I. M. McHardy
YOU?
Author Swipe
View article: VLBI Imaging of Parsec-scale Radio Structures in Nearby Low-luminosity Active Galactic Nuclei
VLBI Imaging of Parsec-scale Radio Structures in Nearby Low-luminosity Active Galactic Nuclei Open
We report the results of high-resolution 5 GHz Very Long Baseline Array and European VLBI Network observations of 36 nearby galaxies, an extension of the Legacy e-MERLIN Multi-band Imaging of Nearby Galaxies survey. Our sample includes 21 …
View article: Testing disc reprocessing models for AGN optical variability by comparison of X-ray and optical power spectra of NGC 4395
Testing disc reprocessing models for AGN optical variability by comparison of X-ray and optical power spectra of NGC 4395 Open
It is generally thought that AGN optical variability is produced, at least in part, by reprocessing of central X-rays by a surrounding accretion disc, resulting in wavelength-dependent lags between bands. Any good model of AGN optical vari…
View article: The ultraviolet luminosity function of star-forming galaxies between redshifts of 0.4 and 0.6
The ultraviolet luminosity function of star-forming galaxies between redshifts of 0.4 and 0.6 Open
We combine ultraviolet imaging of the $13^{H}$ survey field, taken with the XMM–Newton Optical Monitor telescope (XMM–OM) and the Neil Gehrels Swift Observatory Ultraviolet and Optical Telescope (UVOT) in the UVM2 band, to measure rest-fra…
View article: Windy or Not: Radio Parsec-scale Evidence for a Broad-line Region Wind in Radio-quiet Quasars
Windy or Not: Radio Parsec-scale Evidence for a Broad-line Region Wind in Radio-quiet Quasars Open
Does a broad-line region (BLR) wind in radio-quiet (RQ) active galactic nuclei (AGN) extend to parsec scales and produce radio emission? We explore the correlations between a parsec-scale radio wind and the BLR wind in a sample of 19 RQ Pa…
View article: Intensive Broadband Reverberation Mapping of Fairall 9 with 1.8 yr of Daily Swift Monitoring
Intensive Broadband Reverberation Mapping of Fairall 9 with 1.8 yr of Daily Swift Monitoring Open
We present 1.8 yr of near-daily Swift monitoring of the bright, strongly variable Type 1 active galactic nucleus (AGN) Fairall 9. Totaling 575 successful visits, this is the largest such campaign reported to date. Variations within the UV/…
View article: LeMMINGs. Multiwavelength constraints on the co-existence of nuclear star clusters and AGN in nucleated galaxies
LeMMINGs. Multiwavelength constraints on the co-existence of nuclear star clusters and AGN in nucleated galaxies Open
The relation between nuclear star clusters (NSCs) and the growth of the central supermassive black holes (SMBHs), as well as their connection to the properties of the host galaxies, is crucial for understanding the evolution of galaxies. R…
View article: <i>AstroSat</i> and <i>NICER</i> timing view of the Z−type neutron star X-ray binary GX 340 + 0
<i>AstroSat</i> and <i>NICER</i> timing view of the Z−type neutron star X-ray binary GX 340 + 0 Open
The timing properties of the Z-type low-mass X-ray binaries provide insights into the emission components involved in producing the unique Z-shaped track in the hardness–intensity diagrams of these sources. In this work, we investigate the…
View article: AGN STORM 2. VI. Mapping Temperature Fluctuations in the Accretion Disk of Mrk 817
AGN STORM 2. VI. Mapping Temperature Fluctuations in the Accretion Disk of Mrk 817 Open
We fit the UV/optical lightcurves of the Seyfert 1 galaxy Mrk 817 to produce maps of the accretion disk temperature fluctuations δ T resolved in time and radius. The δ T maps are dominated by coherent radial structures that move slowly ( v…
View article: AstroSat and NICER timing view of the Z-type Neutron Star X-ray binary GX 340+0
AstroSat and NICER timing view of the Z-type Neutron Star X-ray binary GX 340+0 Open
The timing properties of the Z-type low-mass X-ray binaries provide insights into the emission components involved in producing the unique Z-shaped track in the hardness-intensity diagrams of these sources. In this work, we investigate the…
View article: AGN STORM 2. VI. Mapping Temperature Fluctuations in the Accretion Disk of Mrk 817
AGN STORM 2. VI. Mapping Temperature Fluctuations in the Accretion Disk of Mrk 817 Open
We fit the UV/optical lightcurves of the Seyfert 1 galaxy Mrk 817 to produce maps of the accretion disk temperature fluctuations $δT$ resolved in time and radius. The $δT$ maps are dominated by coherent radial structures that move slowly (…
View article: AGN STORM 2. II. Ultraviolet Observations of Mrk 817 with the Cosmic Origins Spectrograph on the Hubble Space Telescope*
AGN STORM 2. II. Ultraviolet Observations of Mrk 817 with the Cosmic Origins Spectrograph on the Hubble Space Telescope* Open
We present reverberation mapping measurements for the prominent ultraviolet broad emission lines of the active galactic nucleus Mrk 817 using 165 spectra obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope. Our ultr…
View article: LeMMINGs. VI. Connecting nuclear activity to bulge properties of active and inactive galaxies: radio scaling relations and galaxy environment
LeMMINGs. VI. Connecting nuclear activity to bulge properties of active and inactive galaxies: radio scaling relations and galaxy environment Open
Multiwavelength studies indicate that nuclear activity and bulge properties are closely related, but the details remain unclear. To study this further, we combine Hubble Space Telescope bulge structural and photometric properties with 1.5 …
View article: UV–Optical Disk Reverberation Lags despite a Faint X-Ray Corona in the Active Galactic Nucleus Mrk 335
UV–Optical Disk Reverberation Lags despite a Faint X-Ray Corona in the Active Galactic Nucleus Mrk 335 Open
We present the first results from a 100-day Swift, NICER, and ground-based X-ray–UV–optical reverberation mapping campaign of the Narrow-line Seyfert 1 Mrk 335, when it was in an unprecedented low X-ray flux state. Despite dramatic suppres…
View article: Contrasting X-ray/UV time-lags in Seyfert 1 galaxies NGC 4593 and NGC 7469 using<i>AstroSat</i>observations
Contrasting X-ray/UV time-lags in Seyfert 1 galaxies NGC 4593 and NGC 7469 using<i>AstroSat</i>observations Open
We study accretion disc–corona connection in Seyfert 1 galaxies using simultaneous UV/X-ray observations of NGC 4593 (2016 July 14–18) and NGC 7469 (2017 October 15–19) performed with AstroSat. We use the X-ray (0.5–7.0 keV) data acquired …
View article: The LeMMINGs survey: probing sub-kpc radio structures of nearby galaxies with e-MERLIN
The LeMMINGs survey: probing sub-kpc radio structures of nearby galaxies with e-MERLIN Open
The Legacy e-MERLIN Multi-band Imaging of Nearby Galaxies survey (LeMMINGs) is a statistically-complete census of nuclear accretion and star formation processes in the local Universe. The LeMMINGs observations at 1.5 and 5 GHz yield angula…
View article: The e-MERGE e-MERLIN/VLA/VLBI Wide-field Deep High Angular Resolution Survey of GOODS-N
The e-MERGE e-MERLIN/VLA/VLBI Wide-field Deep High Angular Resolution Survey of GOODS-N Open
The initial description paper for the e-MERGE deep (∼1µJy/bm), (30x30 arcmin field) high-resolution radio survey of GOODS-N is now published. Images are now available to the e-MERGE consortium from Data Release-1 (DR-1) covering tie inner …
View article: AGN STORM 2: II. Ultraviolet Observations of Mrk817 with the Cosmic Origins Spectrograph on the Hubble Space Telescope
AGN STORM 2: II. Ultraviolet Observations of Mrk817 with the Cosmic Origins Spectrograph on the Hubble Space Telescope Open
We present reverberation mapping measurements for the prominent ultraviolet broad emission lines of the active galactic nucleus Mrk817 using 165 spectra obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope. Our ultra…
View article: UV/Optical disk reverberation lags despite a faint X-ray corona in the AGN Mrk 335
UV/Optical disk reverberation lags despite a faint X-ray corona in the AGN Mrk 335 Open
We present the first results from a 100-day Swift, NICER and ground-based X-ray/UV/optical reverberation mapping campaign of the Narrow-Line Seyfert 1 Mrk 335, when it was in an unprecedented low X-ray flux state. Despite dramatic suppress…
View article: The radio detection and accretion properties of the peculiar nuclear transient AT 2019avd
The radio detection and accretion properties of the peculiar nuclear transient AT 2019avd Open
AT 2019avd is a nuclear transient detected from infrared to soft X-rays, though its nature is yet unclear. The source has shown two consecutive flaring episodes in the optical and the infrared bands, and its second flare was covered by X-r…
View article: The radio detection and accretion properties of the peculiar nuclear transient AT 2019avd
The radio detection and accretion properties of the peculiar nuclear transient AT 2019avd Open
AT 2019avd is a nuclear transient detected from infrared to soft X-rays, though its nature is yet unclear. The source has shown two consecutive flaring episodes in the optical and the infrared bands and its second flare was covered by X-ra…
View article: Time-scale-dependent X-ray to UV time lags of NGC 4593 using high-intensity <i>XMM–Newton</i> observations with <i>Swift</i> and <i>AstroSat</i>
Time-scale-dependent X-ray to UV time lags of NGC 4593 using high-intensity <i>XMM–Newton</i> observations with <i>Swift</i> and <i>AstroSat</i> Open
We present a 140 ks observation of NGC 4593 with XMM–Newton providing simultaneous and continuous pn X-ray and OM UV (UVW1 2910 Å) light curves, which sample short-time-scale variations better than previous observations. These observations…
View article: First detection of the outer edge of an AGN accretion disc: very fast multiband optical variability of NGC 4395 with GTC/HiPERCAM and LT/IO:O
First detection of the outer edge of an AGN accretion disc: very fast multiband optical variability of NGC 4395 with GTC/HiPERCAM and LT/IO:O Open
We present fast (∼200 s sampling) $\it ugriz$ photometry of the low -mass AGN NGC 4395 with the Liverpool Telescope, followed by very fast (3 s sampling) us, gs, rs, is, and zs simultaneous monitoring with HiPERCAM on the 10.4m GTC. These …
View article: Timescale-dependent X-ray to UV time lags of NGC 4593 using high-intensity XMM-Newton observations with Swift and AstroSat
Timescale-dependent X-ray to UV time lags of NGC 4593 using high-intensity XMM-Newton observations with Swift and AstroSat Open
We present a 140ks observation of NGC 4593 with XMM-Newton providing simultaneous and continuous PN X-ray and OM UV (UVW1 2910Å) lightcurves which sample short-timescale variations better than previous observations. These observations were…
View article: Hard-X-ray-selected active galactic nuclei – II. Spectral energy distributions in the 5–45 GHz domain
Hard-X-ray-selected active galactic nuclei – II. Spectral energy distributions in the 5–45 GHz domain Open
A wide-frequency radio study of active galactic nuclei (AGN) is crucial to evaluate the intervening radiative mechanisms responsible for the observed emission and relate them with the underlying accretion physics. We present wide-frequency…
View article: The Lick AGN Monitoring Project 2016: Dynamical Modeling of Velocity-resolved Hβ Lags in Luminous Seyfert Galaxies
The Lick AGN Monitoring Project 2016: Dynamical Modeling of Velocity-resolved Hβ Lags in Luminous Seyfert Galaxies Open
We have modeled the velocity-resolved reverberation response of the H β broad emission line in nine Seyfert 1 galaxies from the Lick Active Galactic Nucleus (AGN) Monitoring Project 2016 sample, drawing inferences on the geometry and struc…
View article: The Lick AGN Monitoring Project 2016: Dynamical Modeling of Velocity-Resolved H\b{eta} Lags in Luminous Seyfert Galaxies
The Lick AGN Monitoring Project 2016: Dynamical Modeling of Velocity-Resolved H\b{eta} Lags in Luminous Seyfert Galaxies Open
We have modeled the velocity-resolved reverberation response of the H\b{eta} broad emission line in nine Seyfert 1 galaxies from the Lick Active Galactic Nucleus (AGN) Monitioring Project 2016 sample, drawing inferences on the geometry and…
View article: The Paschen Jump as a Diagnostic of the Diffuse Nebular Continuum Emission in Active Galactic Nuclei*
The Paschen Jump as a Diagnostic of the Diffuse Nebular Continuum Emission in Active Galactic Nuclei* Open
Photoionization modeling of active galactic nuclei (AGN) predicts that diffuse continuum (DC) emission from the broad-line region makes a substantial contribution to the total continuum emission from ultraviolet through near-infrared wavel…
View article: The Lick AGN Monitoring Project 2016: Velocity-resolved Hβ Lags in Luminous Seyfert Galaxies
The Lick AGN Monitoring Project 2016: Velocity-resolved Hβ Lags in Luminous Seyfert Galaxies Open
We carried out spectroscopic monitoring of 21 low-redshift Seyfert 1 galaxies using the Kast double spectrograph on the 3 m Shane telescope at Lick Observatory from 2016 April to 2017 May. Targeting active galactic nuclei (AGNs) with lumin…
View article: Daily variability at milli-arcsecond scales in the radio-quiet NLSy1 Mrk 110
Daily variability at milli-arcsecond scales in the radio-quiet NLSy1 Mrk 110 Open
The origin of radio emission in the majority of active galactic nuclei is still poorly understood. Various competing mechanisms are likely involved in the production of radio emission and precise diagnostic tools are needed to disentangle …
View article: The Lick AGN Monitoring Project 2016: Velocity-Resolved H{\beta} Lags in Luminous Seyfert Galaxies
The Lick AGN Monitoring Project 2016: Velocity-Resolved H{\beta} Lags in Luminous Seyfert Galaxies Open
We carried out spectroscopic monitoring of 21 low-redshift Seyfert 1 galaxies using the Kast double spectrograph on the 3 m Shane telescope at Lick Observatory from 2016 April to 2017 May. Targeting active galactic nuclei (AGNs) with lumin…