Constraining the Accretion Geometry of the Intermediate Polar EX Hya Using NuSTAR, Swift, and Chandra Observations

In magnetically accreting white dwarfs, the height above the white dwarf surface where the standing shock is formed is intimately related with the accretion rate and the white dwarf mass. However, it is difficult to measure. We obtained new data with NuSTAR and Swift that, together with archival Chandra data, allow us to constrain the height of the shock in the intermediate polar EX Hya. We conclude that the shock has to form at least at a distance of about one white dwarf radius from the surface in order to explain the weak Fe Kα 6.4 keV line, the absence of a reflection hump in the high-energy continuum, and the energy dependence of the white dwarf spin pulsed fraction. Additionally, the NuSTAR data allowed us to measure the true, uncontaminated hard X-ray (12-40 keV) flux, whose measurement was contaminated by the nearby galaxy cluster Abell 3528 in non-imaging X-ray instruments.Fil: Luna, Gerardo Juan Manuel. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Mukai, K.. National Aeronautics and Space Administration; Estados UnidosFil: Orio, M.. Università di Padova; ItaliaFil: Zemko, P.. Università di Padova; Itali

Detection of X-rays from the jet-driving symbiotic star Hen 3-1341

Context. Hen 3-1341 is a symbiotic binary system consisting of a white dwarf and a red giant star that is one of about ten symbiotics that show hints of jets. The bipolar jets have been detected through displaced components of emission lines during its outburst from 1998 to 2004. These components disappeared when Hen 3-1341 reached quiescence. On February 23, 2012, Hen 3-1341 started a new outburst with the emergence of new bipolar jets on March 3, 2012. Aims: We observed Hen 3-1341 during quiescence with XMM-Newton in March 2010 with an effective exposure time of 46.8 ks and with Swift on March 8-11, 2012 as ToO observations with an effective exposure time of 10 ks in order to probe the interaction of the jet with the ambient medium and also the accretion onto the white dwarf. Methods: We fitted the XMM-Newton X-ray spectra with XSPEC and examined the X-ray and UV light curves. Results: We report the detection of X-ray emission during quiescence from Hen 3-1341 with XMM-Newton. The spectrum can be fitted with an absorbed one-temperature plasma or an absorbed blackbody. We did not detect Hen 3-1341 during our short Swift exposure. Neither periodic or aperiodic X-ray nor UV variability were found. Conclusions: Our XMM-Newton data suggest that interaction of the residual jet with the interstellar medium might survive for a long time after outbursts and might be responsible for the observed X-ray emission during quiescence. Additional data are strongly needed to confirm these suggestions.Fil: Stute, M. Eberhard Karls Universität Tübingen. Institute for Astronomy and Astrophysics; Alemania;Fil: Luna, Gerardo Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio(i); Argentina; Harvard-Smithsonian Center For Astrophysics; Estados Unidos de América;Fil: Pillitteri, I.F.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio(i); Argentina; Harvard-Smithsonian Center For Astrophysics; Estados Unidos de América;Fil: Sokoloski, J.L.. Columbia University. Columbia Astrophysics Laboratory; Estados Unidos de América

V407 Lup, an intermediate polar nova

We present X-ray and optical observations of nova V407 Lup (Nova Lup 2016), previously well monitored in outburst, as it returned to quiescent accretion. The X-ray light curve in 2020 February revealed a clear flux modulation with a stable period of 564.64±0.64 s, corresponding to the period measured in outburst and attributed to the spin of a magnetized white dwarf in an intermediate polar (IP) system. This detection in quiescence is consistent with the IP classification proposed after the nova eruption. The XMM-Newton EPIC X-ray flux is is ≃ 1.3 × 10-12 erg cm-2 s-1 at a distance, most likely, larger than 5 kpc, emitted in the whole 0.2-12 keV range without a significant cut-off energy. The X-ray spectra are complex; they can be fitted including a power law component with a relatively flat slope (a power law index ≃1), although, alternatively, a hard thermal component at kT≥19 keV also yields a good fit. The SALT optical spectra obtained in 2019 March and 2022 May are quite typical of IPs, with strong emission lines, including some due to a high ionization potential, like He II at 4685.7 Å. Nebular lines of O [III] were prominent in 2019 March, but their intensity and equivalent width appeared to be decreasing during that month, and they were no longer detectable in 2022, indicating that the nova ejecta dispersed. Complex profiles of the He II lines of V407 Lup are also characteristic of IPs, giving further evidence for this classification.Fil: Orio, M.. Istituto Nazionale di Astrofisica; Italia. University of Wisconsin; Estados UnidosFil: Melicherčík, M.. Advanced Technologies Research Institut; EslovaquiaFil: Ciroi, S.. Università di Padova; ItaliaFil: Canton, V.. Università di Padova; ItaliaFil: Aydi, E.. Michigan State University; Estados UnidosFil: Buckley, D. A. H.. University of Cape Town; SudáfricaFil: Dobrotka, A.. Advanced Technologies Research Institut; EslovaquiaFil: Luna, Gerardo Juan Manuel. Secretaria de Investigacion ; Universidad Nacional de Hurlingham; . Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ness, J.. Agencia Espacial Europea. European Space Research And Technology Centre.; Países Bajo

Thomson scattering and collisional ionization in the X-ray grating spectra of the recurrent nova U Scorpii

We present a Chandra observation of the recurrent nova U Scorpii, done with the High Resolution camera-S (HRC-S) detector and the Low Energy Transmission Grating (LETG) on day 18 after the observed visual maximum of 2010, and compare it with XMM?Newton observations obtained on days 23 and 35 after maximum. The total absorbed flux was in the range 2.2?2.6 × 10−11 erg cm−2 s−1, corresponding to unabsorbed luminosity 7?8.5 × 1036 ×(d/12 kpc)2 for N(H) = 2?2.7 × 1021 cm−2. On day 18, 70 per cent of the soft X-tray flux was in a continuum typical of a very hot white dwarf (WD) atmosphere, which accounted for about 80 per cent of the flux on days 23 and 35. In addition, all spectra display very broad emission lines, due to higher ionization stages at later times. With Chandra we observed apparent P Cygni profiles. We find that these peculiar profiles are not due to blueshifted absorption and redshifted emission in photoionized ejecta, like the optical P Cyg of novae, but they are rather a superposition of WD atmospheric absorption features reflected by the already discovered Thomson scattering corona, and emission lines due to collisional ionization in condensations in the ejecta. On days 23 and 35, the absorption components were no longer measurable, having lost the initial large blueshift that displaced them from the core of the broad emission lines. We interpret this as an indication that mass-loss ceased between day 18 and day 23. On day 35, the emission line spectrum became very complex, with several different components. Model atmospheres indicate that the WD atmospheric temperature was about 730 000 K on day 18 and reached 900 000?1000 000 K on day 35. This peak temperature is consistent with a WD mass of at least 1.3 M⊙.Fil: Orio, M.. INAF Osservatorio di Padova; Italia. University of Wisconsin; Estados UnidosFil: Behar, E.. Department of Physics, Technion; IsraelFil: Gallagher, J.. University of Wisconsin; Estados UnidosFil: Bianchini, A.. Universita Di Padova; ItaliaFil: Chiosi, E.. INAF Osservatorio di Padova; ItaliaFil: Luna, Gerardo Juan Manuel. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Nelson, T.. University Of Minnesota; Estados UnidosFil: Rauch, T.. Eberhard Karls University; AlemaniaFil: Schaefer, B. E.. State University Of Louisiana; Estados UnidosFil: Tofflemire, B.. University of Wisconsin; Estados Unido

On the nature of CP Pup

We present new X-ray and optical spectra of the old nova CP Pup (nova Pup 1942) obtained with Chandra and the Cerro Tololo Inter American Observatory (CTIO) 4 m telescope. The X-ray spectrum reveals a multitemperature optically thin plasma reaching a maximum temperature of 36^{+19}_{-16} keV absorbed by local complex neutral material. The time-resolved optical spectroscopy confirms the presence of the ?1.47 h period, with cycle-to-cycle amplitude changes, as well as of an additional long-term modulation which is suggestive either of a longer period or of non-Keplerian velocities in the emission line regions. These new observational facts add further support to CP Pup as a magnetic cataclysmic variable (mCV). We compare the mCV and the non-mCV scenarios and, while we cannot conclude whether CP Pup is a long-period system, all pieces of observational evidence point at an intermediate polar-type CV.Fil: Mason, E.. Osservatorio Astronomico di Trieste; Italia; Space Telescope Science Institute, Estados Unidos de América;Fil: Orio, M.. Osservatorio Astronomico di Padova; Italia;Fil: Mukai, K.. NASA Goddard Space Flight Center; Estados Unidos de América;Fil: Bianchini, A.. Dipartimento di Astronomia; Italia;Fil: de Martino, D.. Osservatorio Astronomico di Capodimonte, Italia;Fil: Di Mille, F.. Australian Astronomical Observatory-Carnegie Observatories, Colina; Chile; Dipartimento di Astronomia; Italia;Fil: Williams, R. E.. Department of Astronomy, University of Wisconsin, Estados Unidos de América;Fil: Abbot, T..Fil: de Propris, R..Fil: Luna, Gerardo Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa, Ciudad Universitaria. Instituto de Astronomía y Física del Espacio (i)

Soft X-ray and FUV observations of Nova Her 2021 (V1674 Her) with AstroSat

Nova Her 2021 or V1674 Her was one of the fastest novae to be observed so far. We report here the results from our timing and spectral studies of the source observed at multiple epochs with AstroSat. We report the detection of a periodicity in the source in soft X-rays at a period of 501.4–501.5 s which was detected with high significance after the peak of the super-soft phase, but was not detected in the far ultraviolet (FUV) band of AstroSat. The shape of the phase-folded X-ray light curves has varied significantly as the nova evolved. The phase-resolved spectral studies reveal the likely presence of various absorption features in the soft X-ray band of 0.5–2 keV, and suggest that the optical depth of these absorption features may be marginally dependent on the pulse phase. Strong emission lines from Si, N, and O are detected in the FUV, and their strength declined continuously as the nova evolved and went through a bright X-ray state.Fil: Bhargava, Yash. No especifíca;Fil: Dewangan, Gulab Chand. International Centre Of Theoretical Science. Tata Institute Of Fundamental Research; EspañaFil: Anupama, G. C.. No especifíca;Fil: Kamath, U. S.. No especifíca;Fil: Sonith, L. S.. No especifíca;Fil: Pal Singh, Kulinder. ndian Institute of Science Education and Research Mohali; IndiaFil: Drake, J. J.. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Beardmore, A. University of Leicester; Reino UnidoFil: Luna, Gerardo Juan Manuel. Secretaria de Investigacion ; Universidad Nacional de Hurlingham; . Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Orio, M.. Istituto Nazionale di Astrofisica; ItaliaFil: Page, K. L.. University of Leicester; Reino Unid

Symbiotic stars in X-rays IV. XMM-Newton, Swift, and TESS observations

White dwarf symbiotic binaries are detected in X-rays with luminosities in the range of 1030–1034 ergs s−1. Their X-ray emission ariseseither from the accretion disk boundary layer, from a region where the winds from both components collide, or from nuclear burningon the surface of the white dwarf (WD). In our continuous effort to identify X-ray-emitting symbiotic stars, we studied four systemsusing observations from the Neil Gehrels Swift Observatory and XMM-Newton satellites in X-rays and from Transiting ExoplanetSurvey Satellite (TESS) in the optical. The X-ray spectra were fit with absorbed optically thin thermal plasma models that are eithersingle- or multitemperature with kT < 8 keV for all targets. Based on the characteristics of their X-ray spectra, we classified BD Camas possible β-type, V1261 Ori and CD −27 8661 as δ-type, and confirmed NQ Gem as β/δ-type. The δ-type X-ray emission most likelyarises from the boundary layer of the accretion disk, while in the case of BD Cam, its mostly soft emission originates from shocks,possibly between the red giant and WD and disk winds. In general, we find that the observed X-ray emission is powered by accretionat a low accretion rate of about 10−11 M yr−1. The low ratio of X-ray to optical luminosities, however indicates that the accretion-diskboundary layer is mostly optically thick and tends to emit in the far or extreme UV. The detection of flickering in optical data providesevidence of the existence of an accretion disk.Fil: de Jesus Lima, Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Luna, Gerardo Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Hurlingham; ArgentinaFil: Mukai, K.. National Aeronautics and Space Administration; Estados Unidos. University of Maryland; Estados UnidosFil: Oliveira, A. S.. Universidade do Vale do Paraíba; BrasilFil: Sokoloski, J. L.. Columbia University; Estados UnidosFil: Walter, F. M.. State University of New York; Estados UnidosFil: Palivanas, N.. Universidade do Vale do Paraíba; BrasilFil: Nuñez, Natalia Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Souza, R. R.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Araujo, R. A. N.. Instituto de Ciencia y Tecnologia ; Universidade Estadual Paulista Julio de Mesquita Filho

X-ray, UV, and optical observations of the accretion disk and boundary layer in the symbiotic star RT Crucis

Compared to mass transfer in cataclysmic variables, the nature of accretion in symbiotic binaries in which red giants transfer material to white dwarfs (WDs) has been difficult to uncover. The accretion flows in a symbiotic binary are most clearly observable, however, when there is no quasi-steady shell burning on the WD to hide them. RT Cru is the prototype of such non-burning symbiotics, with its hard (δ-type) X-ray emission providing a view of its innermost accretion structures. In the past 20 yr, RT Cru has experienced two similar optical brightening events, separated by ∼ 4000 days and with amplitudes of ΔV ∼ 1.5 mag. After Swift became operative, the Burst Alert Telescope (BAT) detector revealed a hard X-ray brightening event almost in coincidence with the second optical peak. Spectral and timing analyses of multi-wavelength observations that we describe here, from NuSTAR, Suzaku, Swift/X-Ray Telescope (XRT) + BAT + UltraViolet Optical Telescope (UVOT) (photometry) and optical photometry and spectroscopy, indicate that accretion proceeds through a disk that reaches down to the WD surface. The scenario in which a massive, magnetic WD accretes from a magnetically truncated accretion disk is not supported. For example, none of our data show the minute-time-scale periodic modulations (with tight upper limits from X-ray data) expected from a spinning, magnetic WD. Moreover, the similarity of the UV and X-ray fluxes, as well as the approximate constancy of the hardness ratio within the BAT band, indicate that the boundary layer of the accretion disk remained optically thin to its own radiation throughout the brightening event, during which the rate of accretion onto the WD increased to 6.7 × 10-9M· yr-1 (d/2 kpc)2. For the first time from a WD symbiotic, the NuSTAR spectrum showed a Compton reflection hump at E > 10 keV, due to hard X-rays from the boundary layer reflecting off of the surface of the WD; the reflection amplitude was 0.77 ± 0.21. The best fit spectral model, including reflection, gave a maximum post-shock temperature of kT = 53 ± 4 keV, which implies a WD mass of 1.25 ± 0.02 M·. Although the long-term optical variability in RT Cru is reminiscent of dwarf-novae-type outbursts, the hard X-ray behavior does not correspond to that observed in well-known dwarf nova. An alternative explanation for the brightening events could be that they are due to an enhancement of the accretion rate as the WD travels through the red giant wind in a wide orbit, with a period of about ∼4000 days. In either case, the constancy of the hard X-ray spectrum while the accretion rate rose suggests that the accretion-rate threshold between a mostly optically thin and thick boundary layer, in this object, may be higher than previously thought.Fil: Luna, Gerardo Juan Manuel. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Mukai, K.. National Aeronautics and Space Administration; Estados UnidosFil: Sokoloski, J. L.. Columbia University; Estados UnidosFil: Lucy, A. B.. Columbia University; Estados UnidosFil: Cusumano, G.. Istituto Nazionale di Astrofisica; ItaliaFil: Segreto, A.. Istituto Nazionale di Astrofisica; ItaliaFil: Jaque Arancibia, Marcelo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Nuñez, Natalia Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio. Universidad Nacional de San Juan. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Puebla, R. E.. Universidad Central del Ecuador; EcuadorFil: Nelson, T.. University of Pittsburgh at Johnstown; Estados UnidosFil: Walter, F. M.. Columbia University; Estados Unido

Does Size Matters? Relationships among Social Dominance and Some Morphometric Traits upon Out-of-Season Reproductive Outcomes in Anestrus Dairy Goats Treated with P4 + eCG

The possible role of the social rank (R) (i.e., low-LSR, middle-MSR, or high-HSR) in anestrus goats exposed to a P4 + eCG (D) (i.e., 100 or 350 IU) estrus induction protocol (EIP) was evaluated. Goats (Alpine-Saanen-Nubian × Criollo; n = 70; 25° North) managed under stall-fed conditions were all ultrasound evaluated to confirm anestrous status, while the social rank was determined 30 d prior to the EIP. The response variables included estrus induction (EI, %), duration of estrus (DUR, h), ovulation rate (OR, n), live weight (LW, kg), thoracic perimeter (TP, cm), thoracic diameter (TD, cm), body length (BL, cm), height at withers (HW, cm), beard length (BEA, cm), compactness index (COM, cm), and anamorphosis index (ANA, cm), as affected by R, D, and the R × D interaction were evaluated, while the correlation coefficients among reproductive and morphometric variables were quantified. An R × D interaction (p 0.05) with any response variable, either reproductive or morphometric. As expected, LW had high correlation coefficients (p < 0.01) with TP (0.86), TD (0.88), BL (0.82), HW (0.75), BEA (0.51), COM (0.97), and ANA (0.75). In general, the morphometric variables as a whole demonstrated important correlation coefficients among them (p < 0.01), ranging from 0.38 up to 0.84. To estimate the importance of the morphometric differences between social rank upon estrus induction, a principal component (PC) analysis was performed based on the correlation matrix derived from the corporal measurements. The PC1 and PC2 explained 70.3% and 17.6% of the morphometric variation, respectively. The PC1 was a measure of the goat size (i.e., small, medium, large) and its association with estrus occurrence was evaluated using a logistic regression model; the bigger the goat, the increased probability of being in estrus, by up to five times compared to small goats. Our results confirm that the higher social ranked, larger goats amalgamated some fundamental factors to be successful: aggressiveness, primacy to food access, augmented live weight, and corporal size; all of these were able to modulate out-of-season reproductive success in crossbred dairy goats subjected to an estrus induction protocol and managed under stall-fed conditions in Northern Mexico