Review: Dark dwarfs & the missing satellite problem

Astronomy twitter journal club met for the first time in 2012 last week to discuss the recent discovery of a distant, dark, dwarf galaxy which may help explain the discrepancy between the predicted and observed number of Milky Way satellites.

The original paper can be found here, our preview is here, and the full transcript of the meeting is here.

The meeting was kindly hosted (at short notice, after a minor panic on my part) by Simon from @RHULPhysics. Onto the review…

Simulations

We don’t see enough satellite gals compared to sims. How significant is this paper? Anyone see any problems with it? – @RHULPhysics

doesn’t that mean that simulations are wrong? why is that wrong? Explain … #devils_advocate – @evanocathain

Yup, I would have always started by assuming sims weren’t right yet, which is why observing more sats is so cool, no? – @RHULPhysics

Gravitational lens model

Interesting paper. I wonder how model dependent it all is… – @KarenLMasters

Do you mean model-dependent in their lensing detection? – @RHULPhysics

yes. Detection is from fitting mass model to the Einstein ring, I don’t understand how much degeneracy in that. – @KarenLMasters

And finally

IIRC there’s quite a few lenses with anomalous image flux ratios suggestive of substructure. – @StephenSerjeant

If other lenses suggest substructure, is this a better detection, or just a braver claim? – @RHULPhysics

Better detection I’d say – @StephenSerjeant

Glad to hear it. Fingers crossed for more! – @RHULPhysics

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