My PhD Research

At a 'new media' in science engagement course that I attended yesterday I was informed about blogging and asked to write about my research (without jargon) in approximately 200 words by Jon Copley (@expeditionlog), here i write my first blog, slightly extending on the 200 word version I cobbled down on the course. I hope this blog will be the first of many in my attempts to engage with all members of the public who wish to know more about astronomy...Here goes...!

Since the re-write I have been told by my dad who has read the original blog that it is not in fact jargon free so the passage below titled My Research Take 1 is the further edited version. It is so hard to write jargon free when you are used to using Jargon...science communication is hard!

Since writing this post back in 2010 I have been again asked by my colleague Pearl John to prepare a few paragraphs on my research...so this attempt is titled My Research Take 2 , this was written in May 2012.
Please do give me feedback on 'Take 2' as I am continually trying to make it as accessible as possible.

My Research Take 2 

The ultimate goal of my research is to better understand the surrounding environment of black holes. Astronomers still do not fully understand AGN and their part, if any, in forming the galaxy it is the centre of.  I did research on the galaxy NGC 4051 which has a supermassive black hole at it's centre. One might think that black holes are a rare thing in our universe but they are actually thought to exist at the centre of all galaxies. The one at the centre of our galaxy, the Milky Way, is very 'quiet' and we only know of its existence by measuring the high speeds of stars at the centre of the galaxy which appear to be orbiting a very massive something. We know it is a black hole and not just a massive something/turtle because physically anything that is 3 times the mass of our Sun could not withstand the forces on the object which result from it being so massive.

The black hole pictured here is not a 'quiet' beast, like the one at the centre of the Milky Way it is  very active, which means matter in the disk of material around the black hole falls in (accretes) inwards, toward the black hole . We think there are large magnetic fields which come out of the 'poles' of the black hole, just like the magnetic field from the poles of our Earth. These magnetic fields are extremely powerful and particles that do not fall into the black hole get accelerated outwards along the magnetic field lines, we see this stream of particles as a jet from the black hole. 

The jets are imaged here using the C array of the Very Large Array(VLA) which is a radio interferometer/telescope in New Mexico, USA . I looked at the centre of the galaxy, NGC 4051, during 2001 every few days to see if the radio core (the darkest part, at the centre of the image) was changing in brightness over time. If the core got brighter over a few days this meant that particles were being injected into the jets at a higher rate than normal. The extended structure shown as contour levels around the core of the galaxy represents the jets that are emitted from the black hole. For my research, I was only interested in the central part of the galaxy because I was not only looking at how the radio brightness at the centre changed but how the X-ray brightness changed. To study the X-rays from NGC 4051 I looked at it with the RXTE X-ray telescope at the same time as I looked with the VLA. I wanted to see if the number of X-rays coming from the core of the galaxy increased when the brightness of the radio increased. An increase in radio and X-ray at a similar time shows there is a relationship between the disc of material around the black hole, which gives out X-rays and the jets which extend from the 'poles' of the black hole, which gives out radio.

The jets from black holes are very mysterious and can extend to sizes far larger than the Milky Way itself, they could be involved in catalysing star formation in nearby galaxies. In fact, we shouldn’t think of black holes as  'monsters'  that gobble every thing up, astronomers are realising that they may actually play a large part in the formation of stars and galaxies in our Universe.

My Research Take 1

My research is about supermassive blackholes. One might think these are a rare in our universe BUT they are actually thought to exist at the centre of ALL galaxies. The one at the centre of our galaxy, the Milky Way, is very 'quiet' and we only know of its existence by measuring the high speeds of stars at the centre of the galaxy which appear to be orbiting a very massive something. We know it is a black hole and not just a massive something/turtle because physically anything that is 3 times the mass of our Sun could not withstand the forces from being so massive...therefore a Black Hole is the only thing it can be.....

...This means our Solar System on the Orion Arm of the Milky Way is slowly rotating around a massive hole.


The black holes (BH) I study are not 'quiet' beasts but instead are very active, they have disks of material around the BH much like the disk of our own Milky Way........the matter in the disk falls in (accretes) onto the BH . From the BH there are large magnetic fields, if you imagine these fields as lines along which particles that do not fall into the BH get accelerated it can help you to understand jets. These 'active' type of BH are officially called Active Galactic Nuclei (AGN). We believe that the large mass of the BH (more than a million times more massive than the Sun!) causes these strong magnetic fields, electron spiral around these fields and do not fall onto BH instead they producing jets . These jets of material come from both the top and bottom of the BH, these jets can extend out so far into the universe, and have lengths which themselves are of the order of the size of the Milky Way itself.


The disc around the BH  emits radiation at X-ray wavelengths and the jets emits at radio wavelengths. To investigate the physics of the AGN we measure the radio brightness and X-ray brightness simultaneously. To detect the X-ray and radio waves we use the X-ray telescope the Rossi X-ray Timing Explorer and the Very Large Array , a radio interferometer in New Mexico, USA respectively. We look at how the light/brightness in X-ray and Radio varies with time and note the time that peaks occur in both curves. We compare the lightcurves and look for time lags i.e. times when X-ray and Radio light might increase at similar times. The time lags between the light curves tell us about material emitted in the disc and in the jet. From this we can deduce information about the physical nature of the blackhole. i.e. if both peak at same time this tells us the disc and jet around the BH are connected and 'know about each other'.


What is particuarly interesting is the relations between jet (radio) and disc (X-ray) brightness/light hold for the smaller blackholes called Galactic Binary BH's (10 times size of sun as opposed to AGN which are a million times as massive). These smaller black holes exist within galaxies, so we can investigate those within our own Milky Way relatively easily. This means we can look at the smaller, closer by blackholes in order to learn more about the supermassive black holes or AGN's. This is particularly useful because even now astronomer know very little about black holes and the jets and disk around them.


The ultimate goal of this research is to better understand the environment of the black hole. Astronomers still do not fully understand AGN and their part, if any, in forming the galaxy it is the centre of. 


Jet's are also very mysterious and can extend to sizes far larger than the Milky Way itself, they could be involved in catalysing star formation in nearby galaxies. Infact, black holes might not be the 'monsters' we are lead to believe they are, they may actually be responsible for alot of galaxy and star formation in our Universe :) .

Centarus A - Galaxy with a super-massive black hole

Being a radio telescope at the Very Large Array, USA