TOTAL TO CENTRAL LUMINOSITY RATIOS OF MASSIVE

Transcription

1 TOTAL TO CENTRAL LUMINOSITY RATIOS OF MASSIVE QUIESCENT GALAXIES IN MODS AS AN INDICATOR OF GALAXY SIZE EVOLUTION Mohammad Akhlaghi Takashi Ichikawa MODS team Astronomical Institute Tohoku University October 27th, 2011 Galaxy Mergers in an Evolving Universe Workshop Hualien, Taiwan

2 OUTLINE 1 BACKGROUND & MOTIVATION In support of significant size evolution Opposing significant size evolution 2 DATA AND ANALYSIS The MOIRCS Deep Survey Definition of luminosity ratio 3 RESULTS & DISCUSSION Results & Discussion

3 IN SUPPORT IN SUPPORT OF SIGNIFICANT SIZE GROWTH Daddi et al. 2005: restframe B Some (4 of 7) bright compact (r e < 1kpc) galaxies with effective were observed in 1.39 < z < 2.47 Trujillo et al. 2006: restframe optical massive galaxies undergo r e = (1 + z) 0.4 Franx et al 2008: restframe g Quiescent, massive galaxies undergo r e = (1 + z) van Dokkum et al. 2009: The velocity dispersion of a massive galaxy much more than local values. van Dokkum et al. 2010: restframe 4000Å Inside-out growth: The outer parts (>5kpc) grow with r e = (1 + z) 1.1. Cassata et al. 2011: restframe optical About 5 times increase in passive ETG effective radius.

4 OPPOSING A SAMPLE RESULT: Results from van Dokkum et al. 2010: Stacked images of about 70galaxies in each redshift bin. Mass (size) growth, is due to the gradual buildup of their outer envelopes

5 OPPOSING AGAINST SIGNIFICANT SIZE GROWTH Cappellari et al 2009: Velocity dispersion of 9 high-z massive ETGs were measured, not significantly different from the local universe. Valentinuzzi et al 2010: A significant population of superdense massive galaxies in the local universe are present Saracco et al & 2011: restframe optical Similar number density of compact early type galaxies between 1 < z < 2 and the local universe

6 OPPOSING A SAMPLE RESULT Saracco et al. 2011: Compact and normal elliptical galaxies are present in all redshifts

7 THE MODS DATA OUR DATA Image: The MOIRCS Deep Survey (MODS) 103arcmin 2 : 70% of GOODS-N region FWHM at worst point: 0.6" 1σ error of 27mag/arcsec 2 Catalog (Kajisawa et al. 2011): SED fit: UBVizJHK, 3.6µm, 4.5µm & 5.8µm Photo-z accuracy: δz/(1 + z) = GALEXEV (Bruzual & Charlot 2003) Salpeter IMF

8 THE MODS DATA HOW RELIABLE IS GALAXY SIZE? Ichikawa, Kajisawa, Akhlaghi 2011 (Submitted): Monte Carlo simulation Red (circles): 1/4 profile, Blue (triangles): exponential profile

9 DEFINITIONS ANALYSIS Luminosity ratio: Luminosity of SExtractor s MAG_AUTO to central 2.6kpc radius. If r e = 2.6kpc then LR(2.6kpc) = 2 Why 2.6kpc? Corresponding to lowest PSF at z=1.64. Comparison with 5kpc radius results Top galaxy: z 2.04, M M : V band 2.6kpc LR: Bottom galaxy: z 2.89, M M : V band 2.6kpc LR: Cosmological parameters used: H 0 = 70, Ω Λ = 0.73 and Ω M = 0.27 (Komatsu+2011)

10 DEFINITIONS ANALYSIS HST/ACS: B, V, i, z Subaru/MOIRCS: J, H, K Restframe V results: i image: 0.16 z < 0.55 z image: 0.55 z < 0.88 J image: 0.88 z < 1.55 H image: 1.55 z < 2.43 K image: 2.43 z < 3.5 Restframe U results: B image: 0.10 z < 0.37 V image: 0.37 z < 0.76 i image: 0.76 z < 1.34 z image: 1.34 z < 1.84 J image: 1.84 z < 2.84 H image: 2.84 z < 3.50 Quiescent galaxies selected through Williams+2009 criteria (all restframe): (U V ) > 0.88 (V J) [0.0<z<0.5] (U V ) > 0.88 (V J) [0.5<z<1.0] (U V ) > 0.88 (V J) [1.0<z<2.0] U V > 1.3 & V J < X-ray bright source was removed. MAG_AUTO< 25 in K were chosen (90% complete). Pixel number corresponding to 2.6kpc in radius calculated. Separated into bins of 0.04pixels. MAG_APER and MAG_AUTO applied to galaxies in each bin through SExtractor s cross-identification.

11 DEFINITIONS ANALYSIS HST/ACS: B, V, i, z Subaru/MOIRCS: J, H, K Restframe V results: i image: 0.16 z < 0.55 z image: 0.55 z < 0.88 J image: 0.88 z < 1.55 H image: 1.55 z < 2.43 K image: 2.43 z < 3.5 Restframe U results: B image: 0.10 z < 0.37 V image: 0.37 z < 0.76 i image: 0.76 z < 1.34 z image: 1.34 z < 1.84 J image: 1.84 z < 2.84 H image: 2.84 z < 3.50 Quiescent galaxies selected through Williams+2009 criteria (all restframe): (U V ) > 0.88 (V J) [0.0<z<0.5] (U V ) > 0.88 (V J) [0.5<z<1.0] (U V ) > 0.88 (V J) [1.0<z<2.0] U V > 1.3 & V J < X-ray bright source was removed. MAG_AUTO< 25 in K were chosen (90% complete). Pixel number corresponding to 2.6kpc in radius calculated. Separated into bins of 0.04pixels. MAG_APER and MAG_AUTO applied to galaxies in each bin through SExtractor s cross-identification.

12 DEFINITIONS ANALYSIS HST/ACS: B, V, i, z Subaru/MOIRCS: J, H, K Restframe V results: i image: 0.16 z < 0.55 z image: 0.55 z < 0.88 J image: 0.88 z < 1.55 H image: 1.55 z < 2.43 K image: 2.43 z < 3.5 Restframe U results: B image: 0.10 z < 0.37 V image: 0.37 z < 0.76 i image: 0.76 z < 1.34 z image: 1.34 z < 1.84 J image: 1.84 z < 2.84 H image: 2.84 z < 3.50 Quiescent galaxies selected through Williams+2009 criteria (all restframe): (U V ) > 0.88 (V J) [0.0<z<0.5] (U V ) > 0.88 (V J) [0.5<z<1.0] (U V ) > 0.88 (V J) [1.0<z<2.0] U V > 1.3 & V J < X-ray bright source was removed. MAG_AUTO< 25 in K were chosen (90% complete). Pixel number corresponding to 2.6kpc in radius calculated. Separated into bins of 0.04pixels. MAG_APER and MAG_AUTO applied to galaxies in each bin through SExtractor s cross-identification.

13 DEFINITIONS ANALYSIS HST/ACS: B, V, i, z Subaru/MOIRCS: J, H, K Restframe V results: i image: 0.16 z < 0.55 z image: 0.55 z < 0.88 J image: 0.88 z < 1.55 H image: 1.55 z < 2.43 K image: 2.43 z < 3.5 Restframe U results: B image: 0.10 z < 0.37 V image: 0.37 z < 0.76 i image: 0.76 z < 1.34 z image: 1.34 z < 1.84 J image: 1.84 z < 2.84 H image: 2.84 z < 3.50 Quiescent galaxies selected through Williams+2009 criteria (all restframe): (U V ) > 0.88 (V J) [0.0<z<0.5] (U V ) > 0.88 (V J) [0.5<z<1.0] (U V ) > 0.88 (V J) [1.0<z<2.0] U V > 1.3 & V J < X-ray bright source was removed. MAG_AUTO< 25 in K were chosen (90% complete). Pixel number corresponding to 2.6kpc in radius calculated. Separated into bins of 0.04pixels. MAG_APER and MAG_AUTO applied to galaxies in each bin through SExtractor s cross-identification.

14 DEFINITIONS ANALYSIS HST/ACS: B, V, i, z Subaru/MOIRCS: J, H, K Restframe V results: i image: 0.16 z < 0.55 z image: 0.55 z < 0.88 J image: 0.88 z < 1.55 H image: 1.55 z < 2.43 K image: 2.43 z < 3.5 Restframe U results: B image: 0.10 z < 0.37 V image: 0.37 z < 0.76 i image: 0.76 z < 1.34 z image: 1.34 z < 1.84 J image: 1.84 z < 2.84 H image: 2.84 z < 3.50 Quiescent galaxies selected through Williams+2009 criteria (all restframe): (U V ) > 0.88 (V J) [0.0<z<0.5] (U V ) > 0.88 (V J) [0.5<z<1.0] (U V ) > 0.88 (V J) [1.0<z<2.0] U V > 1.3 & V J < X-ray bright source was removed. MAG_AUTO< 25 in K were chosen (90% complete). Pixel number corresponding to 2.6kpc in radius calculated. Separated into bins of 0.04pixels. MAG_APER and MAG_AUTO applied to galaxies in each bin through SExtractor s cross-identification.

15 DEFINITIONS ANALYSIS HST/ACS: B, V, i, z Subaru/MOIRCS: J, H, K Restframe V results: i image: 0.16 z < 0.55 z image: 0.55 z < 0.88 J image: 0.88 z < 1.55 H image: 1.55 z < 2.43 K image: 2.43 z < 3.5 Restframe U results: B image: 0.10 z < 0.37 V image: 0.37 z < 0.76 i image: 0.76 z < 1.34 z image: 1.34 z < 1.84 J image: 1.84 z < 2.84 H image: 2.84 z < 3.50 Quiescent galaxies selected through Williams+2009 criteria (all restframe): (U V ) > 0.88 (V J) [0.0<z<0.5] (U V ) > 0.88 (V J) [0.5<z<1.0] (U V ) > 0.88 (V J) [1.0<z<2.0] U V > 1.3 & V J < X-ray bright source was removed. MAG_AUTO< 25 in K were chosen (90% complete). Pixel number corresponding to 2.6kpc in radius calculated. Separated into bins of 0.04pixels. MAG_APER and MAG_AUTO applied to galaxies in each bin through SExtractor s cross-identification.

16 RESULTS & DISCUSSION RESTFRAME V; 5.2KPC LUMINOSITY RATIO All median values have r e < 5.2kpc. No significant growth is observed Quiescent Restframe V Median and MAD 3 Luminosity Ratio (5.2kpc) Redshift Akhlaghi et al (in prep)

17 RESULTS & DISCUSSION RESTFRAME V; 2.6KPC LUMINOSITY RATIO All median values have r e > 2.6kpc. Only few in the local (z<0.5) universe have r e 2.6kpc! Again, no significant size growth is observed Quiescent Restframe V Median and MAD 10 9 Luminosity Ratio (2.6kpc) Akhlaghi et al (in prep) Redshift

18 RESULTS & DISCUSSION RESTFRAME U; 5.2KPC LUMINOSITY RATIO Again, all medians have r e < 5.2kpc. In restframe U very slight growth for z > 1.5 is observed Quiescent Restframe U Median and MAD 3 Luminosity Ratio (5.2kpc) Redshift Akhlaghi et al (in prep)

19 RESULTS & DISCUSSION RESTFRAME U; 2.6KPC LUMINOSITY RATIO A very small number of galaxies demonstrate r e < 2.6kpc. In both cases, dispersion in U is larger than V. No significant growth is observed Quiescent Restframe U Median and MAD 10 9 Luminosity Ratio (2.6kpc) Akhlaghi et al (in prep) Redshift

20 RESULTS & DISCUSSION RESTFRAME U & V, 5.2KPC LUMINOSITY RATIO for z < 2.25; Young, massive stars reside on the outer envelopes The growth in restframe U is slightly stronger than restframe V Restframe V Restframe U 2 Luminosity ratio (2.6kpc) Redshift Akhlaghi et al (in prep)

21 RESULTS & DISCUSSION RESTFRAME U & V; 2.6KPC LUMINOSITY RATIO LR growth in U band, is slightly stronger compared to previous slide indicating possible presence of young massive stars 2.5kpc < r < 5.2kpc LR is steeper in restframe U for z > 1.5 and in restframe V for z < Restframe V Restframe U Luminosity ratio (2.6kpc) Akhlaghi et al (in prep) Redshift

22 RESULTS & DISCUSSION RESTFRAME V; 10.4KPC LUMINOSITY RATIO HST/ACS for z < 0.88 & Subaru/MOIRCS for z Values with LR(10.4kpc) < 1 are observed in Subaru results Possible signiture of very faint < 1.3 Background outerparts 2 Quiescent Restframe V Median and MAD 1.75 Luminosity Ratio (10.4kpc) Redshift Akhlaghi et al (in prep)

23 SUMMARY PRELIMINARY RESULTS The evolution of the total to central luminosity ratio was used to find galaxy size evolution. Significant growth is not observed in rest frame V & U. Outer parts display slightly larger Luminosity ratio in U than V. Outlook Relation between r e and Luminosity ratio for various profiles. Application of the same method to find color gradients. Deeper HST/WFC3 data will provide deeper, higher S/N images.