The search for hot spots associated with the Cygnus X-3 relativistic jet     

J. Martí  D. Pérez-Ramírez  P. Luque-Escamilla  J. L. Garrido  J. M. Paredes  A. Muñoz-Arjonilla  J. R. Sánchez-Sutil 《Astrophysics and Space Science》2007,309(1-4):309-313

We report and shortly discuss here the observational work carried out in order to test the possibility that two previously detected radio sources, in the vicinity of the well known microquasar Cygnus X-3, could be hot spot tracers of interaction between its relativistic jet and the interstellar medium (ISM). The motivation behind this search is in part justified considering recent theoretical models of high energy γ-ray emission which strongly rely on the interaction sites of galactic relativistic jets with nearby ISM clouds. The results presented in this paper include an improved radio exploration of the several arc-minute field around Cygnus X-3 using the Very Large Array (VLA), as well as deep near infrared (NIR) imaging with the Calar Alto 3.5 m telescope. We anticipate here that our observations do not appear to support the initial hot spot hypothesis. Instead, the resulting images suggest that the two radio sources, originally believed to be hot spot candidates, are most likely background or foreground objects.  相似文献   

Compressible turbulence in galaxy clusters: physics and stochastic particle re-acceleration     

G. Brunetti  A. Lazarian 《Monthly notices of the Royal Astronomical Society》2007,378(1):245-275

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Intermittent jet activity in the radio galaxy 4C 29.30?     

M. Jamrozy  C. Konar  D. J. Saikia  &#;. Stawarz  K.-H. Mack  A. Siemiginowska 《Monthly notices of the Royal Astronomical Society》2007,378(2):581-593

We present radio observations at frequencies ranging from 240 to 8460 MHz of the radio galaxy 4C 29.30 (J0840+2949) using the Giant Metrewave Radio Telescope (GMRT), the Very Large Array (VLA) and the Effelsberg telescope. We report the existence of weak extended emission with an angular size of ∼520 arcsec (639 kpc) within which a compact edge-brightened double-lobed source with a size of 29 arcsec (36 kpc) is embedded. We determine the spectrum of the inner double from 240 to 8460 MHz and show that it has a single power-law spectrum with a spectral index of ∼0.8. Its spectral age is estimated to be ≲33 Myr. The extended diffuse emission has a steep spectrum with a spectral index of ∼1.3 and a break frequency ≲240 MHz. The spectral age is ≳200 Myr, suggesting that the extended diffuse emission is due to an earlier cycle of activity. We re-analyse archival X-ray data from Chandra and suggest that the X-ray emission from the hotspots consists of a mixture of non-thermal and thermal components, the latter being possibly due to gas which is shock heated by the jets from the host galaxy.  相似文献   

A deep Giant Metre-wave Radio Telescope 610-MHz survey of the 1^HXMM–Newton/Chandra survey field     

D. Moss  N. Seymour  I. M. McHardy  T. Dwelly  M. J. Page  N. S. Loaring 《Monthly notices of the Royal Astronomical Society》2007,378(3):995-1006

We present the results of a deep 610-MHz survey of the 1 ^H XMM–Newton / Chandra survey area with the Giant Metre-wave Radio Telescope. The resulting maps have a resolution of ∼7 arcsec and an rms noise limit of 60 μJy. To a 5σ detection limit of 300 μJy, we detect 223 sources within a survey area of 64 arcmin in diameter. We compute the 610-MHz source counts and compare them to those measured at other radio wavelengths. The well-known flattening of the Euclidean-normalized 1.4-GHz source counts below ∼2 mJy, usually explained by a population of starburst galaxies undergoing luminosity evolution, is seen at 610 MHz. The 610-MHz source counts can be modelled by the same populations that explain the 1.4-GHz source counts, assuming a spectral index of −0.7 for the starburst galaxies and the steep spectrum active galactic nucleus (AGN) population. We find a similar dependence of luminosity evolution on redshift for the starburst galaxies at 610 MHz as is found at 1.4 GHz (i.e.  ' Q '= 2.45^+0.3_−0.4  ).  相似文献   

Density gradients in Galactic ultra-compact H ii regions     

J. P. Phillips 《Monthly notices of the Royal Astronomical Society》2007,380(1):369-373

We have used recent radiative transfer solutions for cavity-centred shells to investigate the prevalence of density gradients in Galactic ultra-compact H  ii regions. We find that an analysis of 5 and 1.4 GHz data, taken from the recent compilation of Giveon et al., implies that ∼76 per cent of sources may have appreciable density gradients. It would also seem that the central cavities of these sources must be relatively small, with radii no greater than ∼20 per cent of those of the outer shells. The remainder of these sources are presumably homogenous, have much larger cavities, or possess reverse density gradients (densities which increase with increasing radius). A good fraction of the H  ii regions also appear to have high brightness temperatures, implying mean electron temperatures  〈 T _e〉  of the order of  ≈1.3 × 10⁴ K  . This value is higher than has been determined for other such sources.  相似文献   

Superdiscs in radio galaxies: jet–wind interactions     

Gopal-Krishna    Paul J. Wiita  Santosh Joshi † 《Monthly notices of the Royal Astronomical Society》2007,380(2):703-711

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Radio galaxies in the 2SLAQ Luminous Red Galaxy Survey – I. The evolution of low-power radio galaxies to  z∼ 0.7      

Elaine M. Sadler  Russell D. Cannon  Tom Mauch  Paul J. Hancock  David A. Wake  Nic Ross  Scott M. Croom  Michael J. Drinkwater  Alastair C. Edge  Daniel Eisenstein  rew M. Hopkins  Helen M. Johnston  Robert Nichol  Kevin A. Pimbblet  Roberto De Propris  Isaac G. Roseboom  Donald P. Schneider  Tom Shanks 《Monthly notices of the Royal Astronomical Society》2007,381(1):211-227

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High-redshift Fanaroff–Riley type II radio sources: large-scale X-ray environment     

E. Belsole  D. M. Worrall  M. J. Hardcastle  J. H. Croston 《Monthly notices of the Royal Astronomical Society》2007,381(3):1109-1126

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Spectroscopic follow-up of a cluster candidate at z= 1.45     

Caroline van Breukelen  Garret Cotter  Steve Rawlings  Tony Readhead  David Bonfield  Lee Clewley  Rob Ivison  Matt Jarvis  Chris Simpson  Mike Watson 《Monthly notices of the Royal Astronomical Society》2007,382(3):971-984

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On the origins of part-time radio pulsars   总被引：1，自引：0，他引：1  

Bing Zhang  Janusz Gil  Jaroslaw Dyks 《Monthly notices of the Royal Astronomical Society》2007,374(3):1103-1107

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