Publications by Katherine Blundell


Concepts in thermal physics

Oxford University Press, USA, 2006

S Blundell, KM Blundell

This modern introduction to thermal physics contains a step-by-step presentation of the key concepts. The text is copiously illustrated and each chapter contains several worked examples.


SS 433: Observation of the circumbinary disk and extraction of the system mass

ASTROPHYSICAL JOURNAL LETTERS 678 (2008) L47-L50

KM Blundell, MG Bowler, L Schmidtobreick


Radio-loud and radio-quiet quasars: one population, different epochs of observation

ASP Conference Series (2008)

K Blundell

I bring together evidence for the rapidity with which quasars' radio synchrotron lobe emission fades and for the intermittency with which jet plasma is ejected from individual quasars and radio galaxies and affirm the picture presented by Nipoti et al (2005) that the radio-loudness of quasars is a function of the epoch at which they are observed. I briefly illustrate this account with examples of successive episodes of jet activity where the axis along which jet plasma is launched appears to have precessed. A new model for the weak core radio emission from radio-quiet quasars, that is not any kind of jet ejecta, is also briefly described.


The GlobalJetWatch spectrographs: a fibre-fed spectrograph for small telescopes - art. no. 70145A

GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY II, PTS 1-4 7014 (2008) A145-A145

FJ Clarke, AJ Gosling, S Doolin, P Goodall, S Perez, P Pattinson, R Makin, KM Blundell


The Nuclear Bulge extinction

AIP CONF PROC 1010 (2008) 168-170

J Andrew, KM Blundell, RM Bandyopadhyay, P Lucas

We present a new, high resolution (5 '' per pixel) near-infrared extinction map of the Nuclear Bulge using data from the UKIDSS-GPS. Using photometry from the J, H and K-bands we show that the extinction law parameter a is also highly variable in this region on similar scales to the absolute extinction. We show that only when this extinction law variation is taken into account can the extinction be measured consistently at different wavelengths.


Extended Inverse-Compton emission from distant, powerful radio galaxies

ESO Astrophysics Symposia 2008 (2008) 212-214

MC Erlund, AC Fabian, KM Blundell, A Celotti, CS Crawford


Energy... Beyond Oil

OUP Oxford, 2007

FA Armstrong, KM Blundell

This book focuses on solutions to the energy problem, and not just the problem itself.


Low-frequency radio observations of Galactic X-ray binary systems

Proceedings of Science 56 (2007)

J Miller-Jones, A Kapińska, K Blundell, B Stappers, R Braun

© 2018 The author(s). With the advent of facilities enabling wide-field monitoring of the dynamic radio sky, new areas of parameter space will be opened up for exploration. Such monitoring will be done primarily at low frequencies, in order to maximise the available field of view. One class of radio sources known to be highly variable at GHz frequencies are the so-called 'microquasars', X-ray binaries with relativistic jets. To date however, their low-frequency behaviour has not been well constrained by observations. I will present some of the first attempts to measure their low-frequency properties, showing wide-field images made from data taken with the 74-MHz system on the Very Large Array (VLA) and also the Low Frequency Front Ends (LFFEs), the new suite of low-frequency (117-175 MHz) receivers on the Westerbork Synthesis Radio Telescope (WSRT). I will show results including the low-frequency spectra of the three X-ray binaries SS 433, GRS 1915+105 and Cygnus X-3, a low-frequency study of the W 50 nebula surrounding SS 433, a search for synchrotron lobes inflated by the jets of GRS 1915+105, and the evolution of the May 2006 outburst of Cygnus X-3 at MHz frequencies.


On the origin of radio core emission in radio-quiet quasars

Astrophysical Journal 668 (2007)

KM Blundell, Z Kuncic

We present a model for the radio emission from radio-quiet quasar nuclei. We show that a thermal origin for the high brightness temperature, flat spectrum point sources (known as radio "cores") is possible provided that the emitting region is hot and optically thin. We hence demonstrate that optically thin bremsstrahlung from a slow, dense disk wind can make a significant contribution to the observed levels of radio core emission. This is a much more satisfactory explanation, particularly for sources where there is no evidence of a jet, than a sequence of self-absorbed synchrotron components that collectively conspire to give a flat spectrum. Furthermore, such core phenomena are already observed directly via milliarcsecond radio imaging of the Galactic microquasar SS 433 and the active galaxy NGC 1068. We contend that radio-emitting disk winds must be operating at some level in radio-loud quasars and radio galaxies as well (although in these cases, observations of the radio cores are frequently contaminated/dominated by synchrotron emission from jet knots). This interpretation of radio core emission mandates mass accretion rates that are substantially higher than Eddington. Moreover, acknowledgment of this mass-loss mechanism as an AGN feedback process has important implications for the input of energy and hot gas into the intergalactic medium (IGM) since it is considerably less directional than that from jets. © 2007. The American Astronomical Society. All rights reserved.


Radio and X-ray study of Cygnus A

Astrophysics and Space Science 310 (2007) 321-325

KC Steenbrugge, KM Blundell

We present a comparative analysis of 5 GHz VLA and 200 ks Chandra ACIS-I image. In the 5 GHz image the familiar jet and much weaker counterjet are seen, which bend as the jet propagates towards the hotspots. Furthermore, where the lobe detected in 5 GHz emission starts to interact with the jet, we see that the jet "threads". In the 0.2-10 keV X-ray image we do not detect the jet, but do detect a relic of the counterjet. © 2007 Springer Science+Business Media B.V.


Radio and X-ray study of cygnus A

ASTROPHYS SPACE SCI 311 (2007) 323-327

KC Steenbrugge, KM Blundell

We present a comparative analysis of 5 GHz VLA and 200 ks Chandra ACIS-I image. In the 5 GHz image the familiar jet and much weaker counterjet are seen, which bend as the jet propagates towards the hotspots. Furthermore, where the lobe detected in 5 GHz emission starts to interact with the jet, we see that the jet "threads". In the 0.2-10 keV X-ray image we do not detect the jet, but do detect a relic of the counterjet.


Determining the nature of the faint X-ray source population near the Galactic Centre

REV MEX AST ASTR 29 (2007) 54-56

RM Bandyopadhyay, AJ Gosling, KM Blundell, SS Eikenberry, VJ Mikles, P Podsiadlowski, JCA Miller-Jones, FE Bauer

We present results of a multi-wavelength program to study the faint discrete X-ray source population discovered by Chandra in the Galactic Centre (GC). From IR imaging obtained with the VLT we identify candidate K-band counterparts to 75% of the X-ray sources in our sample. By combining follow-up VLT K-band spectroscopy of a subset of these candidate counterparts with the magnitude limits of our photometric survey, we suggest that only a small percentage of the sources are HMXBs, while the majority are likely to be canonical LMXBs and CVs at the distance of the GC. In addition, we present our discovery of highly structured small-scale (5-15 '') extinction towards the Galactic Centre. This is the finest-scale extinction study of the Galactic Centre to date.


Radio and X-ray study of Cygnus a

Astrophysics and Space Science 311 (2007) 323-327

KC Steenbrugge, KM Blundell

We present a comparative analysis of 5 GHz VLA and 200 ks Chandra ACIS-I image. In the 5 GHz image the familiar jet and much weaker counterjet are seen, which bend as the jet propagates towards the hotspots. Furthermore, where the lobe detected in 5 GHz emission starts to interact with the jet, we see that the jet "threads". In the 0.2-10 keV X-ray image we do not detect the jet, but do detect a relic of the counterjet. © 2007 Springer Science+Business Media B.V.


Galactic centre X-ray sources

AIP CONF PROC 924 (2007) 893-896

AJ Gosling, RM Bandyopadhyay, KM Blundell

We report on a campaign to identify the counterparts to the population of X-ray sources discovered at the centre of our Galaxy by Wang et al. [7] using Chandra. We have used deep, near infrared images obtained on VLT/ISAAC to identify candidate counterparts as astrometric matches to the X-ray positions. Follow up K-S-band spectroscopic observations of the candidate counterparts are used to search for accretions signatures in the spectrum, namely the Brackett-gamma emission line [1]. From our small initial sample, it appears that only a small percentage, similar to 2-3% of the similar to 1000 X-ray sources are high mass X-ray binaries or wind accreting neutron stars, and that the vast majority will be shown to be canonical low mass X-ray binaries and cataclysmic variables.


Extended inverse Compton enussion from distant powerful radio galaxies

ESA SP PUBL 604 (2006) 611-612

MC Erlund, AC Fabian, KM Blundell, A Celotti, C Crawford

Chandra observations of 3C432, 3C191 and B2 0902+34 are presented as part of an ongoing search for inverse-Compton scattering of the cosmic microwave background (CMB) from high redshift radio sources (Schwartz, 2000). The energy density of the CMB increases with redshift, z, as (1 + Z)(4), so the relatively high redshift of these powerful radio galaxies makes them good candidates for detecting extended inverse-Compton scattering along the radio jet axis: we do indeed detect radio-aligned X-ray emission.


Determining the nature of the faint X-ray source population near the galactic centre

International Conference Recent Advances in Natural Language Processing, RANLP (2006)

RM Bandyopadhyay, AJ Gosling, KM Blundell, P Podsiadlowski, SE Eikenberry, VJ Mikles, JCA Miller-Jones, FE Bauer

We present results of a multi-wavelength program to study the faint discrete X-ray source population discovered by Chandra in the Galactic Centre (GC). From IR imaging obtained with the VLT we identify candidate K-band counterparts to 75% of the X-ray sources in our sample. By combining follow-up VLT K-band spectroscopy of a subset of these candidate counterparts with the magnitude limits of our photometric survey, we suggest that only a small percentage of the sources are HMXBs, while the majority are likely to be canonical LMXBs and CVs at the distance of the GC. In addition, we present our discovery of highly structured small-scale (5-15′′) extinction towards the Galactic Centre. This is the finest-scale extinction study of the Galactic Centre to date. Finally, from these VLT observationswe are able to place constraints on the stellar counterpart to the "bursting pulsar" GRO J1744-28.


The emission distribution in SS433

International Conference Recent Advances in Natural Language Processing, RANLP (2006)

L Schmidtobreick, K Blundell

We present the results from a large observing campaign where we obtained 61 medium resolution spectra spread over three months. We thus cover roughly five orbits and about half a precession phase. In this paper we describe the analysis of the so-called "stationary" emission lines, which we use to compute Doppler-maps of the emission distribution in the SS433-system. The radial velocities of the individual line components have been analysed. Periodic variations with the orbital period are confirmed, but also variations on longer timescales are found. These long-term variation might be either either related to the precession phase or to some transient phenomen.


Discovery of the Low-Energy Cutoff in a Powerful Giant Radio Galaxy

Astrophysical Journal Letters 644 (2006) L13-L16

KM Blundell, A.C. Fabian, Carolin S. Crawford, M.C. Erlund


On the binary nature of SS 433

ASTROPHYSICS AND SPACE SCIENCE 304 (2006) 271-274

L Schmidtobreick, K Blundell


Extended inverse compton emission from distant powerful radio galaxies

European Space Agency, (Special Publication) ESA SP 2 (2006) 611-612

MC Erlund, AC Fabian, KM Blundell, A Celotti, C Crawford

Chandra observations of 3C432, 3C 191 and B2 0902+34 are presented as part of an ongoing search for inverse-Compton scattering of the cosmic microwave background (CMB) from high redshift radio sources (Schwartz, 2000). The energy density of the CMB increases with redshift, z, as (1 + z)4, so the relatively high redshift of these powerful radio galaxies makes them good candidates for detecting extended inverse-Compton scattering along the radio jet axis: we do indeed detect radio-aligned X-ray emission.

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