Publications (37)
A 78 Day X-ray Period Detected from NGC 5907 ULX1 by Swift
D. J. Walton, F. Fuerst, M. Bachetti +12
We report the detection of a day period in the X-ray lightcurve of the extreme ultraluminous X-ray source NGC 5907 ULX1 ( erg s$^{-1…
The nature of the bright ULX X-2 in NGC3921: a Chandra position and HST candidate counterpart
P. G. Jonker, M. Heida, M. A. P. Torres +6
We report on Chandra observations of the bright ultra-luminous X-ray (ULX) source in NGC3921. Previous XMM observations reported in the literature show the presence of a bright ULX…
Long-term pulse period evolution of the ultra-luminous X-ray pulsar NGC 7793 P13
F. Fuerst, D. J. Walton, M. Heida +14
Ultra-luminous X-ray pulsars (ULXPs) provide a unique opportunity to study super-Eddington accretion. We present the results of a monitoring campaign of ULXP NGC 7793 P13. Over our…
Discovery and analysis of a ULX nebula in NGC 3521
K. M. López, P. G. Jonker, M. Heida +5
We present Very Large Telescope/X-shooter and Chandra X-ray observatory/ACIS observations of the ULX [SST2011] J110545.62+000016.2 in the galaxy NGC 3521. The source identified as…
Characterisation of a candidate dual AGN
D. Lena, G. Panizo-Espinar, P. G. Jonker +2
We present Chandra and optical observations of a candidate dual AGN discovered serendipitously while searching for recoiling black holes via a cross-correlation between the serendi…
The Enhanced Resolution Imager and Spectrograph for the VLT
R. Davies, O. Absil, G. Agapito +81
ERIS, the Enhanced Resolution Imager and Spectrograph, is an instrument that both extends and enhances the fundamental diffraction limited imaging and spectroscopy capability for t…
Accurate positions for the ULXs NGC 7319-X4 and NGC 5474-X1 and limiting magnitudes for their optical counterparts
M. Heida, P. G. Jonker, M. A. P. Torres +1
In this paper we report accurate Chandra positions for two ultraluminous X-ray sources: NGC 7319-X4 at Right Ascension (RA) = 339.02917(2) deg, Declination (Dec) = 33.97476(2) deg…
Near-infrared counterparts of ultraluminous X-ray sources
M. Heida, P. G. Jonker, M. A. P. Torres +7
In this paper we present the results of the first systematic search for counterparts to nearby ultraluminous X-ray sources (ULXs) in the near-infrared (NIR). We observed 62 ULXs in…
A tale of two periods: determination of the orbital ephemeris of the super-Eddington pulsar NGC 7793 P13
F. Fuerst, D. J. Walton, M. Heida +10
We present a timing analysis of multiple XMM-Newton and NuSTAR observations of the ultra-luminous pulsar NGC 7793 P13 spread over its 65d variability period. We use the measured pu…
Discovery of a second outbursting hyperluminous X-ray source
M. Heida, P. G. Jonker, M. A. P. Torres
We report on six Chandra and one HST/WFC3 observation of CXO J122518.6+144545, discovered by Jonker et al. (2010) as a candidate hyperluminous X-ray source (HLX), X-ray bright supe…
VLT/FORS2 observations of four high-luminosity ULX candidates
M. Heida, P. G. Jonker, M. A. P. Torres +4
We obtained VLT/FORS2 spectra of the optical counterparts of four high-luminosity (L_X >= 10^40 erg/s) ULX candidates from the catalog of Walton (2011). We first determined accurat…
Keck/MOSFIRE spectroscopy of five ULX counterparts
M. Heida, P. G. Jonker, M. A. P. Torres +5
We present H-band spectra of the candidate counterparts of five ULXs (two in NGC 925, two in NGC 4136, and Holmberg II X-1) obtained with Keck/MOSFIRE. The candidate counterparts o…
Detecting Stripped Stars While Searching for Quiescent Black Holes
J. Bodensteiner, M. Heida, M. Abdul-Masih +13
While the number of stellar-mass black holes detected in X-rays or as gravitational wave sources is steadily increasing, the known population remains orders of magnitude smaller th…
Evidence for Pulsar-like Emission Components in the Broadband ULX Sample
D. J. Walton, F. Fuerst, M. Heida +7
We present broadband X-ray analyses of a sample of bright ultraluminous X-ray sources with the goal of investigating the spectral similarity of this population to the known ULX pul…
Digging a little deeper: characterising three new extreme ULX candidates
T. P. Roberts, D. J. Walton, A. D. A. Mackenzie +2
A prime motivation for compiling catalogues of any celestial X-ray source is to increase our numbers of rare sub-classes. In this work we take a recent multi-mission catalogue of u…
A Potential Cyclotron Resonant Scattering Feature in the ULX Pulsar NGC 300 ULX1 seen by NuSTAR and XMM-Newton
D. J. Walton, M. Bachetti, F. Fuerst +14
Based on phase-resolved broadband spectroscopy using - and , we report on a potential cyclotron resonant scattering feature at keV in the pulsed sp…
Searching for the Donor Stars of ULX Pulsars
M. Heida, F. A. Harrison, M. Brightman +3
We report on our search for the optical counterparts of two ultraluminous X-ray pulsars with known orbital periods, M82 X-2 and NGC 5907 X-1, in new and archival HST observations,…
Swift and NuSTAR observations of GW170817: detection of a blue kilonova
P. A. Evans, S. B. Cenko, J. A. Kennea +56
With the first direct detection of merging black holes in 2015, the era of gravitational wave (GW) astrophysics began. A complete picture of compact object mergers, however, requir…
HR 6819 is a binary system with no black hole -- revisiting the source with infrared interferometry and optical integral field spectroscopy
A. J. Frost, J. Bodensteiner, Th. Rivinius +16
Two scenarios have been proposed to match the existing observational constraints of the object HR 6819. The system could consist of a close inner B-type giant plus a black hole (BH…
NIR Counterparts to ULXs (III): Completing the photometric survey and selected spectroscopic results
K. M. López, M. Heida, P. G. Jonker +5
We present results from the remaining sources in our search for near-infrared (NIR) candidate counterparts to ultraluminous X-ray sources (ULXs) within 10 Mpc. We observed…
Quiescent NIR and optical counterparts to candidate black hole X-ray binaries
K. M. López, P. G. Jonker, M. A. P. Torres +3
We present near-infrared and optical imaging of fifteen candidate black hole X-ray binaries. In addition to quiescent observations for all sources, we also observed two of these so…
A naked-eye triple system with a nonaccreting black hole in the inner binary
Th. Rivinius, D. Baade, P. Hadrava +2
Several dozen optical echelle spectra demonstrate that HR 6819 is a hierarchical triple. A classical Be star is in a wide orbit with an unconstrained period around an inner 40 d bi…
Constraining the nature of the accreting binary in CXOGBS J174623.5-310550
M. A. P. Torres, S. Repetto, T. Wevers +12
We report optical and infrared observations of the X-ray source CXOGBS J174623.5-310550. This Galactic object was identified as a potential quiescent low-mass X-ray binary accretin…
A Systematic Search for Near-Infrared Counterparts of Nearby Ultraluminous X-ray sources (II)
K. M. López, M. Heida, P. G. Jonker +5
We present the results of our continued systematic search for near-infrared (NIR) candidate counterparts to ultraluminous X-ray sources (ULXs) within 10 Mpc. We observed 42 ULXs in…
The binary mass ratio in the black hole transient MAXI J1820+070
M. A. P. Torres, J. Casares, F. Jiménez-Ibarra +5
We present intermediate resolution spectroscopy of the optical counterpart to the black hole X-ray transient MAXI J1820+070 (=ASASSN-18ey) obtained with the OSIRIS spectrograph on…
Discovery of a red supergiant donor star in SN2010da/NGC 300 ULX-1
M. Heida, R. M. Lau, B. Davies +7
SN2010da/NGC 300 ULX-1 was first detected as a supernova impostor in May 2010 and was recently discovered to be a pulsating ultraluminous X-ray source. In this letter, we present V…
Breaking the limit: Super-Eddington accretion onto black holes and neutron stars
M. Brightman, M. Bachetti, H. P. Earnshaw +10
With the recent discoveries of massive and highly luminous quasars at high redshifts (; e.g. Mortlock et al. 2011), the question of how black holes (BHs) grow in the early…
The mass function of GX 339-4 from spectroscopic observations of its donor star
M. Heida, P. G. Jonker, M. A. P. Torres +1
We obtained 16 VLT/X-shooter observations of GX 339-4 in quiescence in the period May - September 2016 and detected absorption lines from the donor star in its NIR spectrum. This a…
A New Transient Ultraluminous X-ray Source in NGC 7090
D. J. Walton, M. Heida, M. Bachetti +17
We report on the discovery of a new, transient ultraluminous X-ray source (ULX) in the galaxy NGC 7090. This new ULX, which we refer to as NGC 7090 ULX3, was discovered via monitor…
Discovery of a red supergiant counterpart to RX~J004722.4-252051, a ULX in NGC 253
M. Heida, M. A. P. Torres, P. G. Jonker +6
We present two epochs of near-infrared spectroscopy of the candidate red supergiant counterpart to RX~J004722.4-252051, a ULX in NGC 253. We measure radial velocities of the object…
Discovery of a new kind of explosive X-ray transient near M86
P. G. Jonker, A. Glennie, M. Heida +6
We present the discovery of a new type of explosive X-ray flash in Chandra images of the old elliptical galaxy M86. This unique event is characterised by the peak luminosity of 6x1…
A bright off-nuclear X-ray source: A bright off-nuclear X-ray source: a type IIn supernova, a bright ULX or a recoiling super-massive black hole in CXO J122518.6+144545
P. G. Jonker, M. A. P. Torres, A. C. Fabian +3
In this Paper we report the discovery of CXO J122518.6+144545; a peculiar X-ray source with a position 3.6+-0.2",off-nuclear from an SDSS DR7 z=0.0447 galaxy. The 3.6" offset corre…
Dynamical confirmation of a black hole in MAXI J1820+070
M. A. P. Torres, J. Casares, F. Jiménez-Ibarra +4
We present time-resolved 10.4-m GTC and 4.2-m WHT intermediate resolution spectroscopy of the X-ray transient MAXI J1820+070 (=ASASSN-18ey) obtained during its decline to the quies…
Astro 2020 Science White Paper: Time Domain Studies of Neutron Star and Black Hole Populations: X-ray Identification of Compact Object Types
N. Vulic, A. E. Hornschemeier, V. Antoniou +16
What are the most important conditions and processes governing the growth of stellar-origin compact objects? The identification of compact object type as either black hole (BH) or…
Stochastic homogenization of plasticity equations
M. Heida, B. Schweizer
In the context of infinitesimal strain plasticity with hardening, we derive a stochastic homogenization result. We assume that the coefficients of the equation are random functions…
Probing the nature of the low state in the extreme ultraluminous X-ray pulsar NGC 5907 ULX1
F. Fuerst, D. J. Walton, G. L. Israel +13
NGC 5907 ULX1 is the most luminous ultra-luminous X-ray pulsar (ULXP) known to date, reaching luminosities in excess of 1e41 erg/s. The pulsar is known for its fast spin-up during…
The Unusual Broadband X-ray Spectral Variability of NGC 1313 X-1 seen with XMMNewton, Chandra and NuSTAR
D. J. Walton, C. Pinto, M. Nowak +19
We present results from the major coordinated X-ray observing program on the ULX NGC 1313 X-1 performed in 2017, combining -, and , focusing on the e…