Session F1: Astrophysics

Survey of Extremely High Velocity Outflows in Quasars from the Sloan Digital Sky Survey's Ninth Data Release

We present the first survey of extremely high velocity outflows (EHVO) in quasars from the Sloan Digital Sky Survey data release nine quasar catalog (SDSS DR9Q). Our survey draws from the 87,822 spectral targets in DR9Q. EHVO candidates were identified by measurement of Carbon-IV broad absorption features. Due to the use of C-IV absorption as a marker and the wavelength coverage of SDSS spectra (3,600 - 10,500 $\AA$) only quasars with z $>$= 2 were considered for investigation. In order to ensure usable spectral data samples were also limited to spectra with SNR $>$ 10. Spectrum analysis was carried out programmatically with results confirmed by visual inspection. The presented survey is composed of 45 quasars EHVO ranging in velocity from $\sim$50,000 to 30,000 km/s. Our survey will be made available online as a publicly accessible database.   

Mapping the filaments of NGC 1275

The giant elliptical brightest cluster galaxies (BCGs) at the centers of many massive clusters are often surrounded by drawn-out forms of gaseous material. It is believed that this gaseous material is gas condensing from the intracluster medium (ICM) in a ``cooling flow,'' and it can directly impact the growth of the BCG. The galaxy NGC 1275 is one of the closest giant elliptical BCGs and lies at the center of the Perseus cluster. NGC 1275 has large filaments that are thought to be associated with a cooling flow, but they may also be affected by its AGN. To investigate the relationship between the AGN and the cooling flow we have mapped the filaments around NGC 1275 with the Cosmic Web Imager, an image-slicing integral field spectrograph at Palomar Observatories. We employ standard emission-line ratio diagnostics to determine the source of ionizing radiation. We use our analysis to investigate whether the formation of the extended filaments is a result of gas from the ICM collapsing onto the galaxy as it cools or if it is possible that the filaments are a result of the cluster's interaction with the outflow driven by the AGN.~   

VERITAS Detection of gamma-ray emission from the optically bright quasar OJ 287

We report on the~VERITAS~detection of very-high-energy (VHE, E\textgreater 100 GeV) gamma-ray emission from the optically bright quasar OJ 287 which is located at a redshift of z $=$ 0.306. OJ 287 has been observed to display regular optical outbursts with a period of approximately 12 years, with the last outburst having occurred in 2006/2007. In order to explain this periodicity, models involving a binary supermassive black hole system at the core of OJ 287, or a helical jet model, have been developed. Motivated by elevated Swift-XRT count rates, VERITAS observed OJ 287 in February 2017, and detected the object at \textgreater 5 standard deviations above background. This detection prompted further VERITAS, Swift-XRT and multi-wavelength observations of the source. The results of the VERITAS observational campaign along with a study of the relationship of the VHE emission to other wavebands and corresponding implications will be presented.   

The Spectra of Markarian 421

Markarian 421 is a relatively nearby active galaxy of the BL Lac type that at a redshift of z = 0.03 (eg. 122 Megaparsecs). Being one of the closest objects of its type and its active nature, it has been known to be a strong source of very high-energy gamma rays since 1992. The Very Energetic Radiation Imaging Telescope Array (VERITAS), which includes four 12m imaging Cherenkov telescopes and is located at the Fred Lawrence Whipple Observatory in southern Arizona, has been observing Markarian 421 since 2007. I will describe the VERITAS instrument, provide a brief overview of how the gamma-ray might be produced and how information about gamma-ray variability timescales and energy spectra can help us understand the active galaxy.   

Dark Matter Effects are Due to Multiple Causes

Recent results show that the rotation of disk galaxies is determined completely by the visible matter that they contain. This is strong evidence that the explanation for the observed galactic rotation is a modification of the Newtonian gravitation force law, such at MOND. Since the results span orders of magnitude in mass and density, it would require unrealistic dark matter variations and halo formations. Other dark matter effects, such as the large clumps of dark matter observed by weak gravitational lensing, could be explained by the presence of antimatter galaxies that emit invisible antiphotons[1]. [1] W. A. Perkins, "On the matter-antimatter asymmetry", Modern Physics Letters A 30, 1550157-1 (2015).   

The LLNL warm electron beam ion trap (WEBIT): An instrument for calibrating space-borne X-ray spectrometers

We are developing a warm electron beam ion trap (WEBIT) for use as a calibration source for the quantum calorimeter, dubbed Resolve, that will be flown on the X-ray Astrophysics Recovery Mission (XARM) to be launched in \textasciitilde 2021. The WEBIT, is based on a test stand used to develop electron guns for the Lawrence Livermore National Laboratory's EBITs. The WEBIT uses a water-cooled magnet with a field strength of approximately 0.5 T as opposed to the $\sim $3 T field produced by the liquid-helium cooled superconducting Helmholtz coils employed by LLNL's EBIT-I and SuperEBIT. Once complete, WEBIT will be used both at the NASA/GSFC and potentially at JAXA's Tsukuba Space Center to calibrate Resolve's instrumental line shape and gain scale as a function of a variety of operational parameters. Because WEBIT will produce line emission from highly charged helium-like and hydrogenic ions whose transition energies and line shapes are well known, this method is superior to the previous calibration methods that were based on emission from characteristic K$\alpha $ lines produced by X-ray tubes, fluoresced metals, or other radioactive sources. The current status of this project will be presented.   

Density Diagnostics for Solar Physics Using an Electron Beam Ion Trap

Our understanding of the physical conditions in the solar atmosphere hinges, in part, on an accurate determination of the electron density in the observed structures. For example, the electron density is needed to determine the energy flux in various solar regions and to understand the nature of these structures. Spectroscopic diagnostics can be used to infer the electron density, which is commonly measured by taking the intensity ratio of two spectral lines with different density sensitivities. However, spectroscopic density diagnostics can have large uncertainties. They depend sensitively on atomic collisional excitation, de-excitation, and radiative transition rates for multiple atomic levels. Essentially all of these data come from theory and little of the data have been experimentally validated. We are conducting laboratory experiments using the electron beam ion trap (EBIT) at Lawrence Livermore National Laboratory that will provide accurate empirical calibrations for commonly used spectroscopic density diagnostics and will help guide theoretical calculations.   

Improving absolute electron impact excitation cross sections for X-ray astrophysics through laboratory measurements

Recently, the calorimeter SXS onboard the Hitomi X-ray observatory has provided the first high-resolution spectrum of a celestial source - the Perseus galaxy cluster - in the 6 keV spectral region containing signatures of K-shell transitions of Fe group elements. At 5 eV resolution, these spectra have unveiled some short-comings of the plasma models and underlying atomic databases commonly used for spectral analysis in X-ray astrophysics. For such high-quality data as the Hitomi Perseus spectrum, the accuracy of plasma diagnostics, in some cases, is thus no longer limited by instrumental performance, but by the accuracy and completeness of the available atomic physics reference data. In coronal plasmas like the intergalactic medium in galaxy clusters, electron impact excitation (EIE) is an important level population mechanism and strongly influences the line ratios in these spectra. To benchmark and improve the available reference data, we used the EBIT Calorimeter Spectrometer, a calorimeter similar to the SXS, at the LLNL electron beam ion trap EBIT-I to measure absolute EIE cross sections for K-shell transitions in highly charged Fe ions. The new laboratory reference data will help to fully utilize the diagnostic potential of this new era of high-resolution X-ray astrophysics.   

Cosmic Ray Water Cherenkov Detector

Cosmic rays are high energy particles that travel through space and shower Earth. Cherenkov radiation consists of electromagnetic radiation that is produced when remnants of scattering cosmic rays travel through earth's atmosphere and surpass the speed of light in a material medium. The equation, cos$\theta =$ 1/$\beta \eta $, dictates the cone shaped light effect where $\beta $ is equal to the velocity of the particle divided by velocity of light through a vacuum and $\eta $ being the refractive index of the medium. Our research project was to create simple and reliable Cherenkov detectors for use to outreach to high school STEM students. For this, we used two modified thermos bottles with distilled water as the medium to produce Cherenkov radiation. To observe the Cherenkov radiation from cosmic rays, two Photomultiplier detectors (PMT) were used and each was submerged in a thermos bottle and covered with light tight foils. Extensive evaluations were done for various placements of the detectors in both the vertical and the horizontal directions to obtain coincidence cosmic ray events. Results from our experiments indicated that the thermos detectors were detecting Cherenkov radiation produced by cosmic particles.   

Speed of Cosmic Ray Muon Using Silicon Photomultipliers

Recently, the silicon photomultiplier (SiPM) has attracted considerable attention as a possible replacement for conventional photomultiplier detectors (PMT). To realize the practicality of SiPM detectors, we developed a 4-fold coincidence experiment to estimate the speed of the cosmic ray muons. Cosmic rays are highly energetic atomic nuclei mainly originating outside the Solar System. After striking the Earth's atmosphere, cosmic rays are broken into different particles, one of which is the muon. Our experimental apparatus consists of a coincidence setup, a digitizer, and two pairs of cosmic ray detectors involving SiPMs and PMTs. The distance between the two pairs of detectors were periodically altered to determine the arrival time difference between them to accumulate timing histograms with 3000 coincidence events. Detailed data analysis was conducted using the CERN software package Physics Analysis Workstation (PAW) in a Linux-based environment. Utilizing the data for the distance and time difference, we were able to determine the speed of the cosmic ray muons.