NICER monitoring of supersoft X-ray sources

Abstract

We monitored four supersoft sources - two persistent ones, CAL 83 and MR Vel, and the recent novae YZ Ret (Nova Ret 2020) and V1674 Her (Nova Her 2021) - with NICER. The two persistent SSS were observed with unvaried X-ray flux level and spectrum, respectively, 13 and 20 years after the last observations. Short period modulations of the supersoft X-ray source (SSS) appear where the spectrum of the luminous central source was fully visibl (in CAL 83 and V1674 Her) and were absent in YZ Ret and MR Vel, in which the flux originated in photoionized or shocked plasma, while the white dwarf (WD) was not observable. We thus suggest that the pulsations occur on, or very close to, the WD surface. The pulsations of CAL 83 were almost unvaried after 15 years, including an irregular drift of the $\simeq$67 s period by 2.1 s. Simulations, including previous XMM-Newton data, indicate actual variations in period length within hours, rather than an artifact of the variable amplitude of the pulsations. Large amplitude pulsations with a period of 501.53$\pm$0.30 s were always detected in V1674 Her, as long as the SSS was observable. This period seems to be due to rotation of a highly magnetized WD.We cannot confirm the maximum effective temperature of ($\simeq$145,000 K) previously inferred for this nova, and discuss the difficulty in interpreting its spectrum. The WD appears to present two surface zones, one of which does not emit SSS flux.

arXiv commentin press in the Astrophysical Journal

References in corpus (47)

• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• The Relation Between Optical Extinction and Hydrogen Column Density in the Galaxy
• An Extended Grid of Nova Models: II. The Parameter Space of Nova Outbursts
• Hydrogen Burning on Accreting White Dwarfs: Stability, Recurrent Novae, and the Post-Novae Supersoft Source
• The Super-Soft X-ray Phase of Nova RS Ophiuchi 2006
• An ultra-massive fast-spinning white dwarf in a peculiar binary system
• X-ray Spectroscopy of the 2006 Outburst of RS Oph
• The nature of the supersoft X-ray source RX~J0513--69
• The central region of M31 observed with XMM-Newton. II. Variability of the individual sources
• NLTE model atmospheres for the hottest white dwarfs: Spectral analysis of the compact component in nova V4743 Sgr
• Modelling the circumstellar medium in RS Ophiuchi and its link to Type Ia supernovae
• The Extraordinary X-ray Light Curve of the Classical Nova V1494 Aquilae (1999 #2) in Outburst: The Discovery of Pulsations and a "Burst"
• XMM-Newton X-ray and UV observations of the fast nova V2491 Cyg during the supersoft source phase
• NLTE Model Atmosphere Analysis of the LMC Supersoft X-ray Source CAL 83
• Obscuration effects in Super-Soft-Source X-ray spectra
• Resumption of mass accretion in RS Oph
• Short-period $g$-mode pulsations in low-mass white dwarfs triggered by H shell burning
• X-Ray Off States and Optical Variability in CAL 83
• Short-period X-ray oscillations in super-soft novae and persistent SSS
• Multiwavelength observations of V407 Lupi (ASASSN-16kt) --- a very fast nova erupting in an intermediate polar
• Hydrodynamic Studies of the Evolution of Recurrent, Symbiotic, and Dwarf Novae: The White Dwarf Components are Growing in Mass
• The Remarkable Spin-down and Ultra-fast Outflows of the Highly-Pulsed Supersoft Source of Nova Hercules 2021
• XMM-Newton discovery of 217 s pulsations in the brightest persistent supersoft X-ray source in M31
• The Stellar Parameters and Evolutionary State of the Primary in the d'-Symbiotic System StH\alpha190
• Variability and multi-periodic oscillations in the X-ray light curve of the classical nova V4743 Sgr
• The symbiotic recurrent nova V3890 Sgr: binary parameters and pre-outburst activity
• The 2019 eruption of recurrent nova V3890 Sgr: observations by Swift, NICER and SMARTS
• X-ray observations of VY Scl type nova-like binaries in the high and low state
• Optical and X-ray Properties of CAL 83: I. Quasi-periodic Optical and Supersoft Variability
• Chemical and physical parameters from X-ray high resolution spectra of the Galactic nova V959 Mon
• A young contracting white dwarf in the peculiar binary HD 49798/RX J0648.0--4418?
• V4743 Sgr, a magnetic nova?
• The complex X-ray spectrum of the supersoft source MR Vel
• Optical observations of "hot" novae returning to quiescence
• Evolution of X-ray spectra and light curves of V1494 Aquilae
• What we learn from the X-ray grating spectra of Nova SMC 2016
• Spectral analysis of the hybrid PG 1159-type central stars of the planetary nebulae Abell 43 and NGC 7094
• Non-Radial Pulsations in Post-Outburst Novae
• New X-ray observations of the hot subdwarf binary HD49798 / RXJ0648.0-4418
• XMM-Newton observations of MR Vel/RX J0925.7-4758
• Counter evidence against multiple frequency nature of 0.75 mHz oscillation in V4743 Sgr
• Nova LMC 2009a as observed with XMM-Newton, compared with other novae
• X-ray Spectra and Light Curves of Cooling Novae and a Nova-Like
• Chandra grating spectroscopy of three hot white dwarfs
• Chandra observations of nova KT Eridani in outburst
• An eLIMA model for the 67 s X-ray periodicity in CAL 83
• Multiwavelength search for counterparts of supersoft X-ray sources in M31

Cited by in corpus (8)

• The multi-wavelength view of shocks in the fastest nova V1674 Her
• A multiwavelength light curve analysis of the classical nova YZ Ret: An extension of the universal decline law to the nebular phase
• XMM-Newton and SRG/eROSITA observations of the isolated neutron star candidate 4XMM J022141.5-735632
• Mixing of hot shocked plasma with cold gas in Nova YZ Ret 2020
• Application of hydrostatic local thermodynamic equilibrium atmosphere models to interpretations of supersoft X-ray source spectra
• Revisiting multiwavelength data on the supersoft X-ray source CAL 83
• Multi-wavelength study for gamma-ray nova V1405 Cas
• A TESS View of Post-Eruption Variability in the Novae V1405 Cas,V1716 Sco, and V1674 Her