The origin of E+A galaxiesTomo GotoJapan Aerospace Exploration Agency
Tomo Goto
January In JapanIn Chile
Tomo Goto
The origin of E+A galaxiesStrong Balmer absorptionNo [OII], no HPost-starburst
A star + absorption linesE+A galaxiesK+A galaxiesTomo GotoJapan Aerospace Exploration Agency
Tomo Goto
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
Tomo Goto
Morphological Butcher-Oemler effect in CE(Goto, et al. 2003, PASJ, 55,755)More blue galaxies in higher redshiftThe Morphological BO Effect colormorphology
Tomo Goto
Sloan Digital Sky Survey (SDSS)SDSS will produceImaging of 10,000 sq.deg r~23.1In 5 optical bands (ugriz)
Spectra of and in 5 years
Using 2.5m telescope at APO.
Tomo Goto
Tomo Goto
Tomo Goto
Evolution is difficult to observe.? popIII galaxy@z=10Elliptical Galaxy@z=0Spiral galaxy@z=0Important Transition StageIt is important to observe galaxy evolution in action.=> E+As
Tomo Goto
Not much information on past SFHTruncation of SF: galaxy evolution in action
Tomo Goto
How to find E+AsGoto, T. et al. 2003, PASJ, 55, 771 Goto, T. 2005, MNRAS, 357, 937
HEW>4 (2.42%)4 categories. E+A: H
E+A Spectra
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E+A Atlas Images
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HDS+em Spectra
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HDS+em Sample Atlas Images
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HDS+H Spectra[OII] has been used as SF indicator.Could be dust? Metallicity effect?Possible 52% contamination in high-z work
Tomo Goto
HDS+H Atlas Images
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HDS+[OII] SpectraCould be self-absorption?HI gas cloud?
Tomo Goto
HDS+[OII] Atlas Images
Tomo Goto
Three Scenarios for E+ACluster 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
E+A is K+AE+A is sometime called K+A because of its disk-like morphology. However,E+APrevious sample might be contaminated by HDS+H
Tomo Goto
Environment of E+A GalaxiesNot by cluster, not by large-scale structure Goto, T. 2005, MNRAS, 357, 937
Tomo Goto
Three Scenarios for E+ACluster related (ram pressure, tidal interaction, mergingetc; 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
Optical-Infrared color: r-KE+As are not dustier.(c.f., 5 dusty starbursts in Smail et al. are ~1mag redder.)
Tomo Goto
Radio Estimated SFRGoto, T. 2004, A&A, 427, 125No evidence that E+As are not dusty starbursts.
Tomo Goto
Three Scenarios for E+ACluster related (ram pressure, tidal interaction, mergingetc; 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
H_EW vs Time
Tomo Goto
u-g vs HEW
(current SF vs recent SF)Young E+As:closer to burst(130-470 Myrs)
Tomo Goto
Young E+A Spectra (HEW>7)
Tomo Goto
Atlas Image of Young E+As
Tomo Goto
Naccompanying galaxies
Goto, T. 2005, MNRAS, 357, 937 More accompanying galaxies for young E+As at
Three Scenarios for E+ACluster related (ram pressure, tidal interaction, mergingetc; 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
178 Ultra Luminous Infrared Galaxy (ULIRG)
1012Lsun< Lir
Not every meger is E+A.Goto, T. 2005, MNRAS, 360, 322
Tomo Goto
Color gradient of E+As : (Yamauchi & Goto 2005,MNRAS,359,1557)Bluer core in >60% of local E+As
Tomo Goto
Correlation between color-gradient and D4000:
possible merger time clock.
(Yamauchi & Goto 2005,MNRAS,359,1557)
Tomo Goto
Spatially resolved spectroscopy(Yagi & Goto 2006,ApJ,642,152, 2006AJ....131.2050)
Tomo Goto
Spatially resolved spectroscopy (Yagi & Goto 2006,ApJ,642,152, 2006AJ....131.2050)Poststarburst is centered at the core, but spatially extended.
-> rather a merger product than a truncated spiral arm.
x0.89kpc/pixx0.72kpc/pixx0.39kpc/pixAPO3.5m telescope
Tomo Goto
Time sequence of truncation (Yagi & Goto 2006,ApJ,642,152, 2006AJ....131.2050)Possible longer/delayed truncation at the center.
Tomo Goto
Morphological Butcher-Oemler effect in CE(Goto, et al. 2003, PASJ, 55,755)More blue galaxies in higher redshiftThe Morphological BO Effect colormorphology
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
Optical-IR color --- not dustierPS 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
Hdelta-strong AGNs: AGNs outlive starburst in the starburst-AGN connection?(Goto 2006, MNRAS,369,1765 )
Tomo Goto
Hstrong-AGNsPoststarburst & 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
The Origin of E+AsE+As are in all environment including the field.E+As are not cluster/LSS origin.
Optical-IR color is not redder; radio SFR recent SBno emission => non ongoing SF
POST STAR BURST galaxies
Ellipticals line features + A star feature. (Metal lines, Ca, Fe, Mg like K stars)
Balmer=> recent SBno emission => non ongoing SF
POST STAR BURST galaxies
(2 (2 (2 (4 (540/21679)(26/21679 7 with 2MASS)(137/21679 12 with 2MASS)
Images suggests variety of colors, luminosities & morphologies. I will quantify these.Also suggests variety of colors, luminosity, morphology. suggests difference from true E+A.mention High-z study used [OII]Possible cause Ha self absorption.