Publications by Kieran O'Brien


A Microwave Kinetic Inductance Detector for the DAG Telescope

HIGH ENERGY, OPTICAL, AND INFRARED DETECTORS FOR ASTRONOMY VII 9915 (2016)

T Guver, BA Mazin, K O'Brien, B Kay, S Alis, FK Yelkenci, C Yesilyaprak, SK Yerli, A Erol, O Keskin


Detection of the first infra-red quasi-periodic oscillation in a black hole X-ray binary

Monthly Notices of the Royal Astronomical Society Oxford University Press 460 (2016) 3284-3291

M Kalamkar, P Casella, P Uttley, K O'Brien, D Russell, T Maccarone, M van der Klis, F Vincentelli

We present the analysis of fast variability of Very Large Telescope/ISAAC (Infrared Spectrometer And Array Camera) (infra-red), XMM–Newton/OM (optical) and EPIC-pn (X-ray), and RXTE/PCA (X-ray) observations of the black hole X-ray binary GX 339−4 in a rising hard state of its outburst in 2010. We report the first detection of a quasi-periodic oscillation (QPO) in the infra-red band (IR) of a black hole X-ray binary. The QPO is detected at 0.08 Hz in the IR as well as two optical bands (U and V). Interestingly, these QPOs are at half the X-ray QPO frequency at 0.16 Hz, which is classified as the type-C QPO; a weak sub-harmonic close to the IR and optical QPO frequency is also detected in X-rays. The band-limited sub-second time-scale variability is strongly correlated in IR/X-ray bands, with X-rays leading the IR by over 120 ms. This short time delay, shape of the cross-correlation function and spectral energy distribution strongly indicate that this band-limited variable IR emission is the synchrotron emission from the jet. A jet origin for the IR QPO is strongly favoured, but cannot be definitively established with the current data. The spectral energy distribution indicates a thermal disc origin for the bulk of the optical emission, but the origin of the optical QPO is unclear. We discuss our findings in the context of the existing models proposed to explain the origin of variability.


The E-ELT first light spectrograph HARMONI: capabilities and modes

GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY VI 9908 (2016) ARTN 99081X

NAA Thatte, F Clarke, I Bryson, H Schnetler, M Tecza, T Fusco, RM Bacon, J Richard, E Mediavilla, B Neichel, S Arribas, B Garcia-Lorenzo, CJ Evans, A Remillieux, K El Madi, J Miguel Herreros, D Melotte, K O'Brien, IA Tosh, J Vernet, P Hammersley, DJ Ives, G Finger, R Houghton, D Rigopoulou, JD Lynn, JR Allen, SD Zieleniewski, S Kendrew, V Ferraro-Wood, A Pecontal-Rousset, J Kosmalski, F Laurent, M Loupias, L Piqueras, E Renault, J Blaizot, E Daguise, J-E Migniau, A Jarno, A Bornh, AM Gallie, DM Montgomery, D Henry, N Schwartz, W Taylor, G Zins, L Fernando Rodriguez-Ramos, M Cagigas, G Battaglia, R Rebolo Lopez, J Sanchez-Capuchino Revuelta, J Luis Rasilla, E Hernandez-Suarez, J Vicente Gigante-Ripoll, J Piqueras Lopez, M Villa Martin, C Correia, S Pascal, L Blanco, P Vola, B Epinat, C Peroux, A Vigan, K Dohlen, J-F Sauvage, M Lee, A Carlotti, C Verinaud, T Morris, R Myers, A Reeves, M Swinbank, A Calcines, M Larrieu


THE ARCONS PIPELINE: DATA REDUCTION FOR MKID ARRAYS

ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES 219 (2015) ARTN 14

JC van Eyken, MJ Strader, AB Walter, SR Meeker, P Szypryt, C Stoughton, K O'Brien, D Marsden, NK Rice, Y Lin, BA Mazin


KIDSpec: an MKID based medium resolution integral field spectrograph

GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY V 9147 (2014) ARTN 91470G

K O'Brien, N Thatte, B Mazin


Direct detection of SDSS J0926+3624 orbital expansion with ARCONS

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 439 (2014) 2765-2770

P Szypryt, GE Duggan, BA Mazin, SR Meeker, MJ Strader, JC van Eyken, D Marsden, K O'Brien, AB Walter, G Ulbricht, TA Prince, C Stoughton, B Bumble


HARMONI: the first light integral field spectrograph for the E-ELT

GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY V 9147 (2014) ARTN 914725

NA Thatte, F Clarke, I Bryson, H Schnetler, M Tecza, RM Bacon, A Remillieux, E Mediavilla, JM Herreros Linares, S Arribas, CJ Evans, DW Lunney, T Fusco, K O'Brien, IA Tosh, DJ Ives, G Finger, R Houghton, RL Davies, JD Lynn, JR Allen, SD Zieleniewski, S Kendrew, V Ferraro-Wood, A Pecontal-Rousset, J Kosmalski, J Richard, A Jarno, AM Gallie, DM Montgomery, D Henry, G Zins, D Freeman, B Garcia-Lorenzo, L Fernando Rodriguez-Ramos, J Sanchez-Capuchino Revuelta, E Hernandez-Suarez, A Bueno-Bueno, JV Gigante-Ripoll, A Garcia, K Dohlen, B Neichel


EXCESS OPTICAL ENHANCEMENT OBSERVED WITH ARCONS FOR EARLY CRAB GIANT PULSES

ASTROPHYSICAL JOURNAL LETTERS 779 (2013) ARTN L12

MJ Strader, MD Johnson, BA Mazin, GVS Jaeger, CR Gwinn, SR Meeker, P Szypryt, JC van Eyken, D Marsden, K O'Brien, AB Walter, G Ulbricht, C Stoughton, B Bumble


AN EVOLVING COMPACT JET IN THE BLACK HOLE X-RAY BINARY MAXI J1836-194

ASTROPHYSICAL JOURNAL LETTERS 768 (2013) ARTN L35

DM Russell, TD Russell, JCA Miller-Jones, K O'Brien, R Soria, GR Sivakoff, T Slaven-Blair, F Lewis, S Markoff, J Homan, D Altamirano, PA Curran, MP Rupen, TM Belloni, M Cadolle Bel, P Casella, S Corbel, V Dhawan, RP Fender, E Gallo, P Gandhi, S Heinz, EG Kording, HA Krimm, D Maitra, S Migliari, RA Remillard, CL Sarazin, T Shahbaz, V Tudose


Giga-z: A 100,000 OBJECT SUPERCONDUCTING SPECTROPHOTOMETER FOR LSST FOLLOW-UP

ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES 208 (2013) UNSP 8

DW Marsden, BA Mazin, K O'Brien, C Hirata


Jet spectral breaks in black hole x-ray binaries

Monthly Notices of the Royal Astronomical Society 429 (2013) 815-832

DM Russell, S Markoff, P Casella, AG Cantrell, R Chatterjee, RP Fender, E Gallo, P Gandhi, J Homan, D Maitra, JCA Miller-Jones, K O'Brien, T Shahbaz

In X-ray binaries, compact jets are known to commonly radiate at radio to infrared frequencies, whereas at optical to -ray energies, the contribution of the jet is debated. The total luminosity, and hence power of the jet, is critically dependent on the position of the break in its spectrum, between optically thick (self-absorbed) and optically thin synchrotron emission. This break, or turnover, has been reported in just one black hole X-ray binary (BHXB) thus far, GX 339-4, and inferred via spectral fitting in two others, A0620-00 and Cyg X-1. Here, we collect a wealth of multi-wavelength data from the outbursts of BHXBs during hard X-ray states, in order to search for jet breaks as yet unidentified in their spectral energy distributions. In particular, we report the direct detection of the jet break in the spectrum of V404 Cyg during its 1989 outburst, at b = (1.8 ± 0.3) × 1014 Hz (1.7 ± 0.2 μm). We increase the number of BHXBs with measured jet breaks from three to eight. Jet breaks are found at frequencies spanning more than two orders of magnitude, from b = (4.5 ± 0.8) × 1012 Hz for XTE J1118+480 during its 2005 outburst, to b > 4.7 × 1014 Hz for V4641 Sgr in outburst. A positive correlation between jet break frequency and luminosity is expected theoretically; b L ~0.5 ,jet if other parameters are constant. With constraints on the jet break in a total of 12 BHXBs including two quiescent systems, we find a large range of jet break frequencies at similar luminosities and no obvious global relation (but such a relation cannot be ruled out for individual sources). We speculate that different magnetic field strengths and/or different radii of the acceleration zone in the inner regions of the jet are likely to be responsible for the observed scatter between sources. There is evidence that the high-energy cooling break in the jet spectrum shifts from UV energies at LX ~ 10-8LEdd (implying the jet may dominate the X-ray emission in quiescence) to X-ray energies at ~10-3LEdd. Finally, we find that the jet break luminosity scales as L,jet L0.56±0.05 X (very similar to the radio-X-ray correlation), and radio-faint BHXBs have fainter jet breaks. In quiescence the jet break luminosity exceeds the X-ray luminosity. © 2012 The Authors.


ARCONS: A 2024 Pixel Optical through Near-IR Cryogenic Imaging Spectrophotometer

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC 125 (2013) 1348-1361

BA Mazin, SR Meeker, MJ Strader, P Szypryt, D Marsden, JC van Eyken, GE Duggan, AB Walter, G Ulbricht, M Johnson, B Bumble, K O'Brien, C Stoughton


ARCONS: a Highly Multiplexed Superconducting UV-to-Near-IR Camera

IAU Symposium 285 (2012) 385-388-385-388

K O Brien, B Mazin, S McHugh, S Meeker, B Bumble


First Optical Observations with Microwave Kinetic Inductance Detectors

American Astronomical Society Meeting Abstracts #219 219 (2012) #413.06-#413.06

S Meeker, BA Mazin, K O Brien, S McHugh, B Bumble, E Langman, M Navaroli


A readout for large arrays of microwave kinetic inductance detectors

Review of Scientific Instruments 83 (2012)

S McHugh, BA Mazin, B Serfass, S Meeker, K O'Brien, R Duan, R Raffanti, D Werthimer

Microwave kinetic inductance detectors (MKIDs) are superconducting detectors capable of counting single photons and measuring their energy in the UV, optical, and near-IR. MKIDs feature intrinsic frequency domain multiplexing (FDM) at microwave frequencies, allowing the construction and readout of large arrays. Due to the microwave FDM, MKIDs do not require the complex cryogenic multiplexing electronics used for similar detectors, such as transition edge sensors, but instead transfer this complexity to room temperature electronics where they present a formidable signal processing challenge. In this paper, we describe the first successful effort to build a readout for a photon counting optical/near-IR astronomical instrument, the ARray Camera for Optical to Near-infrared Spectrophotometry. This readout is based on open source hardware developed by the Collaboration for Astronomy Signal Processing and Electronics Research. Designed principally for radio telescope backends, it is flexible enough to be used for a variety of signal processing applications. © 2012 American Institute of Physics.


The near-infrared counterpart of 4U 1636-53: (Research Note)

Astronomy and Astrophysics 539 (2012)

DM Russell, K O'Brien, T Muñoz-Darias, P Casella, P Gandhi, MG Revnivtsev

Context. The optical counterpart of the neutron star X-ray binary and well known X-ray burster, 4U 1636-53 (=4U 1636-536 = V801 Ara) has been studied for three decades. However, no infrared studies have been reported to date. Aims. Our aims are to identify and investigate the near-infrared (NIR) counterpart of 4U 1636-53. Methods. We present deep, K S-band (2.2 μm) imaging of the region of 4U 1636-53 taken with the Infrared Spectrometer And Array Camera (ISAAC) on the Very Large Telescope. Archival optical and UV data were used to infer the 0.2-2.2 μm spectral energy distribution (SED). Results. One star is located at coordinates α = 16:40:55.57, δ =-53:45:05.2 (J2000; 1σ positional uncertainty of ∼0.3 arcsec), which is consistent with the known optical position of 4U 1636-53; its magnitude is K S = 16.14 ± 0.12. This star is also detected in the 2MASS survey in the J-band and has a magnitude of J = 16.65 ±0.22. Assuming that the persistent emission is quite steady, the 0.4-2.2 μm de-reddened SED can be described by a power law F νν 1.5 ± 0.3, with some possible curvature (F νν 1.5) at 0.2-0.4 μm. The SED can be approximated by a blackbody of temperature ∼27000 K. This is typical for an active low-mass X-ray binary, and the emission can be explained by the outer regions of a (likely irradiated) accretion disc. We therefore interpret this K S-band star as the NIR counterpart. © 2012 ESO.


A superconducting focal plane array for ultraviolet, optical, and near-infrared astrophysics

Optics Express 20 (2012) 1503-1511

BA Mazin, B Bumble, SR Meeker, K O'Brien, S McHugh, E Langman

Microwave Kinetic Inductance Detectors, or MKIDs, have proven to be a powerful cryogenic detector technology due to their sensitivity and the ease with which they can be multiplexed into large arrays. A MKID is an energy sensor based on a photon-variable superconducting inductance in a lithographed microresonator, and is capable of functioning as a photon detector across the electromagnetic spectrum as well as a particle detector. Here we describe the first successful effort to create a photon-counting, energy-resolving ultraviolet, optical, and near infrared MKID focal plane array. These new Optical Lumped Element (OLE) MKID arrays have significant advantages over semiconductor detectors like charge coupled devices (CCDs). They can count individual photons with essentially no false counts and determine the energy and arrival time of every photon with good quantum efficiency. Their physical pixel size and maximum count rate is well matched with large telescopes. These capabilities enable powerful new astrophysical instruments usable from the ground and space. MKIDs could eventually supplant semiconductor detectors for most astronomical instrumentation, and will be useful for other disciplines such as quantum optics and biological imaging. © 2012 Optical Society of America.


ARCONS: A 1024 pixel superconducting integral field spectrograph

Proceedings of SPIE - The International Society for Optical Engineering 8446 (2012)

K O'Brien, B Mazin, S McHugh, S Meeker, D Marsden, B Bumble

ARCONS, the Array Camera for Optical to Near-infrared Spectrophotometry, was recently commissioned at the Coudé focus of the 200-inch Hale Telescope at the Palomar Observatory. At the heart of this unique instrument is a 1024-pixel Microwave Kinetic Inductance Detector (MKID), exploiting the Kinetic Inductance effect to measure the energy of the incoming photon to better than several percent. The ground-breaking instrument is lens coupled with a pixel scale of 0.23''/pixel, with each pixel recording the arrival time (< 2 μ sec) and energy of a photon (∼ 10%) in the optical to near-IR (0.4-1.1 microns) range. The scientific objectives of the instrument include the rapid follow-up and classification of the transient phenomena. © 2012 SPIE.


The nature of the X-ray transient MAXI J0556-332

mnras 420 (2012) 3538-3544-3538-3544

R Cornelisse, P D Avanzo, S Campana, J Casares, PA Charles, G Israel, T Mu noz-Darias, K O Brien, D Steeghs, L Stella, MAP Torres


The near-infrared counterpart of 4U 1636-53

åp 539 (2012) A53-A53

DM Russell, K O Brien, T Mu noz-Darias, P Casella, P Gandhi, MG Revnivtsev

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