How well can we identify pseudobulges?
Abstract
Since the discovery of rotating galaxy bulges (e.g. Pease 1918; Babcock 1938, 1939), especially in the 1970s (e.g. Rubin, Ford & Kumar 1973; Pellet 1976; Bertola & Capaccioli 1977; Peterson 1978; Mebold et al. 1979; Kormendy & Illingworth 1979), coupled with early computer simulations of disks which formed rotating, exponential-like ``pseudobulges'' (e.g. Bardeen 1975; Hohl 1975, and references therein), a number of often over-looked problems pertaining to the identification of real ``pseudobulges'' have arisen. Drawing on my recent review article of disk galaxy structure and modern scaling laws (Graham 2012), some of these important issues are presented. Topics include: classical spheroids with exponential light distributions; curved but continuous scaling relations involving the `effective' structural parameters; the old age of most bulge stars (e.g. Thomas & Davies 2006; MacArthur et al. 2009); that most disk galaxies have bulge-to-disk flux ratios < 1/3 (Graham & Worley 2008); rotation in simulated merger remnants (e.g. Bekki 2010; Keselman & Nusser 2012) plus many other frustrating yet interesting reasons why rotation may not be a definitive signature of bulges built via secular processes (e.g. Babusiaux et al. 2010; Williams et al. 2010, Qu et al. 2011; Saha et al. 2012)
- Publication:
-
Highlights of Astronomy
- Pub Date:
- March 2015
- DOI:
- 10.1017/S1743921314011326
- Bibcode:
- 2015HiA....16..360G