Search Publications
On the Origin of Radio-loudness in Active Galactic Nuclei Using Far-infrared Polarimetric Observations
Lopez-Rodriguez, Enrique; Blandford, Roger; Begelman, Mitchell C. +3 more
The dichotomy between radio-loud (RL) and radio-quiet (RQ) active galactic nuclei (AGNs) is thought to be intrinsically related to radio jet production. This difference may be explained by the presence of a strong magnetic field (B-field) that enhances, or is the cause of, the accretion activity and the jet power. Here we report the first evidence…
CGM2 + CASBaH: The Mass Dependence of H I Lyα-Galaxy Clustering and the Extent of the CGM
Tripp, Todd M.; Prochaska, J. Xavier; Tejos, Nicolas +9 more
We combine data sets from the CGM2 and CASBaH surveys to model a transition point, R cross, between circumgalactic and intergalactic media (CGM and IGM, respectively). In total, our data consist of 7244 galaxies at z < 0.5 with precisely measured spectroscopic redshifts, all having impact parameters of 0.01-20 comoving Mpc…
The HERBAL Model: A Hierarchical Errors-in-variables Bayesian Lognormal Hurdle Model for Galactic Globular Cluster Populations
Speagle, Joshua S.; Harris, William E.; Eadie, Gwendolyn M. +1 more
Galaxy stellar mass is known to be monotonically related to the size of the galaxy's globular cluster (GC) population for Milky Way sized and larger galaxies. However, the relation becomes ambiguous for dwarf galaxies, where there is some evidence for a downturn in GC population size at low galaxy masses. Smaller dwarfs are increasingly likely to …
A Possible Surviving Companion of the SN Ia in the Galactic SNR G272.2-3.2
Galbany, L.; Ruiz-Lapuente, P.; Figueras, F. +4 more
We use the Gaia EDR3 to explore the Galactic supernova remnant (SNR) G272.2-3.2, produced by the explosion of a Type Ia supernova (SN Ia) about 7500 yr ago, to search for a surviving companion. From the abundances in the SNR ejecta, G272.2-3.2 is a normal SN Ia. The Gaia parallaxes allow us to select the stars located within the estimated distance…
Abundance Analysis of Stars at Large Radius in the Sextans Dwarf Spheroidal Galaxy
Caldwell, Nelson; Placco, Vinicius M.; Mateo, Mario +5 more
We present the stellar parameters and chemical abundances of 30 elements for five stars located at large radii (3.5-10.7 times the half-light radius) in the Sextans dwarf spheroidal galaxy. We selected these stars using proper motions, radial velocities, and metallicities, and we confirm them as metal-poor members of Sextans with -3.34 ≤ [Fe/H] ≤ …
Reanalysis of the X-Ray-burst-associated FRB 200428 with Insight-HXMT Observations
Zhang, S.; Zhang, S. N.; Dai, Z. G. +15 more
A double-peak X-ray burst from the Galactic magnetar SGR J1935+2154 was discovered to be associated with the two radio pulses of FRB 200428 separated by 28.97 ± 0.02 ms. Precise measurements of the timing and spectral properties of the X-ray bursts are helpful for understanding the physical origin of fast radio bursts. In this paper, we have recon…
Giant Impacts and Debris Disk Morphology
Duchêne, Gaspard; Esposito, Thomas M.; Kalas, Paul +2 more
Certain debris disks have nonaxisymmetric shapes in scattered light which are unexplained. The appearance of a disk depends on how its constituent Keplerian ellipses are arranged. The more the ellipses align apsidally, the more nonaxisymmetric the disk. Apsidal alignment is automatic for fragments released from a catastrophic collision between sol…
Origin of Quasi-periodic Pulsation at the Base of a Kink-unstable Jet
Srivastava, A. K.; Kayshap, Pradeep; Rajaguru, S. P. +3 more
We studied a blowout jet that occurred at the west limb of the Sun on 2014 August 29 using high-resolution imaging/spectroscopic observations provided by the Solar Dynamics Observatory/Atmospheric Imaging Assembly and the Interface Region Imaging Spectrograph. An inverse γ-shaped flux rope appeared before the jet-morphological indication of the on…
Green Bank Telescope Discovery of the Redback Binary Millisecond Pulsar PSR J0212+5321
Perez, Karen I.; Bogdanov, Slavko; Halpern, Jules P. +1 more
We report the discovery of a 2.11 ms binary millisecond pulsar during a targeted search of the redback optical candidate coincident with the γ-ray source 3FGL J0212.5+5320 using the Robert C. Byrd Green Bank Telescope (GBT) with the Breakthrough Listen backend at L band. Over a seven month period, five pointings were made near inferior conjunction…
ALMA High-frequency Long Baseline Campaign in 2021: Highest Angular Resolution Submillimeter Wave Images for the Carbon-rich Star R Lep
Hirota, Akihiko; Hales, Antonio S.; Takahashi, Satoko +11 more
The Atacama Large Millimeter/submillimeter Array (ALMA) was used in 2021 to image the carbon-rich evolved star R Lep in Bands 8-10 (397-908 GHz) with baselines up to 16 km. The goal was to validate the calibration, using band-to-band (B2B) phase referencing with a close phase calibrator J0504-1512, 1.°2 from R Lep in this case, and the imaging pro…