TY  - JOUR
A1  - González-Galán, Ana
A1  - Oskinova, Lida
A1  - Popov, Sergei B.
A1  - Haberl, F.
A1  - Kühnel, M.
A1  - Gallagher, John S.
A1  - Schurch, Matthew
A1  - Guerrero, Martín A.
T1  - A multiwavelength study of SXP 1062, the long-period X-ray pulsar associated with a supernova remnant
JF  - Monthly notices of the Royal Astronomical Society
N2  - SXP 1062 is a Be X-ray binary (BeXB) located in the Small Magellanic Cloud. It hosts a long-period X-ray pulsar and is likely associated with the supernova remnant MCSNR J0127−7332. In this work we present a multiwavelength view on SXP 1062 in different luminosity regimes. We consider monitoring campaigns in optical (OGLE survey) and X-ray (Swift telescope). During these campaigns a tight coincidence of X-ray and optical outbursts is observed. We interpret this as typical Type I outbursts as often detected in BeXBs at periastron passage of the neutron star (NS). To study different X-ray luminosity regimes in depth, during the source quiescence we observed it with XMM–Newton while Chandra observations followed an X-ray outburst. Nearly simultaneously with Chandra observations in X-rays, in optical the RSS/SALT telescope obtained spectra of SXP 1062. On the basis of our multiwavelength campaign we propose a simple scenario where the disc of the Be star is observed face-on, while the orbit of the NS is inclined with respect to the disc. According to the model of quasi-spherical settling accretion our estimation of the magnetic field of the pulsar in SXP 1062 does not require an extremely strong magnetic field at the present time.
KW  - stars: neutron
KW  - pulsars: individual: SXP 1062
KW  - galaxies: individual: Small Magellanic Cloud
KW  - X-rays: binaries
Y1  - 2017
U6  - https://doi.org/10.1093/mnras/stx3127
SN  - 0035-8711
SN  - 1365-2966
VL  - 475
IS  - 2
SP  - 2809
EP  - 2821
PB  - Oxford University Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Postnov, K.
A1  - Oskinova, Lida
A1  - Torrejon, J. M.
T1  - A propelling neutron star in the enigmatic Be-star gamma Cassiopeia
JF  - Monthly notices of the Royal Astronomical Society
N2  - gamma Cassiopeia (gamma Cas), is known to be a binary system consisting of a Be-type star and a low-mass (M similar to 1M(circle dot)) companion of unknown nature orbiting in the Be-disc plane. Here, we apply the quasi-spherical accretion theory on to a compact magnetized star and show that if the low-mass companion of gamma Cas is a fast spinning neutron star, the key observational signatures of. Cas are remarkably well reproduced. Direct accretion on to this fast rotating neutron star is impeded by the propeller mechanism. In this case, around the neutron star magnetosphere a hot shell is formed which emits thermal X-rays in qualitative and quantitative agreement with observed properties of the X-ray emission from gamma Cas. We suggest that gamma Cas and its analogues constitute a new subclass of Be-type X-ray binaries hosting rapidly rotating neutron stars formed in supernova explosions with small kicks. The subsequent evolutionary stage of gamma Cas and its analogues should be the X Per-type binaries comprising low-luminosity slowly rotating X-ray pulsars. The model explains the enigmatic X-ray emission from gamma Cas, and also establishes evolutionary connections between various types of rotating magnetized neutron stars in Be-binaries.
KW  - stars: emission-line, Be
KW  - stars: neutron
Y1  - 2017
U6  - https://doi.org/10.1093/mnrasl/slw223
SN  - 0035-8711
SN  - 1365-2966
VL  - 465
IS  - 1
SP  - L119
EP  - L123
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Chromey, A. J.
A1  - Cui, Wei
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, J. P.
A1  - Fortson, Lucy
A1  - Furniss, Amy
A1  - Gent, A.
A1  - Gueta, O.
A1  - Hanna, David
A1  - Hassan, T.
A1  - Hervet, Olivier
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - McCann, A.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Otte, Adam Nepomuk
A1  - Pandel, D.
A1  - Park, N.
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Sadeh, I
A1  - Santander, Marcos
A1  - Scott, S. S.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Sushch, Iurii
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Williamson, T. J.
A1  - Zitzer, B.
T1  - A Search for Pulsed Very High-energy Gamma-Rays from 13 Young Pulsars in Archival VERITAS Data
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We conduct a search for periodic emission in the very high-energy (VHE) gamma-ray band (E > 100 GeV) from a total of 13 pulsars in an archival VERITAS data set with a total exposure of over 450 hr. The set of pulsars includes many of the brightest young gamma-ray pulsars visible in the Northern Hemisphere. The data analysis resulted in nondetections of pulsed VHE gamma-rays from each pulsar. Upper limits on a potential VHE gamma-ray flux are derived at the 95% confidence level above three energy thresholds using two methods. These are the first such searches for pulsed VHE emission from each of the pulsars, and the obtained limits constrain a possible flux component manifesting at VHEs as is seen for the Crab pulsar.
KW  - gamma rays: general
KW  - pulsars: general
KW  - stars: neutron
Y1  - 2019
U6  - https://doi.org/10.3847/1538-4357/ab14f4
SN  - 0004-637X
SN  - 1538-4357
VL  - 876
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Hosseinzadeh, Griffin
A1  - Cowperthwaite, Philip S.
A1  - Gomez, Sebastian
A1  - Villar, Victoria Ashley
A1  - Nicholl, Matt
A1  - Margutti, Raffaella
A1  - Berger, Edo
A1  - Chornock, Ryan
A1  - Paterson, Kerry
A1  - Fong, Wen-fai
A1  - Savchenko, Volodymyr
A1  - Short, Phil
A1  - Alexander, Kate D.
A1  - Blanchard, Peter K.
A1  - Braga, Joao
A1  - Calkins, Michael L.
A1  - Cartier, Regis
A1  - Coppejans, Deanne L.
A1  - Eftekhari, Tarraneh
A1  - Laskar, Tanmoy
A1  - Ly, Chun
A1  - Patton, Locke
A1  - Pelisoli, Ingrid Domingos
A1  - Reichart, Daniel E.
A1  - Terreran, Giacomo
A1  - Williams, Peter K. G.
T1  - Follow-up of the Neutron Star Bearing Gravitational-wave Candidate Events S190425z and S190426c with MMT and SOAR
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters
N2  - On 2019 April 25.346 and 26.640 UT the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo gravitational-wave (GW) observatory announced the detection of the first candidate events in Observing Run 3 that contained at least one neutron star (NS). S190425z is a likely binary neutron star (BNS) merger at d(L) = 156 +/- 41 Mpc, while S190426c is possibly the first NS-black hole (BH) merger ever detected, at d(L) = 377 +/- 100 Mpc, although with marginal statistical significance. Here we report our optical follow-up observations for both events using the MMT 6.5 m telescope, as well as our spectroscopic follow-up of candidate counterparts (which turned out to be unrelated) with the 4.1 m SOAR telescope. We compare to publicly reported searches, explore the overall areal coverage and depth, and evaluate those in relation to the optical/near-infrared (NIR) kilonova emission from the BNS merger GW170817, to theoretical kilonova models, and to short gamma-ray burst (SGRB) afterglows. We find that for a GW170817-like kilonova, the partial volume covered spans up to about 40% for S190425z and 60% for S190426c. For an on-axis jet typical of SGRBs, the search effective volume is larger, but such a configuration is expected in at most a few percent of mergers. We further find that wide-field gamma-ray and X-ray limits rule out luminous on-axis SGRBs, for a large fraction of the localization regions, although these searches are not sufficiently deep in the context of the gamma-ray emission from GW170817 or off-axis SGRB afterglows. The results indicate that some optical follow-up searches are sufficiently deep for counterpart identification to about 300 Mpc, but that localizations better than 1000 deg(2) are likely essential.
KW  - binaries: close
KW  - gravitational waves
KW  - methods: observational
KW  - stars: black holes
KW  - stars: neutron
Y1  - 2019
U6  - https://doi.org/10.3847/2041-8213/ab271c
SN  - 2041-8205
SN  - 2041-8213
VL  - 880
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  -