That's a story.

Our viewers where

you are what you're

this is not for

the poor man very

you know that he is
a really excellent black or

actually we was actually brought
back recently in France but

you know that was thank you
very much to Mark plant.

And thanks for the invite to come and

speak to it's been a great day visiting
Georgia Tech my first time here and

it really is a wonderful campus of
The Great to speak to a number of you.

So I want to tell you today about the work
we've been doing over the past few years

on black holes and Black Hole spin and
this is going to be largely

an observational talk and no there'll
be some some more theoretical topics we

have to touch on at the beginning so that
you become convinced I'm actually doing

something meaningful to me because
I don't that's a good pointer.

OK let me begin by just
outlining my collaborators

this list of collaborators Also I
want to flag in particular and

loafing is my current
graduate student who has done

quite a bit of the work I'll be showing
you also Laura Brennaman is my former

grad student history is now at the harvest
Missoni in Center for Astrophysics.

She's also been very important in a lot
of the work I'll be talking about so

I'll start off by telling you
about black hole spin and

you know why we should care about black
hole spin you know white white and

why we should care about black holes much
we care about black holes spin and then

I want to start telling you about
the theoretical basis for measurements of

black hole space you know black holes are
perfect spherical black objects so they

actually can be quite challenging to the
Tech where the one of them is spinning or

not and I want to tell you about how we go
about actually trying to detect that spin.

And then I'll actually show
you the results we have and

in particular I'm going to show you case
studies from a big project that we've been

executing this is awkward
here in Spin survey and

I'll wrap up with you know putting things
together and try and tell you some of

the actual physical implications of
the results that we have to date.

So why should we care
about black hole spin.

Well we can answer that both as
physicists and also after the system.

So as as physicists black holes
are one of the ultimate means for

studying strong field gravity for

studying gravitational fields
in the very very strong and

that we have no hair theorem or generative
A-T. no health or a general to it.

He tells us that a black hole especially
a black hole is isolated by itself

in the middle of.

Of space is completely
described by just three

numbers they got a mass
a charge in the spin.

And basically these are just the three
quantities that you know macroscopic we

conserved as the collapsing object
is forming as a black hole.

Now physically we believe
that charge is irrelevant

because if you if we were to somehow
form a very strongly charged black hole.

All that in any realistic ash physical
environment is plasma around and

would very quickly pull opposite
charges out of the surroundings and

will discharge the black hole.

So in practice we believe the ash
visible black holes are described just

by their mass and by their spin and
the mathematical description of.

Of that space time is
the is the Kermit trick.

So I'm talking about isolated black holes

right now this there's a lot
of fabulous work done here for

example on merging black holes and
in the history of merging black holes

the space time can get much more
interesting and become very dynamic all.

And it's not described by the current
metric of these isolated black holes

the curve metrics that ascription.

So if we want to actually use black holes
as a laborious these isolated black holes

as a laboratory for
studying strong field gravity.

Then the most direct way of doing
this is we find a black hole

we measure its mass we measure its spin.

And if G.R. is correct.

We now know everything about
that black hole in your predict

the motion of particles around they're all
pretty color caught other quantities and

we can compare that to the observations
and look at the relations from.

From G.R. So that's the sort of
the physicist answer of why we care about

black hole spin actually physically and
I'm Asheville's this.

This thing excites me
most as to physically.

Black Hole spin is important for a couple
of distinct reasons one is a black holes

are black holes spin is a potentially
very important source of energy.

And in we have these systems here.

This is a picture of the radio galaxy and
maybe seven this is a radio picture

of a nearby galaxy and at the center
of the galaxy which is there.

We have we believe a six billion
solar mass black hole and

it's generating a pair of jets.

And we see those jets
principly in the radio but

in fact in this object
we see them across the.

All it might expect from and
those jets are inflating

in this object they get the Jets
propagate out several killer past six.

So maybe about ten thousand light
years before inflating this giant low.

We only see one jets because
we see the approaching

jet because relativistic
beaming roast aberration.

We believe there is actually an object
going the other way which we don't see

because the radiation is being beamed
away from us what powers these

jets the huge amount of energy
coming out of these jets and

in fact a whole other talk I could give is
what we believe is enough energy coming

out of these jets to actually impact the
evolution of the galaxy by many ways who

believe the galaxies the evolution
of galaxies such as early as seven

are actually truncated actually
controlled by that black hole.

So there's a huge wave
energy coming out here.

What I mean Joyce is that jets
that jets one of the basic ideas.

That's in play today is that that
jet is powered by black hospital.

So black or spin is important for
systems such as this one way to quantify

these jetted a these jetted black
holes I just to show you example

of is in this kind of plot I show you
now I'm going to show it later on.

As well.

So we can plot for
example the accretion rates going down

into the black hole just a measure of
how much material is falling in and

we put it in dimensionless units with the
ratio it to the so-called Edington rate.

And we can plot that against
a radio loudness which is

operationally is the radio live
not see of the of the system

divided by in this case
the optical luminosity the system.

But it's a measure of how much power is
coming out in those jets and we find that.

The things since massive black holes
are talking about divide into two general

categories as two tracks on this plot
here and it's been a long stand.

Question Why are there
these two classes of

of active galaxies the two
classes of A.G.M..

And one of the standard ideas
the so-called spinning paradigm is that

these objects are rapidly spinning black
holes these objects are slogan black holes

that nature produces slowly spinning and
rapidly spinning black holes and

that dictates what you have one of these
powerful radio sources with strong jets or

when you don't have.

The final reason why Black Hostin
is interesting is that

spin is a fossil record of
how the black hole formed.

And black hole formation is is an issue of
greatest risk when first in particular.

Again if we look at super massive black
holes in the centers of galaxies.

It's a profound mystery is how
those black holes got there.

Their One possibility is that back
in the early universe there were

you know wholesale collapse of of
saying hundred thousand solar masses of

gas that form the black hole.

It could have been formed from
early generations of stars it's

a family history as to how those because
what they are and then how they for

how they grew so
the spin rate of black holes today

is a is a fossil record of how
the black hole actually grew.

It records where the black hole grew in.

Sort of monolithic accretion
events where you took.

A large scale accretion disk and let it
feed into the black hole that was spinning

up or whether the black hole forms through
your randomly align mergers that would

lead to a slow spinning like hole so black
or spinning is a is a record of that.

And just to show your plot
from mater voluntary and

collaborators that illustrates
this we see in this calculation.

The spin distribution of black holes so

these are histogram showing the spin rate
of a model population of black holes.

Versus different assumptions for
how the black holes group.

So in the picture where.

Today's black hole's group purely through
mergers of small black holes created

early times versus a picture
where accretion from

immigration desks was an important source
of growth and you see that in the creation

picture you end up with a population
very rapidly spinning black holes.

Whereas in the merger picture not much
more modestly spinning black holes.

Now just to orient you and many of you
know this already but on this plot.

I put this you're a parameter this and

I told you this is the spin
of the black hole.

What actually is this quantity.

It's this so.

This is a so-called dimension
the spin parameter the black hole.

J is the actual angular
momentum of the black hole and

all we've done here is taken the anger
meant when the black hole and

put it in the obvious to
mention the seen it is.

And it involves dividing it by two
powers of the Massey Energy in and

multiplying by C.

And G R tells us that for this to be an
honest to goodness black hole meaning it

must have been horizon has been promised
must be between minus one and one.

OK so that's why we should
care about black holes spin.

How do we actually go about
measuring the black hole spent.

So this is a just a fairly old
movie now just to give you a vision

impression of what a creating a black hole
might look like if you could actually sort

of sit near it and and
look at what you're seeing here is

the turbulence accretion disk that
orbiting around the black hole.

And of course there's a black
hole in the middle here.

But the important thing
to recognize in this.

In this simulation isn't what you
see is a black hole here is not

actually the black hole the black hole is
a rather small object sits inside of here.

What you're seeing here.

Is the point where the Creation desk stops
all butting in a dissipative manner and

then just conservatively plunges into
the black hole you're seeing a transition

increase in this where you
commission this goes dark and

then just plunges conservatively into
the black hole that location is called

the innermost table circular orbit and
is just the point where G.R. predicts

that circular orbits become unstable no
Newtonian gravity any circular orbit is

stable you perturb it a little bit and you
just have a slight perturb circular orbit.

In G.R. within this critical radius.

If you perturb a circular orbit.

Then the party will just
spiral into the black hole.

So you know why and why does.

Why does this matter.

Well it turns out that when going
straight directly from the Kermit trick

the location of this in a stable circular
orbit is a function of black hole spin.

And this is not a paper by.

By James by Dean from seventy two.

And this shows you how the location
of the Isco changes as a front so

this is the spin which
is shows you that for

the non-spinning black holes it's a six
gravitational radial six and to use.

Relativists technology and as you spin
up to maximally spinning black holes.

It goes down to one M..

That's four pro-grade.

Orbits.

If a particle is going retrogrades
to the direction of the black hole

then in fact this is code is bigger and
for

regulate orbits it moves
outwards to about nine and.

Four for activities in Michael's.

So if we can attach some observables
to this Isco the fact that

disco depends upon spin gives us away we
can actually go after the black hole spin.

Observationally.

And so we make this Isco
conjecture that the flow proper.

The creation of this undergo this
distinct change as the creation disk

flows across the Isco in this
basic conjecture is very fried by

the simulations accretion disk and
if that's true.

This transition will actually
leave imprints on the observables

it will increase the efficiency of the
creation desk because you're now getting

deeper into the potential before
the material plunges into the black hole

the characteristic
gravitational redshift of

all of the signatures of all the spectral
Simpsons of the creation this

will be increased because you now close
the black hole because you're getting more

energy out the temperature of
the creationist could be higher.

And if you can measure any
temporal frequencies we

sampled the orbital frequency of
that in a rage that would be higher.

So all these things are in principle
observables the observable I'm going to

use is attached to gravitational Richard.

So that's the sort of the basis
of how we're going to do this.

So now we need some spectral
signatures that we can

try to attach to it so
that in a stable circular orbit and

here's where just your
nature has been kind to us.

So if we look at one of the super
massive black holes in a nearby galaxy.

We find purely Imperatori that it's
a very strong X. ray source X.

rays pouring out of the system matters.

But in fact on the first glance such
a hard thing to understand because

if we just make a model
of the accretion disk

around a black hole and
with some very robust and

simple assumptions we can calculate
the temperature of that creation

Discman turns out to be something
about one hundred thousand kelvin.

And that's a new resource.

That's not an X. ray source.

So when the X. rays come from.

This is where we have to weigh
the hands of the whole bit and

say well you know just as in the case of
the Sun The Sun is also next resource

even though it's only six
thousand cal the black body.

Those X. rays come from a Corona and
they come from this energized

a million degree gas that surrounds
the sun which is heated magnetically.

And radiates thermally in the X. rays.

So somewhere in our system there is enter
there is this highly energized gas or

at least as high enjoys electrons which
we generically refer to as a Corona.

And the other is just represented
by this cloud here and it's

presumably heated magnetically because
creation disk is fundamentally Might it.

Objects and is cooled not thermally but
is a pool from inverse compromise ocean

where it was Constance cattery of photons
through it so this is where the X.

rays come from the X. rays come from
this extended structure that's not

the accretion disk is associated
The question is not the Krishnas and

you know roughly half the X.
rays are produced come straight up and

we observe them because we're up here and

half of them shine back down on
the crease in this and all for

rest the accretion disk failure they
flash the creation disk with with with X.

rays and when you take relatively
cold matter and to an X.

ray astronomer from his have walked
impressions of temperature a case of one

hundred thousand kelvin is cold to others
so when you have hundred thousand held in

gas and
your flash it with with hard X. rays.

There's a lot of almost
neutral elements or not.

Lowly ionized elements in that
gas that will be excited in

the caress you'll get Compton scattering
their clothes off so you get the spectrum

that you get shining back off the Krishnas
called the reflection spectrum.

Using some reflection poorly.

So it's reflection spectrum
that comes off the.

Of the accretion disk.

And because it's in the very sensual
regions of this black hole accretion desk.

We don't see the reflection spectrum as a.

Comes off in the rest frame we see it once
is being strongly affected by Doppler

shift in and by the gravitational Ridge
shipping with ember that's really a thing.

Rafter So this blue spectrum
here this blue model Spectrum

shows just this reflection spectrum
here can volved with the expected

Doppler shift some gravitational
red shifts for a typical system and

in particular what you want to focus on
is in there in the a reflective spectrum.

There's actually a very
powerful emission line.

That's almost isolated by itself here and

it's in a very convenient part of
the spectrum is a six six and a half.

Kaley.

Which is just a place where we have
plenty of X. for telescopes working.

So this is the iron through essence line.

This is the threatens line of.

Of I in the case of present line and
because it's relatively isolated

it produces a nice broad feature in
the spectrum that we can try to.

Try to look for.

OK So operationally what we do well and

we're going to try to take real data and
model pull these effects and.

And try to destroy the black hole spin so
what we do is this is a so

humoristic cartoon of what an A.T.M.
inspection would look like one of these

active galaxies spectrums would look
like all the way from you know some

infrared band optical infrared
band up to hard exercise and

what we see is a big bump here which is
just the black body like Thurman emission

from the creation disk and
then we see this inverse comet and

scattered reduced emissions concentration
tile the comes from this Corona.

And this is the classical X. ray band.

Here.

So if we just zoom in on that classical X.
ray band The important thing of this

is a the underlying X.
ray continuum is pretty much you.

Early A power is pretty
close to a power law.

So it's the operational
that's often how we model it.

So what we're going to do is
we're going to take real data and

then we're going to model it.

Assuming this kind of continuum
this continent ocean continuum

whatever we look outside our galaxy we
have to put the effects of lighting

absorption in we're looking through
some column of gas out of our galaxy.

We usually find these active
galaxies is actually.

Absorption close to the black hole
itself accretion disk have winds for

example that are often looking through
they have the use of photon eyes wins.

So we have to put that in.

And then we have to put in the effects of
this extra reflection I was talking about.

And we often find that almost always
find that there's a reflection

component from a material that's
a long way from the black hole.

Those of you who know about active
galaxies know there's a whole

phenomenology about how active
galaxies look different.

If you're looking at different angles.

Because we think that there are for

example toroid of cold gas surrounding
surrounding the black hole.

And that Taurus will get through.

S..
Just like anything else.

So we often find example a sharp narrow
emission line of the spectrum that

comes from that and then what we want
to do is to put in the accretion

disk component which is this blue
piece and we have to broaden it.

OK so the name of the game for what I'll
be showing you is going to be taking

the best quality A.G.N.
spectral we can best quality

guy special we can and
decomposing it into these pieces and

we're ultimately after doing is
studying this blue piece and

trying to pull out of that in this case
the black hole space but you know we can.

We can study many things from it.

This is just the sort of
drive home the point that

what we're after doing here
is looking at how strong.

These broadening affects our know how

how strongly do I have to broaden
this blue piece to fit the data.

And what we've done here is
just get a particular mission

line just focusing on
the particular mission line and

make models of that mission line
profile as a functional black hole

spins to show that as you go to
more rapidly spinning black holes.

You're just drawing this tile
out on the on the emission line

these missionize have this
characteristic skewed shape and

this is what you get if you have if
you're looking at a disk or intermediate

inclination and you're putting in
the combined effects of Doppler shifts and

gravitational red shifts you get
this very characteristic shape here.

OK So let me show you some real data
showing some real data after after

all that this is just showing you that
you actually see these kind of broadened

skewed line profiles when you look
at a host of relativistic systems.

So this is an example of
a super massive black hole.

This is one of these active
galaxies I'm talking about and

this is the line profile you see.

This is the example for a stellar mass
black hole from a work by by John Miller

and then this is the case for

the neutron stars you also see
these features a neutron stars to.

The lines are narrow in neutron stars
because the potential is not as deep

as around the black hole.

OK And then I think the very recently
this new star which is a brand new

hard experience there actually
also saw the same effect.

This is a hump and
they were galaxy on here.

This is an active galaxy N.G.C.
thirteen sixty five and there.

There is our broad line profile.

You also see this big hump
here in the spectrum.

And just to show you.

That's this hump here.

Which is just Compton scattered X.
rays of beans reflected off the.

Of the disk.

OK so that's now start talking
about black hole spin.

And the situation if you go back
five years or so is that there

was a specially one galaxy with
good enough data we could actually

really chase after the suspects in this
galaxy was M.C.G. Maya six to the fifteen

now this is a remarkable object you
know many of us who have been in this

field have cut our teeth on this object
I mean David has in the past and so on.

I have but it is just one object.

And the.

This is the first object where
these broad lines were discovered

with the Aska satellites
back in ninety five.

This this is this what
the discovery what here.

It was looked at intensively by the X. and
M. satellites the European exercise light

and by this is awkward satellite which
is the current Japanese are like and

again we can characterize these features
and this was the first object where we

really felt we could implement this
sort of scheme that I just laid out

about trying to systematically decompose
all the pieces of the spectrum and go

after a black hole spins so Laura better
than I tried this in in two thousand and

six and
we came up with a very rapid spin for

this object a very rapidly spinning object
spinning greater than point nine eight.

Now this is the formal result strickly
assuming that the disk truncates Appius

go for stocks rapidly spinning black
holes the Isco is almost right

up against the horizon.

OK so.

That a star that formal
assumption may start to go wrong

finite thickness affects might
become relevant in the disk example.

So I think if you go through
some of those arguments.

This limit may reduce to about point nine
to a greater than point nine two but

it still rock is getting back on.

So the problem was there just
weren't enough objects with

with high quality data so.

So in in two thousand eighty S she
thousand in two thousand and nine and.

We proposed for a key project result with
satellite and the idea was to go out and

get a large quantity of data on
about half a dozen more A.G.N.

so we could actually go after spin

in a sample of objects albeit a very small
sample but still a sample of objects.

So this is awkward satellite just for
those of you who aren't on the top where

it is the currently operating X.
ray Japanese.

And Japanese X. ray Observatory.

It's actually a joint Japanese U.S.
collaboration the U.S. provided one of

the key instruments for the satellite
which unfortunately failed to do so.

Integration era but.

But still a go since at times we operated
as a joint Japanese US collaboration and

the key aspect of this is
arc which is crucial for

this work is it has a very broad coverage
of energy back of energy band it.

It has high throughput spectrometers
in The point five to ten K.B.

range and then it has a hard X. ray
detector which operates from about fifteen

up to six hundred K. now if any of the
sources I'm talking about we run out of

photons about fifty K.V. the fancy goes up
six hundred is like here and there but but

still we can get from about twenty five
to fifty K.B. coverage for our objects.

So the idea of the key project was
the target Originally we had six but

in the end we got five.

Nearby A.G.N.

with high enough quality data we can
actually go after spin in those objects.

And we're pretty much just
concluding that project now with as

one objects Mark Herron eight for
one where we've yet to actually.

Fully digest the data we've
digested the data for all of the or

the others missed what would be so
in your summit some results from.

So just to show you sort of the first
result from from that program.

This was a nearby A.G.M.
and you see thirty seven eighty three.

It's in the book all of these are bright
nearby active galaxies and those of those

who study active galaxies these are so
nearby family members that we we know and

love and this will show you
the features in the spectrum.

If you take a spectrum and
just divide it by sort of a completely

familiar to each of the spectrum we
just divide the spectrum by a power law.

We can see the structure
in the spectrum and

this is what we get who is bytes
taken out of spectrum here.

And then we have these features here so
this big bite here

is the absorption I was telling your
powers when we're looking at this object

we're looking at the central X. ray source
which is very close to the black hole.

There's a lot of photo nice
plasma in the way which is

part of the creation disk wind.

We believe and that gives you
this biters the spectrum but

we can model that very accurately and and

take that bite out of spectrum but we
also have this narrow emission line here.

That's what this distance stuff that I was
telling you about this is distant cold and

cereal and
then when we take that out you can see

it's just about seeing the specialist for
the inflection point in the data here.

That's the onset of these.

Red specifically brought in features
that I'm I'm I'm discussing.

So we can we can model especially
in the way that I was describing.

And we can start to see how the.

Black Hole spin affects
the goodness of fit to the data.

So we actually go through.

Used to a formal comparison
of the model with all the.

Opponents fitting freely
to the to the data and

we can for example plot the goodness
of fit parameter the Delta Chi squared

versus spin as you see in this plot.

We prefer rapidly spinning
black hole again.

The different lines here are just for

different modeling assumptions and
different data handling assumptions and

the most conservative one here the green
one is where we just assume we don't trust

anything above anything below three K.B.
which throw all this out.

Assuming that we don't understand anything
about this absorber and you see that even

then we get a weak constraint on
the spin that put it as it does we can.

Just showing all of us if we
take a base in approach and

use Monte Carlo Markov chain methods
to analyze the dataset we can get

a formal probability distribution for
the black hole spend and this shows you

the same thing that the Alice's was
telling you that in this particular object

your push to rapidly spinning black hole
greater than about point eight eight.

I think is the limit.

Now we can we actually use this object
as a test bed to study a lot of our

systematic and I just want to show you
your what we were actually looking at in

the data when we take a non-spinning black
hole model in a spinning black hole model.

This is the best fit to the data and

these are the model components here
if we force in a non-spinning model

force in a non-spinning spectral model we
can see that we produce the residuals to

the fit with this wave and this is what
we're looking at fundamentally what's

going on here is if you force in
a non spinning black hole then these

brought this broadened online feature this
thing in blue is a bit too narrow and

it's sort of overboard fitting the core of
this line commune negative residual here

and under fitting the the wing
giving a pulse of residual here.

So these are uses a very subtle.

Effect it's a few percent.

Either way which is why we
need such high quality data.

Let me skip over that.

OK So moving on.

This is another very well known object is
for all nine another nearby active galaxy

and this one has no absorption so that
this is arguably a slightly cleaner object

and again this is the spectrum ray
showed against a simple power law and

you see that this is again a narrow
mission line from the distant material and

again we see this broad
line start of our four.

For four and a half by the or
so and we can fit this.

And again this is another test case
where we could look at a lot of

the modeling degeneracy S.
We found for example that.

There were narrow emission
lines Juta ionized hydrogen

in the spectrum those hydrogen twenty
five hundred twenty six emission lines.

They were blending with
the blue edge of the.

Broad ion line we're looking at.

So we had to try to figure
out how to disentangle that.

And we did that by taking
multiple POCs of data and

since we believe those ionized
lines are coming from.

An extended region.

They can be assumed to be constant ways of
the elses flittering in flowing around.

So we can disentangle those and

the final number we get here is we
actually get into media spin value.

So this is nice.

It shows that our methodology doesn't
always get was rapidly spinning

black holes.

We actually got an intermediate
value here for the lattice been.

Really time.

So so that's the sort of two radio loud so

I Radio Choir at A.G.N.
where we did during the spin cycle radio

quiet meaning they don't have
those powerful jets members.

Certainly the project by consummate before

was also interesting of course in
the light of what I was telling.

Telling you about with the.

Jet Jet dichotomy to
look at jetted objects.

So one of her really nice examples of
a jet an object is three C one twenty.

This is a very bright A.G.N.
that's quite close by and and

it's quite intensively studied and

there's a there's a very interesting
going phenomenology surrounding it.

Surrounding the saucer.

Involving the physics
of what makes the jet.

So in this source those some some worked
on some seminal work done by Alan Marsh or

and followed up by other members
of his group showing the.

As the source.

Well let's start off with this plot.

So this this this is
this is the bilby I map.

This is a very high resolution
radio map of this object and

what you're seeing here is the jet.

And you are literally
saying blobs in the jet.

That are moving outwards with time
you're See you're seeing distinct.

Shock saw you know some kind

of feature probably a shock in
the jet that's marching out with time.

And as you look over time you can actually
track how a distinct blobs move outwards.

Now interestingly if you just say you
know what's that linear distance here and

how quickly are those
blobs moving outwards.

Right.

They're often moving out superluminal in
the movie are three four five six times

the speed of light and
that's a sort of optical illusion effect

is because you have this thing moving out
towards you almost relativistic speeds or.

It's moving out at relativistic
speeds almost the speed of light and

it's sort of chasing up after
the light that it's sending out.

So it's its apparent separation in the sky
was apparent motion in the sky appears

to be superluminal.

So you.

We have these blobs of the coming out
now interest we can actually track

when these blobs
are generated in the core.

So there's well defined events for

these blobs are generated and
then shot out along the jet.

And we find that when
those blobs are generated

the core radio flux goes
through big flares.

That's what was going on here and
at the same time the X. ray flux crashes.

And the basic interpretation of this

is what's been coined
the jet cycle which is that.

And this is purely a cartoon
of what we think is going on.

There's no physics here
we have an accretion this

around the object which is emitting X.
rays.

There in a regions where many X. rays and

then some process some instability
destroys the in a region of that this.

Just removes it blows it off and
therefore it stops emitting X.

rays and either associated with that
time or very shortly afterwards.

There is an ejection of
energy down the jet.

So it could be at least two steps of the
same thing where the some instability that

triggers a wholesale
injection down the jet and

actually inject the mass of
the inner accretion disk.

And then the Christian disc refills.

And you're back to the stage.

So this explains why there's
a flare in the radio.

This explains why the the the the the jet
strongly reenergizes at

the same time the X. rays crash the X.
was occurring from this.

So in addition to looking
a black hole spin effects

we can actually use our techniques
to probe this because we

can actually probe where the inner
edge of the disk is we don't

have to assume most of the disco we can we
can actually probe with our ears and so

that's what we're doing with with
with three C. warm on twenty.

So this is this is the radio.

So this is the X.
ray like a three C one twenty for me.

Our extremist that.

Right.

And I'll show you here is
the time of a few observations.

This is an ex a member of ration
in two thousand and three.

We actually David published.

And this is a set of says UK
observations from two thousand and

six and then we had a campaign
in two thousand and twelve.

I'll show you in a second.

And.

Nature was beautifully kind to us.

Turns out you go back after the fact that
there were other ejection events as well.

I just put it to relevant ones on here.

There was an objection event very
soon after the X. members of a sion.

And it was an injection event very soon
before as is our course of regimes.

So this gives a beautiful
laboratory to test

these ideas are a sister
just to me around.

So if you do this and

are specific cartoon figure out here but
the numbers are put up are actually based

on this multi component analysis that
I described a few minutes ago we

find that at the time the external
savation you need a very.

Broadened.

Line profile you need an in
a radius of two R G or so.

It pushes you to a to a rapidly spinning
black hole with a creationist It goes

all the way down to go all the way down to
the center so rapidly spinning black hole.

This is awkward situation on the other
hand this time could require

quite a truncated disk with a disk is out
of it you know twelve thirteen R G or so.

So that's nicely kind of very
fine those ideas I will show you.

And then coming up to the moment
campaign came this was us is our

clubs of ation which was a much more
much higher quality spectrum than

the previous are who especially And
we believe there was

an injection event just before
this is the build the new V.L.B.I.

data and we believe there's
an injection of interest before and.

Again we get a truncated Krishna's we
get Krishnas seem to be truncated at but

forty got a patient radio.

So this seems to be nicely
supporting this place objects

like a picture but then also you know from
the point of view of the Earth spins study

it tells of the spin of this object
is his own is directly spinning.

Now this is one example of how sometimes
you need to look at multiple data sets to

be able to tell us going on because if
we just looked at this dataset alone and

saw a diskless truncated quite far out we
would not be of the same thing about spin.

OK what's going on here.

Well we don't really know but

just to share one idea from
a colleague of mine in Maryland.

John McCain me he has
things i'd this idea of so

can manage to clear rested accretion mad
and the idea is that the accretion disk.

These are some.

Relativistic M.H.D.

simulations that Jonathan has been
pursuing the ideas of the creation desk

has basically force fed as much my net IT
field on to the black hole as it can take.

And we're getting a very strong
jet out because of that.

And what happens is that every so

often there's there's an instability and
basically the managing field.

The pressure humanity field is now able to
push its way back out into the creation

desk where the magic pressure
is now comparable to

the gram pressure of the flow.

So the minutes become pushes way back
out into creation this that truncates

essential part of the creation this and
then either with disturbances associated

with doing that or the the sort of re
squeezing of the field back into the black

hole is what could give you a disturbance
that propagates down the damage or.

OK So let me move on to the ash
physical implications for

you and finish off with without
physical education of what's going on.

And there we sort of put all of the
current spin measurements that we have on

the plot so let's say when when we started
this exercise is really only one object we

can do this we put another four
to happens onto this one in this

plot and then in the meantime rest
the community has also been busy and

we have now about twenty objects
which we can with some degree and

you can tell so many are about a large but

with with varying degree of certainty
we can put a black hole spins down.

So this is the mass mass versus spin
plot of the super massive black

holes that we have right now and there's
a few interesting things to note one

is that there certainly are a large number
of black holes that are rapidly spinning.

And this is important because there
is your whole whole discussion in

the literature about whether we would ever
expect any black holes rapidly spinning

because the there
are certainly some authors who

would argue it quite strongly that all
accretion on to suit my supply holes.

Should be this incoherent accretion
where you have small pockets of

matter coming in.

And so that seems to at least
not be true for at least

some black holes in this mass range of
few million solar masses up to a few

tens of millions of masses this into a
rapidly spinning black holes which implies

that there is actually coherent
accretion going on now with with

some degree of uncertainty I would
say is still very preliminary.

It looks like.

As you go to more rapid to more
massive black holes we may be seeing

a new population coming there
maybe a new population of

less rapidly spinning black
holes come in if you sort

of stare is plot it's really all dominated
by two points but you know that point.

Which is.

Yes that point and it's that point
this point here is the fair online

point that I was telling you about this.

So.

And the other big Kaviak on their
switch the astronomers can certainly.

Sympathise with me for
is that the selection affects of

the objects we go into this plot
are almost impossible to quantify

because these are objects
of been studied because

you know they happen to be nearby and
bright but not in a systematic

way we haven't looked at all the brightest
objects yet only be interesting for

some other reason it is very
heterogeneous sample of objects and so

whenever you're trying to make statements
about populations in astrophysics.

It's very dangerous to do that without
very well formed samples but one thing

that is guaranteed is these objects
not selected on some previous bias for

their spin should be because no one
had any previous biases so so so

these were not selected on
previous by spin and so

that gives you some some reason to think
there may be something to the state in

that as you go to more rapidly
them to more massive black holes.

We're starting to pick up some objects and
more moderately spinning.

Doesn't want to show you is coming back
to this spinning like the economy plot.

Well this this and this radio
allow really quite dichotomy plot.

So remember that in this plot.

These are basically
the one jetted objects and

these are the jetted
objects of radio loud.

And the idea was of this talk branch and

main correspond to
rapidly spinning objects.

So I put some of our measurements on here.

The the red balls are the back of
the spinning objects and the this

is blue like the red balls although
the red ball is a slow spinning object and

the blue balls are the rapid
has been the object.

This is going for online.

And we can see that this picture
is falling apart already because

that clearly seems to be no
particular preference for

slowly spinning black holes
down on this lower branch.

That's not to say that so.

Then may not be the ultimate
power source of these jets.

Because hoops.

This is the three she won twenty
point if something doesn't tear up

the spinning object.

So it's not to say the spin may not
be the ultimate power source but

it's not the only thing that determines
whether a source is jetted or

macho attitude and those people
who have studied X. ray binary

in our galaxy have known this fact for
a long time that jets can turn on and off.

For other reasons.

OK So let me come to my conclusions.

So black hole span is an interesting
quantity both infill both from a physicist

point of view but also to nationalise a
point to do as basically it's an important

probe of black hole growth and
also it's important source of energy.

So there is an interesting quantity
to try to pin down and there's

a fairly well developed theoretical
framework for trying to do this.

I have told you about
the so-called your I AM line or

the relativistic reflection technique for
probing spend

those other groups out there for
example the group the space the Harvard.

Who've been looking at the temperature
of the creation desk and for

various technical reasons you
centrally can't do this in

the super massive black holes
I've been telling you about.

But you can actually develop test
this technique quite nicely for

the start of mass black holes and
they have been pursuing that but

ultimately all comes down to this idea of
a transition at the Isco that is giving

the observables a spin dependence.

And so I told you about the observational
status of black hole spins in the super

massive black holes and I think
the most interesting thing right now

is maybe the hint that there is something
there are rapidly spinning black

holes out there and there may be a little
bit there maybe some mass the painless

that's been that's the kind of thing which
we can try to push out as time goes on.

So.
I want to start to you know advertise that

this field is not standing still.

There's a great results coming
down from the new star.

Mission which is so new a new
mission that was just launched and.

Some was involved.

I think I was involved in that and.

Then there's also asteroids
which is a new Japanese U.S.

Observatory which will be a very
capable spectrometer for everything

goes well and will will sort of lift
a lot of these things up to a new level.

So at a point I'll stop there and
take any questions.

Thank you thank you for

what was most likely

you are you know that great.

And then you or

underestimate millions if not all.

Maybe you are there any way

you are a good good question.

So that the first question about
my answer personally Isco this is

this may well be important for
very strong magnetic

fields that would probably
need a sort of super Edington

disk to confine and
women this become super enter the big

the Isco become ceases to sort of
take on a special role anyway so

for the geometrically film
disks that are probably

relevant in the accretion right
injures that our sources inhabit.

Then we don't believe many
think fields will be that

that important but for
setting of the location of the escape.

I mean this is the kind of stuff where he
Jonathan simulations that he is pushing or

more will sort of tell tell
us whether that's true or

not most important thing to do to assess.

So your second question about
about the correctness of G.R..

So if there are alternative models that

push the Isco way out
during pushing out so.

You know beyond ten or twenty.

I think we can we can squeeze those models

that model and I'll turn it over to G.R.
which sort of imprint first or

second order changes on the nature of
the orbits very close to the black hole.

I think we're still not the days we're
still not of the level of being able to.

To to do that and in fact to actually
push on those kind of ideas.

We don't most certainly need to go to
the time resolved work because the problem

is that what I've been showing now these
are time average spectra we've averaged

over many many orbital periods of the in
interest to actually form the spectra.

And so in many ways.

All we have is a.

Sort of the redshift histogram if you
like you know how much of the disk is or

what particular redshift.

And if you break free of G.R. That leaves

a huge degeneracy Now you can imagine
shuffling things in many different ways.

So I think we'd have to go to a time
resolved picture where for example you or

you are following me into orbits of
individual hotspots on the disk and

tracing their spectra evolution
to look at the relations between.

When this.

With Ray again.

Yes So the sixty six K.B. line is sort
of the trail for Essence line of iron.

So you have an eye on ATOM
it could be a neutral.

I now turn and a hard X.
ray from the Corona comes in and

he jacks the in a shell electron Village
X. the shell electron will integrate this

or that as it does so

that then equals two to and it was
warmest in six point four K. but I am

cold I'm never I know
his time is it's higher.

So my understanding of this is go over.

You're making things up like
it was all the way down.

Is there any evidence that it's already or

what would be in the situation
that there's you're not actually.

I guess results.

Yes but

if you are because if you were completely
Ike Gnostic about whether the disk.

Could you know cause the Esko maybe it
could be like one of the half time his God

then the spin measurements where
getting should be treated as

it was lower limits on this but.

What you can do in principle which is
actually what we did in practice with we

see one twenty is look at
a whole slew of data and.

You have a model which allows for

the in a radius to not be of use go but
also of a spin and

the model will essentially lock onto the
period of time when the line is broadest.

And will sort of step that to
be the look that has the spin.

But yes so if if the disk can.

Truncate to one of the hard
disk goes all summer and

these are limits on the on line.

Record of every night here at

all about me my

life after that after.

It is like yeah that's it that's
it that's a really good question.

I spent a lot of time thinking
about this one more like and

I couldn't even really define the RAM
pressure very convenient myself

in the systems we are very
close of the horizon.

I think what actually happens
here is that it's more over

for Brady Taylor like instability
than the really blowing off storage

only into the into the RAM pressure
as more so the fingers of minutes.

It feels can kind of work their way out in
a non axis metric like as much or why but

you know twit also me if
you get your road times.

Will it be squared ro time C.
squared minus put pussy in there and

to be greater than the be squared over
over the pithe and then it can you

can do this it can force it has enough for
pressure in principle to force as well.

But there.
It's I think they're still trying to

understand how from
the assimilation how that happens.

Next.