Skip to main content
Home
Department Of Physics text logo
  • Research
    • Our research
    • Our research groups
    • Our research in action
    • Research funding support
    • Summer internships for undergraduates
  • Study
    • Undergraduates
    • Postgraduates
  • Engage
    • For alumni
    • For business
    • For schools
    • For the public
Menu
Relativistic Jet from Black Hole

An artist's impression of a relativistic jet propagating away from a black hole at close to the speed of light. Such jets are formed by the inner regions of the accretion flow: matter flowing inwards towards the black hole, via processes which are not yet fully understood. The accretion flow emits primarily in X-rays, the relativistic jet in the radio band: by combing observations in each band we can try and understand how such jets form and how much energy they carry away from the black hole.

Professor Rob Fender

Professor of Astrophysics

Research theme

  • Astronomy and astrophysics

Sub department

  • Astrophysics

Research groups

  • Hintze Centre for Astrophysical Surveys
  • MeerKAT
  • Pulsars, transients and relativistic astrophysics
  • Rubin-LSST
  • The Square Kilometre Array (SKA)
  • Gamma-ray astronomy
Rob.Fender@physics.ox.ac.uk
Telephone: 01865 (2)73435
Denys Wilkinson Building, room 712
  • About
  • Publications

Detecting highly dispersed bursts with next-generation radio telescopes

Monthly Notices of the Royal Astronomical Society 436:1 (2013) 371-379

Authors:

TE Hassall, EF Keane, RP Fender

Abstract:

Recently, there have been reports of six bright, dispersed bursts of coherent radio emission found in pulsar surveys with the Parkes Multibeam Receiver. Not much is known about the progenitors of these bursts, but they are highly energetic, and probably of extragalactic origin. Their properties suggest extreme environments and interesting physics, but in order to understand and study these events, more examples need to be found. Fortunately, the recent boom in radio astronomy means many 'next-generation' radio telescopes are set to begin observing in the near future. In this paper we discuss the prospects of detecting short extragalactic bursts, in both beamformed and imaging data, using these instruments. We find that often the volume of space probed by radio surveys of fast transients is limited by the dispersion measure of the source, rather than its physical distance (although the two quantities are related). This effect is larger for low-frequency telescopes, where propagation effects are more prominent, but their larger fields-of-view are often enough to compensate for this. Our simulations suggest that the low-frequency component of Square Kilometre Array Phase 1 could find an extragalactic burst every hour.We also show that if the sensitivity of the telescope is above a certain threshold, imaging surveysmay prove more fruitful than beamformed surveys in finding these sorts of transients. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
More details from the publisher
More details

Early science with the Karoo Array Telescope test array KAT-7

South African Journal of Science 109:7-8 (2013)

Authors:

PA Woudt, RP Fender, RP Armstrong, C Carignan
More details from the publisher
More details

Inclination and relativistic effects in the outburst evolution of black hole transients

Monthly Notices of the Royal Astronomical Society 432:2 (2013) 1330-1337

Authors:

T Muñoz-Darias, M Coriat, DS Plant, G Ponti, RP Fender, RJH Dunn

Abstract:

We have systematically studied the effect of the orbital inclination in the outburst evolution of black hole transients. We have included all the systems observed by the Rossi X-ray Timing Explorer in which the thermal, accretion disc component becomes strongly dominant at some point of the outburst. Inclination is found to modify the shape of the tracks that these systems display in the colour/luminosity diagrams traditionally used for their study. Black hole transients seen at low inclination reach softer spectra and their accretion discs look cooler than those observed closer to edge-on. This difference can be naturally explained by considering inclination-dependent relativistic effects on accretion discs. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.
More details from the publisher
More details
Details from ArXiV

Multiwavelength campaign on Mrk 509: XI. Reverberation of the Fe K α line

Astronomy and Astrophysics 549 (2013)

Authors:

G Ponti, M Cappi, E Costantini, S Bianchi, JS Kaastra, B De Marco, RP Fender, PO Petrucci, GA Kriss, KC Steenbrugge, N Arav, E Behar, G Branduardi-Raymont, M Dadina, J Ebrero, P Lubiński, M Mehdipour, S Paltani, C Pinto, F Tombesi

Abstract:

Context.We report on a detailed study of the Fe K emission/absorption complex in the nearby, bright Seyfert 1 galaxy Mrk 509. The study is part of an extensive XMM-Newton monitoring consisting of 10 pointings (∼60 ks each) about once every 4 days, and includes a reanalysis of previous XMM-Newton and Chandra observations. Aims.We aim at understanding the origin and location of the Fe K emission and absorption regions. Methods.We combine the results of time-resolved spectral analysis on both short and long time-scales including model-independent rms spectra. Results.Mrk 509 shows a clear (EW = 58±4 eV) neutral Fe Ka emission line that can be decomposed into a narrow (s = 0.027 keV) component (found in the Chandra HETG data) plus a resolved (s = 0.22 keV) component.We find the first successful measurement of a linear correlation between the intensity of the resolved line component and the 3-10 keV flux variations on time scales of years down to a few days. The Fe Ka reverberates the hard X-ray continuum without any measurable lag, suggesting that the region producing the resolved Fe Ka component is located within a few light days to a week (r ≲ 103 rg) from the black hole (BH). The lack of a redshifted wing in the line poses a lower limit of =40 rg for its distance from the BH. The Fe Ka could thus be emitted from the inner regions of the BLR, i.e. within the ∼80 light days indicated by the Hß line measurements. In addition to these two neutral Fe Ka components, we confirm the detection of weak (EW ∼ 8-20 eV) ionised Fe K emission. This ionised line can be modelled with either a blend of two narrow Fe xxv and Fe xxvi emission lines (possibly produced by scattering from distant material) or with a single relativistic line produced, in an ionised disc, down to a few rg from the BH. In the latter interpretation, the presence of an ionised standard a-disc, down to a few rg, is consistent with the source high Eddington ratio. Finally, we observe a weakening/disappearing of the mediumand high-velocity high-ionisation Fe K wind features found in previous XMM-Newton observations. Conclusions. This campaign has made the first reverberation measurement of the resolved component of the Fe Ka line possible, from which we can infer a location for the bulk of its emission at a distance of r ∼ 40-1000 rg from the BH. © 2012 ESO.
More details from the publisher
More details

Radio continuum surveys with square kilometre array pathfinders

Publications of the Astronomical Society of Australia 30:1 (2013)

Authors:

RP Norris, J Afonso, D Bacon, R Beck, M Bell, RJ Beswick, P Best, S Bhatnagar, A Bonafede, G Brunetti, T Budavári, R Cassano, JJ Condon, C Cress, A Dabbech, I Feain, R Fender, C Ferrari, BM Gaensler, G Giovannini, M Haverkorn, G Heald, K Van Der Heyden, AM Hopkins, M Jarvis, M Johnston-Hollitt, R Kothes, H Van Langevelde, J Lazio, MY Mao, A Martínez-Sansigre, D Mary, K McAlpine, E Middelberg, E Murphy, P Padovani, Z Paragi, I Prandoni, A Raccanelli, E Rigby, IG Roseboom, H Röttgering, J Sabater, M Salvato, AMM Scaife, R Schilizzi, N Seymour, DJB Smith, G Umana, GB Zhao, PC Zinn

Abstract:

In the lead-up to the Square Kilometre Array (SKA) project, several next-generation radio telescopes and upgrades are already being built around the world. These include APERTIF (The Netherlands), ASKAP (Australia), e-MERLIN (UK), VLA (USA), e-EVN (based in Europe), LOFAR (The Netherlands), MeerKAT (South Africa), and the Murchison Widefield Array. Each of these new instruments has different strengths, and coordination of surveys between them can help maximise the science from each of them. A radio continuum survey is being planned on each of them with the primary science objective of understanding the formation and evolution of galaxies over cosmic time, and the cosmological parameters and large-scale structures which drive it. In pursuit of this objective, the different teams are developing a variety of new techniques, and refining existing ones. To achieve these exciting scientific goals, many technical challenges must be addressed by the survey instruments. Given the limited resources of the global radio-astronomical community, it is essential that we pool our skills and knowledge. We do not have sufficient resources to enjoy the luxury of re-inventing wheels. We face significant challenges in calibration, imaging, source extraction and measurement, classification and cross-identification, redshift determination, stacking, and data-intensive research. As these instruments extend the observational parameters, we will face further unexpected challenges in calibration, imaging, and interpretation. If we are to realise the full scientific potential of these expensive instruments, it is essential that we devote enough resources and careful study to understanding the instrumental effects and how they will affect the data. We have established an SKA Radio Continuum Survey working group, whose prime role is to maximise science from these instruments by ensuring we share resources and expertise across the projects. Here we describe these projects, their science goals, and the technical challenges which are being addressed to maximise the science return. © 2013 Astronomical Society of Australia.
More details from the publisher
More details
Details from ArXiV

Pagination

  • First page First
  • Previous page Prev
  • …
  • Page 101
  • Page 102
  • Page 103
  • Page 104
  • Current page 105
  • Page 106
  • Page 107
  • Page 108
  • Page 109
  • …
  • Next page Next
  • Last page Last

Footer Menu

  • Contact us
  • Giving to the Dept of Physics
  • Work with us
  • Media

User account menu

  • Log in

Follow us

FIND US

Clarendon Laboratory,

Parks Road,

Oxford,

OX1 3PU

CONTACT US

Tel: +44(0)1865272200

University of Oxfrod logo Department Of Physics text logo
IOP Juno Champion logo Athena Swan Silver Award logo

© University of Oxford - Department of Physics

Cookies | Privacy policy | Accessibility statement

Built by: Versantus

  • Home
  • Research
  • Study
  • Engage
  • Our people
  • News & Comment
  • Events
  • Our facilities & services
  • About us
  • Current students
  • Staff intranet