Direct imaging of AGN jets and black hole vicinity Tiziana Venturi [email protected] Active...

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Direct imaging of AGN jets and black hole vicinity Tiziana Venturi [email protected] Active Galactic Nuclei 9 Ferrara, 27.05.2010

Transcript of Direct imaging of AGN jets and black hole vicinity Tiziana Venturi [email protected] Active...

Page 1: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Direct imaging of AGN jets and black hole vicinity

Tiziana Venturi

[email protected]

Active Galactic Nuclei 9 Ferrara, 27.05.2010

Page 2: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Radio VLBI as the most direct way to look into the inner regions of AGNs

Knowledge of the inner jets in AGN even more relevant these days due to the current γ-ray observatories: true simultaneous radio/γ-ray studies of correlated variability, essential to locate the γ-ray emission.

Current hot VLBI studies of AGNs

- Simultaneous radio/γ –ray monitoring (radio imaging) of flaring blazars

- The very faint Universe: low power nearby AGN (see Giroletti) & powerful high-z quasars

z=0.01 -> 1 mas = 0.2 pcz=0.1 -> 1 mas = 1.8 pcz=2 -> 1 mas = 8 pc

Page 3: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Unified view of Radio Loud AGNLow power

FR I and BL Lacs

High power

FR II and FSRQ

Unification models (Orr & Browne 1982; Urry & Padovani 1995) successfully tested in the radio band for the two power ranges : viewing angles and intrinsic relativistic speeds at the jet base

Page 4: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

AGNs all very similar from a morphological point of view when looked on the parsec-scale: mostly core-dominated with an asymmetric jet, regardless of the classification (radio galaxies, BL Lacs, FSRQ)

Orientation and relativistic velocities at the jet base

Markarian 421 – Blue BL BL Lac – Red BL 3C454.3 - FSRQ

Cygn A - FRIIM87 - FRI

Images from MOJAVE at 15GHz

Mkn 421

BL Lac

3C454.3

M87 Cygnus A

Page 5: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Sample of low/intermediate power radio galaxies

(Giovannini et al. 2001)

Sample of neraby BLLacs

(Giroletti et al. 2004)

Consistency in the distribution of Lorentz factors

Page 6: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Sample of low power radio galaxies (Giovannini et al. 2001)

Sample of nearby BLLacs

(Giroletti et al. 2004)

Distribution of viewing angles consistent with the idea that the two classes of radio sources belong to the same population of objects seen under differentangles to the line of sight

Page 7: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

The nuclear radio properties of highly beamed sources

The Blazar World

When we look at the powerful radio sources aligned at small angles to the line of sight, the most extreme properties are found:

- Strong flux density variability

- Morphological changes implying superluminal speeds

- Instabilities in the radio jet

Observer

Page 8: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Flux density variability

Venturi et al. 2001 & 2003

Expanding cloud of relativistic electrons initially thick at some frequencies and viewed very close to the line of sight

Page 9: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

PKS 1510-089HPRQ; z=0.36βapp= 23.76c

2200+420BLLac; z=0.0686βapp= 10.57c

1995 - 2010 1995 - 2010 1995 - 2010

3C454.3HPRQ; z=0.859βapp= 14.19c

Structural variability and superluminal motion

Favourable viewing angle and high intrinsic speed of the radio emitting plasma, lead to superluminal proper motion

Polarization and total intensity movies from MOJAVE

Page 10: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

3C279 VLBA 43GHz

HPRQ, z=0.536

βapp = 20.57c

Radio galaxy, z=0.033

βapp = 5.43

Page 11: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Current studies. I. Statistics from the MOJAVE survey

The sample & the project

- Nearly 300 compact AGN in the Northern Sky, 135 of which form a complete flux density limited sample (δ > -20o, S2cm > 1.5 Jy at any epoch between 1994 and 2004)

- Monitoring carried out with the VLBA at 2 cm starting from 1994

- Statistical analysis made on the basis of the original sample:

135 sources

526 separate features in 127 jets (no speed measurements for 8 sources)

database consisting of 2424 images

Ideal band: high angular resolution, very good image sensitivity and better reliability compared to BU monitoring

Page 12: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Analysis carried out for BL Lacs, FSRQ and radio galaxies separately (Lister et al. 2009)

Fastest component moving at 50.6c and interpreted as the upper end of the AGN jet Lorentz factor distribution

Peak at ~ 10c

Apparent velocity vs redshift: the distribution is not the result of observational limitations

Page 13: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Locus of (βapp,L) for sources with γ=32 and

L=1025 W/Hz

VLBA observational limit set at S=0.5 Jy and μ=4 mas/yr

Radio galaxies BL Lacs Quasars

Page 14: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Before the advent of AGILE, FERMI and ground-based new VHE observatories,only a handful of simultaneous multiband campaign carried out on the best known blazars (i.e. 3C279, Mrk 421 …) with

a variety of results (Hartmann et al. 2001; Blazejowski et al. 2005), or a posteriori correlations (Jorstad et al. 2001)

Current studies. II. Simultaneous radio/γ-ray monitoring with VLBI imaging

radio

γ-ray

γ-ray flare

Superluminal ejection

Page 15: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

PKS 1510-089 (Marscher et al. 2010)

VLBA 43 GHz monitoring & Fermi LAT and AGILE observations

Optical and γ-ray flares in good coincidence

Rotation of the optical polarization vector

2 new superluminal features with speeds of

24±2 c and 21.6±0.6 c

Multiband observations interpreted as a single

feature (seen as superluminal) moving

through a helical magnetic field in the jet acceleration

zone

Page 16: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

3C454.3 (Vercellone et al. 2010)

VLBA 15 GHz monitoring & AGILE observations

15 GHz - 7 Aug 2007

Total flux density increase due to the radio core (component C)Flux density of the main jet components stable or decreasingNo proper motion along the jetNo birth of new components so farFrom the core variability at 43 GHz it was derived that the source is viewed at θ~1.5° and that Γ~20

Flares in the optical and γ-ray band

Slow monotonic flux density increase at radio wavelengths

Page 17: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

The case of M87 (Giroletti et al. 2010)

Coordinated radio-VHE (VERITAS) observational campaign

VHE flares on 9/2/2010 and April 2010

Second radio galaxy, beyond 3C84, detected at high energies

Page 18: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

ATel #2431 – VHE flare on 9 Feb 2010eVLBI monitoring – 2 epochs before the flare and 4 during and after the flare

Inner jet HST-1

Evidence for flux density increase at the jet base (~10%) and continued proper motion in HST-1 with vapp~7c

Page 19: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

VLBI results:• EVN detection rate 100% at 1.6 GHz (top row) as well as at 5 GHz

(bottom row)(the sample was not selected on flat radio spectrum!) • Compact sources, but 4 out of 5 have steep spectrum (α~-0.6) on this

scale

Current studies. III. VLBI Imaging of high-z quasars - Frey et al.

High-z radio quasars with available SDSS spectroscopy

Sample selection: z>4.5; compact on FIRST with

8.8 mJy < S1.4GHz <28.8 mJy

z=4.92

α=-0.60

z=5.01

α=-0.58

z=4.73

α=-0.55

z=4.87

α=-0.58

Page 20: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Main current ground VLBI facilities

VLBA (δ≥ -30o) : 327 MHz - 43 GHz, 512 Mbps www.nrao.edu

GMVA (δ≥ -30o ): up to 86 GHz

LBA (southern hemisphere): up to 22 GHz

European VLBI Network (δ ≥ -10o): 1.4- 22 GHz, 1 Gbps

e-EVN, more flexible and more frequent than EVN

www.evlbi.org

Major support provided to new users by the JIVE staff

Page 21: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Future Space VLBI missions

Space Radio Telescope – 2011 327 MHz, 1.6, 4.8, 15-22 GHz www.asc.rssi.ru/radioastron/news/news.html

ASTRO-G – 2014 www.vsop.iasa.ac.jp/vsop2

Dual Pol. – 8.4, 22, 43 GHz

sub-mas to μas resolutions from 327 MHz to 43 GHz

Page 22: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Final Considerations

VLBI is the only way to directly image the central regions in AGNs

The present performances and flexibility of VLBI and e-EVN make AGN cores and jets and very faint AGN the most targeted sources these days

The new space and ground-based high energy observatories have revived the interest in the study of the inner regions in powerful radio galaxies: monitoring of large samples are the current approach

Page 23: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Current radio programs - I. Imaging Monitoring

MOJAVE

Imaging + monitoring survey (~200 sources) – VLBA @15 GHz

TANAMI

southern monitoring of blazars (~80 sources) – LBA @ 8.4 & 22 GHz

BU Blazar Group

22 & 43 GHz VLBA imaging monitoring of ~ 20 sources

VIPS

VLBI Imaging and Polarimetry Survey, VLBA@5 GHz, ~1200 sources

USNO-RRFID

Database of geodetic observations at 2.3/8.4 GHz and 22 GHz

DXRBS

EVN observations at 5 GHz of ~ 100 sources from the DXRBS sample

Page 24: Direct imaging of AGN jets and black hole vicinity Tiziana Venturi tventuri@ira.inaf.it Active Galactic Nuclei 9 Ferrara, 27.05.2010.

Current radio programs - II. Single dish monitoring

UMRAO

UMich Radio Observatory, full polarization long term monitoring at 4.8, 8.4, 15 GHz of ~ 50 bright sources

Ratan

monitoring survey of ~ 700 bright sources

Metsahovi

long term monitoring (~ 100 sources) @ 22 & 37 GHz

OVRO

daily monitoring of ~ 1000 sources @ 15 GHz

FGamma

Eb (11cm to mm)/IRAM (1,2,3 mm) simultaneous monitoring

Medicina and Noto

Monthly monitoring of ~ 30 sources at 5, 8.4 and 22 GHz