MARIANGELA BERNARDI
Assistant Professor
University of Pennsylvania
Dept. of Physics & Astronomy
209 South 33rd Street
Philadelphia, PA 19104-6396
(215) 573-6251
 bernardm@physics.upenn.edu


Mariangela Bernardi is currently an assistant professor in the Department of Physics and Astronomy at the University of Pennsylvania. Early-type galaxies are her main research interest. She assembled, maintained and analyzed the ENEAR database used for peculiar velocity studies; it is still the only all-sky early-type galaxy database. She demonstrated that chemical compositions of early-type galaxies in the ENEAR sample show little dependence on environment. She also used the SDSS database to assemble and analyze the largest catalog of early-type galaxies. She used it to analyze the Fundamental Plane at ~ 0.1; to demonstrate that velocity dispersion is the key physical parameter which determines galaxy properties; and to make the first direct measurements of the distribution of galaxy sizes, masses and velocity dispersions. She is also acknowledged as an SDSS builder.
She has published work on the IGM and quasars at intermediate and high redshift: she showed that the effective optical depth in the Ly-alpha forest region of SDSS quasar spectra decreases suddenly, by about ten percent with respect to a smoother evolution, at z ~ 3.2. Although initially controversial, recent work by other groups, with higher resolution spectra, has confirmed the existence of this feature. The strength and duration of the feature in the optical depth is consistent with numerical simulations of the effect of He II reionization, a field in which the SDSS was never expected to make a contribution.
At Penn, she has used the SDSS to assemble two different candidate samples for the most massive galaxies in the Universe; one sample contains the most luminous galaxies (usually called Brightest Cluster Galaxies) and the other contains galaxies with extremely large velocity dispersions. BCGs appear to be slightly less dense than average, whereas the other sample contains some of the densest galaxies in the Universe -- both samples constrain the latest galaxy formation models. The most massive galaxies are expected to contain the most massive black holes in the Universe; she has shown how some correlations traced by black hole hosts are different from those defined by the bulk of the SDSS early-type galaxy population. She is currently exploring the implications of the observation that the epoch when most of the stars in early-type galaxies formed coincides with the time in the Universe's history when quasars were most active. She has also been the first to show that the sizes and velocity dispersion of massive early-type galaxies are evolving even at small lookback times, in a manner which suggests that a shift in paradigm is needed: minor rather than major mergers may have been an important formation mechanism for the most massive galaxies.


LINKS

  • Publications and CV
  • Research Statement
  • Teaching Statement

    • RESEARCH AREA

  • Observational Cosmology
  • Early-type Galaxies: formation, evolution, and environmental dependence
  • Super-massive black holes
  • Large-scale structures and peculiar motions
  • QSOs and Ly-alpha forest
  • Galaxy structure


    • SELECTED PUBLICATIONS (by topic):

    Distributions of galaxy observables

  • Galaxy luminosities, stellar masses, sizes, velocity dispersions as a function of morphological type
    • Bernardi, M., Shankar, F., Hyde, J. B., Mei, S., Marulli, F. & Sheth, R. K. 2009, MNRAS, submitted (arXiv:0910.1093)

    Joint distributions of early-type galaxy observables

  • Early-type galaxies in the SDSS. II. Correlations between observables
    • M. Bernardi, R. K. Sheth, J. Annis et al. 2003, AJ, 125, 1849
  • Colors, magnitudes and velocity dispersions in early-type galaxies: Implications for galaxy ages and metallicities
    • M. Bernardi, R. K. Sheth, R. C. Nichol et al. 2005, AJ, 129, 61
  • Curvature in the scaling relations of early-type galaxies
    • J. B. Hyde & M. Bernardi 2009, MNRAS, 394, 1978

    Fundamental Plane

  • Early-type galaxies in the SDSS. III. The Fundamental Plane
    • M. Bernardi, R. K. Sheth, J. Annis et al. 2003, AJ, 125, 1866
  • The luminosity and stellar mass Fundamental Plane of early-type galaxies
    • J. B. Hyde & M. Bernardi 2009, MNRAS, 396, 1171

    Environmental dependence

  • Cluster versus Field Elliptical Galaxies and Clues on Their Formation
    • M. Bernardi, A. Renzini, L. N. da Costa, G. Wegner, M. V. Alonso, P. Pellegrini, C. Rité, & C. N. A. Willmer 1998, ApJ Letters, 508, 143
  • Evolution and environment of early-type galaxies
    • M. Bernardi, R. C. Nichol, R. K. Sheth, et al. 2006, AJ, 131, 1288

    Brightest Cluster Galaxies

  • The luminosities, sizes and velocity dispersions of Brightest Cluster Galaxies: Implications for formation history
    • M. Bernardi, J. B. Hyde, R. K. Sheth, C. J. Miller & R. C. Nichol 2007, AJ, 133, 1741
  • Evolution in the structural properties of early-type brightest cluster galaxies at small lookback time and dependence on the environment
    • M. Bernardi 2009, MNRAS, 395, 1491
  • Colour Gradients and the Colour-Magnitude Relation: Different Properties of Brightest Cluster Galaxies and E/S0 Galaxies in the Sloan Digital Sky Survey
    • N. Roche, M. Bernardi & J. B. Hyde 2009, MNRAS, submitted (arXiv:0911.0044)

    BigSigs: Galaxies with the highest velocity dispersion

  • A search for the most massive galaxies: Double Trouble?
    • M. Bernardi, Sheth, R. K., Nichol, R. C. et al. 2006, AJ, 131, 2018
  • A search for the most massive galaxies. II. Structure, environment and formation
    • M. Bernardi, J. B. Hyde, A. Fritz, R. K. Sheth, K. Gebhardt & R. C. Nichol 2008, MNRAS, 391, 1191
  • A search for the most massive galaxies. III. Surface brightness profiles and structural properties from HST images
    • J. B. Hyde, M. Bernardi, A. Fritz, R. K. Sheth & R. C. Nichol 2008, MNRAS, 391, 1559

    Super-massive black holes

  • Selection bias in the M_bh-sigma and M_bh-L correlations and its consequences
    • M. Bernardi, R. K. Sheth, E. Tundo & J. B. Hyde 2007, ApJ, 660, 267
  • On the inconsistency between the black hole mass function inferred from M_bh-sigma and M_bh-L correlations
    • E. Tundo, M. Bernardi, J. B. Hyde, R. K. Sheth & A. Pizzella 2007, ApJ, 663, 53

    Peculiar velocities

  • Redshift-distance Survey of Early-type Galaxies. I. The ENEARc Cluster Sample
    • M. Bernardi, M. V. Alonso, L. N. da Costa, C. N. A. Willmer, G. Wegner, P. S. Pellegrini, C. Rite` & M. A. G. Maia 2002, AJ, 123, 2990
  • Redshift-Distance Survey of Early-Type Galaxies: Dipole of the Velocity Field
    • L. N. da Costa, M. Bernardi, M. V. Alonso, G. Wegner, C. N. A. Willmer, P. S. Pellegrini, M. A. G. Maia & S. Zaroubi 2000, ApJ Letters, 537, 81

    Ly-alpha forest and He II reionization

  • A feature at z ~ 3.2 in the evolution of the Ly-alpha forest optical depth
    • M. Bernardi, R. K. Sheth, M. Subbarao et al. 2003, AJ, 125, 32
  • Detection of He II reionization in the SDSS quasar sample
    • T. Theuns, M. Bernardi, J. Frieman, P. Hewett, J. Schaye, R. K. Sheth, & M. Subbarao 2002, ApJ Letters, 111, 114