Bulletin of the American Physical Society
2019 Joint Fall Meeting of the Texas Sections of APS, AAPT and Zone 13 of the SPS
Volume 64, Number 18
Friday–Saturday, October 25–26, 2019; Lubbock, Texas
Session F05: Astrophysics III |
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Chair: David Pooley, Trinity University Room: Student Union Building Red Raider Lounge |
Friday, October 25, 2019 4:00PM - 4:12PM |
F05.00001: Investigating state transition luminosities of Galactic black hole transients in the outburst decay Armin Vahdat Motlagh, Emrah Kalemci, Thomas Maccarone We have performed a comprehensive spectral and timing analyses of Galactic black hole transients (GBHTs) during outburst decay in order to obtain the distribution of state transition luminosities. Using the archival data of the Rossi X-ray Timing Explorer (RXTE), we have calculated the weighted mean for state transition luminosities of 11 BH sources in 19 different outbursts and for disk and power-law luminosities separately. We also produced histograms of these luminosities in terms of Eddington luminosity fraction (ELF) and fitted them with a Gaussian. Our results show the tightest clustering in bolometric power-law luminosity with a mean logarithmic ELF of -1.70 $\pm$ 0.21 during the index transition (as the photon index starts to decrease towards the hard state). We obtained mean logarithmic ELF of -1.80 $\pm$ 0.25 during the transition to the hard state (as the photon index reaches the lowest value) and -1.50 $\pm$ 0.32 for disk blackbody luminosity (DBB) during the transition to the hard-intermediate state (HIMS). We discussed the reasons for clustering and possible explanations for sources that show a transition luminosity significantly below or above the general trends. [Preview Abstract] |
Friday, October 25, 2019 4:12PM - 4:24PM |
F05.00002: The first superoutburst of the ultracompact white dwarf binary SDSS J141118.31+481257.6 Liliana Rivera Sandoval, Thomas Maccarone SDSS J141118.31+481257.6 is an ultracompact white dwarf binary (or AM CVn system) with an orbital period of 46 min. The first ever recorded superoutburst of the system took place after at least 13 yr of quiescence and it showed the largest luminosity amplitude ever discovered in any AM CVn. We will discuss the behavior of the binary at different bands and we will also discuss the importance of AM CVn studies in the context of the superoutburst duration versus orbital period relation. [Preview Abstract] |
Friday, October 25, 2019 4:24PM - 4:36PM |
F05.00003: Development of An Eclipse Mapping Routine Using Python for Analysis of Kepler Data Nathan Smith A development and implementation of the eclipse mapping method using Python is discussed. The code utilizes Scipy's minimize function along with its various solving methods, primarily Sequential Least-Squares Programming (SLSQP). These methods are used to solve the maximum entropy equation with a chi-squared constraint to the observed photometric light curve. These methods are first evaluated on two-dimensional Gaussian test data with no chi-squared constraint and then used to image the accretion disks of the Cataclysmic Variable KIC 20132510, revealing its Gaussian structure. The structure of the code, along with potential design flaws, other errors, and parameter effects are examined. Factors such as the variance within the Gaussian weighting algorithm, the resolution of the disk image, the number of points within the observed light curve data, and the constraint level of the algorithm can drastically affect the quality of the image. The above methods and parameters are then considered as a whole and conclusions are drawn regarding the steps for further research. Finally, the code's GitHub repository is discussed for version control and open source development. [Preview Abstract] |
Friday, October 25, 2019 4:36PM - 4:48PM |
F05.00004: Compact Binaries in Globular Clusters Manuel Pichardo Marcano Globular clusters are very old groups of stars. Due to their age and the gravitational interactions dominating the dynamics of the clusters, they are home to a significant fraction of compact binaries. The formation and evolution of these kinds of binaries is still not completely understood. Using MUSE and Hubble archival data we plan to characterize the compact binary population in them. With MUSE in the cluster NGC 6397, we have been able so far to spectrocopically confirm two new CV candidates as well as retrieve higher quality spectra of the four previously identified CVs and of a candidate millisecond pulsar (MSP). With Hubble archival data we have been able to recover the period for the brightest CVs, as well as for the MSP candidate. The found 1.9 days period for the MSP, suggest that it is a new redback pulsar candidate. Altogether we have demonstrated how an IFU like MUSE, and archival data from Hubble can be used to efficiently study the population of compact objects in globular clusters. [Preview Abstract] |
Friday, October 25, 2019 4:48PM - 5:00PM |
F05.00005: Kepler 212700993 (HS Vir): A Cataclysmic Variable in Superoutburst in the Kepler Campaign 17 Field William Morris We present results from short cadence (SC) light curve or EPIC 212700993 observed during the \textit{Kepler }K2 Campaign 17. The occurrence of a superoutburst and the frequency of the outbursts confirms that this system is a cataclysmic variable (CV) dwarf nova of the SU UMa type. Lomb-Scargle periodograms show that the orbital period is estimated to be P$_{\mathrm{orb}} \quad =$ 0.0780873 days (1.874 hr). The SC light curve captures the star in outburst three times which lasted for 4 days on average had an increase in magnitude of 1.2 on average. The SC light curve also contains a superoutburst with a duration of 14.5 days and an increase in magnitude of 2.3. The SC light curve reveals a positive superhump period of P$_{\mathrm{+}} \quad =$ 0.086181 days (2.068 hr). The superhump period yields a secondary-to-primary mass ratio of q $=$ 0.2978. [Preview Abstract] |
Friday, October 25, 2019 5:00PM - 5:12PM |
F05.00006: Z Cha as seen by TESS: A New Method to trace the State of the Disk During Outburst James Court I present the results of a study on the eclipsing CV Z Cha using data from TESS observations of the source during both an outburst and a superoutburst in 2019. Using our data we are able to place better constraints on the postulated third body in this system which causes periodic fluctuations in the observed orbital period over time. We also present a new method for tracing the period associated with a superhump, and show that it tends towards the orbital period on the same timescale that the superoutburst decays. Finally, we show evidence for hysteresis in a plot of eclipse depth against out-of-eclipse flux during an outburst, and show how this hysteresis can be used to estimate the response time between the disk increasing in temperature and the disk increasing in size, breaking this long-standing degeneracy. [Preview Abstract] |
Friday, October 25, 2019 5:12PM - 5:24PM |
F05.00007: A Chandra X-ray Visionary Project reveals the formation efficiency of high-mass X-ray binaries Vallia Antoniou, Andreas Zezas, Jeremy Drake X-ray binaries (XRBs) are our main tool for studying the populations of compact objects in galaxies, and the formation and evolution of intermediate and higher mass binary stellar systems. Systematic studies of nearby galaxies have provided initial estimates of the formation rate of XRBs as a function of the star-formation rate (SFR) and stellar mass (M*) of their host galaxies. A strong dependence of the XRB formation rate on age and metallicity has been predicted. The Small Magellanic Cloud (SMC) is the ideal target to study the dependence of the formation efficiency of XRBs on the age of their parent stellar population. In this talk, I will present our measurement of the formation efficiency of the SMC HMXB populations as a function of their age, the most detailed such measurement so far, using data from our deep Chandra X-ray Visionary Project. We find that the HMXB formation efficiency increases as a function of time (following a burst of star formation) up to \textasciitilde 40-60 Myr, and then gradually decreases. The formation efficiency peaks at \textasciitilde 30-40 Myr with average rates of N(HMXB)/SFR$=$339\textasciicircum \textbraceleft $+$78\textbraceright \textunderscore \textbraceleft -83\textbraceright (Mo/yr)\textasciicircum \textbraceleft -1\textbraceright , and N(HMXB)/M*$=$(8.74\textasciicircum \textbraceleft $+$1.0\textbraceright \textunderscore \textbraceleft -0.92\textbraceright )x10\textasciicircum \textbraceleft -6\textbraceright Mo\textasciicircum \textbraceleft -1\textbraceright , in good agreement with previous estimates of the average formation efficiency in the broad \textasciitilde 20-60 Myr age range. [Preview Abstract] |
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