Search Publications
The Colors and Sizes of Recently Quenched Galaxies: A Result of Compact Starburst before Quenching
Bell, Eric F.; D'Eugenio, Francesco; Franx, Marijn +11 more
We analyze the colors and sizes of 32 quiescent (UVJ-selected) galaxies with strong Balmer absorption (EW(Hδ) ≥ 4 Å) at z ∼ 0.8 drawn from DR2 of the LEGA-C survey to test the hypothesis that these galaxies experienced compact, central starbursts before quenching. These recently quenched galaxies, usually referred to as post-starburst galaxies, sp…
A closer look at the spur, blob, wiggle, and gaps in GD-1
Gieles, M.; Erkal, D.; de Boer, T. J. L.
The GD-1 stream is one of the longest and coldest stellar streams discovered to date, and one of the best objects for constraining the dark matter properties of the Milky Way. Using data from Gaia DR2, we study the proper motions (PMs), distance, morphology, and density of the stream to uncover small-scale perturbations. The PM cleaned data show a…
Clouds of Fluffy Aggregates: How They Form in Exoplanetary Atmospheres and Influence Transmission Spectra
Okuzumi, Satoshi; Tazaki, Ryo; Ohno, Kazumasa
Transmission spectrum surveys have suggested the ubiquity of high-altitude clouds in exoplanetary atmospheres. Theoretical studies have investigated the formation processes of the high-altitude clouds; however, cloud particles have been commonly approximated as compact spheres, which is not always true for solid mineral particles that likely const…
The unusual broad-band X-ray spectral variability of NGC 1313 X-1 seen with XMM-Newton, Chandra, and NuSTAR
Harrison, F. A.; Stern, D.; Fabian, A. C. +19 more
We present results from the major coordinated X-ray observing programme on the ULX NGC 1313 X-1 performed in 2017, combining XMM-Newton, Chandra, and NuSTAR, focusing on the evolution of the broad-band (∼0.3-30.0 keV) continuum emission. Clear and unusual spectral variability is observed, but this is markedly suppressed above ∼10-15 keV, qualitati…
Searching for ultra-fast outflows in AGN using variability spectra
Schartel, N.; Santos-Lleó, M.; Buisson, D. J. K. +9 more
We present a qualitative search for ultra-fast outflows (UFOs) in excess variance spectra of radio-quiet active galactic nuclei (AGNs). We analyse 42 sources from the spectroscopic UFO detection sample, and an additional 22 different sources from the variability sample. A total of 58 sources have sufficient observational data from XMM-Newton EPIC-…
Investigating the Effect of Galaxy Interactions on the Enhancement of Active Galactic Nuclei at 0.5 < z < 3.0
Hathi, Nimish P.; Kartaltepe, Jeyhan S.; Kocevski, Dale D. +30 more
Galaxy interactions and mergers are thought to play an important role in the evolution of galaxies. Studies in the nearby universe show a higher fraction of active galactic nuclei (AGNs) in interacting and merging galaxies than in their isolated counterparts, indicating that such interactions are important contributors to black hole growth. To inv…
Exploring the Evolution of Stellar Rotation Using Galactic Kinematics
Angus, Ruth; Foreman-Mackey, Daniel; van Saders, Jennifer +9 more
The rotational evolution of cool dwarfs is poorly constrained after ∼1-2 Gyr due to a lack of precise ages and rotation periods for old main-sequence stars. In this work, we use velocity dispersion as an age proxy to reveal the temperature-dependent rotational evolution of low-mass Kepler dwarfs and demonstrate that kinematic ages could be a usefu…
Revived fossil plasma sources in galaxy clusters
Di Gennaro, G.; Brunetti, G.; Shimwell, T. W. +10 more
It is well established that particle acceleration by shocks and turbulence in the intra-cluster medium can produce cluster-scale synchrotron emitting sources. However, the detailed physics of these particle acceleration processes is still not well understood. One of the main open questions is the role of fossil relativistic electrons that have bee…
ALMA Observations of Multiple CO and C Lines toward the Active Galactic Nucleus of NGC 7469: An X-Ray-dominated Region Caught in the Act
Baba, Shunsuke; Meier, David S.; Turner, Jean L. +15 more
We used the Atacama Large Millimeter/submillimeter Array to map 12CO(J = 1-0), 12CO(J = 2-1), 12CO(J = 3-2), 13CO(J = 2-1), and [C I](3P1-3P0) emission lines around the type 1 active galactic nucleus (AGN) of NGC 7469 (z = 0.0164) at ∼100 pc resolutions. The CO…
The soft X-ray excess: NLS1s versus BLS1s
Gliozzi, Mario; Williams, James K.
The soft X-ray excess - the excess of X-rays below 2 keV with respect to the extrapolation of the hard X-ray spectral continuum model - is a very common feature among type 1 active galactic nuclei (AGNs); yet the nature of the soft X-ray excess is still poorly understood and hotly debated. To shed some light on this issue, we have measured in a mo…