The main target audience for Muse is in the 15-24 category. As Muse gained in popularity their music moved further and further away from their roots towards the mainstream resulting in being named "sell outs", losing hardcore fans each album but gaining more of the mainstream fans as they gained in popularity. Because of this shift in the sound of the music and the movement towards the mainstream they appealed more to the younger audiences who were interested in their type of music.
Magazines such as Kerrang who are aimed at the teenager audience review the bands albums and recent live performances meaning that they get seen by readers of the magazine. As they get featured more often they appeal more and more to the magazines target audience. NME who are aimed at a more mainstream teenage audience unlike Kerrang who are aimed at the rock/metal genre. As Muse gained in popularity they moved away from Kerrang's type of music and further towards NME where they get featured very often in the magazine as well as being featured in online polls etc. The band even got their own Special Collector's Edition NME Magazine just for the band featuring 100+ pages just about them.
Secondary Audience - 25-40
Since the release of Origin of Symmetry (2001) the audience who listened to the band back then are now 10 years older meaning that a large amount of the audience fits into this category. Q magazine is aimed at the older generation where the secondary audience is located. The secondary audience for Muse is also defined by the fact that the older generations children listen to the band and ultimatley they end up listening to them too.
The Classic Rock Magazine produce a small niche sub-genre magazine based on the Progressive-Rock genre. Muse coming from prog-rock roots therefore fit into this category, this means that they appeal to fans of the prog-rock genre. Typically this audience is 40+ due to the fact that Prog-rock was big in the late 60s/early 70s from bands such as Rush or King Crimson. Today the genre has pretty much died out with only a few small bands such as Porcupine Tree or Tool still keeping to the genre. Muse have very clear influences from the genre meaning they appeal to the older generation who are into that genre. This means that they are appealing to this audience and expanding their appeal over many generations.