Ravi Kopparapu - Postdoctoral Scholar
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Physical Address:334D Whitmore Laboratory |
Mailing Address:The Pennsylvania State University |
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Ph.D. Thesis
POPULATION BOUNDARIES AND GRAVITATIONAL-WAVE TEMPLATES FOR WHITE DWARF BINARIES.
Research
Publications List
Gravitational-wave Astrophysics
I am invloved in projects studying the sources of gravitational-waves that are relevant to ground based gravitational-wave (GW) detector LIGO and proposed space based gravitational-wave detector, LISA. At present I am working on the following research projects:
LIGO
Gamma-ray bursts (GRBs) are thought to be the most electromagnetically luminous astronomical events in the universe. The progenitors of GRBs are believed to be associated with hypernovae events (explosion resulting from the collapse and bounce of a massive star) mergers of Neutron star-Neutron star (NS-NS) binaries. They are also one of the most promising gravitational-wave (GW) sources. Including myself, Our research group involving Sam Finn, Ruxandra Bondarescu, Megan Lang, Tiffany Summerscales study how joint GRB and gravitational-wave (GW) observations can test these and other progenitor models, using a coherent data-analysis technique applied to data from a network of gravitational-wave detectors. Using GRB trigger times (i.e, the time at which a GRB is detected through electromagnetic observations), our goal is to search GW data at those times to identify the source GW waveform, which could tell us about the progenitors of GRBs.
LISA
Working on the astrophysics of gravitational-wave sources such as double white dwarfs (DWDs) and white dwarf-Neutron star (WD-NS) binaries. These are guaranteed low frequency GW sources that can be detected by the proposed NASA/ESA space-based gravitational-wave observatory, LISA (Laser Interferometer Space Antenna), which is planned to be launched in the next decade.
In collaboration with Joel Tohline from LSU, I have studied various evolutionary phases that DWDs and NSWDs undergo and mapped them on to a distance indepenent GW amplitude-frequency space (similar to a "color-magnitude" diagram for stars in traditional astronomy). These studies help in improving the understanding of various evolutionary stages these systems undergo during their lifetime and help determine the characteristics of these objects such as their masses and distances.
With help of this mapping and theoretical constraints on the properties of WDs, one can identify whether a given system falls into a distinct sub-domain of astrophysical interest such as an inspiral or an AM CVn system etc. If the system's frequency evolution is not measurable, then once can put bounds on the system's parameters such as the individual component masses and also on the distance to the system.
Extrasolar Planets
My main interest is in studying the dynamical stabitlity of extrasolar planets (mainly terrestrial mass planets, mass <10 M_E) in the habitable zone. Dynamical stability means to see if a planet remains stable in it's orbit over a long evolutionary (dynamical) time-scale (typically, I see it as 10 million years ). Classically, Habitable zone is defined as the range of orbits for which a terrestrial mass planet with favorable atmospheric conditions, can sustain liquid water on its surface (Kasting et al. 1993, Selsis et al. 2007).
I work with Rory Barnes and Sean Raymond on this project and we published a paper on a possible terrestrial mass planet in the habitable zone of HD 47186 planetary system. I am also a member of Virtual Planetary Lab (VPL) of NASA Astrobiology Institute (NAI).