Abstract Details
| Name: Kameswara Bharadwaj Mantha Affiliation: University of Missouri Kansas City Conference ID: ASI2018_1537 Title : A Tale of Two Galaxy Merger Identification Techniques: Empirical and Theoretical Investigation of Close-Pairs and Tidal Features Authors and Co-Authors : Daniel H. McIntosh (UMKC), Cody Ciaschi (UMKC), Rubyet Evan (UMKC), Logan Fries (UMKC), Luther Landry (UMKC), Scott Thompson (UMKC), Ryan Brennan (U. Rutgers), Daniel Ceverino (U. Heidelberg), Joshua S. Cook (UMKC), Christopher J. Conselice (U. Nottingham), Darren J. Croton (U. Berkeley), Avishai Dekel (U. Hebrew), Sandra M. Faber (UCSC), Henry C. Ferguson (STScI), Yicheng Guo (U. Mizzou), Nimish P. Hathi (STScI), Dritan Kodra (U. Pittsburgh), David C. Koo (UCSC), Jennifer M. Lotz (STScI), Jeffrey A. Newman (U. Pittsburgh), Gergo Popping (ESO), Joel Primack (UCSC), Marc Rafelski (STScI), Vicente Rodriguez-Gomez (JHU), Brooke D. Simmons (Oxford), Raymond Simons (JHU), Rachel S. Somerville (U. Rutgers), Amber N. Straughn (NASA-GSFC), Gregory F. Synder (STScI), Stijn Wuyts (U. Bath), Lu Yu (Carnegie Observations), Xianzhong Zheng (PMO). Abstract Type : Contributed Talk Abstract Category : Extragalactic astronomy Abstract : Cosmological simulations predict that the rate of merging between similar-mass massive galaxies should increase towards early cosmic-time. We study the incidence of major (stellar mass ratio SMR<4) close-pairs among log(Mstellar/Msun) > 10.3 galaxies spanning 01.5, which is in strong disagreement with theoretical merger rate predictions. On the other hand, if we compare to a simulation-tuned, evolving timescale prescription from Snyder et al., 2017, we find that the merger rate evolution agrees with theory out to z=3. These results highlight the need for robust calibrations of the complex and presumably redshift-dependent pair-to-merger-rate conversion factors to improve constraints on the empirical merger history. To address this, we use a unique compilation of mock datasets produced by three independent state-of-the-art Semi-Analytic Models (SAMs). We present preliminary calibrations of the close-pair observability timescale and outlier fraction as a function of redshift, stellar-mass, mass-ratio, and local over-density. Furthermore, to verify the hypothesis by previous empirical studies that SMR-selection of major pairs may be biased, we present a new analysis of the baryonic (gas+stars) mass ratios of a subset of close pairs in our sample. For the first time, our preliminary investigation highlights that a noticeable fraction of SMR-selected minor pairs (SMR>4) have major baryonic-mass ratios (BMR<4), which indicate that merger rates based on SMR selection may be under-estimated. Additionally, I will showcase the preliminary results of a novel multi-wavelength approach to extract and quantify tidal features and discuss their calibrations to the intrinsic merger-progenitor properties from VELA zoom-in simulations. Finally, I will present the preliminary results of an automated tidal-feature detection algorithm trained using deep-learning techniques. |