Search Publications
NuSTAR Observations and Multiwavelength Modeling of the High-redshift BL Lacertae Object 4FGL J2146.5-1344
Ajello, M.; Kaur, A.; Hartmann, D. +3 more
High synchrotron peak (HSP; ${\nu }_{\mathrm{sy}}^{\mathrm{pk}}\gt {10}^{15}$ Hz) BL Lac objects are some of the most extreme accelerators in the universe. Those found at high redshifts (z > 1) challenge our understanding of blazar evolution models and are crucial for cosmological measurements of the extragalactic background light. In this pape…
A Strong-lensing Model for the WMDF JWST/GTO Very Rich Cluster A1489
Finkelstein, Steven L.; Koekemoer, Anton M.; Larson, Rebecca L. +19 more
We present a first strong-lensing model for the galaxy cluster RM J121218.5+273255.1 (z = 0.35; hereafter RMJ1212; also known as A1489). This cluster is among the top 0.1% richest clusters in the redMaPPer catalog; it is significantly detected in X-ray and through the Sunyaev-Zel'dovich effect in ROSAT and Planck data, respectively, and its optica…
Dynamical Masses for the Pleiades Binary System HII-2147
Torres, Guillermo; Crepp, Justin R.; Dupuy, Trent J. +3 more
We report our long-term spectroscopic monitoring of the Pleiades member HII-2147, which was previously spatially resolved at radio wavelengths in very long baseline interferometry (VLBI) observations. It has also been claimed to be a (presumably short-period) double-lined spectroscopic binary with relatively sharp lines, although no orbit has ever…
Unraveling the Nature of the Deeply Embedded Wolf-Rayet Star WR 121a
Pandey, J. C.; Arora, Bharti
An X-ray study of the deeply embedded Wolf-Rayet star WR 121a has been carried out using long-term (spanning over ∼12 yr) archival observations from Chandra and XMM-Newton. For the first time, a periodic variation of 4.1 days has been detected in the X-ray light curve of WR 121a. No companion is seen in a merged and exposure-corrected Chandra X-ra…
Fast Magnetosonic Waves and Flows in a Solar Prominence Foot: Observations and Modeling
Ofman, Leon; Kucera, Therese A.
We study recent observations of propagating fluctuations in a prominence foot with Hinode Solar Optical Telescope (SOT) high-resolution observations in Ca II and Hα emission, which we identify as nonlinear fast magnetosonic waves. Here we analyze further the observations of propagating waves and flows with Interface Region Imaging Spectrograph Mg …
A New Metal-poor Globular Cluster and Resolved Stars in the Outer Disk of the Black Eye Galaxy M64: Implication for the Origin of the Type III Disk Break
Lee, Myung Gyoon; Kang, Jisu; Jang, In Sung +1 more
M64 is a nearby spiral galaxy with a Type III antitruncation component. To trace the origin of the Type III component, we present Hubble Space Telescope/Advanced Camera for Surveys (ACS) F606W/F814W photometry of resolved stars in a field located in the outer disk ( $2\buildrel{\,\prime}\over{.} 5\lesssim r\lesssim 6\buildrel{\,\prime}\over{.} 5$ …
NuSTAR Observations of G11.2-0.3
Fryer, C. L.; Grefenstette, B. W.; Madsen, K. K. +3 more
We present in this paper the hard X-ray view of the pulsar wind nebula in G11.2-0.3 and its central pulsar powered pulsar J1811-1925 as seen by NuSTAR. We complement the data with Chandra for a more complete picture and confirm the existence of a hard, power-law component in the shell with photon index ${\rm{\Gamma }}=2.1\pm 0.1$ , which we attrib…
Continuum Enhancements, Line Profiles, and Magnetic Field Evolution during Consecutive Flares
Mathioudakis, Mihalis; Murabito, Mariarita; Guglielmino, Salvo L. +5 more
During solar flares, magnetic energy can be converted into electromagnetic radiation from radio waves to γ-rays. Enhancements in the continuum at visible wavelengths, as well as continuum enhancements in the FUV and NUV passbands, give rise to white-light flares. In addition, the strong energy release in these events can lead to the rearrangement …
XMM-Newton and NICER Measurement of the Rms Spectrum of the Millihertz Quasiperiodic Oscillations in the Neutron-star Low-mass X-Ray Binary 4U 1636-53
Altamirano, D.; Méndez, Mariano; Zhang, Guobao +4 more
We used two XMM-Newton and six Neutron Star Interior Composition Explorer observations to investigate the fractional rms amplitude of the millihertz quasiperiodic oscillations (mHz QPOs) in the neutron-star low-mass X-ray binary 4U 1636-53. We studied, for the first time, the fractional rms amplitude of the mHz QPOs versus energy in 4U 1636-53 dow…
Searching for Balmer-dominated Type Ia Supernova Remnants in M33
Chu, You-Hua; Li, Chuan-Jui; Lin, Chris Ding-Jyun +1 more
We searched for Balmer-dominated Type Ia supernova remnants (SNRs) in M33 by selecting thermal X-ray sources with ${L}_{{\rm{X}}}\geqslant 5\times {10}^{35}$ erg s-1, identifying associated Hα emission features, and checking their [S II] and [O III] emission properties. Our search did not find any Balmer-dominated Type Ia SNRs in M33. T…