Search Publications
Gaia and the Galactic Center Origin of Hypervelocity Stars
Geller, Margaret J.; Brown, Warren R.; Kenyon, Scott J. +1 more
We use new Gaia measurements to explore the origin of the highest velocity stars in the hypervelocity star (HVS) survey. The measurements reveal a clear pattern in B-type stars. Halo stars dominate the sample at speeds of ≃100 km s-1 below Galactic escape velocity. Disk runaway stars have speeds up to ≃100 km s-1 above Galact…
LensFlow: A Convolutional Neural Network in Search of Strong Gravitational Lenses
Cooray, Asantha; Nayyeri, Hooshang; Pourrahmani, Milad
In this work, we present our machine learning classification algorithm for identifying strong gravitational lenses from wide-area surveys using convolutional neural networks; LENSFLOW. We train and test the algorithm using a wide variety of strong gravitational lens configurations from simulations of lensing events. Images are processed through mu…
Three-dimensional motions in the Sculptor dwarf galaxy as a glimpse of a new era
Massari, D.; Helmi, A.; Brown, A. G. A. +3 more
The three-dimensional motions of stars in small galaxies beyond our own are minute, yet they are crucial for understanding the nature of gravity and dark matter1,2. Even for the dwarf galaxy Sculptor—one of the best-studied systems, which is inferred to be strongly dark matter dominated3,4—there are conflicting reports5-…
Detection of Reflection Features in the Neutron Star Low-mass X-Ray Binary Serpens X-1 with NICER
Fabian, A. C.; Miller, J. M.; Homan, J. +17 more
We present Neutron Star Interior Composition Explorer (NICER) observations of the neutron star (NS) low-mass X-ray binary Serpens X-1 during the early mission phase in 2017. With the high spectral sensitivity and low-energy X-ray passband of NICER, we are able to detect the Fe L line complex in addition to the signature broad, asymmetric Fe K line…
Results from a Systematic Survey of X-Ray Emission from Hydrogen-poor Superluminous SNe
Berger, E.; Chornock, R.; Lunnan, R. +11 more
We present the results from a sensitive X-ray survey of 26 nearby hydrogen-poor superluminous supernovae (SLSNe-I) with Swift, Chandra, and XMM. This data set constrains the SLSN evolution from a few days until ∼2000 days after explosion, reaching a luminosity limit L x ∼ 1040 erg s-1 and revealing the presence o…
MICROSCOPE limits for new long-range forces and implications for unified theories
Fayet, Pierre
Many theories beyond the standard model involve an extra U (1 ) gauge group. The resulting gauge boson U , in general mixed with the Z and the photon, may be massless or very light and very weakly coupled. It may be viewed as a generalized dark photon interacting with matter through a linear combination [ɛQQ +ɛBB +ɛL
RELICS: Strong Lens Models for Five Galaxy Clusters from the Reionization Lensing Cluster Survey
Frye, Brenda L.; Bradač, Maruša; Lovisari, Lorenzo +31 more
Strong gravitational lensing by galaxy clusters magnifies background galaxies, enhancing our ability to discover statistically significant samples of galaxies at {\boldsymbol{z}}> 6, in order to constrain the high-redshift galaxy luminosity functions. Here, we present the first five lens models out of the Reionization Lensing Cluster Survey (RE…
Constraining warm inflation with CMB data
Bhattacharya, Sukannya; Dutta, Koushik; Gangopadhyay, Mayukh Raj +1 more
We confront the warm inflation observational predictions directly with the latest CMB data. We focus on a linear temperature (T) dissipative coefficient combined with the simplest model of inflation, a quartic chaotic potential. Although excluded in its standard cold inflation version, dissipation reduces the tensor-to-scalar ratio and brings the …
A 3.5 million Solar masses black hole in the centre of the ultracompact dwarf galaxy fornax UCD3
Romanowsky, Aaron J.; Neumayer, Nadine; Strader, Jay +16 more
The origin of ultracompact dwarfs (UCDs), a class of compact stellar systems discovered two decades ago, still remains a matter of debate. Recent discoveries of central supermassive black holes in UCDs likely inherited from their massive progenitor galaxies provide support for the tidal stripping hypothesis. At the same time, on statistical ground…
Identifying Typical Mg II Flare Spectra Using Machine Learning
Krucker, Säm; Kleint, Lucia; Panos, Brandon +4 more
The Interface Region Imaging Spectrograph (IRIS) performs solar observations over a large range of atmospheric heights, including the chromosphere where the majority of flare energy is dissipated. The strong Mg II h&k spectral lines are capable of providing excellent atmospheric diagnostics, but have not been fully utilized for flaring atmosph…