Missing Mass Discovered

[CraigS]

Another Oz Astrophysics first from an undergraduate student !

Universe's not-so-missing mass

A Monash student has made a breakthrough in the field of astrophysics, discovering what has until now been described as the Universe's 'missing mass'. Amelia Fraser-McKelvie, working within a team at the Monash School of Physics, conducted a targeted X-ray search for the matter and within just three months found it – or at least some of it.
..
"It was thought from a theoretical viewpoint that there should be about double the amount of matter in the local Universe compared to what was observed. It was predicted that the majority of this missing mass should be located in large-scale cosmic structures called filaments - a bit like thick shoelaces," said Dr Pimbblet.

Astrophysicists also predicted that the mass would be low in density, but high in temperature - approximately one million degrees Celsius. This meant that, in theory, the matter should have been observable at X-ray wavelengths. Amelia Fraser-McKelvie's discovery has proved that prediction correct.

… oh no ! ….

Cheers

[adman (Adam)]

I wouldn't start baking the humble pie just yet !

[CraigS]

Nothing humble in that pie, Adam.

Cheers

[renormalised (Carl)]

Good on her

That's great to see undergrads get in on the action and actually contribute to our knowledge. Should happen more often.

[astroron (Ron)]

Sounds like Joclyne Bell all over again
Well done to her
Cheers

[higginsdj]

So does this signal the death of Dark Energy and Matter?

Cheers

[renormalised (Carl)]

Originally Posted by higginsdj

So does this signal the death of Dark Energy and Matter?

Cheers

No, not by a long shot.

All they have done is added to the baryonic matter content and they'll have to revise the numbers, depending on how much there is. They'll also have to take this into account with the factor of 3 increase in the numbers of late class stars they've discovered recently.

[CraigS]

Take a look at the challenges being faced at present when trying to detect these intergalactic filaments:

- the densities of the structures predicted by models is expected to be in the range of 10^-6 to 10 ^-4 electrons per cubic centimetre.
- the temperatures are in the range of 10 ^5 to 10^7 K
- the path length of the filamentary structures detected to date, are in the order 10-14.6 Mpc in length!

These filaments must be close to infinite conductivity, and thereby resulting in giant intergalactic frozen-in magnetic fields !

What are the key detection methods ?..

Filaments are expected to be detected at X-ray wavelengths via thermal bremmstrahlung emission, although some of the first detections have been made by observing 0.65 keV O line in absorption or emission.
...
Dietrich et al.(2004) used gravitational lensing to detect the surface mass density of a suspected filament between Abell 222 and Abell 223. This detection was backed up by similar detections in the optical and X-ray bands in the same study.

This study used a not-thus-far-used data analysis technique, applied to the 2 degree Field Galaxy Redshift Survey (2dFGRS) and ROSAT All-Sky Survey data.

Why haven’t they been detected before ? ...

Hence, our failure to detect individual filaments of galaxies using current methods is not in conflict with model predictions.
…
The new generation of more sensitive X-ray satellites such as Suzaku and upcoming missions should improve the search for such low-density high-temperature sources as these filaments (e.g. Sato et al 2010). Indeed, Kawahara et al. (2011) have presented evidence for a galaxy group forming at the intersection of several filaments of galaxies from Suzaku observations, and further detections from Suzaku hold much promise in this regard.

Great stuff ! Good on 'em.

Paper here.

Cheers

[higginsdj]

The 'missing mass discovered' title is a little misleading since Dark Matter and Energy were 'invented' to account for the 'missing mass' in the first place!

Cheers

[CraigS]

Originally Posted by higginsdj

So does this signal the death of Dark Energy and Matter?

Cheers

From the paper ..

Significantly, Arag ́on-Calvo, van de Weygaert & Jones (2010) suggest that filaments occupy 10 per cent by volume and 39 per cent by mass of the Universe, although this figure could be as high as 50 per cent (Bond et al. 1996).

I think this refers to the baryonic component of the universe (which is pretty big chunk of the total baryonic mass eh) ?

I think the rough proportions are (today):
- dark matter ~ 23%;
- dark energy ~ 72%
- baryonic ~ 5%

Cheers
PS: Gotta be careful .. these figures account for the mass-energy density of the observable universe only. In the bigger picture of the entire universe, to maintain the correct mass/energy density, they require about 83% DM, with ordinary matter being only about 17%.

[CraigS]

Originally Posted by higginsdj

The 'missing mass discovered' title is a little misleading since Dark Matter and Energy were 'invented' to account for the 'missing mass' in the first place!

Cheers

C'mon David;

The dark matter isn't missing !
Its as real as dark energy !



Cheers

[higginsdj]

My understanding is that baryonic is a measure of what we can see and measure (about 5% of the total predicted mass of the universe) and the rest is 'dark' to account for the 'missing mass' required for physics to work as predicted!

So if we are finding 'missing mass' then this is in addition to the 5% already known. So for the more mass we find, the less the percentage of 'dark' - no?

[renormalised (Carl)]

Originally Posted by CraigS

Take a look at the challenges being faced at present when trying to detect these intergalactic filaments:

- the densities of the structures predicted by models is expected to be in the range of 10^-6 to 10 ^-4 electrons per cubic centimetre.
- the temperatures are in the range of 10 ^5 to 10^7 K
- the path length of the filamentary structures detected to date, are in the order 10-14.6 Mpc in length!

These filaments must be close to infinite conductivity, and thereby resulting in giant intergalactic frozen-in magnetic fields !


Cheers

My God!!!!...don't let the sparkyboys know about this!!!

They'll ignore the rest of the data and zero in on this

[renormalised (Carl)]

Originally Posted by higginsdj

My understanding is that baryonic i sa measure of what we can see and measure (about 5% of the total predicted mass of the universe) and the rest is 'dark' to account for the 'missing mass' required for physics to work as predicted!

So if we are finding 'missing mass' then this is in addition to the 5% already known. So for the mosre mass we find, the less the percentage of 'dark' - no?

That's why I wrote before that they'll have to revise their numbers a bit to account for the new material. It's not going to make a big difference, nor will it substantially change the theory but it will mean more of the ordinary stuff is hanging around.

[astroron (Ron)]

As the detection methods improve I think they will find more and more Baryonic matter.
Carl do you think they are to rigid in their percentages of different matter as New Baryonic matter is being discovered quite ofton now
Cheers

[CraigS]

Originally Posted by renormalised

My God!!!!...don't let the sparkyboys know about this!!!

They'll ignore the rest of the data and zero in on this

Thought you'd like that bit …

They completely refuse to accept near-to infinite conductivity plasma, and frozen-in magnetic fields. (For secret, undisclosed reasons).

But take a look at the temperatures/densities these guys have measured ! If ever there was empirical data supporting primordial, intergalactic frozen-in magnetic fields, I would have thought this was it !?

I'll bet they'll see this article, and spin it in the 'usual' directions, though.

Cheers

[higginsdj]

Alternatively, is this the start of the detection of dark matter? Basically finding matter we were previously unable to see!

[CraigS]

Originally Posted by higginsdj

Alternatively, is this the start of the detection of dark matter? Basically finding matter we were previously unable to see!

Nup !
This stuff was detected in the X-Ray spectrum !
.. Ie: they finally saw it !

'Twasn't dark enough !
(Ie: it emits/interacts in the EM spectrum).


Cheers

[higginsdj]

True, but what constitutes Dark Matter in 'theory' is just a hypothisis - so at the very basic level, anything that we previously could not detect but now can detect could in fact be what was previously known as dark matter!

[renormalised (Carl)]

Originally Posted by astroron

As the detection methods improve I think they will find more and more Baryonic matter.
Carl do you think they are to rigid in their percentages of different matter as New Baryonic matter is being discovered quite ofton now
Cheers

The percentages of baryonic to dark matter to dark energy are pretty fluid. It depends on who you talk to, but the accepted figures are fairly much in line with the theory. If more or less of any of the constituents are accounted for or discounted by theory and observation, they'll just change the figures.