400 citations · 3.1k across the 38 of their papers we have counts for
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An Extremely Luminous Flare Recorded from a Supermassive Black Hole
Matthew J. Graham, Barry McKernan, K. E. Saavik Ford +17
Since their discovery more than 60 years ago, accreting supermassive black holes in active galactic nuclei (AGN) were recognized as highly variable sources, requiring an extremely…
A Highly Magnified Gravitationally Lensed Red QSO at z = 2.5 with a Significant Flux Ratio Anomaly
Eilat Glikman, Cristian E. Rusu, Geoff C. -F. Chen +12
We present the discovery of a gravitationally lensed dust-reddened QSO at z = 2.517, identified in a survey for QSOs by infrared selection. Hubble Space Telescope imaging reveals a…
Science with the Ultraviolet Explorer (UVEX)
S. R. Kulkarni, Fiona A. Harrison, Brian W. Grefenstette +53
UVEX is a proposed medium class Explorer mission designed to provide crucial missing capabilities that will address objectives central to a broad range of modern astrophysics. The…
Gaia GraL: Gaia DR2 Gravitational Lens Systems. VII. XMM-Newton Observations of Lensed Quasars
Thomas Connor, Daniel Stern, Alberto Krone-Martins +23
We present XMM-Newton X-ray observations of nine confirmed lensed quasars at identified by the Gaia Gravitational Lens program. Eight systems are strongly…
Gaia GraL: Gaia DR2 Gravitational Lens Systems. VI. Spectroscopic Confirmation and Modeling of Quadruply-Imaged Lensed Quasars
D. Stern, S. G. Djorgovski, A. Krone-Martins +23
Combining the exquisite angular resolution of Gaia with optical light curves and WISE photometry, the Gaia Gravitational Lenses group (GraL) uses machine learning techniques to ide…
Deep modeling of quasar variability
Yutaro Tachibana, Matthew J. Graham, Nobuyuki Kawai +4
Quasars have long been known as intrinsically variable sources, but the physical mechanism underlying the temporal optical/UV variability is still not well understood. We propose a…
Gaia GraL: Gaia DR2 Gravitational Lens Systems. V. Doubly-imaged QSOs discovered from entropy and wavelets
A. Krone-Martins, M. J. Graham, D. Stern +22
The discovery of multiply-imaged gravitationally lensed QSOs is fundamental to many astronomical and cosmological studies. However, these objects are rare and challenging to discov…
The first high-redshift changing-look quasars
Nicholas P. Ross, Matthew J. Graham, Giorgio Calderone +3
We report on three redshift quasars with dramatic changes in their C IV emission lines, the first sample of changing-look quasars (CLQs) at high redshift. This is also the fi…
Understanding extreme quasar optical variability with CRTS: II. Changing-state quasars
Matthew J. Graham, Nicholas P. Ross, Daniel Stern +8
We present the results of a systematic search for quasars in the Catalina Real-time Transient Survey exhibiting both strong photometric and spectroscopic variability over a decadal…
Results of a systematic search for outburst events in 1.4 million galaxies
A. J. Drake, S. G. Djorgovski, M. J. Graham +5
We present an analysis of nine years of Catalina Surveys optical photometry for 1.4 million spectroscopically confirmed SDSS galaxies. We find 717 outburst events that were not rep…
Changing-Look Quasar Candidates: First Results from Follow-up Spectroscopy of Highly Optically Variable Quasars
Chelsea L. MacLeod, Paul J. Green, Scott F. Anderson +15
Active galactic nuclei (AGN) that show strong rest-frame optical/UV variability in their blue continuum and broad line emission are classified as "changing-look" AGN, or at higher…
Luminous WISE-selected Obscured, Unobscured, and Red Quasars in Stripe 82
E. Glikman, M. Lacy, S. LaMassa +11
We present a spectroscopically complete sample of 147 infrared-color-selected AGN down to a 22 m flux limit of 20 mJy over the 270 deg of the SDSS Stripe 82 region. Mo…
A Mid-IR Selected Changing-Look Quasar and Physical Scenarios for Abrupt AGN Fading
Daniel Stern, Barry McKernan, Matthew J. Graham +11
We report a new changing-look quasar, WISE~J105203.55+151929.5 at , found by identifying highly mid-IR variable quasars in the WISE/NEOWISE data stream. Compared to multi-…
A new physical interpretation of optical and infrared variability in quasars
Nicholas P. Ross, K. E. Saavik Ford, Matthew Graham +8
Changing-look quasars are a recently identified class of active galaxies in which the strong UV continuum and/or broad optical hydrogen emission lines associated with unobscured qu…
Understanding extreme quasar optical variability with CRTS: I. Major AGN flares
Matthew J. Graham, S. G. Djorgovski, Andrew J. Drake +5
There is a large degree of variety in the optical variability of quasars and it is unclear whether this is all attributable to a single (set of) physical mechanism(s). We present t…
Extreme Variability in a Broad Absorption Line Quasar
Daniel Stern, Matthew J. Graham, Nahum Arav +9
CRTS J084133.15+200525.8 is an optically bright quasar at z=2.345 that has shown extreme spectral variability over the past decade. Photometrically, the source had a visual magnitu…
Detection of quasars in the time domain
Matthew J. Graham, S. G. Djorgovski, Daniel J. Stern +2
The time domain is the emerging forefront of astronomical research with new facilities and instruments providing unprecedented amounts of data on the temporal behavior of astrophys…
Infrared Time Lags for the Periodic Quasar PG 1302-102
Hyunsung D. Jun, Daniel Stern, Matthew J. Graham +5
The optical light curve of the quasar PG 1302-102 at shows a strong, smooth 5.2 yr periodic signal, detectable over a period of yr. Although the interpretatio…
A systematic search for close supermassive black hole binaries in the Catalina Real-Time Transient Survey
Matthew J. Graham, S. G. Djorgovski, Daniel Stern +6
Hierarchical assembly models predict a population of supermassive black hole (SMBH) binaries. These are not resolvable by direct imaging but may be detectable via periodic variabil…
A possible close supermassive black-hole binary in a quasar with optical periodicity
Matthew J. Graham, S. George Djorgovski, Daniel Stern +6
Quasars have long been known to be variable sources at all wavelengths. Their optical variability is stochastic, can be due to a variety of physical mechanisms, and is well-describ…