Search Publications
Hard X-ray emission of the Earth's atmosphere: Monte Carlo simulations
Sunyaev, R.; Revnivtsev, M.; Sazonov, S. +1 more
We perform Monte Carlo simulations of cosmic ray-induced hard X-ray radiation from the Earth's atmosphere. We find that the shape of the spectrum emergent from the atmosphere in the energy range 25-300 keV is mainly determined by Compton scatterings and photoabsorption, and is almost insensitive to the incident cosmic ray spectrum. We provide a fi…
The Space Motion of the Globular Cluster NGC 6397
Anderson, Jay; Lépine, Sébastien; Rich, R. Michael +12 more
As a by-product of high-precision, ultradeep stellar photometry in the Galactic globular cluster NGC 6397 with the Hubble Space Telescope, we are able to measure a large population of background galaxies whose images are nearly pointlike. These provide an extragalactic reference frame of unprecedented accuracy, relative to which we measure the mos…
The cooling of atomic and molecular gas in DR21
Schneider, N.; Ossenkopf, V.; Bontemps, S. +5 more
Aims: We present an overview of a high-mass star formation region through the major (sub-)mm, and far-infrared cooling lines to gain insight into the physical conditions and the energy budget of the molecular cloud.
Methods: We used the KOSMA 3 m telescope to map the core (10'× 14') of the Galactic star-forming region DR21/DR21 (OH) in the Cyg…
A Probabilistic Approach to Classifying Supernovae Using Photometric Information
Kuznetsova, Natalia V.; Connolly, Brian M.
This paper presents a novel method for determining the probability that a supernova candidate belongs to a known supernova type (such as Ia, Ibc, IIL, etc.) using its photometric information alone. It is validated with Monte Carlo simulations, and both space- and ground-based data. We examine the application of the method to well-sampled as well a…
Warm-Hot Intergalactic Medium Associated with the Coma Cluster
Finoguenov, A.; Mitsuda, K.; Tamura, T. +4 more
Hydrodynamic simulations predict that low-redshift baryons are predominantly in a warm-hot intergalactic medium (WHIM), which should exhibit absorption and emission lines in the soft X-ray region. The WHIM is predicted to be most dense around clusters of galaxies. We present our XMM-Newton RGS observations of X Comae, an active galactic nucleus be…
Chandra Observations of the Eagle Nebula. I. Embedded Young Stellar Objects near the Pillars of Creation
Linsky, Jeffrey L.; Andersen, Morten; Gagné, Marc +2 more
We present and analyze the first high-resolution X-ray images ever obtained of the Eagle Nebula star-forming region. On 2001 July 30 the Chandra X-Ray Observatory obtained a 78 ks image of the Eagle Nebula (M16) that includes the core of the young galactic cluster NGC 6611 and the dark columns of dust and cold molecular gas in M16 known as the ``P…
The Ultraluminous X-Ray Sources Near the Center of M82
Pun, C. S. J.; Kong, A. K. H.; Yang, Y. J. +2 more
We report the identification of a recurrent ultraluminous X-ray source (ULX), a highly absorbed X-ray source (possibly a background AGN), and a young supernova remnant near the center of the starburst galaxy M82. From a series of Chandra observations taken from 1999 to 2005, we found that the transient ULX first appeared in 1999 October. The sourc…
Now you see it, now you don't - the circumstellar disc in the GRO J1008-57 system
Hill, A. B.; Coe, M. J.; Bird, A. J. +7 more
Multiwavelength observations are reported here of the Be/X-ray binary pulsar system GRO J1008-57. Over ten years worth of data are gathered together to show that the periodic X-ray outbursts are dependant on both the binary motion and the size of the circumstellar disc. In the first instance an accurate orbital solution is determined from pulse pe…
X-Ray Spectrum of Sagittarius A East
Maeda, Yoshitomo; Koyama, Katsuji; Matsumoto, Hironori +5 more
Sgr A East is a young SNR located in the Galactic Center (GC) region. Since the GC region is occupied by diffuse X-ray emission (GCDX) with a strong 6.7keV line, an estimation of the GCDX is crucial to study the X-ray spectrum of Sgr A East. The flux and spectrum of the GCDX are found to be smoothly distributed around and across Sgr A East, and he…
A new numerical model for the simulation of ELF wave propagation and the computation of eigenmodes in the atmosphere of Titan: Did Huygens observe any Schumann resonance?
Rodrigo, R.; López-Moreno, J. J.; Fulchignoni, M. +18 more
The propagation of extremely low frequency (ELF) electromagnetic waves in the Earth's ionospheric cavity and the associated resonance phenomena have been extensively studied, in relation with lightning activity. We perform a similar investigation for Titan, the largest moon of Saturn. There are important differences between Earth and Titan, as far…