Search Publications
Probing sub-galactic mass structure with the power spectrum of surface-brightness anomalies in high-resolution observations of galaxy-galaxy strong gravitational lenses. II. Observational constraints on the subgalactic matter power spectrum
Vegetti, S.; McKean, J. P.; Treu, T. +5 more
Stringent observational constraints on the subgalactic matter power spectrum would allow one to distinguish between the concordance ΛCDM and the various alternative dark-matter models that predict significantly different properties of mass structure in galactic haloes. Galaxy-galaxy strong gravitational lensing provides a unique opportunity to pro…
Ruling Out New Physics at Low Redshift as a Solution to the H0 Tension
Shafieloo, Arman; Keeley, Ryan E.
We make the case that there can be no low-redshift solution to the H0 tension. To robustly answer this question, we use a very flexible parametrization for the dark energy equation of state such that every cosmological distance still allowed by data exists within this prior volume. To then answer whether there exists a satisfactory solu…
Energy wrinkles and phase-space folds of the last major merger
Grand, Robert J. J.; Fattahi, Azadeh; Vasiliev, Eugene +5 more
Relying on the dramatic increase in the number of stars with full 6D phase-space information provided by the Gaia Data Release 3, we resolve the distribution of the stellar halo around the Sun to uncover signatures of incomplete phase-mixing. We show that, for the stars likely belonging to the last massive merger, the (vr, r) distributi…
The rebrightening of a ROSAT-selected tidal disruption event: repeated weak partial disruption flares from a quiescent galaxy?
Liu, Z.; Buchner, J.; Nandra, K. +11 more
The ROSAT-selected tidal disruption event (TDE) candidate RX J133157.6-324319.7 (J1331) was detected in 1993 as a bright [0.2-2 keV flux of (1.0 ± 0.1) × 10-12 erg s-1 cm-2], ultra-soft (kT = 0.11 ± 0.03 keV) X-ray flare from a quiescent galaxy (z = 0.051 89). During its fifth all-sky survey (eRASS5) in 2022, Spect…
Tormund's return: Hints of quasi-periodic eruption features from a recent optical tidal disruption event
Miniutti, G.; Clerc, N.; Webb, N. A. +8 more
Context. Quasi-periodic eruptions (QPEs) are repeating thermal X-ray bursts associated with accreting massive black holes, the precise underlying physical mechanisms of which are still unclear.
Aims: We present a new candidate QPE source, AT 2019vcb (nicknamed Tormund by the Zwicky Transient Facility Collaboration), which was found during an …
From Images to Dark Matter: End-to-end Inference of Substructure from Hundreds of Strong Gravitational Lenses
Marshall, Philip J.; Birrer, Simon; Darragh-Ford, Elise +4 more
Constraining the distribution of small-scale structure in our universe allows us to probe alternatives to the cold dark matter paradigm. Strong gravitational lensing offers a unique window into small dark matter halos (<1010 M ⊙) because these halos impart a gravitational lensing signal even if they do not host luminous ga…
On the impact of f(Q) gravity on the large scale structure
Sokoliuk, Oleksii; Arora, Simran; Praharaj, Subhrat +2 more
We investigate the exponential f(Q) symmetric teleparallel gravitation, namely $f(Q)=Q+\alpha Q_0(1-e^{-\beta \sqrt{Q/Q_0}})$ using ME-GADGET code to probe the structure formation with box sizes LBox = 10/100 Mpc h-1 and middle resolution $N_p^{1/3}=512$. To reproduce viable cosmology within the aforementioned modified gravit…
The Pan-STARRS1 z > 5.6 Quasar Survey. II. Discovery of 55 Quasars at 5.6 < z < 6.5
Hennawi, Joseph F.; Noirot, Gaël; Fan, Xiaohui +20 more
The identification of bright quasars at z ≳ 6 enables detailed studies of supermassive black holes, massive galaxies, structure formation, and the state of the intergalactic medium within the first billion years after the Big Bang. We present the spectroscopic confirmation of 55 quasars at redshifts 5.6 < z < 6.5 and UV magnitudes -24.5 <…
Optimized Photometric Redshifts for the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS)
Finkelstein, Steven L.; Pérez-González, Pablo G.; Santini, Paola +27 more
We present the first comprehensive release of photometric redshifts (photo- z's) from the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) team. We use statistics based upon the Quantile-Quantile (Q-Q) plot to identify biases and signatures of underestimated or overestimated errors in photo- z probability density functions …
Pegasus IV: Discovery and Spectroscopic Confirmation of an Ultra-faint Dwarf Galaxy in the Constellation Pegasus
Zenteno, A.; James, D. J.; Li, T. S. +31 more
We report the discovery of Pegasus IV, an ultra-faint dwarf galaxy found in archival data from the Dark Energy Camera processed by the DECam Local Volume Exploration Survey. Pegasus IV is a compact, ultra-faint stellar system ( ${r}_{1/2}={41}_{-6}^{+8}$ pc; M V = -4.25 ± 0.2 mag) located at a heliocentric distance of ${90}_{-6}^{+4}\…