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

Tomo Goto

E+A Atlas Images

Tomo Goto

HDS+em Spectra

Tomo Goto

HDS+em Sample Atlas Images

Tomo Goto

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

Tomo Goto

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.