2015A&A...579A..24B


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.08CEST03:45:26

2015A&A...579A..24B - Astronomy and Astrophysics, volume 579A, 24-24 (2015/7-1)

Quasi-periodic oscillations in accreting magnetic white dwarfs. I. Observational constraints in X-ray and optical.

BONNET-BIDAUD J.M., MOUCHET M., BUSSCHAERT C., FALIZE E. and MICHAUT C.

Abstract (from CDS):

Quasi-periodic oscillations (QPOs) are observed in the optical flux of some polars with typical periods of 1 to 3s but none have been observed yet in X-rays where a significant part of the accreting energy is released. QPOs are expected and predicted from shock oscillations. Most of the polars have been observed by the XMM-Newton satellite. We made use of the homogeneous set of observations of the polars by XMM-Newton to search for the presence of QPOs in the (0.5-10keV) energy range and to set significant upper limits for the brightest X-ray polars. We extracted high time-resolution X-ray light curves by taking advantage of the 0.07s resolution of the EPIC-PN camera. Among the 65 polars observed with XMM-Newton from 1998 to 2012, a sample of 24 sources was selected on the basis of their counting rate in the PN instrument to secure significant limits. We searched for QPOs using Fast Fourier Transform (FFT) methods and defined limits of detection using statistical tools. Among the sample surveyed, none shows QPOs at a significant level. Upper limits to the fractional flux in QPOs range from 7% to 71%. These negative results are compared to the detailed theoretical predictions of numerical simulations based on a 2D hydrodynamical code presented in Paper II. Cooling instabilities in the accretion column are expected to produce shock quasi-oscillations with a maximum amplitude reaching ∼40% in the bremsstrahlung (0.5-10keV) X-ray emission and ∼20% in the optical cyclotron emission. The absence of X-ray QPOs imposes an upper limit of ~(5-10)g/cm2/s on the specific accretion rate but this condition is found inconsistent with the value required to account for the amplitudes and frequencies of the observed optical QPOs. This contradiction outlines probable shortcomings with the shock instability model.

Abstract Copyright:

Journal keyword(s): accretion, accretion disks - instabilities - shock waves - white dwarfs - X-rays: binaries

Simbad objects: 27

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Number of rows : 27

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 V* BL Hyi NL* 01 41 00.3995669445 -67 53 27.469105974   14.9       Am 201 0
2 V* FL Cet AM* 01 55 43.4035546376 +00 28 07.157100597   16.6 15.5     ~ 45 0
3 V* AI Tri AM* 02 03 48.6152251668 +29 59 25.898735063           M2.5 39 1
4 V* WW Hor AM* 02 36 11.45 -52 19 13.5   18.4       ~ 74 0
5 V* EF Eri NL* 03 14 13.2527107604 -22 35 42.917018996   15.4 14.53 13.5   ~ 410 0
6 V* UZ For AM* 03 35 28.6515678221 -25 44 21.765602833           M4.5 245 0
7 V* V1309 Ori AM* 05 15 41.4123841919 +01 04 40.479107028           M0.5 99 0
8 V* BY Cam AM* 05 42 48.8013255299 +60 51 31.375887904   16.60       ~ 234 0
9 V* HS Cam AM* 07 19 14.5151105423 +65 57 44.305352490   19.01       ~ 23 0
10 V* EU Lyn CV* 07 52 40.4514761660 +36 28 23.199330756           ~ 13 0
11 V* VV Pup AM* 08 15 06.8010742098 -19 03 17.765651066     13.90     M7V 384 0
12 RX J1007.5-2017 AM* 10 07 34.6534874108 -20 17 32.448845919     18.0     ~ 26 0
13 V* GG Leo AM* 10 15 34.6778640025 +09 04 41.987298295           ~ 44 0
14 V* AN UMa AM* 11 04 25.6556953228 +45 03 13.941355292     14.90     ~ 245 0
15 V* ST LMi AM* 11 05 39.7662126421 +25 06 28.744817170   15.10       DAH+M 210 0
16 V* DP Leo AM* 11 17 15.9238061197 +17 57 41.680410866           ~ 210 1
17 V* EV UMa AM* 13 07 53.8583243765 +53 51 30.498937628           ~ 60 0
18 V* V834 Cen AM* 14 09 07.2853539143 -45 17 16.015131476   16.0       M6.5 301 0
19 2MASS J14534105-5521387 CV* 14 53 41.0567066564 -55 21 38.719483656           ~ 31 0
20 V* V2301 Oph NL* 18 00 35.5318080632 +08 10 13.920659251           ~ 88 0
21 V* AM Her AM* 18 16 13.2546541781 +49 52 04.759861155     12.30     M4.5 911 0
22 V* V347 Pav AM* 18 44 48.2635326025 -74 18 34.218756613           ~ 57 0
23 V* EP Dra AM* 19 07 06.1869434379 +69 08 43.874477498   18       ~ 57 0
24 V* QS Tel AM* 19 38 35.8145594082 -46 12 57.107614734           ~ 110 0
25 2MASS J20501785-0536269 CV* 20 50 17.86 -05 36 26.9           ~ 16 0
26 V* HU Aqr AM* 21 07 58.1945403160 -05 17 40.557984218   15.1   15.4   D+M4V 256 1
27 V* CD Ind AM* 21 15 41.0456943110 -58 40 54.060875785           ~ 79 0

    Equat.    Gal    SGal    Ecl

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2020.07.08-03:45:26

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