The Comoving Infrared Luminosity Density: Domination of Cold Galaxies across 0 (2009)
Seymour, N., Symeonidis, M., Page, M. J., Huynh, M., Dwelly, T., McHardy, I. M., ...
In this paper we examine the contribution of galaxies with different infrared (IR) spectral energy distributions (SEDs) to the comoving infrared luminosity density, a proxy for the comoving star...
A correlation between the spectral and timing properties of AGN (2009)
Papadakis, I. E., Sobolewska, M., Arevalo, P., Markowitz, A., McHardy, I. M., Miller, L., ...
We present the results from a combined study of the average X-ray spectral and timing properties of 14 nearby AGN. For 11 of the sources in the sample, we used all the available data from the RXTE...
D'Ammando, F., Pucella, G., Raiteri, C. M., Villata, M., Vittorini, V., Vercellone, S., ...
We report the detection by the AGILE satellite of a rapid gamma-ray flare from the powerful gamma-ray quasar PKS 1510-089, during a pointing centered on the Galactic Center region from 1 March to 30...
X-Ray Variability of AGN and Relationship to Galactic Black Hole Binary Systems (2009)
Over the last 12 years, AGN monitoring by RXTE, has revolutionised our understanding of the X-ray variability of AGN, of the relationship between AGN and Galactic black hole X-ray binaries (BHBs) and...
Investigating the far-IR/radio correlation of star-forming Galaxies to z= 3 (2009)
Seymour, N., Huynh, M., Dwelly, T., Symeonidis, M., Hopkins, A., McHardy, I. M., ...
In order to examine the far-infrared (far-IR)/radio correlation at high redshift, we have studied the Spitzer 70 μm /far-IR properties of sub-mJy radio sources from the 13^H XMM–Newton/Chandra...
X-ray narrow line region variability as a geometry probe: The case of NGC 5548 (2009)
Detmers, R. G., Kaastra, J. S., McHardy, I. M.
We study the long time scale variability of the gas responsible for the X-ray narrow emission lines in the Seyfert 1 galaxy NGC 5548, in order to constrain the location and geometry of the emitting...
Investigating the Far-IR/Radio Correlation of Star Forming Galaxies to z=3 (2009)
Seymour, N., Huynh, M., Dwelly, T., Symeonidis, M., Hopkins, A., McHardy, I. M., ...
In order to examine the far-IR/radio correlation at high redshift we have studied the Spitzer 70um/far-infrared (far-IR) properties of sub-mJy radio sources from the 13^H XMM-Newton/Chandra Deep...
Correlation and time delays of the X-ray and optical emission of the Seyfert Galaxy NGC3783 (2009)
Arevalo, P., Uttley, P., Lira, P., Breedt, E., McHardy, I. M., Churazov, E.
We present simultaneous X-ray and optical B and V band light curves of the Seyfert Galaxy NGC3783 spanning 2 years. The flux in all bands is highly variable and the fluctuations are significantly...
Extragalactic Hard X-ray Surveys: From INTEGRAL to Simbol-X (2009)
Paltani, S., Dwelly, T., Walter, R., Marscher, A. P., Jorstad, S. G., McHardy, I. M., ...
We present some results of the deepest extragalactic survey performed by the INTEGRAL satellite. The fraction of very absorbed AGN is quite large. The sharp decrease in the absorption fraction with...
Correlation and time delays of the X-ray and optical emission of the Seyfert galaxy NGC 3783 (2009)
Arévalo, P., Uttley, P., Lira, P., Breedt, E., McHardy, I. M., Churazov, E.
Long term optical and X-ray variability of the Seyfert galaxy Markarian 79 (2008)
Breedt, E., Arévalo, P., McHardy, I. M., Uttley, P., Sergeev, S. G., Minezaki, T., ...
We present the results of concurrent X-ray and optical monitoring of the Seyfert 1 galaxy Mrk 79 over a period of more than five years. We find that on short to medium time-scales (days to a few tens...
AGN population in the deepest hard X-ray extragalactic survey (2008)
Paltani, S., Courvoisier, T. J. -L., Dwelly, T., McHardy, I. M., Walter, R.
We present the results of the analysis of the AGN population in the deepest extragalactic hard X-ray survey. The survey is based on INTEGRAL observation of the 3C 273/Coma cluster region, and covers...
Properties of X-ray-selected broad absorption-line quasars (2008)
Blustin, A. J., Dwelly, T., Page, M. J., McHardy, I. M., Seymour, N., Kennea, J. A., ...
Broad absorption-line quasars (commonly termed BALQSOs) contain the most dramatic examples of active galactic nucleus (AGN) driven winds. The high absorbing columns in these winds, ~10^24 cm^-2,...
Properties of X-ray selected Broad Absorption Line Quasars (2008)
Blustin, A. J., Dwelly, T., Page, M. J., McHardy, I. M., Seymour, N., Kennea, J. A., ...
Broad absorption line quasars (commonly termed BALQSOs) contain the most dramatic examples of AGN-driven winds. The high absorbing columns in these winds, ~10^24 cm^-2, ensure that BALQSOs are...
Correlated Multi-Waveband Variability in the Blazar 3C~279 from 1996 to 2007 (2008)
Chatterjee, R., Jorstad, S. G., Marscher, A. P., Oh, H., McHardy, I. M., Aller, M. F., ...
We present the results of extensive multi-waveband monitoring of the blazar 3C~279 between 1996 and 2007 at X-ray energies (2-10 keV), optical R band, and 14.5 GHz, as well as imaging with the Very...
Correlated X-ray/Optical Variability in the Quasar MR2251-178 (2008)
Arévalo, P., Uttley, P., Kaspi, S., Breedt, E., Lira, P., McHardy, I. M.
Emission from Active Galactic Nuclei is known to vary strongly over time over a wide energy band, but the origin of the variability and especially of the inter-band correlations is still not well...
The multiwavelength variability of 3C 273 (2008)
Soldi, S., Türler, M., Paltani, S., Aller, H. D., Aller, M. F., Burki, G., ...
We present an update of 3C 273's database hosted by the ISDC, completed with data from radio to gamma-ray observations over the last 10 years. We use this large data set to study the multiwavelength...
A deep INTEGRAL hard X-ray survey of the 3C 273/Coma region (2008)
Paltani, S., Walter, R., McHardy, I. M., Dwelly, T., Steiner, C., Courvoisier, T. J. -L.
(abridged) We present an analysis of the deepest hard X-ray survey to date of about 2500 deg^2 performed by the IBIS instrument on board INTEGRAL in the 20-60 keV band, with a total exposure time of...
The warm absorber in NGC 5548: The lean years (2008)
Detmers, R. G., Kaastra, J. S., Costantini, E., McHardy, I. M., Verbunt, F.
We study the variability of the warm absorber and the gas responsible for the emission lines in the Seyfert 1 galaxy NGC 5548, in order to constrain the location and physical properties of these...
X-ray Variability of the Seyfert 1 Markarian 335: Power Spectrum and Time Lags (2008)
Arevalo, P., McHardy, I. M., Summons, D. P.
To investigate further the comparison between AGN and black hole X-ray binaries, we have studied the main X-ray variability properties of the Seyfert 1 Galaxy Markarian 335. We put particular...
Fourier-resolved energy spectra of the Narrow Line Seyfert 1 Mkn 766 (2008)
Arevalo, P., McHardy, I. M., Markowitz, A., Papadakis, I. E., Turner, T. J., Miller, L., ...
We compute Fourier-resolved X-ray spectra of the Seyfert 1 Markarian 766 to study the shape of the variable components contributing to the 0.3-10 keV energy spectrum and their time-scale dependence....
The warm absorber in NGC 5548 : the lean years (2008)
Detmers, R.G., Kaastra, J.S., Costantini, E., McHardy, I.M., Verbunt, F.W.M.
We study the variability of the warm absorber and the gas responsible for the emission lines in the Seyfert 1 galaxy NGC 5548 to constrain the location and physical properties of these components....
McHardy, I. M., Arevalo, P., Uttley, P., Papadakis, I. E., Summons, D. P., Brinkmann, W., ...
We present a power spectral analysis of a 100 ksec XMM-Newton observation of the narrow line Seyfert 1 galaxy Ark~564. When combined with earlier RXTE and ASCA observations, these data produce a...
A 610 MHz Survey of the 1H XMM-Newton/Chandra Survey Field (2007)
Moss, D., Seymour, N., McHardy, I. M., Dwelly, T., Page, M. J., Loaring, N. S.
We present the results of a deep 610 MHz survey of the 1^H XMM/Chandra survey area with the GMRT. The resulting maps have a resolution of ~7 arcsec and an rms noise limit of 60 microJy. To a 5 sigma...
Timing evidence in determining the accretion state of the Seyfert galaxy NGC 3783 (2007)
Summons, D. P., Arevalo, P., McHardy, I. M., Uttley, P., Bhaskar, A.
Previous observations with the Rossi X-ray Timing Explorer (RXTE) have suggested that the power spectral density (PSD) of NGC 3783 flattens to a slope near zero at low frequencies, in a similar...
2003--2005 INTEGRAL and XMM-Newton observations of 3C 273 (2007)
Chernyakova, M., Neronov, A., Courvoisier, T. J. -L., Turler, M., Soldi, S., Beckmann, V., ...
The aim of this paper is to study the evolution of the broadband spectrum of one of the brightest and nearest quasars 3C 273. We analyze the data obtained during quasi-simultaneous INTEGRAL and XMM...
Active Galactic Nuclei as scaled-up Galactic black holes (2006)
McHardy, I M, Koerding, E, Knigge, C, Uttley, P, Fender, R P
A long-standing question is whether active galactic nuclei (AGN) vary like Galactic black hole systems when appropriately scaled up by mass (refs 1-3). If so, we can then determine how AGN should...
Spectral-timing evidence for a Very High State in the Narrow Line Seyfert 1 Ark 564 (2006)
Arevalo, P., Papadakis, I. E., Uttley, P., McHardy, I. M., Brinkmann, W.
We use a 100 ks long XMM-Newton observation of the Narrow-Line Seyfert 1 galaxy Ark 564 and combine it with the month-long monitoring of the same source produced by ASCA, to calculate the phase lags...
A historic jet-emission minimum reveals hidden spectral features in 3C 273 (2006)
Turler, M., Chernyakova, M., Courvoisier, T. J. -L., Foellmi, C., Aller, M. F., Aller, H. D., ...
Aims. The aim of this work is to identify and study spectral features in the quasar 3C 273 usually blended by its strong jet emission. Method. A historic minimum in the sub-millimetre emission of 3C...
Spectral-timing evidence for a very high state in the narrow-line Seyfert 1 Ark 564 (2006)
Arévalo, P., Papadakis, I. E., Uttley, P., McHardy, I. M., Brinkmann, W.
Active galactic nuclei as scaled-up Galactic black holes (2006)
McHardy, I.M., Koerding, E., Knigge, C., Uttley, P., Fender, R.P.
A long-standing question is whether active galactic nuclei (AGN) vary like Galactic black hole systems when appropriately scaled up by mass. If so, we can then determine how AGN should behave on...
Spectral-timing evidence for a very high state in the narrow-line Seyfert 1 Ark 564 (2006)
Arévalo, P., Papadakis, I.E., Uttley, P., McHardy, I.M., Brinkmann, W.
We use a 100ks long XMM-Newton observation of the narrow-line Seyfert 1 galaxy Ark 564 and combine it with the month-long monitoring of the same source produced by ASCA, to calculate the phase lags...
Spectral-timing evidence for a very high state in the narrow-line Seyfert 1 Ark 564 (2006)
Ar¿lo, P., Papadakis, I.E., Uttley, P., McHardy, I.M., Brinkmann, W.
We use a 100ks long XMM-Newton observation of the narrow-line Seyfert 1 galaxy Ark 564 and combine it with the month-long monitoring of the same source produced by ASCA, to calculate the phase lags...
X-ray variability of NGC 3227 and NGC 5506 and the nature of AGN `states' (2005)
We use X-ray monitoring data obtained over a broad range of time-scales to measure the broadband power spectral density functions (PSDs) of two Seyfert galaxies, the broad line Seyfert 1 NGC 3227 and...
Submillimetre photometry of X-ray absorbed QSOs: their formation and evolutionary status (2005)
Stevens, J. A., Page, M. J., Ivison, R. J., Carrera, F. J., Mittaz, J. P. D., Smail, Ian, ...
We present an analysis of the submillimetre/X-ray properties of 19 X-ray absorbed, Compton-thin quasi-stellar objects (QSOs) selected to have luminosities and redshifts which represent the peak of...
MCG-6-30-15: Long Timescale X-Ray Variability, Black Hole Mass and AGN High States (2005)
McHardy, I M, Gunn, K F, Uttley, P, Goad, M R
We present a detailed study of the long-timescale X-ray variability of the Narrow Line Seyfert 1 (NLS1) Galaxy MCG-6-30-15, based on 8 years of frequent observations with the Rossi X-ray Timing...
Non-linear X-ray variability in X-ray binaries and active galaxies (2005)
Uttley, P., McHardy, I. M., Vaughan, S.
We show that the rms-flux relation recently discovered in the X-ray light curves of Active Galactic Nuclei (AGN) and X-ray binaries (XRBs) implies that the light curves have a formally non-linear,...
McHardy, I.M., Gunn, K.F., Uttley, P., Goad, M.R.
We present a detailed study of the long time-scale X-ray variability of the Seyfert 1 Galaxy MCG–6-30-15, based on eight years of frequent monitoring observations with the Rossi X-ray Timing...
Non-linear x-ray variability in x-ray binaries and active galaxies (2005)
Uttley, P., McHardy, I.M., Vaughan, S.A.
We show that the rms–flux relation recently discovered in the x-ray light curves of active galactic nuclei (AGN) and x-ray binaries (XRBs) implies that the light curves have a formally non-linear,...
Relativistic O VIII emission and ionized outflow in NGC 4051 measured with XMM-Newton (2004)
Ogle, P.M., Mason, K.O., Page, M.J., Salvi, N.J., Cordova, F.A., McHardy, I.M., ...
We present XMM-Newton Reflection Grating Spectrometer observations of the soft X-ray spectrum of NGC 4051 and explore their implications for the inner accretion disk and ionized outflow in the active...
Radio Observations of the 13hr XMM/ROSAT Deep X-ray Survey Area (2004)
Seymour, N., McHardy, I. M., Gunn, K. F.
In order to determine the relationship between the faint X-ray and faint radio source populations, and hence to help understand the X-ray and radio emission mechanisms in those faint source...
Consistency between the radio and MIR faint source counts using the radio-MIR correlation (2004)
Seymour, N., McHardy, I. M., Gunn, K.
We show from the recent extrapolation of the radio-FIR correlation to the MIR that the 20 cm and 15 um differential source counts are likely to come from the same parent population.
Relativistic O VIII Emission and Ionized Outflow in NGC 4051 (2004)
Ogle, P. M., Mason, K. O., Page, M. J., Salvi, N. J., Cordova, F. A., McHardy, I. M., ...
We present XMM-Newton RGS observations of the soft X-ray spectrum of NGC 4051, and explore their implications for the inner accretion disk and ionized outflow in the active galactic nucleus. We fit...
Combined long and short time-scale X-ray variability of NGC 4051 with RXTE and XMM-Newton (2004)
McHardy, I.M., Papadakis, I.E., Uttley, P., Page, M.J., Mason, K.O.
We present a comprehensive examination of the X-ray variability of the narrow-line Seyfert 1 (NLS1) galaxy NGC 4051, one of the most variable active galactic nuclei (AGN) in the sky. We combine over...
Combined Long and Short Timescale X-ray Variability of NGC4051 with RXTE and XMM-Newton (2003)
McHardy, I. M., Papadakis, I. E., Uttley, P., Page, M. J., Mason, K. O.
We present over 6.5 years of frequent X-ray observations of the NLS1 galaxy NGC4051 by RXTE together with a >100ks observation by XMM-Newton and so derive a 2-10 keV PSD covering an unprecedent...
Complex X-ray spectral behaviour of NGC 4051 in the low flux state (2003)
Uttley, P., Taylor, R. D., McHardy, I. M., Page, M. J., Mason, K. O., Lamer, G., ...
The Narrow Line Seyfert 1 galaxy NGC 4051 was observed in one of its prolonged low-lux states by XMM-Newton in November 2002. Here we present the results of an analysis of EPIC-pn data obtained...
Catching NGC4051 in the low state with XMM-Newton (2003)
Uttley, P., Taylor, R. D., McHardy, I. M., Page, M. J., Mason, K. O., Lamer, G., ...
The Narrow Line Seyfert 1 galaxy NGC4051 shows unusual low flux states, lasting several months, when the 2-10 keV X-ray spectrum becomes unusually hard (photon index
Combined Long and Short Timescale X-ray Variability of NGC4051 with RXTE and XMM-Newton (2003)
McHardy, I. M., Papadakis, I. E., Uttley, P., Mason, K. O., Page, M. J.
We present a comprehensive examination of the X-ray variability of the narrow line Seyfert 1 (NLS1) galaxy NGC4051. We combine over 6.5 years of frequent monitoring observations by RXTE with a >100ks...
An absorption event in the X-ray lightcurve of NGC 3227 (2003)
Lamer, G., Uttley, P., McHardy, I. M.
We have monitored the Seyfert galaxy NGC 3227 with the Rossi X-ray Timing Explorer (RXTE) since January 1999. During late 2000 and early 2001 we observed an unusual hardening of the 2-10 keV X-ray...
Complex Optical-X-ray Correlations in the Narrow-Line Seyfert 1 Galaxy NGC 4051 (2003)
Shemmer, O., Uttley, P., Netzer, H., McHardy, I. M.
This paper presents the results of a dense and intensive X-ray and optical monitoring of the narrow-line Seyfert 1 galaxy NGC 4051 carried out in 2000. Results of the optical analysis are consistent...
A medium deep Chandra and Subaru survey of the 13hr XMM/ROSAT deep survey area (2003)
McHardy, I. M., Gunn, K. F., Newsam, A. M., Mason, K. O., Page, M. J., Takata, T., ...
We present the results of a Chandra ACIS-I survey of a high latitude region at 13h +38 which was earlier observed with ROSAT (McHardy et al. 1998) and which has recently been observed by XMM-Newton...
Mason, K.O., Branduardi-Raymont, G., Ogle, P.M., Page, M.J., Puchnarewicz, E.M., Behar, E., ...
Competing models for broad spectral features in the soft X-ray spectrum of the Seyfert I galaxy Mrk 766 are tested against data from a 130 ks XMM-Newton observation. A model including...
The nature of X-ray spectral variability in Seyfert galaxies (2003)
Taylor, R.D., Uttley, P., McHardy, I.M.
We use a model-independent technique to investigate the nature of the 2–15 keV X-ray spectral variability in four Seyfert galaxies and distinguish between spectral pivoting and the two-component...
X-ray and optical properties of X-ray sources in the 13hr XMM-Newton/Chandra deep survey (2002)
Page, M. J., McHardy, I. M., Gunn, K. F., Loaring, N. S., Mason, K. O., Sasseen, T., ...
The 13hr XMM-Newton/Chandra deep survey is the first of two extremely deep XMM-Newton fields observed by the XMM-OM consortium. A 120 ks Chandra mosaic, covering 0.2 square degrees, provides...
Radio observations of the XMM-Newton/Chandra 13hr deep survey field (2002)
Gunn, K. F., McHardy, I. M., Seymour, N., Newsam, A. M., Page, M. J., Mason, K. O., ...
Our VLA observations of the XMM-Newton/Chandra 13hr deep survey field (see Page et al., this proceedings) result in one of the two deepest 1.4GHz radio maps ever made. Within the 15' radius field...
XMM-Newton observations of a possible light echo in the Seyfert 1 nucleus of NGC 4051 (2002)
Mason, K.O., McHardy, I.M., Page, M.J., Uttley, P., Córdova, F.A., Maraschi, L., ...
We discuss a 1.5 day long observation of the bright variable Seyfert 1 galaxy NGC 4051 that was obtained with the X-ray and ultraviolet telescopes on XMM-Newton and extended in the X-ray band using...
Mason, K. O., Branduardi-Raymont, G., Ogle, P. M., Page, M. J., Puchnarewicz, E. M., Behar, E., ...
Competing models for broad spectral features in the soft X-ray spectrum of the Seyfert I galaxy Mrk766 are tested against data from a 130 ks XMM-Newton observation. A model including relativistically...
X-ray spectral variability of the Seyfert galaxy NGC 4051 (2002)
Lamer, G., McHardy, I. M., Uttley, P., Jahoda, K.
We report on the X-ray spectral variability of the Seyfert 1 galaxy NGC 4051 observed with the Rossi X-ray Timing Explorer (RXTE) during a 1000 day period between May 1996 and March 1999. The spectra...
Soft X-ray properties of a high redshift sample of QSOs observed with ROSAT (2002)
Dewangan, G. C., Singh, K. P., Gunn, K. F., Newsam, A. M., McHardy, I. M., Jones, L. R.
In order to study systematically the soft X-ray emission of Active Galactic Nuclei (AGNs) at medium to high redshifts, we have analyzed ROSAT PSPC and HRI data of QSOs at 0.26
Measuring the broad-band power spectra of active galactic nuclei with RXTE (2002)
Uttley, P., McHardy, I.M., Papadakis, I.E.
We develop a Monte Carlo technique to test models for the true power spectra of intermittently sampled light curves against the noisy, observed power spectra, and produce a reliable estimate of the...
Long Term Spectral Variability of Seyfert Galaxies from RXTE Color-Flux Diagrams (2002)
Papadakis, I. E., Petrucci, P. O., Maraschi, L., McHardy, I. M., Uttley, P., Haardt, F.
We present results from RXTE data obtained during a systematic monitoring program of four Seyfert galaxies (NGC5548, NGC5506, MCG-6-30-15 and NGC4051). We studied the variability of three hardness...
Measuring the broadband power spectra of active galactic nuclei with RXTE (2002)
Uttley, P., McHardy, I. M., Papadakis, I. E.
We have developed a Monte Carlo technique to test models for the true power spectra of intermittently sampled lightcurves against the noisy, observed power spectra, and produce a reliable estimate of...
Starburst activity in a ROSAT narrow emission-line galaxy (2001)
Gunn, Katherine F., McHardy, I.M., Almaini, O., Shanks, T., Sumner, T.J., Muxlow, T.W.B., ...
We present multiwaveband photometric and optical spectropolarimetric observations of the R=15.9 narrow emission-line galaxy R117_A which lies on the edge of the error circle of the ROSAT X-ray source...
Hartman, R. C., Villata, M., Balonek, T. J., Bertsch, D. L., Bock, H., Boettcher, M., ...
Light curves of 3C 279 are presented in optical (R-band), X-rays (RXTE/PCA), and gamma rays (CGRO/EGRET) for 1999 Jan-Feb and 2000 Jan-Mar. During both of those epochs the gamma-ray levels were high,...
Optical and X-ray characteristics of a newly discovered narrow-line QSO : RX J1334.2+3759 (2001)
Dewangan, G. C., Singh, K. P., Jones, L. R., McHardy, I. M., Mason, K. O., Newsam, A. M.
We report the discovery of a narrow-line QSO (NLQSO) RX J1334.2+3759 with a steep soft X-ray spectrum. Soft X-ray emission from the NLQSO is highly variable. Changes in the intensity by a factor of...
Standard shot-noise models, which seek to explain the broadband noise variability that characterizes the X-ray light curves of X-ray binaries and active galaxies, predict that the power spectrum of...
Discovery of a new NLQSO: RX J1334.2+3759 (2001)
Dewangan, G. C, Singh, K. P, Jones, L. R, McHardy, I. M, Newsam, A. M, Mason, K. O
A new narrow-line QSO, RX J1334.2+3759, has been identified at a redshift of 0.3858. The QSO has intrinsic soft X-ray luminosity ~ 2.8 x 1044 erg s-1. Soft X-ray emission from the QSO is highly...
Starburst activity in a ROSAT Narrow Emission-Line Galaxy (2000)
Gunn, K. F., McHardy, I. M., Almaini, O., Shanks, T., Sumner, T. J., Muxlow, T. W. B., ...
We present multiwaveband photometric and optical spectropolarimetric observations of the R=15.9 narrow emission line galaxy R117_A which lies on the edge of the error circle of the ROSAT X-ray source...
RXTE observations of the Seyfert galaxy NGC 5506: evidence for reflection from disk and torus (2000)
Lamer, G., Uttley, P., McHardy, I. M.
We report on observations of the narrow line Seyfert galaxy NGC 5506 with the Rossi X-ray TIming Explorer. The observations cover a time interval of ~1000 days during which the source showed strong...
X-Ray and Optical Variability in NGC 4051 and the Nature of Narrow-Line Seyfert 1 Galaxies (2000)
Peterson, B. M., McHardy, I. M., Wilkes, B. J., Berlind, P., Bertram, R., Calkins, M., ...
We report on the results of a three-year program of coordinated X-ray and optical monitoring of the narrow-line Seyfert 1 galaxy NGC 4051. The rapid continuum variations observed in the X-ray spectra...
Variability of NGC 4051 and the Nature of Narrow-Line Seyfert 1 Galaxies (2000)
Peterson, B. M., McHardy, I. M., Wilkes, B. J.
We report on a three-year program of coordinated X-ray and optical monitoring of the Narrow-Line Seyfert 1 galaxy NGC 4051. The rapid continuum variations observed in the X-ray spectra are not...
VLBI observations of 3C273 at 22 GHz and 43 GHz. II: test of Synchrotron Self-Compton process (1999)
Mantovani, F., Junor, W., McHardy, I. M., Valerio, C.
The VLBI observations at 22 GHz and 43 GHz of the quasar 3C273 obtained during a multi-frequency campaign in late 1992 in the radio, millimetre and X-ray bands allow us to derive the components'...
Simultaneous EUV and X-ray variability of NGC 4051 (1999)
Uttley, P., McHardy, I. M., Papadakis, I. E., Cagnoni, I., Fruscione, A.
We present a flux variability study of simultaneous RXTE and EUVE observations of the highly variable Seyfert galaxy NGC4051. We find a strong correlation between variability in the EUV and medium...
The unusual host galaxy of the BL Lac object PKS 1413+135 (1999)
Lamer, G., Newsam, A. M., McHardy, I. M.
The BL Lacertae object PKS 1413+135 is associated with a disk dominated galaxy which heavily absorbs the BL Lac nucleus at optical and X-ray wavelengths. It has been argued whether this galaxy is...
Cross-correlation of the unresolved X-ray background with faint galaxies (1999)
Newsam, A. M., McHardy, I. M., Jones, L., Mason, K.
At the faint end of the deepest X-ray surveys, a population of X-ray luminous galaxies is seen. In this paper, we present the results of a cross-correlation between the residual, unresolved X-ray...
The swansong in context: long-timescale X-ray variability of NGC 4051 (1999)
Uttley, P., McHardy, I. M., Papadakis, I. E., Guainazzi, M., Fruscione, A.
On 9-11 May 1998, the highly-variable, low luminosity Seyfert 1 galaxy NGC4051 was observed in an unusual low flux state by BeppoSAX (Guainazzi et al. 1998) RXTE and EUVE. We present fits of the 4-15...
30 years of multi-wavelength observations of 3C 273. (1999)
Turler, M., Paltani, S., Courvoisier, T. J-L., Aller, M., Aller, H., Blecha, A., ...
Constraints on a soft X-ray excess in the quasar 3C 279 (1998)
We present the results of a three-week daily monitoring campaign on the quasar 3C 279 by the X-ray satellites RXTE and ROSAT. A cross correlation provides no evidence for any time lag between the...
EUVE-RXTE simultaneous observations of NGC 4051: variability and spectrum (1998)
Cagnoni, I., Fruscione, A., McHardy, I. M., Papadakis, I. E.
We present timing and spectral analysis of the data collected by the Extreme Ultraviolet Explorer Satellite (EUVE) for the Seyfert 1 galaxy NGC 4051 during 1996. NGC 4051 was observed twice in May...
30 years of multi-wavelength observations of 3C 273 (1998)
Turler, M., Paltani, S., Courvoisier, T. J. -L., Aller, M. F., Aller, H. D., Blecha, A, ...
We present a wide multi-wavelength database of most observations of the quasar 3C 273 obtained during the last 30 years. This database is the most complete set of observations available for an active...
Ultraviolet Isotropic Emission from the Blazar 3C 279 (1998)
Pian, E., Koratkar, A., Maraschi, L., Urry, C. M., Madejski, G., McHardy, I. M., ...
Archival IUE SWP and HST FOS spectra show the presence of a relatively strong, broad Lyman alpha emission line superposed onto the UV spectral continuum of the blazar 3C 279. As opposed to a factor...
The discovery of very red counterparts to faint X-ray sources (1997)
Newsam, A. M., McHardy, I. M., Jones, L. R., Mason, K. O.
We present deep K-band imaging at the positions of four very faint X-ray sources found in the UK ROSAT Deep Survey to have no optical counterpart brighter than R~23. Likely identifications are found...
McHardy, I. M., Jones, L. R., Merrifield, M. R., Mason, K. O., Abraham, R. G., Newsam, A. M., ...
We present the results of the deepest optically identified X-ray survey yet made. The X-ray survey was made with the ROSAT PSPC and reaches a flux limit of 1.6x10^-15 erg cm^-2 s^-1 (0.5--2.0 keV)....
X-ray QSO evolution from a very deep ROSAT survey (1996)
Jones, L. R., McHardy, I. M., Merrifield, M. R., Mason, K. O., Smith, P. J., Abraham, R. G., ...
In the deepest optically identified X-ray survey yet performed, we have identified 32 X-ray selected QSOs to a flux limit of 2x10^{-15} erg cm^{-2} s^{-1} (0.5-2 keV). The survey, performed with the...
ROSAT PSPC spectra of X-ray selected Narrow Emission Line Galaxies (1996)
Romero-Colmenero, E., Branduardi-Raymont, G., Carrera, F. J., Jones, L. R., Mason, K. O., McHardy, I. M., ...
We analyse the ROSAT PSPC spectrum of 19 X-ray selected Narrow Emission Line Galaxies (NELGs) discovered during the optical identification of sources in the ROSAT UK Deep Survey. Their properties are...