Refining the MBH– σ∗ Relation: Improving on Re Measurements and σ∗ Estimates for a Sample of Early-Type Galaxies using GALFIT and SAURON IFS Data Open Access

Abstract

In this project, we develop 2-D computational models, using the software GALFIT, to fit the luminosity profiles for a set of five galaxies from the quiescent galaxy sample of Batiste et al. (2017b) in order to improve measurements of the bulge effective radius, Re. The galaxies investigated include NGC 3384, NGC 3945, NGC 3998, NGC 4382, and NGC 4472. We develop multi-component fits to model the light distributions of these galaxies, using Hubble Space Telescope imaging data from the ACS/WFC and WFC3/IR cameras. With these improved models, we are able to identify the dominant structural components within each galaxy, and examine how each structure emits light according to various surface brightness profiles. This allows us to isolate the bulge component for each galaxy and better constrain its effective radius, Re, which is the location at which half the luminosity is contained for this structure. Comparing our measurement to previous work in determining Re for this sample, we find that the previous values for the radii are significantly overestimated, by as much as 11×. Finally, we use publicly available stellar kinematic data from the SAURON Integral Field Unit to make an updated estimate of the stellar velocity dispersion, σ∗ within Re for each galaxy. These data are then used to make a preliminary assessment of the impact of these improvements on the MBH– σ∗ relation, which correlates the mass of a central supermassive black hole (MBH) and the stellar velocity dispersion in the bulge of the host galaxy.

Table of Contents

1 Introduction (pg. 1)

2 Galaxy Structures and Types (pg. 9)

3 Data and Analysis Methods (pg. 11)

3.1 Hubble Space Telescope (pg. 11)

3.2 Luminosity Function Fitting and GALFIT (pg. 12)

3.2.1 Luminosity Function Fitting (pg. 12)

3.2.2 GALFIT (pg. 12)

3.3 SAURON Integral-Field Spectroscopy (pg. 17)

3.4 ATLAS3D Survey (pg. 18)

4 The Sample (pg. 21)

5 Results and Discussion (pg. 27)

5.1 Image Decomposition (pg. 27)

5.1.1 Additional Galaxies (pg. 38)

5.2 Discussion on Re (pg. 40)

6 The MBH – σ∗ Relation (pg. 45)

7 Conclusions and Future Work (pg. 50)

8 Appendix (pg. 52)

8.1 Output Log of NGC 0524 (pg. 52)

8.2 Output Log of NGC 3384 (pg. 55)

8.3 Output Log of NGC 3945 (pg. 81)

8.4 Output Log of NGC 3998 (pg. 117)

8.5 Output Log of NGC 4382 (pg. 137)

8.6 Output Log of NGC 4472 (pg. 144)

8.7 Output Log of NGC 4596 (pg. 155)

About this Honors Thesis

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School	Emory College
Department	Physics and Astronomy
Degree	B.S.
Submission	Honors Thesis
Language	English
Research Field	Physics, Astronomy and Astrophysics
Keyword	MBH-σ∗ Early-Type Galaxies 2D Computational Modeling
Committee Chair / Thesis Advisor	Batiste, Merida, Emory University
Committee Members	Bans, Alissa, Emory University Bonning, Erin, Emory University Rieser, Jennifer, Emory University

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