Search Publications
Mass Modeling of Frontier Fields Cluster MACS J1149.5+2223 Using Strong and Weak Lensing
Treu, Tommaso; Bradač, Maruša; Schrabback, Tim +8 more
We present a gravitational-lensing model of MACS J1149.5+2223 using ultra-deep Hubble Frontier Fields imaging data and spectroscopic redshifts from HST grism and Very Large Telescope (VLT)/MUSE spectroscopic data. We create total mass maps using 38 multiple images (13 sources) and 608 weak-lensing galaxies, as well as 100 multiple images of 31 sta…
A Slowly Precessing Disk in the Nucleus of M31 as the Feeding Mechanism for a Central Starburst
Ghez, A. M.; Rich, R. M.; Lu, J. R. +3 more
We present a kinematic study of the nuclear stellar disk in M31 at infrared wavelengths using high spatial resolution integral field spectroscopy. The spatial resolution achieved, FWHM = 0.″12 (0.45 pc at the distance of M31), has only previously been equaled in spectroscopic studies by space-based long-slit observations. Using adaptive-optics-cor…
Parallaxes of Cool Objects with WISE: Filling in for Gaia
Theissen, Christopher A.
This paper uses the multi-epoch astrometry from the Wide-field Infrared Survey Explorer (WISE) to demonstrate a method to measure proper motions and trigonometric parallaxes with precisions of ∼4 mas yr-1 and ∼7 mas, respectively, for low-mass stars and brown dwarfs. This method relies on WISE single exposures (Level 1b frames) and a Ma…
Spatially Resolved Broadband Synchrotron Emission from the Nonthermal Limbs of SN1006
Bregman, Joel N.; Acero, Fabio; Ballet, Jean +6 more
We present ∼400 ks NuSTAR observations of the northeast (NE) and southwest (SW) nonthermal limbs of the Galactic SNR SN1006. We discovered three sources with X-ray emission detected at ≳50 keV. Two of them are identified as background active galactic nuclei. We extract the NuSTAR spectra from a few regions along the nonthermal limbs and jointly an…
Searching for Exoplanets around X-Ray Binaries with Accreting White Dwarfs, Neutron Stars, and Black Holes
Di Stefano, Rosanne; Imara, Nia
We recommend that the search for exoplanets around binary stars be extended to include X-ray binaries (XRBs) in which the accretor is a white dwarf, neutron star, or black hole. We present a novel idea for detecting planets bound to such mass transfer binaries, proposing that the X-ray light curves of these binaries be inspected for signatures of …
EUV Emission and Scattered Light Diagnostics of Equatorial Coronal Holes as Seen by Hinode/EIS
Landi, Enrico; Wendeln, Carolyn
Spectroscopic diagnostics of solar coronal plasmas critically depends on the uncertainty in the measured line intensities. One of the main sources of uncertainty is instrumental scattered light, which is potentially most important in low-brightness areas. In the solar corona, such areas include polar and equatorial coronal holes, which are the sou…
A Changing Wind Collision
Corcoran, Michael F.; Hillier, D. John; Nazé, Yaël +4 more
We report on the first detection of a global change in the X-ray emitting properties of a wind-wind collision, thanks to XMM-Newton observations of the massive Small Magellenic Cloud (SMC) system HD 5980. While its light curve had remained unchanged between 2000 and 2005, the X-ray flux has now increased by a factor of ∼2.5, and slightly hardened.…
On Measuring the Variation of High-energy Cutoff in Active Galactic Nuclei
Wang, Jun-Xian; Zhang, Ji-Xian; Zhu, Fei-Fan
The variation in the high-energy cutoff, E c , in active galactic nuclei (AGNs) uniquely probes the corona physics. In this work, we show that the ratio of two NuSTAR spectra (analogous to the difference-imaging technique widely used in astronomy) is uniquely useful in studying E c variations. The spectra ratio could direc…
Strong Lensing Modeling in Galaxy Clusters as a Promising Method to Test Cosmography. I. Parametric Dark Energy Models
Jullo, Eric; Limousin, Marceau; Magaña, Juan +3 more
In this paper we probe five cosmological models for which the dark energy equation of state parameter, w(z), is parameterized as a function of redshift using strong lensing data in the galaxy cluster Abell 1689. We constrain the parameters of the w(z) functions by reconstructing the lens model under each one of these cosmologies with strong lensin…
Quiet-Sun and Coronal Hole in Mg II k Line as Observed by IRIS
Solanki, Sami K.; Peter, Hardi; Kayshap, Pradeep +1 more
Coronal hole (CH) regions are dark in comparison to the quiet Sun (QS) at coronal temperatures. However, at chromospheric and transition region temperatures, the QS and CHs are hardly distinguishable. In this study, we have used the Mg II 2796.35 Å spectral line recorded by the Interface Region Imaging Spectrometer (IRIS) to understand the similar…