Search Publications
Why is IGR J17091-3624 So Faint? Constraints on Distance, Mass, and Spin from "Phase-resolved" Spectroscopy of the "Heartbeat" Oscillations
Rao, Anjali; Vadawale, S. V.
IGR J17091-3624 is a transient X-ray source and is believed to be a Galactic black hole candidate. Recently, it has received considerable attention due to the detection of peculiar variability patterns known as "heartbeats," which are quasi-periodic mini-outbursts repeated over timescales ranging between 5 and 70 s. So far, such variability patter…
Measurements of the Sun's High-latitude Meridional Circulation
Hathaway, David H.; Rightmire-Upton, Lisa; Kosak, Katie
The meridional circulation at high latitudes is crucial to the buildup and reversal of the Sun's polar magnetic fields. Here, we characterize the axisymmetric flows by applying a magnetic feature cross-correlation procedure to high-resolution magnetograms obtained by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observator…
Using the Bullet Cluster as a Gravitational Telescope to Study z >~ 7 Lyman Break Galaxies
Stiavelli, Massimo; Treu, Tommaso; Bradač, Maruša +7 more
We use imaging obtained with the Hubble Space Telescope Wide Field Camera 3 to search for z 850 dropouts at z ~ 7 and J 110 dropouts at z ~ 9 lensed by the Bullet Cluster. In total we find 10 z 850 dropouts in our 8.27 arcmin2 field. Using magnification maps from a combined weak- and strong-lensing mass …
Internal Structure of Protocluster Galaxies: Accelerated Structural Evolution in Overdense Environments?
Zirm, Andrew W.; Toft, Sune; Tanaka, Masayuki
We present a high spatial resolution Hubble Space Telescope/NICMOS imaging survey in the field of a known protocluster surrounding the powerful radio galaxy MRC1138-262 at z = 2.16. Previously, we have shown that this field exhibits a substantial surface overdensity of red J-H galaxies. Here we focus on the stellar masses and galaxy effective radi…
X-Ray Emission from the Wolf-Rayet Bubble S 308
Gruendl, R. A.; Smith, R. C.; Chu, Y. -H. +4 more
The Wolf-Rayet (WR) bubble S 308 around the WR star HD 50896 is one of the only two WR bubbles known to possess X-ray emission. We present XMM-Newton observations of three fields of this WR bubble that, in conjunction with an existing observation of its northwest quadrant, map most of the nebula. The X-ray emission from S 308 displays a limb-brigh…
A Possible Ultra Strong and Broad Fe Kα Emission Line in Seyfert 2 Galaxy IRAS 00521-7054
Shu, X. W.; Wang, J. X.; Tan, Y. +1 more
We present XMM-Newton spectra of the Seyfert 2 Galaxy IRAS 00521-7054. A strong feature at ~6 keV (observer's frame) can be formally fitted with a strong (EW = 1.3 ± 0.3 keV in the rest frame) and broad Fe Kα line, extending down to 3 keV. The underlying X-ray continuum could be fitted with an absorbed power law (with Γ = 1.8 ± 0.2 and N H
On the Shapes and Structures of High-redshift Compact Galaxies
Glazebrook, Karl; Chevance, Mélanie; Abraham, Roberto G. +5 more
Recent deep Hubble Space Telescope WFC3 imaging suggests that a majority of compact quiescent massive galaxies at z ~ 2 may contain disks. To investigate this claim, we have compared the ellipticity distribution of 31 carefully selected high-redshift massive quiescent compact galaxies to a set of mass-selected ellipticity and Sérsic index distribu…
AE Aurigae: First Detection of Non-thermal X-Ray Emission from a Bow Shock Produced by a Runaway Star
Miceli, M.; Bonito, R.; Romero, G. E. +6 more
Runaway stars produce shocks when passing through interstellar medium at supersonic velocities. Bow shocks have been detected in the mid-infrared for several high-mass runaway stars and in radio waves for one star. Theoretical models predict the production of high-energy photons by non-thermal radiative processes in a number sufficiently large to …
Direct Measurement of the X-Ray Time-delay Transfer Function in Active Galactic Nuclei
Turner, T. J.; Kraemer, S. B.; Reeves, J. N. +3 more
The origin of the observed time lags, in nearby active galactic nuclei (AGNs), between hard and soft X-ray photons is investigated using new XMM-Newton data for the narrow-line Seyfert I galaxy Ark 564 and existing data for 1H 0707-495 and NGC 4051. These AGNs have highly variable X-ray light curves that contain frequent, high peaks of emission. T…
Spectroscopic Confirmation of a z = 6.740 Galaxy behind the Bullet Cluster
Fontana, Adriano; Stiavelli, Massimo; Treu, Tommaso +7 more
We present the first results of our spectroscopic follow-up of 6.5 < z < 10 candidate galaxies behind clusters of galaxies. We report the spectroscopic confirmation of an intrinsically faint Lyman break galaxy (LBG) identified as a z 850LP-band dropout behind the Bullet Cluster. We detect an emission line at λ = 9412 Å at >5σ s…