One of the biggest problem with the missing satellite problem is that it heavily relies on a sample of one. There aren't as many satellite galaxies detected around our own Milky Way galaxy as models predict, which is very annoying. But is this just because our own Galaxy happens to be weird, or does it reflect a much bigger problem with cosmological theory ? There are hints, through statistical analyses of large galaxy populations, that it's the latter, but it would be far more satisfying to point to another individual galaxy system and say, "Ahah ! This system does [or does not] have the right number of satellites." Only then can we really start commenting as to why our Galaxy is strange, if indeed that's the case.
This paper presents observations which look for satellites around 10 more potential host galaxies, finding a total of 153 candidate satellites of which 93 are new. Huzzah ! Right ? Well, no.
There's nothing much wrong with what they do, so far as I can tell. They have very deep imaging and carefully mask the brightest stars and galaxies, using a semi-automatic method to find candidates which are then subjected to a good old visual inspection. Totally fine. They do photometry on the candidates to measure their colours and brightness, and plot nice maps of their distribution on the sky - perhaps we could also see if there are any more satellite planes as well. They test their procedures with simulated galaxies to see how efficient their procedures should be at recovering real galaxies with different properties. They give full catalogues of everything they've done and comment in some detail on every system they examine. All well and good so far.
Where it starts to go a bit wrong is that they don't have distance measurements for the satellite galaxies. That means they can't say how bright they are and thus how well they (mis)match theoretical predictions, or say if they're found in planes or clouds. But "wrong" is really too strong a word, though, as they do say their data is enough for them to eventually be able to measure distances using surface brightness profiles. So this is just a preliminary catalogue. Fair enough, really, there's an awful lot of work gone into this, so it should be published.
No, where things get disappointing is when they try a preliminary examination of the data under the assumption that the dwarf galaxies are at the same distance as their potential hosts. In that case, the colours and basic structural parameters of the "dwarfs" don't much look anything like other dwarfs at all. In fact they are so different that, "From these plots, it is apparent that many of the candidates are background". So all of that work and they can't even say anything much about the satellite galaxies except that these candidates are pretty lousy.
Oh well, that's the way it goes. Eventually we will get better statistics to address the missing satellite problem, but blimey - getting there is going to be like pulling teeth.
Wide-Field Survey of Dwarf Satellite Systems Around 10 Hosts in the Local Volume
We present the results of an extensive search for dwarf satellite galaxies around 10 primary host galaxies in the Local Volume (D$<$12 Mpc) using archival CFHT/MegaCam imaging data. The hosts span a wide range in properties, with stellar masses ranging from that of the LMC to ${\sim}3$ times that of the Milky Way (MW).
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