- Assistant Professor, University of Pennsylvania (2009-)
- Postdoctoral Research Associate, Harvard-Smithsonian Center for Astrophysics (2007-2009)
- ITC Postdoctoral Fellow, Harvard-Smithsonian Center for Astrophysics (2004-2007)
Ph.D., Physics, Columbia University (2004)
B.A., Physics, The University of Chicago (1996)
I work in theoretical astrophysics and cosmology. I am interested in the formation and evolution of large scale structure, i.e., in understanding how the Universe evolves from a smooth, simple initial state to its present day complexity with galaxies, galaxy clusters, and other structures. A key period in our story of cosmological structure formation is the Epoch of Reionization (EoR), when the first generations of galaxies and/or quasars formed, emitted ultraviolet light, and ionized "bubbles" of hydrogen gas around them. The ionized bubbles grew, merged, and eventually filled essentially the entire volume of the Universe. The EoR and the preceding "dark ages" -- the period after cosmological recombination but before the birth of the first luminous sources -- are the only remaining phases of structure formation as yet to be directly observed. While we know relatively little about this important epoch thus far, we anticipate a confluence of data sets from a variety of wavebands, promising significant advances over the next few years. In particular we expect a wealth of observational data from high redshift quasar absorption spectra, increasingly deep narrow band surveys for Lyman-alpha emitting galaxies, optical afterglow spectra of gamma ray bursts, improved measurements of the cosmic microwave background (CMB) polarization, small-scale CMB fluctuations, and 21 cm observations, among other probes. Much of my recent work involves constructing theoretical models of the EoR to make predictions for these upcoming observations, and to interpret existing observations. I attack these problems using a combination of cosmological simulations, analytic methods, and analysis of observational data. While helium very likely becomes singly ionized along with hydrogen, the first luminous sources may not emit energetic enough photons to also doubly ionize helium. Helium may be doubly ionized only later on, perhaps around z~3 when the Universe is roughly 2 billion years old. I am actively trying to understand the impact of this event on the hydrogen Lyman-alpha forest, and to search for its signatures in observational Lyman-alpha forest data. Other research interests include modeling quasar clustering -- examining how clustering observations inform models for quasar fueling and lifecyles; and extracting constraints on cosmological parameters from Lyman-alpha forest observations.
Phys 533 - Topics in Cosmology
Phys 433 - Order of Magnitude Physics
Sipple, J., Lidz, A., Grin, G., & Sun, G. 2024, "Fuzzy Dark Matter Constraints from the Hubble Frontier Fields", ApJ submitted, arXiv:2407.17059 Cheng, Y.T., Chang, T.C., & Lidz, A. 2024, "Is the Radio Source Dipole from NVSS Consistent with the CMB and LCDM?", ApJ, 965, 32 Sipple, J., & Lidz, A. 2024, "The Star Formation Efficiency During Reionization as Inferred from the Hubble Frontier Fields", ApJ, 961,50 Yang, S., Lidz, A., Smith, A., Benson, A., & Li, H. 2023, "Efficient simulations of ionized ISM emission lines: A detailed comparison between the FIRE high-redshift suite and observations", MNRAS, 525, 5989 La Plante, P., Sipple, J., & Lidz, A. 2022, "Prospects for kSZ^2-Galaxy Cross-Correlations during Reionization", ApJ, 928, 162 Lidz, A., Chang, T.C., Mas-Ribas, L., & Sun, G. 2021, "Future Constraints on the Reionization History and the Ionizing Sources from Gamma-ray Burst Afterglows", ApJ, 917, 58 Yang, S., & Lidz, A. 2020, "An analytic model for OIII fine structure emission from high redshift galaxies", MNRAS, 499, 3417 Beane, A., Villaescusa-Navarro, F., & Lidz, A. 2018, "Measuring the EoR Power Spectrum Without Measuring the EoR Power Spectrum", ApJ, 874, 133 Vikram, V., Lidz, A., & Jain, B. 2017, "A Measurement of the Galaxy-Group Thermal Sunyaev-Zel'dovich Effect Cross-Correlation Function", MNRAS, 467, 2315 Lidz, A., & Taylor, J. 2016, "On Removing Interloper Contamination from Intensity Mapping Power Spectrum Measurements", ApJ, 825, 143 Malloy, M., & Lidz, A. 2014, "How to Search for Neutral Hydrogen in the z ~ 5.5 IGM", ApJ 799, 179 Lidz, A., Furlanetto, S.R., Oh, S.P., Aguirre, J., Chang, T.-C., Dore, O., & Pritchard, J.R. 2011, "Intensity Mapping with Carbon Monoxide Emission Lines and the Redshifted 21 cm Line", ApJ, 741, 70 Lidz, A., Faucher-Giguere, C.A., Dall'Aglio, A., McQuinn, M., Fechner, C., Zaldarriaga, M., Hernquist, L., & Dutta, S. 2010, "A Measurement of Small Scale Structure in the $2.2 \leq z \leq 4.2$ Lyman-alpha Forest", ApJ, 718, 199 Faucher-Giguere, C.A., Lidz, A., Zaldarriaga, M., & Hernquist, L. 2009, "A New Calculation of the Ionizing Background and the Effects of HeII Reionization", ApJ, 703, 1416 McQuinn, M., Lidz, A., Zaldarriaga, M., Hernquist, L., Hopkins, P.F., Dutta, S., & Faucher-Giguere, C.A. 2009, "HeII Reionization and its Effect on the IGM", ApJ, 694, 842 Lidz, A., Zahn, O., Furlanetto, S.R., McQuinn, M., Hernquist, L., & Zaldarriaga, M. 2009, "Probing Reionization with the 21 cm-Galaxy Cross Power Spectrum", ApJ, 690, 252 Lidz, A., Zahn, O., McQuinn, M., Zaldarriaga, M., & Hernquist, L. 2008, "Detecting the Rise and Fall of 21 cm Fluctuations with the Murchison Widefield Array", ApJ 680, 962 Lidz, A., McQuinn, M., Zaldarriaga, M., Hernquist, L., & Dutta, S. 2007, "Quasar Proximity Zones and Patchy Reionization", ApJ, 670, 39 McQuinn, M., Lidz, A., Zahn, O., Dutta, S., Hernquist, L., & Zaldarriaga, M. 2007, "The Morphology of HII Regions During Reionization", MNRAS, 377, 1043 Lidz, A., Zahn, O., McQuinn, M., Zaldarriaga, M., Dutta, S., & Hernquist, L. 2007, "Higher Order Contributions to the 21 cm Power Spectrum", ApJ, 659, 865 Zahn, O., Lidz, A., McQuinn, M., Dutta, S., Hernquist, L., Zaldarriaga, M., & Furlanetto, S.R. 2007, "Simulations and Analytic Calculations of Bubble Growth During Hydrogen Reionization", ApJ, 654, 12