Reverberation mapping of
3C390.3
Pasquale Galianni
SUPA/School of Physics &Astronomy, the University of St. Andrews
Common properties of AGNs
Luminosity: AGNs are the most powerful persistent
sources of radiation in the Universe. The brightest
AGNs have luminosities Lagn > 1012 Lsun
★
Broad continuum: AGNs emit radiation over the
whole spectrum, from radio waves to hard X-rays
★
★ Strong
(EW~30-80 Å) and broad (102-103 km/s)
emission lines
★ Presence
of relativistic jets
Reverberation Mapping of 3C390.3
2/11
Unified model of AGNs
≈10 light days
< 10-­‐8 ‘’ at 3C273 distance
With the reverberation mapping
technique we can substitute
temporal to spatial resolution to
probe AGNs inner regions.
Reverberation Mapping of 3C390.3
3/11
Reverberation mapping
The light from the central source propagate in the surrounding environment, and can
be reprocessed by the disk, the BLR and the Torus.
Time delay τ ≈ (1+z)r/c due to the light travel time to the reprocessing zone
(a few light days for disk reprocessing, weeks or months for the BLR and the Torus).
Disk: τ between light curves in different optical bands (for example B and R)
BLR: τ between continuum and emission lines (for example Hβ)
Torus: τ between optical and IR light curves
Reverberation Mapping of 3C390.3
4/11
Disk reverberation at a glance
Reverberation Mapping of 3C390.3
5/11
Our project
AIM:
use disk reverberation to measure the distances of Type 1 AGNs.
Pros of disk reverberation:
★ Short time delays: 1-2 days to <10 days at high z
★ Can use smaller telescopes: Wider bands (B,V,R) = more flux
★ Simple physics (thin accretion disk model)
Cons:
★ Needs hi-cadence monitoring (can be ensured using robotic telescopes)
★ Sensitive to galaxy contamination (can be accounted for)
Reverberation Mapping of 3C390.3
6/11
Disk vs EM lines for cosmology
Hβ reverberation results for 38 AGNs
(Watson, Denney & Vestergaard 2012).
Reverberation Mapping of 3C390.3
Disk reverberation results (Cackett, Horne &
Winkler 2007).
7/11
3C390.3 basic facts
Bright and nearby BLRG in Draco
One of the best observed AGN
Highly variable (10 yrs to 1 day)
Huge radio lobes and X-ray jets
Double peaked EM lines
3C390.3 is one of the 12 targets that we are observing in optical with
LT/FTN and in IR with Spitzer (D. Axon PI) to study the structure of
AGN tori (next talk by B. Vasquez).
Reverberation Mapping of 3C390.3
8/11
Multi band optical/IR observations
Reverberation Mapping of 3C390.3
9/11
τ measurements
τ(B-V)=0.5(1) d
τ(B-R)=1.0(1) d
Reverberation Mapping of 3C390.3
10/11
FINAL REMARKS
➤ Disk reverberation is a promising technique potentially useful
to constrain cosmology.
➤ Our results show that sub-day time delays can be measured given
sufficient cadence and photometric accuracy.
➤ Time delays between 3C390.3 BVR light curves can be
accounted for by a simple thin accretion disk model
Reverberation Mapping of 3C390.3
11/11
THANK YOU!