Spurious Galaxies

Halo 13 ID 0

Final stage of merging

In the process of merging with a more massive galaxy (that contains a 10^9 Msun BH). This merging causes it to jump from 10.3 to 8.35 in Mstar

Halo 16 ID 0

Spurious

Very weird pattern emerging: like an octagon with stars/dust? Looks like a side effect of merging process. It is embedded in a larger, way more massive subhalo (294), which is the central of its group

Halo 21 ID 7

Final stage of merging

It (53750) is merging with galaxy 15713, and right at the last snap, subfind decides a large chunk of this galaxy belongs to 15713. It thus drops from Mstar 10.9 to 8.3. would not be an outlier at Mstar =10.3

Halo 21 ID 5

Ejected BH

The BH becomes this massive due to a major merger of 6.6 (gal 949) and 8 (gal 5153) Msun at z=2.07, which triggers the rapid growth phase. You can nicely see the AGN feedback blast at z =1.25 in the gas density. The most probable explanation for its central BH being of such high mass, is due to this major merger triggering the rapid growth phase.

At z =2.25 the 6.6 Msun black hole has settled in the galaxy. Then quickly after this, an 8 Msun BH settles in at z=2.073. This major merger causes the Mbh to rapidly grow to 9.0 Msun. This triggers AGN feedback (at z=1.99 ), clearing its immediate environment, but it looks a bit like this feedback was not enough. Gas falls back onto the galaxy and a second AGN blast is seen at z =1.25. This time really clearing its environment of all gas.

At z=0.6 a fly by causes some stellar stripping. Then many fly-by's from z=0.46,to z =0.17 severely stripping its outer .stellar disk and halo.

Its MStar gets severely stripped by BCG 202, from about z=0.101 . At this point the BH decouples from the main stellar density peak.

The particles it is left with at z=0 where all part of galaxy 5153 at snap 20 , which is the true progenitor of this galaxy. Only left with 23 particles at z=0.

(F21 / SH_29 = 38926 / G* = 5153): BH growth starts at z = 4 after what looks like major merger.

Reaches 10^8 M_sun by z = 2.5, then jump to 10^9 due to major merger at z = 2. Local central up to z = 1, then flybys of larger galaxy. Flyby around z = 0.57 leads to some stellar stripping. Flyby at z = 0.44, then series of close flybys up to z = 0.24. First of many flythroughs with major stripping at z = 0.22. BH decouples from stellar density peak around z = 0.075. Flyby with other major galaxy at z = 0.02 with more stripping/dispersal of stars.

At z = 0: no significant stellar over-density at location of subhalo/UMBH, consistent with random fluctuation.

Halo 22 ID 6

Final stage of merging

Very large galaxy, essentially a BCG. Grows by many mergers at high z > 2.

At z = 0.03 it gets punctured by a galaxy (11485) with an ~euqal mass BH (~9). This galaxy flies though stealing some stars, and comes back at z=0.009 causing teardrop shapes both times

UMBH-G (F22 / SH_29 = 151148/ G =16550): BH growth starts around z = 3.7 during complicated multi-merger/interaction, several nearby galaxies already have > 10^7 BHs. All these components merge to one galaxy by z = 2.8. Central BH coalescence complete by z = 1.85 with M_BH = 10^9.25. Galaxy is then a local central with many smaller galaxies continually merging - central BH reaches 9.35 at z = 0.5.

Similarly massive galaxy approaches at z = 0.27, then comes in for merger at z = 0.11. Major flythrough/interaction at z = 0.034, second flythrough at z = 0.003. At z = 0: major merger in final stage.

Target galaxy is most likely the ‘real' BCG (sits closer to centre of stellar distribution and has same orientation), but it is classified as central ==> severely truncated stellar mass.

As we’d seen before, this is an ongoing major merger between two massive galaxies with the lower-right one (in the picture) being the UMBH since almost all of the stellar mass in this double-galaxy is assigned to the top-left core, which is the `central’ at z = 0 (but not earlier). I think this is a central-satellite mis-classification - the ‘UMBH’ lies closer to the centre of the stellar mass, and unlike the top-left one, its orientation matches the stellar halo very well. If this were chosen as the central instead, it would automatically (re-)gain all the stellar envelope and shift back to the main relation. A lot of this stellar mass also came in with the ‘UMBH’ galaxy, so the low stellar mass at z = 0 is really quite arbitrary. So as with B, I think this one — if you decide keep it — should be marked clearly as non-standard and you should discuss in the text that it’s only a pseudo-UMBH.

Halo 22 ID 7

Spurious

It is embedded in galaxy 988 which has Mstar 11.8. Looks like it is actually part of this larger galaxy, the Mbh = 9.4 wouls then not be classified as an outlier. Cannot be traced before z 0.6

Halo 22 ID 8

Spurious

Only exists in the last snap. Is embeded in a more massive Halo (4008), which has Mstar 11.3 => not an outlier anymore. They both contain a Mbh ~8.

Halo 25 ID 5

Spurious

Quite big. Has lots of tiny satellites around z-0. Is at the edge of being an outlier. Has a BH merger at z=1.5 (8+7), immediately grows to 10^9. Is not really an outlier because there is an even more massive neighbour arouns at snap 29 which steals all its outer stars and Bhs. Would not be an outlier if it would get these stars and Bhs back (it is already on the edge of being an outlier)

Halo 28 ID 4

Final stage of merging

Quite big. Has lots of tiny satellites around z-0. Is at the edge of being an outlier. Has a BH merger at z=1.5 (8+7), immediately grows to 10^9. Is not really an outlier because there is an even more massive neighbour around at snap 29 which steals all its outer stars and Bhs. Would not be an outlier if it would get these stars and Bhs back (it is already on the edge of being an outlier)

Halo 28 ID 7

Final stage of merging

BH grows from seedmass to 8.15 from z = 2.3 to z=1.5 (very gradually without merging). It is being ripped apart by a galaxy containing a binary BH that appears at z=0.04. In the very last snipshots, clear sign of merging (teardrop shape ) is visible at z=0.

(F28 / SH_29 = 193785 / G = 100917): Rapid BH growth phase from z = 2.6 to z = 2.1 during final stage of major merger (up to ~7.7). Galaxy is clearly dominating its immediate surroundings afterwards. BH grows to 8.0 by z = 1.3. Second galaxy appears around z = 0.7, similar size but much smaller BH (5.7). At z ~ 0.3, second neighbour appears, MBH ~ 7.8, and then third (8.3) at z = 0.25. Possibly slight mass loss due to interactions afterwards. At z = 0, the galaxy is just past first merger-passage through the 8.3 galaxy. Category ‘ongoing merger’.

At z = 0: galaxy stretched into elongated tail without clear core.

Halo 40 ID 8

Spurious

Nothing really in focus, Only at z=0.2, there are galaxies coming in, though they are not the galaxy that is being traced. Looks like a spurious artefact