Quasars and
Massive Black Holes
Stephen Fine
Outline
• What is a quasar
• How do we study quasar black holes
• Why do we study quasar black holes
• What are the current difficulties in studying
black holes
• How can we improve on the current situation
What is a quasar?
This is not a quasar
What is a quasar?
This is not a quasar
This is a picture
of a quasar
This is a spectrum
of a quasar
Reverberation mapping
𝒓~𝒄𝝉
Broad-line region
𝒓
Continuum source
𝝉
Reverberation mapping
results: Line stratification
Weaker continuum
Low-ionisation lines
Hβ, MgII…
Broad
Line
Region
Strong continuum
High-ionisation lines
CIV, HeII…
Ionising continuum
source
Reverberation mapping
results: Velocity structure
Solid lines give 𝑣 2 ∝ 𝜏 −1 ∝ 𝑟 −1
Reverberation mapping
results: The r—L relation
SMBH mass estimation
For a virialised system:
𝑀𝐵𝐻
𝑟𝑣
=
𝐺
2
SMBH mass estimation
Reverberation mapping
• Assume the broad-line
region is virialised
• The width of an
emission line gives 𝑣𝐵𝐿𝑅
• 𝑟𝐵𝐿𝑅 is given by the time
lag between continuum
and emission line flux
variations
𝑀𝐵𝐻
𝑟𝑣
=
𝐺
2
SMBH mass estimation
Without reverberation
mapping (single-epoch)
• Assume the broad-line
region is virialised
• The width of an
emission line gives 𝑣𝐵𝐿𝑅
• The radius-luminosity
relation can be used to
get an empirical
estimate of 𝑟𝐵𝐿𝑅
𝑀𝐵𝐻
𝑟𝑣
=
𝐺
2
SMBH mass estimation:
extending to high z
Can’t we do any better?
Standard reverberation
mapping
• Cross correlate continuum and
emission line light curves.
• Requires 10s to 100s of observational
epochs to build up the light curves.
• Extremely observationally expensive.
• For brighter objects the situation is
worse since they have longer
timescales and vary less.
• To date essentially no reverberation
mapping has been performed at z>0.1,
M<-24 or with UV lines.
Stacked reverberation
mapping
emission line
continuum
A first attempt
• We have repeat
spectroscopy from MMT
Hectospec of 368 quasars in
a Pan-STARRS field that is
monitored photometricaly
~weekly
• 100/75 of these have a
good MgII/CIV line in their
spectrum.
• Is this enough to do some
reverberation mapping?
First results:
MgII and CIV
First results:
CIV r-L relation
First results:
CIV r-L relation
Summary
• Until recently we have only been able to
study the most nearby black holes directly.
• Through modern instruments and new
techniques we are pushing out to the
parameter space occupied by the vast
majority of known quasars.
Obligatory last-slide
SKA/MeerKAT reference
• Time-domain astronomy is just now kicking
into gear.
• Time-resolved surveys are current or
coming from the X-ray (e-ROSITA) to
UV/optical/NIR (Pan-STARRS, DES,
Skymapper, LSST).
• Transient/variability surveys are major
science drivers for MeerKAT, ASKAP and
the SKA.
MANY THANKS!