UC Berkeley UC Berkeley Electronic Theses and Dissertations Title Host Galaxies of Type Ia Supernovae from the Nearby Supernova Factory Permalink https://escholarship.org/uc/item/468120pf Author Childress, Michael Joseph Publication Date 2011 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California Host Galaxies of Type Ia Supernovae From the Nearby Supernova Factory by Michael Joseph Childress A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Physics in the Graduate Division of the University of California, Berkeley Committee in charge: Dr. Greg Aldering, Co-Chair Professor Saul Perlmutter, Co-Chair Professor Marc Davis Professor Chung-Pei Ma Fall 2011 Host Galaxies of Type Ia Supernovae From the Nearby Supernova Factory Copyright 2011 by Michael Joseph Childress 1 Abstract Host Galaxies of Type Ia Supernovae From the Nearby Supernova Factory by Michael Joseph Childress Doctor of Philosophy in Physics University of California, Berkeley Dr. Greg Aldering, Co-Chair Professor Saul Perlmutter, Co-Chair Type Ia Supernovae (SNe Ia) are excellent distance indicators, yet the full details of the underlying physical mechanism giving rise to these dramatic stellar deaths remain unclear. As large samples of cosmological SNe Ia continue to be collected, the scatter in brightnesses of these events is equally affected by systematic errors as statistical. Thus we need to understand the physics of SNe Ia better, and in particular we must know more about the progenitors of these SNe so that we can derive better estimates for their true intrinsic brightnesses. The host galaxies of SNe Ia provide important indi- rect clues as to the nature of SN Ia progenitors. In this Thesis we utilize the host galaxies of SNe Ia discovered by the Nearby Supernova Factory (SNfactory) to pursue several key investigations into the nature of SN Ia progenitors and their effects on SN Ia brightnesses. We first examine the host galaxy of SN 2007if, an important member of the subclass of SNe Ia whose extreme brightnesses indicate a progenitor that exceeded the canonical Chandrasekhar-mass value presumed for normal SNe Ia, and show that the host galaxy of this SN is composed of very young stars and has extremely low metallicity, providing important constraints on progenitor scenarios for this SN. We then uti- lize the full sample of SNfactory host galaxy masses (measured from photometry) and metallicities (derived from optical spectroscopy) to examine several global properties of SN Ia progenitors: (i) we show that SN Ia hosts show tight agreement with the normal galaxy mass-metallicity relation; (ii) comparing the observed distribution of SN Ia host galaxy masses to a theoretical model that couples galaxy physics to the SN Ia delay time distribution (DTD), we show the power of the SN Ia host mass distribution in constraining the SN Ia DTD; and (iii) we show that the lack of ultra-low metallicities in the SNfactory SN Ia host sample gives provisional support for the theorized low- metallicity inhibition of SNe Ia. Finally we revisit recent studies which found that the corrected brightness of SNe Ia (after application of the standard light curve width and color corrections) cor- relate with the masses of their host galaxies. We confirm this trend with host mass using SNfactory data, and for the first time confirm that an analogous trend exists with host metallicity. We then apply a spectroscopic standardization technique developed by SNfactory and show that this method significantly reduces the observed bias. In this Thesis we show that SN Ia host galaxies continue to provide key insight into SN Ia progenitors, and also illuminate possible biases in SN Ia brightness standardization techniques. i To my wife, Elonwy Elvenstar Hickey, who is the awesomest wife ever, and our fantastic son, Fionntan´ Malcolm Hickey, born June 2nd, 2011. ii Contents List of Figures iv List of Tables vi 1 Introduction 1 1.1 Type Ia Supernova Cosmology ............................ 2 1.2 Progenitors of SNe Ia ................................. 3 1.3 Why Study SN Ia Host Galaxies? ........................... 3 1.4 Organization of this Thesis .............................. 4 2 Host Galaxies of SNe Ia 6 2.1 SN Ia Progenitors ................................... 6 2.1.1 SN Ia Explosion Physics ........................... 6 2.1.2 Binary Evolution and SNe Ia ......................... 8 2.1.3 Metallicity Effects in SNe Ia ......................... 10 2.2 SN Ia Host Galaxies .................................. 11 2.2.1 SN Ia Brightnesses and Host Galaxy Properties ............... 11 2.2.2 SN Ia Rates and Host Galaxy Properties ................... 12 2.2.3 Observational Measurements of the SN Ia Delay Time Distribution . 13 2.2.4 Spatial Distributions of SNe Ia in their Host Galaxies ............ 14 3 SN and Host Galaxy Data 16 3.1 Supernova Sample: The Nearby Supernova Factory ................. 16 3.1.1 SNfactory Search ............................... 16 3.1.2 SNfactory Followup: SNIFS ......................... 17 3.1.3 SNfactory Light Curve Fits .......................... 18 3.1.4 SNfactory Science .............................. 21 3.1.5 SNfactory Host Galaxy Sample ....................... 23 3.2 Host Galaxy Photometric Data ............................ 26 3.2.1 SNIFS Photometry .............................. 26 3.2.2 Host Galaxy Common Aperture Photometry ................. 29 3.2.3 Host Galaxy Masses and Star-Formation Rates from Photometry ...... 30 3.3 Host Galaxy Spectroscopic Data ........................... 33 3.3.1 SNfactory Host Spectroscopy Observations ................. 33 iii 3.3.2 Redshifts and Emission Line Fluxes ..................... 34 3.3.3 Host Gas Phase Metallicities ......................... 37 4 The Host Galaxy of SN 2007if 39 4.1 SN 2007if Host Observations ............................. 40 4.2 SN 2007if Host Metallicity .............................. 44 4.3 SN 2007if Host Age and Stellar Mass ........................ 47 4.4 HOST07if Analysis Cross-Checks .......................... 58 4.5 Implications of HOST07if Properties ......................... 61 4.6 Summary ....................................... 67 5 Masses and Metallicities of SN Ia Host Galaxies 69 5.1 SN Ia Host Galaxies and the Galaxy Mass-Metallicity Relation ........... 70 5.1.1 The Fiducial Galaxy Mass-Metallicity Relation ............... 70 5.1.2 SNfactory SN Ia Hosts and the MZ Relation ................. 71 5.2 SN Ia Host Galaxy Mass Distributions ........................ 73 5.2.1 Simplified “A+B” Model ........................... 73 5.2.2 General Power Law DTD .......................... 79 5.2.3 Results and Future Work ........................... 80 5.3 Low Luminosity SN Ia Host Galaxies ........................ 82 5.3.1 Low-Luminosity SN Ia Host Sample ..................... 83 5.3.2 Hostless SNe Ia ................................ 87 5.3.3 KN09 Threshold with SNfactory Data .................... 91 5.3.4 Discussion .................................. 96 6 The Dependence of SN Ia Brightnesses on the Properties of Their Host Galaxies 99 6.1 Stretch- and Color-Corrected SN Ia Brightnesses and Host Properties from SNfactory100 6.1.1 Hubble Residuals vs. Galaxy Properties ................... 100 6.1.2 SN Ia Cosmology Fits Split By Galaxy Properties .............. 105 6.2 Flux Ratio-Corrected SN Ia Brightness and Host Properties ............. 106 6.3 Discussion ....................................... 106 6.3.1 Comparison To Previous Studies ....................... 108 6.3.2 Origin of Observed Bias ........................... 109 6.3.3 Correcting Bias in SN Ia Data ........................ 110 7 Conclusions 113 7.1 Host Galaxies of Super-Chandrasekhar-Mass SNe Ia ................ 113 7.2 Statistical Properties of SN Ia Host Galaxies ..................... 114 7.3 SN Ia Brightnesses and the Properties of Their Host Galaxies ............ 117 7.4 Final Remarks ..................................... 118 iv List of Figures 3.1 SNfactory Time Series ................................ 19 3.2 K-Corrections ..................................... 20 3.3 SNfactory Light Curve ................................ 22 3.4 Bailey Ratio Hubble Residuals ............................ 24 3.5 SNfactory Host Mosiac ................................ 27 3.6 SNIFS filter throughputs vs. SDSS. ......................... 28 3.7 Common Aperture Photometry Example ....................... 30 3.8 ZPEG Example Fit .................................. 31 3.9 ZPEG Output Comparison .............................. 32 3.10 Example Spectrum Fit ................................ 35 3.11 Emission Line Fit vs. SDSS ............................. 36 3.12 SNfactory Hosts BPT Diagram ............................ 38 4.1 HOST07if: Keck LRIS image ............................ 41 4.2 HOST07if: Spectroscopic Aperture ......................... 43 4.3 HOST07if: Keck Spectrum .............................. 45 4.4 HOST07if: SFH Diagram ............................... 49 4.5 HOST07if: Age Reconstruction Validation ...................... 51 4.6 HOST07if: Age PDF for recent starburst ....................... 52 4.7 HOST07if: Reconstructed spectrum ......................... 55 4.8 HOST07if: Old star tests ............................... 56 4.9 HOST07if: Reddening ................................ 60 4.10 Super-Chandra SN Ia Hosts - MZ Diagram ...................... 65 5.1 SNfactory MZ Diagram ................................ 72 5.2 MZ Agreement Example 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