Steve Kraemer

Department

  • Physics

    • School

  • School of Arts and Sciences

    • Research Interests

    Dr. Kraemer is an extra-galactic astrophysicist and has extensive experience in the modeling of photoionized nebulae and the analysis of X-ray, UV, optical and IR spectra of active galaxies, in particular Seyfert galaxies. He has been PI of observing programs using Chandra, XMM-Newton, Hubble Space Telescope, and Spitzer. Dr. Kraemer was a co-investigator on the Space Telescope Imaging Spectrograph Instrument Development Team. Specific areas of research, which Kraemer conducts with Professor Mike Crenshaw (Georgia State University), Dr. Jane Turner (Eureka), Dr. Henrique Schmitt (Naval Research Lab), Dr. Marcio Melendez (UMCP), Dr. T. Cody Fischer (GSU), among others, include:

    1. Mass Outflows in AGN and AGN feedback. The relationship between the mass of the central bulge of galaxies and that of the super-massive black holes that reside within suggests co-evolution. One possible mechanism is the clearing of gas by winds generated by the AGN, i.e. "AGN feedback". Mass outflows, in the form of blueshifted absorption lines in the UV and X-ray, are found in approximately half of all Seyfert galaxies, with radial velocities up to several 1000 km/s. These outflows may be powerful enough to affect the host galaxy and hence may provide insight into AGN feedback processes.
    2. Physical conditions in the gas in the narrow-line regions (NLR) of Seyfert galaxies. Of particular interest is the question: is this gas ionized solely by EUV-Xray radiation from the central nuclear source or are there other important effects, such as ionization by relativistic particles associated with radio ``jets''? Furthermore, we have found that star-formation makes a significant contribution to the mid-IR emission-line spectra of many Seyfert galaxies and, likely, to optical spectra of the NLR.
    3. The kinematics of the narrow-line gas in Seyfert galaxies. Understanding the motion of gas in the inner regions of Seyfert galaxies may provide important clues regarding the evolution of this phase of activity. By combining the kinematic studies with the physical parameters of the NLR derived from photo-ionization modeling, we have found that NLR outflows may be more important to AGN feedback than outflows originating close to the AGN.

    Professional Affiliations

    American Astronomical Society
    Astronomical Society of the Pacific

    Professional Experience

    Co-Investigator, Space Telescope Imaging Spectrograph team
    Research on Seyfert Galaxies
    Computer modeling of astrophysical plasmas
    Spectroscopy - ultraviolet and optical
    Development of embedded software to operate astronomical instruments
    Operation of astronomical satellites
    Calibration of astronomical instruments
    Supervising graduate student research

    Research Grants and Activities

    Member of peer review committees for HST, NuSTAR, Chandra, NSF Astrophysics, and XRISM.

    Current and Former Graduate Students

    Selected Recent Papers


    "Star Formation Rates in [Ne V] 3426 Å Selected Active Galactic Nuclei: Evidence for a Decrease along the Main Sequence?", Feuillet, L. M., Meléndez, M., Kraemer, S., et al. 2024, ApJ, 968, 91, doi: 10.3847/1538-4357/ad47bb

    "Classifying Intermediate-redshift Galaxies in SDSS: Alternative Diagnostic Diagrams", Feuillet, L. M., Meléndez, M., Kraemer, S., et al. 2024, ApJ, 962, 104, doi: 10.3847/1538-4357/ad1a09

    "Resolving Dual Active Galactic Nuclei with ~100 pc separation in MCG-03-34-64", Trindade Falcao, A., Kraemer, S. B., Crenshaw, D. M., et al. 2022, MNRAS, 511, 1420, doi: 10.1093/mnras/stac173

    "Tracking X-ray outflows with optical/infrared footprint lines", Trindade Falcao, A., Kraemer, S. B., Crenshaw, D. M., et al. 2022, MNRAS, 511, 1420, doi: 10.1093/mnras/stac173

    "Hubble Space Telescope [O III] emission-line kinematics in two nearby QSO2s: a case for X-ray feedback", Trindade Falcao, A., Kraemer, S. B., Fischer, T. C., et al. 2021, MNRAS, 505, 3054, doi: 10.1093/mnras/stab1549

    "Gauging the effect of supermassive black holes feedback on quasar host galaxies", Dall’Agnol de Oliveira, B., Storchi-Bergmann, T., Kraemer, S. B., et al. 2021, MNRAS, 504, 3890, doi: 10.1093/mnras/stab1067

    "Hubble Space Telescope observations of [O III] emission in nearby QSO2s: physical properties of the ionized outflows", Trindade Falcao, A., Kraemer, S. B., Fischer, T. C., et al. 2021, MNRAS, 500, 1491, doi: 10.1093/mnras/staa3239

    "Mass outflow of the X-ray emission line gas in NGC 4151", Kraemer, S. B., Turner, T. J., Couto, J. D., et al. 2020, MNRAS, 493, 3893, doi: 10.1093/mnras/staa428

     

    Other Stuff

    Steve Kraemer is the only member of the American Astronomical Society to get a mention in Christiane Bird's "Guide to Live Jazz and Blues in the U.S."