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The origin of E+A galaxies. Tomo Goto Japan Aerospace Exploration Agency. January. In Chile. In Japan. 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. Tomo Goto Japan Aerospace Exploration Agency.
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The origin of E+Agalaxies Tomo Goto Japan Aerospace Exploration Agency Tomo Goto
January In Chile In Japan
The origin of E+Agalaxies • Strong Balmer absorption • No [OII], no Hα • Post-starburst A star + absorption lines • E+A galaxies • K+A galaxies Tomo Goto Japan Aerospace Exploration Agency Tomo Goto
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. Two puzzles on E+A(post-starburst) Tomo Goto
Morphological Butcher-Oemler effect in CE(Goto, et al. 2003, PASJ, 55,755) color morphology More blue galaxies in higher redshift The Morphological BO Effect Tomo Goto
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. Sloan Digital Sky Survey (SDSS) Tomo Goto
Evolution is difficult to observe. Elliptical Galaxy@z=0 Important Transition Stage popIII galaxy@z=10 ? Spiral galaxy@z=0 It is important to observe galaxy evolution in action.=> E+As Tomo Goto
Not much information on past SFH • Truncation of SF: galaxy evolution in action Tomo Goto
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%) How to find E+AsGoto, T. et al. 2003, PASJ, 55, 771 Goto, T. 2005, MNRAS, 357, 937 The largest catalog of 564 E+As out of 650,000 galaxies. Tomo Goto
E+A Spectra Tomo Goto
E+A Atlas Images Tomo Goto
HDS+em Spectra Tomo Goto
HDS+em Sample Atlas Images Tomo Goto
[OII] has been used as SF indicator. Could be dust? Metallicity effect? Possible 52% contamination in high-z work HDS+Hα Spectra Tomo Goto
HDS+Hα Atlas Images Tomo Goto
HDS+[OII] Spectra • Could be self-absorption? • HI gas cloud? Tomo Goto
HDS+[OII] Atlas Images Tomo Goto
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) Three Scenarios for E+A Tomo Goto
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
Environment of E+A Galaxies Goto, T. 2005, MNRAS, 357, 937 Not by cluster, not by large-scale structure Tomo Goto
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) Three Scenarios for E+A Tomo Goto
Optical-Infrared color: r-K E+As are not dustier. (c.f., 5 dusty starbursts in Smail et al. are ~1mag redder.) Tomo Goto
Radio Estimated SFR Goto, T. 2004, A&A, 427, 125 No evidence that E+As are not dusty starbursts. Tomo Goto
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) Three Scenarios for E+A Tomo Goto
Hδ_EW vs Time Tomo Goto
u-gvs HδEW(current SF vs recent SF) Young E+As: closer to burst (130-470 Myrs) Tomo Goto
Young E+A Spectra (HδEW>7Å) Tomo Goto
Atlas Image of Young E+As Tomo Goto
Naccompanying galaxies More accompanying galaxies for young E+As at <100kpc scale. Goto, T. 2005, MNRAS, 357, 937 Tomo Goto
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) Three Scenarios for E+A Tomo Goto
178 Ultra Luminous Infrared Galaxy (ULIRG) 1012Lsun< Lir<1013LsunLargest Sample of ULIRG before ASTROF Goto, T. 2005, MNRAS, 360, 322 Tomo Goto
Not every meger is E+A. Goto, T. 2005, MNRAS, 360, 322 Tomo Goto
Morphological Butcher-Oemler effect in CE(Goto, et al. 2003, PASJ, 55,755) color morphology More blue galaxies in higher redshift The Morphological BO Effect Tomo Goto
Passive Spiral Galaxies in the SDSS(Goto et al. 2003,PASJ,55,757) Spiral but no star formation. What are these? Tomo Goto
Close this Window Optical-IR color --- not dustier Yamauchi, Chisato & Goto, TomotsuguAre passive spiral galaxies truly 'passive' and 'spiral'? A near-infrared perspective.Monthly Notices of the Royal Astronomical Society352 (3), 815-822.doi: 10.1111/j.1365-2966.2004.07966.x PS do not look like dusty star forming galaxies. Yamauchi & Goto 2004 MNRAS, 352, 815 Tomo Goto
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
Morphology Radius Relation(Goto et al. 2003, MNRAS, 346, 601,) SFR :Gomez et al. 2003 Tomo Goto
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 Naccompanyinggalaxies . Merger/interaction is most likely to be responsible for the E+As. Consistent with E morphology. The Origin of E+As Tomo Goto