University of Michigan
Department of Astronomy
+1 (734) 615-1585
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Date of Birth: January 22, 1977
Place of Birth: Hanover, New Hampshire

Ph.D. in Astronomy, University of Maryland, College Park -- August 2006
Advisor: Dr. M. Coleman Miller
Thesis: "Growing Intermediate-Mass Black Holes with Gravitational Waves" (Download PDF)
Ph.D. Candidate in Astronomy, University of Maryland, College Park -- March 2002
M.S. in Astronomy, University of Maryland, College Park -- December 2002
B.A. with Distinction in Physics (Astrophysics concentration), University of Pennsylvania -- May 1999
Advisor: Dr. David Koerner - Thesis: "A Circumstellar Disk around the High-Mass Protostar L1206A"

1. [+] Abstract - ADS - arXiv - PDF - Reprint - BibTeX
   Gültekin, Kayhan, Cackett, Edward M., Miller, Jon M., Di Matteo, Tiziana, Markoff, Sera, & Richstone, Douglas O. (Nov 2009), “The Fundamental Plane of Accretion onto Black Holes with Dynamical Masses,” The Astrophysical Journal, Volume 706, Issue 1, pp. 404-416 (2009). [1 citations]
   
   Black hole accretion and jet production are areas of intensive study in astrophysics. Recent work has found a relation between radio luminosity, X-ray luminosity, and black hole mass. With the assumption that radio and X-ray luminosities are suitable proxies for jet power and accretion power, respectively, a broad fundamental connection between accretion and jet production is implied. In an effort to refine these links and enhance their power, we have explored the above relations exclusively among black holes with direct, dynamical mass-measurements. This approach not only eliminates systematic errors incurred through the use of secondary mass measurements, but also effectively restricts the range of distances considered to a volume-limited sample. Further, we have exclusively used archival data from the Chandra X-ray Observatory to best isolate nuclear sources. We find log LR = (4.80 ± 0.24) + (0.78 ± 0.27)log M BH + (0.67 ± 0.12)log LX , in broad agreement with prior efforts. Owing to the nature of our sample, the plane can be turned into an effective mass predictor. When the full sample is considered, masses are predicted less accurately than with the well-known M-σ relation. If obscured active galactic nuclei are excluded, the plane is potentially a better predictor than other scaling measures.
   
2. [+] Abstract - ADS - arXiv - PDF - Reprint - BibTeX
   Gültekin, Kayhan et al. (Jun 2009), “The M-σ and M-L Relations in Galactic Bulges, and Determinations of Their Intrinsic Scatter,” The Astrophysical Journal, Volume 698, Issue 1, pp. 198-221 (2009). [27 citations]
   
   We derive improved versions of the relations between supermassive black hole mass (M BH) and host-galaxy bulge velocity dispersion (σ) and luminosity (L; the M-σ and M-L relations), based on 49 M BH measurements and 19 upper limits. Particular attention is paid to recovery of the intrinsic scatter (epsilon0) in both relations. We find log(M BH/M sun) = α + βlog(σ/200 km s-1) with (α, β, epsilon0) = (8.12 ± 0.08, 4.24 ± 0.41, 0.44 ± 0.06) for all galaxies and (α, β, epsilon0) = (8.23 ± 0.08, 3.96 ± 0.42, 0.31 ± 0.06) for ellipticals. The results for ellipticals are consistent with previous studies, but the intrinsic scatter recovered for spirals is significantly larger. The scatter inferred reinforces the need for its consideration when calculating local black hole mass function based on the M-σ relation, and further implies that there may be substantial selection bias in studies of the evolution of the M-σ relation. We estimate the M-L relationship as log(M BH/M sun) = α + βlog(LV /1011 L sun,V ) of (α, β, epsilon0) = (8.95 ± 0.11, 1.11 ± 0.18, 0.38 ± 0.09); using only early-type galaxies. These results appear to be insensitive to a wide range of assumptions about the measurement errors and the distribution of intrinsic scatter. We show that culling the sample according to the resolution of the black hole's sphere of influence biases the relations to larger mean masses, larger slopes, and incorrect intrinsic residuals.
   
3. [+] Abstract - ADS - arXiv - PDF - Reprint - BibTeX
   Gültekin, Kayhan et al. (Apr 2009), “A Quintet of Black Hole Mass Determinations,” The Astrophysical Journal, Volume 695, Issue 2, pp. 1577-1590 (2009). [8 citations]
   
   We report five new measurements of central black hole masses based on Space Telescope Imaging Spectrograph and Wide Field Planetary Camera 2 observations with the Hubble Space Telescope (HST) and on axisymmetric, three-integral, Schwarzschild orbit-library kinematic models. We selected a sample of galaxies within a narrow range in velocity dispersion that cover a range of galaxy parameters (including Hubble type and core/power-law surface density profile) where we expected to be able to resolve the galaxy's sphere of influence based on the predicted value of the black hole mass from the M-σ relation. We find masses for the following galaxies: NGC 3585, M BH = 3.4+1.5 -0.6 × 108 M sun; NGC 3607, M BH = 1.2+0.4 -0.4 × 108 M sun; NGC 4026, M BH = 2.1+0.7 -0.4 × 108 M sun; and NGC 5576, M BH = 1.8+0.3 -0.4 × 108 M sun, all significantly excluding M BH = 0. For NGC 3945, M BH = 9+17 -21 × 106 M sun, which is significantly below predictions from M-σ and M-L relations and consistent with M BH = 0, though the presence of a double bar in this galaxy may present problems for our axisymmetric code. Based on observations made with the Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with GO proposals 5999, 6587, 6633, 7468, and 9107.
   
4. [+] Abstract - ADS - arXiv - PDF - Reprint - BibTeX
   Holley-Bockelmann, Kelly, Gültekin, Kayhan, Shoemaker, Deirdre, & Yunes, Nicolas (Oct 2008), “Gravitational Wave Recoil and the Retention of Intermediate-Mass Black Holes,” The Astrophysical Journal, Volume 686, Issue 2, pp. 829-837. [14 citations]
   
   During the inspiral and merger of a binary black hole, gravitational radiation is emitted anisotropically due to asymmetries in the merger configuration. This anisotropic radiation leads to a gravitational wave kick, or recoil velocity, as large as ~4000 km s-1. We investigate the effect gravitational recoil has on the retention of intermediate-mass black holes (IMBHs) within the population of Galactic globular clusters by simulating the response of IMBHs to black hole mergers. Assuming that our current understanding of IMBH formation is correct and yields an IMBH seed in every globular cluster, we find a significant problem in retaining low-mass IMBHs (<~1000 Msolar) in the typical merger-rich globular cluster environment. Given a uniform black hole spin distribution and orientation and a stellar-mass black hole mass function generated in a low-metallicity system, we find that only three of the Milky Way globular clusters can retain an IMBH with an initial mass of 200 Msolar. Even if IMBHs have an initial mass of 1000 Msolar, only 60 would remain within Milky Way globular clusters, and each would reside only in the most massive clusters. Our calculations show that if there are black holes of mass M>50 Msolar in a cluster, repeated IMBH-black hole encounters will eventually eject a M=1000 Msolar IMBH with greater than 30% probability. As a consequence, a large population of rogue black holes may exist in our Milky Way halo. We briefly discuss the dynamical implications of this process and its possible connection to ultraluminous X-ray sources (ULXs).
   
5. [+] Abstract - ADS - arXiv - PDF - Reprint - BibTeX
   Volonteri, Marta, Haardt, Francesco, & Gültekin, Kayhan (Mar 2008), “Compact massive objects in Virgo galaxies: the black hole population,” Monthly Notices of the Royal Astronomical Society, Volume 384, Issue 4, pp. 1387-1392. [5 citations]
   
   We investigate the distribution of massive black holes (MBHs) in the Virgo cluster. Observations suggest that active galactic nuclei activity is widespread in massive galaxies (M* >~ 1010Msolar), while at lower galaxy masses star clusters are more abundant, which might imply a limited presence of central black holes in these galaxy-mass regimes. We explore if this possible threshold in MBH hosting is linked to nature, nurture or a mixture of both. The nature scenario arises naturally in hierarchical cosmologies, as MBH formation mechanisms typically are efficient in biased systems, which would later evolve into massive galaxies. Nurture, in the guise of MBH ejections following MBH mergers, provides an additional mechanism that is more effective for low mass, satellite galaxies. The combination of inefficient formation, and lower retention of MBHs, leads to the natural explanation of the distribution of compact massive objects in Virgo galaxies. If MBHs arrive to the correlation with the host mass and velocity dispersion during merger-triggered accretion episodes, sustained tidal stripping of the host galaxies creates a population of MBHs which lie above the expected scaling between the holes and their host mass, suggesting a possible environmental dependence.
   
6. [+] Abstract - ADS - arXiv - PDF - Reprint - BibTeX
   Gültekin, Kayhan, Miller, M. Coleman, & Hamilton, Douglas P. (Mar 2006), “Three-Body Dynamics with Gravitational Wave Emission,” The Astrophysical Journal, Volume 640, Issue 1, pp. 156-166. [29 citations]
   
   We present numerical three-body experiments that include the effects of gravitational radiation reaction by using equations of motion that include the 2.5-order post-Newtonian force terms, which are the leading-order terms of energy loss from gravitational waves. We simulate binary-single interactions and show that close-approach cross sections for three 1 Msolar objects are unchanged from the purely Newtonian dynamics except for close approaches smaller than 10-5 times the initial semimajor axis of the binary. We also present cross sections for mergers resulting from gravitational radiation during three-body encounters for a range of binary semimajor axes and mass ratios including those of interest for intermediate-mass black holes (IMBHs). Building on previous work, we simulate sequences of high-mass-ratio three-body encounters that include the effects of gravitational radiation. The simulations show that the binaries merge with extremely high eccentricity such that when the gravitational waves are detectable by LISA, most of the binaries will have eccentricities e>0.9, although all will have circularized by the time they are detectable by LIGO. We also investigate the implications for the formation and growth of IMBHs and find that the inclusion of gravitational waves during the encounter results in roughly half as many black holes ejected from the host cluster for each black hole accreted onto the growing IMBH.
   
7. [+] Abstract - ADS - arXiv - PDF - Reprint - BibTeX
   Gültekin, Kayhan, Miller, M. Coleman, & Hamilton, Douglas P. (Nov 2004), “Growth of Intermediate-Mass Black Holes in Globular Clusters,” The Astrophysical Journal, Volume 616, Issue 1, pp. 221-230. [42 citations]
   
   We present results of numerical simulations of sequences of binary-single scattering events of black holes in dense stellar environments. The simulations cover a wide range of mass ratios from equal mass objects to 1000:10:10 Msolar and compare purely Newtonian simulations to simulations in which Newtonian encounters are interspersed with gravitational wave emission from the binary. In both cases, the sequence is terminated when the binary's merger time due to gravitational radiation is less than the arrival time of the next interloper. We find that black hole binaries typically merge with a very high eccentricity (0.93<=e<=0.95 pure Newtonian; 0.85<=e<=0.90 with gravitational wave emission) and that adding gravitational wave emission decreases the time to harden a binary until merger by ~30%-40%. We discuss the implications of this work for the formation of intermediate-mass black holes and gravitational wave detection.
   
8. [+] Abstract - ADS - arXiv - PDF - Reprint - BibTeX
   Koerner, D. W., Jensen, E. L. N., Cruz, K. L., Guild, T. B., & Gultekin, K. (Apr 2000), “A Single Circumbinary Disk in the HD 98800 Quadruple System,” The Astrophysical Journal, Volume 533, Issue 1, pp. L37-L40. [28 citations]
   
   We present subarcsecond thermal infrared imaging of HD 98800, a young quadruple system composed of a pair of low-mass spectroscopic binaries separated by 0.8" (38 AU), each with a K-dwarf primary. Images at wavelengths ranging from 5 to 24.5 μm show unequivocally that the optically fainter binary, HD 98800B, is the sole source of a comparatively large infrared excess on which a silicate emission feature is superposed. The excess is detected only at wavelengths of 7.9 μm and longer, peaks at 25 μm, and has a best-fit blackbody temperature of 150 K, indicating that most of the dust lies at distances greater than the orbital separation of the spectroscopic binary. We estimate the radial extent of the dust with a disk model that approximates radiation from the spectroscopic binary as a single source of equivalent luminosity. Given the data, the most likely values of disk properties in the ranges considered are Rin=5.0+/-2.5 AU, ΔR=13+/-8 AU, λ0=2+4-1.5 μm, γ=0+/-2.5, and σtotal=16+/-3 AU2, where Rin is the inner radius, ΔR is the radial extent of the disk, λ0 is the effective grain size, γ is the radial power-law exponent of the optical depth τ, and σtotal is the total cross section of the grains. The range of implied disk masses is 0.001-0.1 times that of the Moon. These results show that, for a wide range of possible disk properties, a circumbinary disk is far more likely than a narrow ring.
   

1. [+] Abstract - ADS - BibTeX
   Gultekin, Kayhan (Sep 2009), “COMBH: Chandra Observations of M-sigma Black Holes,” Chandra proposal ID #11900514
   Galaxies with dynamically-measured central BH masses allow us to understand BH accretion, jets, and interactions between BHs and host galaxies with a clarity not possible in random surveys. By measuring true Eddington fractions, we can calculate the energy in radiation vs mechanical jet energy and the efficacy of BHs in heating nuclear regions and affecting star formation. Remarkably, 1/3 of SMBHs making up the M-sigma relation have been poorly observed or totally unobserved with Chandra. We propose a survey of 15 M-sigma galaxies to complete the sample of reliable M-sigma SMBHs. For each galaxy we propose to obtain 30-60 ks exposures and an hour-long VLA observation. This survey will test and extend the fundamental plane of BH activity and facilitate studies of the origin of M-sigma.
   
2. [+] Abstract - ADS - BibTeX
   Gultekin, Kayhan, & Richstone, D. O. (Dec 2007), “The Fundamental Plane for Nuclear Black Hole Masses,” American Astronomical Society, AAS Meeting #211, #144.07; Bulletin of the American Astronomical Society, Vol. 39, p.997
   We present the latest analysis of the relationship between nuclear black hole mass and properties of the host galaxy or bulge, notably stellar velocity dispersion. This analysis includes six new measurements of black hole masses based on observations with HST using STIS and WFPC2 as well as the most recent results from the literature for a total of about 50 dynamical black hole mass measurements. We also include in our analysis, for the first time, 15 measured upper limits on black hole mass. Studies of supermassive black holes in galaxy centers have led to the discoveries that most or all hot galaxies contain massive dark objects at their centers, presumably black holes; and that there is a remarkably tight correlation between the black-hole mass and the luminosity-weighted velocity dispersion of the hot component of the galaxy. This M-sigma relationship suggests a strong link between black-hole formation, AGN activity, and galaxy formation, and once it is understood, this link should advance our understanding of all three processes. In this work we (1) present the most current fit to the M-sigma relation; (2) measure the scatter in the relation, which previous studies claim to be consistent with zero scatter; and (3) investigate the role of possible second parameters in predicting black hole mass, that is a fundamental plane relationship.
   
3. [+] Abstract - ADS - BibTeX
   Holley-Bockelmann, Kelly, Gultekin, K., Shoemaker, D., & Yunes, N. (Dec 2007), “Gravitational Wave Recoil and the Retention of Intermediate Mass Black Holes,” American Astronomical Society, AAS Meeting #211, #49.02; Bulletin of the American Astronomical Society, Vol. 39, p.811
   During the inspiral and merger of a binary black hole, gravitational radiation is emitted anisotropically due to asymmetries in the merger configuration. This anisotropic radiation leads to a gravitational wave kick, or recoil velocity, as large as 4000 km/sec. We investigate the effect gravitational recoil has on the retention of intermediate mass black holes (IMBH) within Galactic globular clusters. Assuming that our current understanding of IMBH-formation is correct and yields an IMBH-seed in every globular cluster, we find a significant problem retaining low mass IMBHs in the typical merger-rich globular cluster environment. Given a uniform black hole spin distribution and orientation and a Kroupa IMF, we find that at most 3 percent of the globular clusters can retain an IMBH larger than 1000 solar masses today. For a population of black holes that better approximates mass loss from winds and supernovae, we find that 16 percent of globulars can retain an IMBH larger than 1000 solar masses. Our calculations show that if there are black holes larger than 60 solar masses in a cluster, repeated IMBH-BH encounters will eventually eject a 1000 solar mass IMBH with greater than 30 percent probability. As a consequence, a large population of rogue black holes may exist in our Milky Way halo. We discuss the dynamical implications of this subpopulation, and its possible connection to ultraluminous X-ray sources (ULXs).
   
4. [+] Abstract - ADS - BibTeX
   Gultekin, Kayhan, Holley-Bockelmann, K., Miller, M. C., Shoemaker, D., & Yunes, N. (Jul 2007), “Gravitational Wave Kicks of Intermediate-Mass Black Holes,” American Astronomical Society, DDA meeting #38, #2.02
   Recent numerical relativistic simulations have found that recoil from gravitational wave emission of merging black holes can produce kicks up to 1000 km/s. Because intermediate-mass black holes (IMBHs) are thought to form in dense stellar clusters, their ejection from the cluster becomes a real possibility. In this talk we present results on the retention probability of IMBHs as they interact with the host cluster's stellar-mass black hole population. We consider the ramifications of gravitational wave recoil and potential for further growth as the IMBHs merge with stellar mass black holes. We consider IMBHs that are the evolution of Population III stars, core-collapse runaway merger remnants (including multiples), and those built up from mergers of stellar-mass black holes.
   
5. [+] Abstract - ADS - Reprint - BibTeX
   Gultekin, Kayhan (Jun 2006), “Growing intermediate-mass black holes with gravitational waves,” PhD Thesis, Proquest Dissertations And Theses 2006. Section 0117, Part 0606 126 pages; [Ph.D. dissertation].United States -- Maryland: University of Maryland, College Park; 2006. Publication Number: AAT 3222352. Source: DAI-B 67/06, Dec 2006
   We present results of numerical simulations of sequences of binary-single scattering events of black holes in dense stellar environments. The simulations cover a wide range of mass ratios from equal mass objects to 1000:10:10 [Special characters omitted.] and compare purely Newtonian simulations with a relativistic endpoint, simulations in which Newtonian encounters are interspersed with gravitational wave emission from the binary, and simulations that include the effects of gravitational radiation reaction by using equations of motion that include the 2.5-order post-Newtonian force terms, which are the leading-order terms of energy loss from gravitational waves. In all cases, the sequence is terminated when the binary's merger time due to gravitational radiation is less than the arrival time of the next interloper. We also examine the role of gravitational waves during an encounter and show that close approach cross-sections for three 1 [Special characters omitted.] objects are unchanged from the purely Newtonian dynamics except for close approaches smaller than 10-5 times the initial semimajor axis of the binary. We also present cross-sections for mergers resulting from gravitational radiation during three-body encounters for a range of binary semimajor axes and mass ratios including those of interest for intermediate-mass black holes (IMBHs). We find that black hole binaries typically merge with a very high eccentricity- --extremely high when gravitational waves are included during the encounter such that when the gravitational waves are detectable by LISA, most of the binaries will have eccentricities e > 0.9 though all will have circularized by the time they are detectable by LIGO. We also investigate the implications for the formation and growth of IMBHs and find that the inclusion of gravitational waves during the encounter results in roughly half as many black holes ejected from the host cluster for each black hole accreted onto the growing IMBH. The simulations show that the Miller & Hamilton (2002b) model of IMBH formation is a viable method if it is modified to start with a larger seed mass.
   
6. [+] Abstract - ADS - BibTeX
   Gultekin, K., Miller, M. C., & Hamilton, D. P. (Dec 2005), “Three-Body Interactions of Black Holes with Gravitational Wave Emission,” American Astronomical Society Meeting 207, #102.02; Bulletin of the American Astronomical Society, Vol. 37, p.1331
   We present numerical three-body experiments that include the effects of gravitational radiation reaction by using equations of motion that include the 2.5-order post-Newtonian force terms, which are the leading order terms of energy loss from gravitational waves. Building on previous work, we simulate sequences of high-mass-ratio three-body encounters as they would occur in a dense stellar system. The simulations show that the binaries merge with extremely high eccentricity such that when the gravitational waves are detectable by LISA, most of the binaries will have eccentricities e > 0.9 though all will have circularized by the time they are detectable by LIGO. We also investigate the implications for the formation and growth of intermediate-mass black holes (IMBHs) and find that the inclusion of gravitational waves during the encounter results in roughly half as many black holes ejected from the host cluster for each black hole accreted onto the growing IMBH.
   
7. [+] Abstract - ADS - arXiv - Reprint - BibTeX
   Gültekin, Kayhan, Miller, M. Coleman, & Hamilton, Douglas P. (Oct 2003), “Three-Body Encounters of Black Holes in Globular Clusters,” THE ASTROPHYSICS OF GRAVITATIONAL WAVE SOURCES. AIP Conference Proceedings, Volume 686, pp. 135-140 (2003). [4 citations]
   
   Evidence has been mounting for the existence of black holes with masses from 102 to 104 Msolar associated with stellar clusters. Such intermediate-mass black holes (IMBHs) will encounter other black holes in the dense cores of these clusters. The binaries produced in these interactions will be perturbed by other objects as well thus changing the orbital characteristics of the binaries. These binaries and their subsequent mergers due to gravitational radiation are important sources of gravitational waves. We present the results of numerical simulations of high mass ratio encounters, which help clarify the interactions of intermediate-mass black holes in globular clusters and help determine what types of detectable gravitational wave signatures are likely.
   
8. [+] Abstract - ADS - BibTeX
   Gultekin, K., Miller, M. C., & Hamilton, D. P. (Dec 2001), “Three Body Interactions of Black Holes in Globular Clusters,” American Astronomical Society, 199th AAS Meeting, #05.02; Bulletin of the American Astronomical Society, Vol. 33, p.1308
   Recent x-ray observations suggest that a number of galaxies may harbor black holes with masses between 102 and 103-4 MSun. These intermediate-mass black holes may require a formation mechanism different from those of stellar-mass black holes and supermassive black holes. Several models have been proposed to account for their origin, one of which proposes that stellar-mass black holes in dense globular clusters may grow to the required masses through mergers. We investigate this scenario numerically, by examining the role of interactions between binary black holes and single black holes. We present results of numerical simulations of these encounters and discuss their implications for the formation of intermediate-mass black holes and for their detectability with gravitational wave detectors such as LISA and LIGO-II.
   
9. [+] Abstract - ADS - BibTeX
   Koerner, D. W., Jensen, E. L. N., Cruz, K., Guild, T. B., & Gultekin, K. (Dec 1999), “A Single Circumbinary Disk in the HD 98800 Quadruple System,” American Astronomical Society, 195th AAS Meeting, #25.02; Bulletin of the American Astronomical Society, Vol. 31, p.1409
   We present sub-arcsecond thermal infrared imaging of HD 98800, a young quadruple system composed of a pair of low-mass spectroscopic binaries separated by 0.8'', each with a K-dwarf primary. Images at wavelengths ranging from 5 to 24.5 microns show unequivocally that the optical secondary, HD 98800B, is the sole source of a comparatively large infrared excess upon which a silicate emission feature is superposed. The excess is detected only at wavelengths of 7.9 microns and longer, peaks at 25 microns, and has a best-fit black-body temperature of 146 K. With the assumption that the dust is in radiative equilibrium with the central stars, these characteristics require its location to be in a configuration that is circumbinary to the spectroscopic pair. A simple black-body fit underpredicts emission in the region of the broad silicate feature, however, and the feature itself requires a dust component with temperatures higher than 146 K by at least a factor of two. Further, the spectral slope at sub-millimeter wavelengths is flatter than expected for a collision-induced size-distribution of grains, suggesting a range of temperatures present at longer wavelengths. These facts suggest that the circumbinary dust is not confined to a narrow ring but is wide enough to exhibit a range of temperatures.
   
10. [+] Abstract - ADS - BibTeX
    Gultekin, K., Koerner, D. W., & Ressler, M. E. (Dec 1998), “A Circumstellar Disk around the High-Mass Protostar L1206A,” American Astronomical Society, 193rd AAS Meeting, #72.07; Bulletin of the American Astronomical Society, Vol. 30, p.1360
    We present aperture synthesis mapping of a circumstellar disk around the high-mass protostellar source, L1206A. A contour map at 110 GHz reveals dust emission with peak flux density 32.5 +/-3 mJy in a circular 2'' beam, and integrated intensity 62 +/-6 mJy. The emission is elongated perpendicular to a bipolar reflection nebula with a nominal FWHM diameter of 2.3+/-0.05'' (deconvolved), corresponding to 2300 AU at the 1 kpc distance estimated for the Lynds 1206 cloud. Visibility amplitudes are well-matched by those predicted from a model of dust radiation arising from a circumstellar disk. Preliminary model-fitting suggests the disk has outer radius 4000 AU and mass greater than 0.3M_sun.
    

1. AAS International Travel Grant Award Winner - 2006
2. Jacob K. Goldhaber Travel Grant Award Winner - 2006
3. American Astronomical Society Member - 1999 - Present

1. August 12, 2009 “The Scatter in the M–σ and M–L Relations,” IAU, Rio, Brazil.
2. April 2, 2009 “The IMBH–SMBH Connection,” IMBH Workshop, UC Irvine, CA.
3. December 4, 2008 “Scatting about M–σ,” Astronomy Department Colloquium, University of Michigan, Ann Arbor.
4. September 21, 2006 “Growing Intermediate-Mass Black Holes with Gravitational Waves,” Extra-Galactic Astronomy Seminar, University of Texas, Austin.
5. July 27, 2006 “Growing Black Holes in Globular Clusters,” Galactic Nuclei Workshop, Lorentz Center, Leiden, The Netherlands.
6. September 14, 2005 “Growth of Intermediate-Mass Black Holes in Globular Clusters and their Gravitational Waves,” Space Sciences Seminar, George Mason University, Fairfax, VA.
7. December 6, 2004 “Making IMBHs and Gravitational Waves in Globular Clusters,” Astronomy Seminar, Caltech, Pasadena, CA.
8. November 16, 2004 “The Role of Three-Body Encounters in IMBH Formation,” Center for Astrophysical Sciences Seminar, Johns Hopkins University, Baltimore, MD.
9. October 20, 2004 “From Newtonian Dynamics to Gravitational Waves,” University of Pennsylvania Astrophysics Seminar, Philadelphia, PA.
10. October 19, 2004 “Growing IMBHs in Globular Clusters,” University of Virginia and NRAO Seminar, Charlottesville, VA.
11. October 15, 2004 “The Role of Three-Body Dynamics in IMBH Formation and their Gravitational Waves,” LHEA Seminar, GSFC, Greenbelt, MD.
12. March 3, 2003 “Close Encounters of the Three-Body Kind,” Penn State Astronomy Seminar, State College.

Postdoctoral Fellow for Douglas O. Richstone, University of Michigan, August 2006-Present
   Modelled mass distribution and stellar kinematics of galactic nuclei to compare with HST and ground-based data to determine masses of supermassive black holes in galactic centers.

Research Assistant for M. Coleman Miller, University of Maryland, College Park, June 2001-August 2006
   Investigated interactions of black hole dynamics in cluster cores, developed and adapted code to perform numerical simulations of sequences of three-body encounters, and used the data from these simulations to test intermediate-mass black hole formation models and to predict likely gravitational wave signatures.

Beowulf Cluster Co-Administrator, VAMPIRE, University of Maryland, June 2001-August 2006
   Installed and currently maintain Condor job management software on department computers to utilize unused computing power of over thirty desktop workstations to create a combined 21 GFlop cluster, created tutorial for use of cluster, and assisted faculty and students in use of cluster.

Observer, Berkeley Illinois Maryland Association (BIMA), Hat Creek, CA 2000-2001
   Operate telescope, scheduled observing queue, verified data quality, and responded to telescope alarms.

Research Assistant for Laboratory for Millimeter-Wave Astronomy, University of Maryland, College Park, Summer 2000
   Assisted in design of water vapor radiometers planned for use with BIMA millimeter-wave radio interferometer antennae (now part of CARMA), analyzed data from prototype radiometers to evaluate efficacy, and assisted in installation of prototype radiometers on antennae.

Undergraduate Research Assistant for Dr. David Koerner, Planetary Origins Research Group, University of Pennsylvania, 1998-1999.
   Reduced Keck MIRLIN infrared data of debris disk in quadruple system, and developed code to model OVRO millimeter data of the circumstellar disk around a high-mass protostar.

2007 - 2009 Mentor for University of Michigan undergraduate student research projects.
2004 - Guest lecturer for graduate astronomy courses Numerical Astrophysics and Introduction to Research.
2000 - 2001 Instructor for astronomy observing class. Planned, facilitated, and taught class for undergraduate non-majors in use of small telescopes and naked-eye observations.
1999 - Telescope operator, facilitator, and educational reference for department open houses and special public events.
1999 - 2000 Teaching Assistant for introductory astronomy classes. Taught discussion session, graded, and led special review sessions for undergraduate classes.