Search Publications
The Sudden Death of the Nearest Quasar
Schawinski, Kevin; Józsa, Gyula I. G.; Keel, William C. +13 more
Galaxy formation is significantly modulated by energy output from supermassive black holes at the centers of galaxies which grow in highly efficient luminous quasar phases. The timescale on which black holes transition into and out of such phases is, however, unknown. We present the first measurement of the shutdown timescale for an individual qua…
Cool core remnants in galaxy clusters
Rossetti, M.; Molendi, S.
Context. X ray clusters are conventionally divided into two classes: “cool core” (CC) and “non-cool core” (NCC) objects, on the basis of the observational properties of their central regions. Recent results have shown that the cluster population is bimodal.
Aims: We want to understand whether the observed distribution of clusters is due to a …
Local Luminous Infrared Galaxies. I. Spatially Resolved Observations with the Spitzer Infrared Spectrograph
Pérez-González, Pablo G.; Colina, Luis; Rieke, George H. +5 more
We present results from the Spitzer Infrared Spectrograph spectral mapping observations of 15 local luminous infrared galaxies (LIRGs). In this paper, we investigate the spatial variations of the mid-IR emission which includes fine structure lines, molecular hydrogen lines, polycyclic aromatic features (PAHs), continuum emission, and the 9.7 &micr…
“Island surfing” mechanism of electron acceleration during magnetic reconnection
Fujimoto, M.; Phan, T. D.; Shinohara, I. +1 more
One of the key unresolved problems in the study of space plasmas is to explain the production of energetic electrons as magnetic field lines “reconnect” and release energy in an explosive manner. Recent observations suggest possible roles played by small-scale magnetic islands in the reconnection region, but their precise roles and the exact mecha…
Recent X-ray Variability of η Carinae: The Quick Road to Recovery
Corcoran, M. F.; Owocki, S. P.; Russell, C. M. P. +4 more
We report continued monitoring of the superluminous binary system η Car by the Proportional Counter Array on the Rossi X-ray Timing Observatory (RXTE) through the 2009 X-ray minimum. The RXTE campaign shows that the minimum began on 2009 January 16, consistent with the phasings of the two previous minima, and overall, the temporal behavior of the …
Hemispheric asymmetry of the magnetic field wrapping pattern in the Venusian magnetotail
Kallio, E.; Luhmann, J. G.; Russell, C. T. +7 more
We examine statistically the magnetic field in the Venusian magnetotail which is formed by the draping of interplanetary magnetic field lines. Although the near-planet and distant magnetotail regions have been sampled by the various missions to Venus and the general magnetic features of the distant magnetotail are well established, the near wake r…
Unveiling the nature of INTEGRAL objects through optical spectroscopy. VIII. Identification of 44 newly detected hard X-ray sources
Palazzi, E.; Minniti, D.; Masetti, N. +17 more
Hard X-ray surveys performed by the INTEGRAL satellite have discovered a conspicuous fraction (up to 30%) of unidentified objects among the detected sources. Here we continue our program of identification of these objects by (i) selecting probable optical candidates by means of positional cross-correlation of the INTEGRAL detections with soft X-ra…
Neptune's atmospheric composition from AKARI infrared spectroscopy
Fletcher, L. N.; Encrenaz, T.; Burgdorf, M. +2 more
Aims: Disk-averaged infrared spectra of Neptune between 1.8 and 13 µm, obtained by the AKARI infrared camera (IRC) in May 2007, have been analysed to (a) determine the globally-averaged stratospheric temperature structure; (b) derive the abundances of stratospheric hydrocarbons; and (c) detect fluorescent emission from CO at 4.7 µ…
Near-tropical subsurface ice on Mars
Bibring, Jean-Pierre; Mustard, John; Forget, François +4 more
Near-surface perennial water ice on Mars has been previously inferred down to latitudes of about 45° and could result from either water vapor diffusion through the regolith under current conditions or previous ice ages precipitations. In this paper we show that at latitudes as low as 25° in the southern hemisphere buried water ice in the shallow (…
Probing ~L* Lyman-break galaxies at z ~ 7 in GOODS-South with WFC3 on Hubble Space Telescope
Wilkins, Stephen M.; Bunker, Andrew J.; Ellis, Richard S. +5 more
We analyse recently acquired near-infrared Hubble Space Telescope imaging of the Great Observatories Origins Deep Survey (GOODS)-South field to search for star-forming galaxies at z ~ 7.0. By comparing Wide Field Camera 3 (WFC3) 0.98µm Y-band images with Advanced Camera for Surveys (ACS) z-band (0.85µm) images, we identify objects with…