1. The origin of E+A galaxies
Elliptical’s line features + A star feature. (Metal lines, Ca, Fe, Mg like K stars)
Balmer=> recent SB
no emission => non ongoing SF
POST STAR BURST galaxies
Tomo Goto
Japan Aerospace Exploration Agency
Tomo Goto

2. January
In Japan
In Chile

3. The origin of E+A galaxies
Strong Balmer absorption
No [OII], no Hα
Post-starburst
A star + absorption lines
E+A galaxies
K+A galaxies
Elliptical’s line features + A star feature. (Metal lines, Ca, Fe, Mg like K stars)
Balmer=> recent SB
no emission => non ongoing SF
POST STAR BURST galaxies
Tomo Goto
Japan Aerospace Exploration Agency
Tomo Goto

4. Two puzzles on E+A(post-starburst)
What caused star burst?
What stopped it?
Cluster related. Found to live in cluster region (MORPHS, Dressler & Gunn 83)
Dust enshrouded star formation.(Poggianti et al. 1999; Smail et al. 1999)
Merger/Interaction (Zabludoff et al 1996)
　 Still puzzles
Very rare(21/11113 in LCRS). Phase is short(1Gyr). Million spectra of SDSS provide good opportunity to address this 20-year-old puzzle.
Galaxy evolution in action.
Tomo Goto

6. color
Morphological Butcher-Oemler effect in CE (Goto, et al. 2003, PASJ, 55,755)
morphology
More blue galaxies in
higher redshift
The Morphological BO Effect
Tomo Goto

7. Sloan Digital Sky Survey (SDSS)
SDSS will produce
Imaging of 10,000 sq.deg r~23.1
In 5 optical bands (ugriz)
Spectra of
and in 5 years
Using 2.5m telescope at APO.
Tomo Goto

8. Tomo Goto

9. Tomo Goto

10. Evolution is difficult to observe.
Elliptical
Important Transition Stage
popIII ?
Spiral
It is important to observe galaxy evolution in action.=> E+As
Tomo Goto

11. Not much information on past SFH
Truncation of SF: galaxy evolution in action
Tomo Goto

12. The largest catalog of 564 E+As out of 650,000 galaxies.
How to find E+As Goto, T. et al. 2003,  PASJ, 55, 771 Goto, T. 2005, MNRAS, 357, 937
HδEW>4Å (2.42%)
4 categories.
E+A: Hα<1σ, [OII]<1σ, No emission lines. (0.04%)
HDS+[OII]: Hα<1σ, [OII]≧1σ (0.09%)
HDS+Hα: Hα≧1σ, [OII]<1σ (0.04%)
HDS+em: Hα≧1σ, [OII]≧1σ, Significant emission lines. (2.25%)
(～2σ） (～2σ） (～2σ） (～4σ）
(540/21679)
(26/ with 2MASS)
(137/ with 2MASS)
The largest catalog of 564 E+As out of 650,000 galaxies.
Tomo Goto

13. E+A Spectra
Tomo Goto

14. E+A Atlas Images Tomo Goto
Images suggests variety of colors, luminosities & morphologies. I will quantify these.
Tomo Goto

15. HDS+em Spectra
Tomo Goto

16. HDS+em Sample Atlas Images
Also suggests variety of colors, luminosity, morphology. suggests difference from true E+A.
Tomo Goto

17. HDS+Hα Spectra [OII] has been used as SF indicator.
mention High-z study used [OII]
[OII] has been used as SF indicator.
Could be dust? Metallicity effect?　
Possible 52% contamination in high-z work
Tomo Goto

18. HDS+Hα Atlas Images
Tomo Goto

19. HDS+[OII] Spectra Could be self-absorption? HI gas cloud? Tomo Goto
Possible cause Ha self absorption.
Could be self-absorption?
HI gas cloud?
Tomo Goto

20. HDS+[OII] Atlas Images
Tomo Goto

21. Three Scenarios for E+A
Cluster Related (ram pressure, tidal interaction with cluster potential, …etc; Dressler et al. 1999; Poggianti et al. 1999)
Dusty Starburst (2/15 of E+As have radio SF; Miller et al. 2002; Smail et al. 1997;)
Interaction/Merger (tidal features in 5/21 E+As in Zabludoff et al. 1996)
Tomo Goto

22. E+A
E+A is K+A
“E+A” is sometime called “K+A” because of its disk-like morphology. However,…
Previous sample might be contaminated by HDS+Hα
Tomo Goto

23. Environment of E+A Galaxies
Goto, T. 2005, MNRAS, 357, 937
Not by cluster,
not by large-scale structure
Tomo Goto

24. Three Scenarios for E+A
Cluster related (ram pressure, tidal interaction, merging…etc; Dressler et al. 1999; Poggianti et al. 1999)
Dusty Starburst (2/15 of E+As have radio SF; Miller et al. 2002; Smail et al. 1997;)
Interaction/Merger (tidal features in 5/21 E+As in Zabludoff et al. 1996)
Tomo Goto

25. Optical-Infrared color: r-K
E+As are not dustier.
(c.f., 5 dusty starbursts in Smail et al. are ~1mag redder.)
Tomo Goto

26. Radio Estimated SFR No evidence that E+As are not dusty starbursts.
Goto, T. 2004, A&A, 427, 125
No evidence that E+As are not dusty starbursts.
Tomo Goto

27. Three Scenarios for E+A
Cluster related (ram pressure, tidal interaction, merging…etc; Dressler et al. 1999; Poggianti et al. 1999)
Dusty Starburst (2/15 of E+As have radio SF; Miller et al. 2002; Smail et al. 1997;)
Interaction/Merger (tidal features in 5/21 E+As in Zabludoff et al. 1996)
Tomo Goto

28. Hδ_EW vs Time
Tomo Goto

29. u-g vs HδEW (current SF vs recent SF)
Young E+As:
closer to burst
( Myrs)
Tomo Goto

30. Young E+A Spectra (HδEW>7Å)
Tomo Goto

31. Atlas Image of Young E+As
Tomo Goto

32. Naccompanying galaxies
More accompanying galaxies for young E+As at <100kpc scale.
Goto, T. 2005, MNRAS, 357, 937
Tomo Goto

33. Three Scenarios for E+A
Cluster related (ram pressure, tidal interaction, merging…etc; Dressler et al. 1999; Poggianti et al. 1999)
Dusty Starburst (2/15 of E+As have radio SF; Miller et al. 2002; Smail et al. 1997;)
Interaction/Merger (tidal features in 5/21 E+As in Zabludoff et al. 1996)
Tomo Goto

34. 178 Ultra Luminous Infrared Galaxy (ULIRG) Lsun< Lir<1013Lsun Largest Sample of ULIRG before ASTROF
Goto, T. 2005, MNRAS, 360, 322
Tomo Goto

35. Not every meger is E+A.
Goto, T. 2005, MNRAS, 360, 322
Tomo Goto

36. Color gradient of E+As : (Yamauchi & Goto 2005,MNRAS,359,1557)
Bluer core
in >60% of local E+As
Tomo Goto

37. Correlation between color-gradient and D4000: possible merger time clock. (Yamauchi & Goto 2005,MNRAS,359,1557)
Tomo Goto

38. Spatially resolved spectroscopy (Yagi & Goto 2006,ApJ,642,152, 2006AJ
Tomo Goto

39. Spatially resolved spectroscopy (Yagi & Goto 2006,ApJ,642,152, 2006AJ
APO3.5m telescope
x0.89kpc/pix
x0.39kpc/pix
Poststarburst is centered at the core, but spatially extended.
-> rather a merger product than a truncated spiral arm.
x0.72kpc/pix
Tomo Goto

40. Possible longer/delayed truncation at the center.
Time sequence of truncation (Yagi & Goto 2006,ApJ,642,152, 2006AJ )
Possible longer/delayed truncation at the center.
Tomo Goto

41. color
Morphological Butcher-Oemler effect in CE (Goto, et al. 2003, PASJ, 55,755)
morphology
More blue galaxies in
higher redshift
The Morphological BO Effect
Tomo Goto

42. Passive Spiral Galaxies in the SDSS (Goto et al. 2003,PASJ,55,757)
Spiral but no star formation. What are these?
Tomo Goto

43. Optical-IR color --- not dustier
  Close this Window
Yamauchi, Chisato & Goto, Tomotsugu Are passive spiral galaxies truly 'passive' and 'spiral'? A near-infrared perspective. Monthly Notices of the Royal Astronomical Society  352 (3),  doi: /j x
Optical-IR color --- not dustier
PS do not look like dusty star forming galaxies.
Yamauchi & Goto 2004 MNRAS, 352, 815
Tomo Goto

44. The Environment of Passive Spirals (Goto et al. 2003,PASJ,55,757)
Passive spirals may be a smoking gun in cluster galaxy evolution.
Tomo Goto

45. Morphology Radius Relation (Goto et al. 2003, MNRAS, 346, 601,)
SFR :Gomez et al. 2003
Tomo Goto

46. Hdelta-strong AGNs: AGNs outlive starburst in the starburst-AGN connection? (Goto 2006, MNRAS,369,1765 )
Tomo Goto

47. Hδstrong-AGNs
Poststarburst & AGN are spatially correlated, suggesting underlying physical connection.
The existence of poststarburst-AGN suggests that AGNs outlive starburst. Hdelta/D4000 can possibly used as a time clock to understand the AGN lifecycle.
Tomo Goto

48. The Origin of E+As E+As are not cluster/LSS origin.
E+As are in all environment including the field.
E+As are not cluster/LSS origin.
Optical-IR color is not redder; radio SFR<10Msun/yr.
E+As are not likely to be Dusty Starburst.
Excess in Naccompanying galaxies .
Merger/interaction is most likely to be responsible for the E+As. Consistent with E morphology.
Tomo Goto