Astronomy and astrophysics

Zombeck, Martin V.

doi:10.1017/cbo9780511536359.004

Cited by 71 publications

(89 citation statements)

References 12 publications

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“…Various estimates result in values corrected for the absorption of (1−5)×10 37 erg/s (Hartmann et al 1997;Zombeck 2007), but are dependent on the assumed spectral model and absorbing material column density.…”

Section: Energetics Of the Infrared Emissionmentioning

confidence: 99%

Fine-structure infrared lines from the Cassiopeia A knots

Docenko

Sunyaev

2010

A&A

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Aims. Archival observations of infrared fine-structure lines of the young Galactic supernova remnant Cassiopeia A allow us to test existing models and determine the physical parameters of various regions of the fast-moving knots, which are metal-dominated clouds of material ejected by the supernova explosion. Spitzer data are used to determine the fluxes of the O, Ne, Si, S, Ar, and Fe ion fine-structure lines originating in the fast-moving knots. The ratios of these line fluxes are used as plasma diagnostics. We also determine the infrared line flux ratios with respect to the optical [O iii] 5007 Å line in the knots with previously measured reddening. Additionally, we analyze several optical and near-infrared observations of the fast-moving knots to obtain clearer insight into the post-shock photoionized region structure. Results. We show that the infrared oxygen line flux predictions of all existing theoretical models are correct only to within a factor of a several. Comparison of the model predictions shows that to reproduce the observations it is essential to include the effects of the electron conductivity and dust. Detailed analysis of the diagnostic line flux ratios of various ions allows us to qualitatively confirm the general model of fast-moving knot emission and determine observationally for the first time the physical conditions in the photoionized region after the shock. We infer from the [O iii] line flux ratios that the pre-shock cloud densities are higher than assumed in existing theoretical models and most probably correspond to several hundred particles per cm 3 . We also determine the Cas A luminosity in the infrared continuum and lines. We show that accounting for the charge exchange processes in the post-shock photoionized region allows us to reproduce most of the relevant spectral line ratios even in the frame of a single-temperature model of this region. We also estimate its plasma parameters, thickness, and carbon abundance.

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Section: Energetics Of the Infrared Emissionmentioning

confidence: 99%

Fine-structure infrared lines from the Cassiopeia A knots

Docenko

Sunyaev

2010

A&A

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“…where is the EarthÏs dipole moment and k^k^/R2 \ 60 GV (Zombeck 1982 ;Donato et al 2000). The term h is the angle between the direction of arrival of the particle and the tangent to the circle of latitude.…”

Section: Geomagnetic Rigiditymentioning

confidence: 99%

A Novel Antimatter Detector Based on X‐Ray Deexcitation of Exotic Atoms

Mori

Hailey

Baltz

et al. 2002

ApJ

102

156

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We propose a novel antiparticle detector. The gaseous antiparticle spectrometer (GAPS) e †ects particle identiÐcation through the characteristic X-rays emitted by antiparticles when they form exotic atoms in gases. GAPS obtains particularly high grasp (e †ective areaÈsolid angle product) at lower particle energies, where conventional schemes are most limited in their utility. The concept is simple and lightweight, so it can be readily employed on balloon-and space-based missions. An extremely powerful potential application of GAPS is a space-based search for the neutralino through the detection of a neutralino annihilation by-productÈthe antideuteron. Paradoxically, this space-based search for the neutralino is capable of achieving comparable sensitivity to as yet unrealized third-generation, underground dark matter experiments. And GAPS can obtain this performance in a very modest satellite experiment. GAPS can also provide superior performance in searches for primary antiprotons produced via neutralino annihilation and black hole evaporation and in probing subdominant contributions to the antiproton Ñux at low energies. In a deep space mission, GAPS will obtain higher sensitivity for a given weight and power than BGO calorimeters.

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“…6.1). The R band flux, f (R), was then computed by converting R magnitudes to specific fluxes and then multiplying by the width of the R filter (Zombeck 1990), as in Fiore et al (2003).…”

Section: Finding the Optical Counterpartsmentioning

confidence: 99%

Discovery of optically faint obscured quasars with Virtual Observatory tools

Padovani

Allen

Rosati

et al. 2004

A&A

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Abstract. We use Virtual Observatory (VO) tools to identify optically faint, obscured (i.e., type 2) active galactic nuclei (AGN) in the two Great Observatories Origins Deep Survey (GOODS) fields. By employing publicly available X-ray and optical data and catalogues we discover 68 type 2 AGN candidates. The X-ray powers of these sources are estimated by using a previously known correlation between X-ray luminosity and X-ray-to-optical flux ratio. Thirty-one of our candidates have high estimated powers (L x > 10 44 erg/s) and therefore qualify as optically obscured quasars, the so-called "QSO 2". Based on the derived X-ray powers, our candidates are likely to be at relatively high redshifts, z ∼ 3, with the QSO 2 at z ∼ 4. By going ∼3 mag fainter than previously known type 2 AGN in the two GOODS fields we are sampling a region of redshift -power space which was previously unreachable with classical methods. Our method brings to 40 the number of QSO 2 in the GOODS fields, an improvement of a factor ∼ 4 when compared to the only 9 such sources previously known. We derive a QSO 2 surface density down to 10 −15 erg cm −2 s −1 in the 0.5−8 keV band of > ∼ 330 deg −2 , ∼30% of which is made up of previously known sources. This is larger than current estimates and some predictions and suggests that the surface density of QSO 2 at faint flux limits has been underestimated. This work demonstrates that VO tools are mature enough to produce cutting-edge science results by exploiting astronomical data beyond "classical" identification limits (R < ∼ 25) with interoperable tools for statistical identification of sources using multiwavelength information.

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Astronomy and astrophysics

Cited by 71 publications

References 12 publications

Fine-structure infrared lines from the Cassiopeia A knots

Fine-structure infrared lines from the Cassiopeia A knots

A Novel Antimatter Detector Based on X‐Ray Deexcitation of Exotic Atoms

Discovery of optically faint obscured quasars with Virtual Observatory tools

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