Are there blue, massive E/S0 galaxies at z < 1 ? Kinematics of blue spheroidal galaxy candidates

Myungshin Im, S. M. Faber, Karl Gebhardt, David C. Koo, Andrew C. Phillips, Ricardo P. Schiavon, Luc Simard, Christopher N.A. Willmer

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


Several recent studies find that 10%-50% of morphologically selected field early-type galaxies at redshifts z ≲ 1 have blue colors indicative of recent star formation. Such "blue spheroids" might be massive early-type galaxies with active star formation, perhaps induced by recent merger events. Alternatively, they could be starbursting, low-mass spheroids. To distinguish between these two choices, we have selected 10 "Blue Spheroid Candidates" (BSCs) from a quantitatively selected E/S0 sample to study their properties, including kinematics from Keck spectra obtained as part of the DEEP Groth Strip Survey (GSS). Most BSCs (70%) turn out to belong to two broad categories, while the remaining objects are likely to be misclassified objects. Type 1 BSCs have underlying red stellar components with bluer inner components. Type 2 BSCs do not show an obvious sign of the underlying red stellar component, and their overall colors are quite blue [(U - B)rest < 0]. Both type 1 and type 2 BSCs have internal velocity dispersions measured from emission lines σ ≲ 80 km s-1 and estimated dynamical masses of only a few × 1010 M or less. For type 1 BSCs, we estimate σ of the red component using the fundamental plane relation of distant field absorption-line galaxies and find that these σ estimates are similar to the σ measured from emission lines. Overall, we conclude that our type 1 and type 2 BSCs are more likely to be star-forming low-mass spheroids than star-forming, massive, early-type galaxies.

Original languageEnglish (US)
Pages (from-to)750-763
Number of pages14
JournalAstronomical Journal
Issue number2
StatePublished - Aug 2001
Externally publishedYes


  • Cosmology: observations
  • Galaxies : elliptical and lenticular, cD
  • Galaxies: dwarf
  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: high-redshift
  • Galaxies: kinematics and dynamics

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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