VHE information:spectral and short time variability!

Fermi observations show that the maximum Jet power in blazars is emitted at high energy.

The high variability implies that emitting regions are very small,however we do not know if these regions are at the jet beginning very near to the SMBH, or are compact jet sub-structures at largedistance from the SMBH (> BLR).

To understand physical properties of these regions is crucial to investigate the connection between radio properties and high energy emission:-- time variability comparison-- flux density variability comparison-- high resolution VLBI images of the SMBH in comparison with VHE data.

JD-6 at the IAU GA in Bejing (2012):

The Connection between Radio Properties and High EnergyEmission in AGN.

Presentations in: www.ira.inaf.it/meetings/iau2012jd6/Program.html

Thank YouRadioastron launchon 18 July 2011from Baikonur