Toward Robust Detection of a Faint Narrow Line in X-Rays – the Role of Continuum-Induced Systematics

  • D. O. Savchenko Bogolyubov Institute for Theoretical Physics
  • D. A. Iakubovskyi Discovery Center, Niels Bohr Institute, Bogolyubov Institute for Theoretical Physics
Keywords: X-rays, general line, identification of the dark matter

Abstract

Some of recent detections of a narrow emission line at ∼3.5 keV have been accompanied by subsequent non-detections in the same sources, raising discussion about the actual level of systematic errors. In this paper, we study the systematics caused by an imperfect knowledge of a continuum model. Our simple theoretical estimate and detailed modeling of simulated spectra allow us to calculate the value of this “continuum-induced” systematics for the first time. We show that, for some objects such as the M31 central part or the Draco dwarf spheroidal galaxy, the obtained level of systematics within a well-defined continuum model allows one to fully reconcile the controversial results claimed previously by different groups of authors. To minimize the effect of “continuum-induced” systematics, we show that one should reasonably decrease the size of the spectral bin and increase the modeled energy range.

References

J. Truemper, W. Pietsch, C. Reppin, W. Voges, R. Staubert, E. Kendziorra. Evidence for strong cyclotron line emission in the hard X-ray spectrum of Hercules X-1. Astrophys. J. 219, L105 (1978).

https://doi.org/10.1086/182617

T.-P. Li, Y.-Q. Ma. Analysis methods for results in gammaray astronomy. Astrophys. J. 272, 317 (1983).

https://doi.org/10.1086/161295

R. Protassov, D.A. van Dyk, A. Connors, V.L. Kashyap, A. Siemiginowska. Statistics, handle with care: Detecting multiple model components with the likelihood ratio test. Astrophys. J. 571, 545 (2002), astro-ph/0201547.

https://doi.org/10.1086/339856

K. Nandra, P.M. O'Neill, I.M. George, J.N. Reeves. An XMM–newton survey of broad iron lines in Seyfert galaxies. Mon. Not. R. Astr. Soc. 382, 194 (2007).

https://doi.org/10.1111/j.1365-2966.2007.12331.x

M.G. Malygin, D.A. Iakubovskyi. Search for cyclotron absorptions from > magnetars in the quiescence with XMMNewton . In Proceedings of the 17th Conference of Young Scientists, edited by V. Choliy, G. Ivashchenko, and O. Ivaniuk (2011), p. 43.

M. Ackermann, M. Ajello, A. Albert, L. Baldini, G. Barbiellini, K. Bechtol, R. Bellazzini, B. Berenji, R.D. Blandford, E.D. Bloom et al. Fermi LAT search for dark matter in gamma-ray lines and the inclusive photon spectrum. Phys. Rev. D 86, 022002 (2012).

https://doi.org/10.1103/PhysRevD.86.022002

A. Abramowski, F. Acero, F. Aharonian, A. G. Akhperjanian, G. Anton, S. Balenderan, A. Balzer, A. Barnacka, Y. Becherini, J. Becker Tjus et al. Search for photonlinelike signatures from dark matter annihilations with H.E.S.S. Phys. Rev. Lett. 110, 041301 (2013).

https://doi.org/10.1103/PhysRevLett.110.041301

S. Campana, V. Braito, P. D'Avanzo, G. Ghirlanda, A. Melandri, A. Pescalli, O.S. Salafia, R. Salvaterra, G. Tagliaferri, S.D. Vergani. Searching for narrow absorption and emission lines in XMM-Newton spectra of gamma-ray bursts. Astr. Astrophys. 592, A85 (2016).

https://doi.org/10.1051/0004-6361/201628402

D. Iakubovskyi. Observation of the new line at 3.55 keV in X-ray spectra of galaxies and galaxy clusters. Adv. Astr. Space Phys. 6, 3 (2016).

https://doi.org/10.17721/2227-1481.6.3-15

E. Bulbul, M. Markevitch, A. Foster, R.K. Smith, M. Loewenstein, S.W. Randall. Detection of an unidentified emission line in the stacked X-ray spectrum of galaxy clusters. Astrophys. J. 789, 13 (2014).

https://doi.org/10.1088/0004-637X/789/1/13

F. Jansen, D. Lumb, B. Altieri, J. Clavel, M. Ehle, C. Erd, C. Gabriel, M. Guainazzi, P. Gondoin, R. Much et al. XMM-Newton observatory. I. The spacecraft and operations. Astr. Astrophys. 365, L1 (2001).

https://doi.org/10.1051/0004-6361:20000036

M.C. Weisskopf, H.D. Tananbaum, L.P. Van Speybroeck, S.L. O'Dell. Chandra X-ray observatory (CXO): Overview. In X-Ray Optics, Instruments, and Missions III, edited by J.E. Truemper and B. Aschenbach. Proc. SPIE 4012, 2 (2000); astro-ph/0004127.

A. Boyarsky, O. Ruchayskiy, D. Iakubovskyi, J. Franse. Unidentified line in X-ray spectra of the Andromeda galaxy and Perseus galaxy cluster. Phys. Rev. Lett. 113, 251301 (2014).

https://doi.org/10.1103/PhysRevLett.113.251301

T. Jeltema, S. Profumo. Discovery of a 3.5 keV line in the Galactic Centre and a critical look at the origin of the line across astronomical targets. Mon. Not. R. Astr. Soc. 450, 2143 (2015).

https://doi.org/10.1093/mnras/stv768

A. Boyarsky, J. Franse, D. Iakubovskyi, O. Ruchayskiy. Comment on the paper "Dark matter searches going bananas: The contribution of potassium (and chlorine) to the 3.5 keV line" by T. Jeltema and S. Profumo. e-prints http://adsabs.harvard.edu/abs/ 2014arXiv1408.4388B (2014).

T. Jeltema, S. Profumo. Reply to two comments on "Dark matter searches going bananas: The contribution of potassium (and chlorine) to the 3.5 keV line". e-prints http://adsabs.harvard.edu/abs/ 2014arXiv1411.1759J (2014).

T. Jeltema, S. Profumo. Deep XMM observations of Draco rule out at the 99 per cent confidence level a dark matter decay origin for the 3.5 keV line. Mon. Not. R. Astr. Soc. 458, 3592 (2016).

https://doi.org/10.1093/mnras/stw578

O. Ruchayskiy, A. Boyarsky, D. Iakubovskyi, E. Bulbul, D. Eckert, J. Franse, D. Malyshev, M. Markevitch, A. Neronov. Searching for decaying dark matter in deep XMM–Newton observation of the Draco dwarf spheroidal. Mon. Not. R. Astr. Soc. 460, 1390 (2016).

https://doi.org/10.1093/mnras/stw1026

M.J.L. Turner, A. Abbey, M. Arnaud, M. Balasini, M. Barbera, E. Belsole, P.J. Bennie, J.P. Bernard, G.F. Bignami, M. Boer et al. The European photon imaging camera on XMM-Newton: The MOS cameras: The MOS cameras. Astr. Astrophys. 365, L27 (2001), astro-ph/0011498.

L. Str¨uuder, U. Briel, K. Dennerl, R. Hartmann, E. Kendziorra, N. Meidinger, E. Pfeffermann, C. Reppin, B. Aschenbach, W. Bornemann et al. The European photon imaging camera on XMM-Newton: The pn-CCD camera. Astr. Astrophys. 365, L18 (2001).

https://doi.org/10.1051/0004-6361:20000066

K. Mitsuda, M. Bautz, H. Inoue, R.L. Kelley, K. Koyama, H. Kunieda, K. Makishima, Y. Ogawara, R. Petre, T. Takahashi et al. The X-ray observatory Suzaku. Publ. Astr. Soc. Jap. 59, 1 (2007).

https://doi.org/10.1093/pasj/59.sp1.S1

O. Urban, N. Werner, S. W. Allen, A. Simionescu, J.S. Kaastra, L.E. Strigari. A Suzaku search for dark matter emission lines in the X-ray brightest galaxy clusters. Mon. Not. R. Astr. Soc. 451, 2447 (2015).

https://doi.org/10.1093/mnras/stv1142

J. Franse, E. Bulbul, A. Foster, A. Boyarsky, M. Markevitch, M. Bautz, D. Iakubovskyi, M. Loewenstein, M. McDonald, E. Miller et al. Radial profile of the 3.55 keV line out to _200 in the Perseus cluster. Astrophys. J. 829, 124 (2016).

https://doi.org/10.3847/0004-637X/829/2/124

T. Tamura, R. Iizuka, Y. Maeda, K. Mitsuda, N.Y. Yamasaki. An X-ray spectroscopic search for dark matter in the zerseus cluster with Suzaku. Publ. Astr. Soc. Jap. 67, 23 (2015).

Hitomi Collaboration, F. A. Aharonian, H. Akamatsu, F. Akimoto, S. W. Allen, L. Angelini, K. A. Arnaud, M. Audard, H. Awaki, M. Axelsson et al. Hitomi constraints on the 3.5 keV line in the Perseus galaxy cluster. Astrophys. J. 837, L15 (2017).

https://doi.org/10.3847/2041-8213/aa61fa

E. Bulbul, M. Markevitch, A. Foster, E. Miller, M. Bautz, M. Loewenstein, S.W. Randall, R.K. Smith. Searching for the 3.5 keV line in the stacked Suzaku observations of galaxy clusters. Astrophys. J. 831, 55 (2016).

https://doi.org/10.3847/0004-637X/831/1/55

F. Mernier, J. de Plaa, C. Pinto, J.S. Kaastra, P. Kosec, Y.-Y. Zhang, J. Mao, N. Werner. On the origin of central abundances in the hot intra-cluster medium – I. Individual and average abundance ratios from XMM-Newton EPIC. Astr. Astrophys. 592, A157 (2016).

https://doi.org/10.1051/0004-6361/201527824

F. Hofmann, J.S. Sanders, K. Nandra, N. Clerc, M. Gaspari. 7.1 keV sterile neutrino constraints from X-ray observations of 33 clusters of galaxies with Chandra ACIS. Astr. Astrophys. 592, A112 (2016).

https://doi.org/10.1051/0004-6361/201527977

D. Iakubovskyi, E. Bulbul, A.R. Foster, D. Savchenko, V. Sadova. Testing the origin of ∼3.55 keV line in individual galaxy clusters observed with XMM-Newton. e-prints http://adsabs.harvard.edu/abs/ 2015arXiv150805186I (2015).

P.R. Bevington, D.K. Robinson. Data reduction and error analysis for the physical sciences. 3rd ed. (McGraw-Hill, 2003) [ISBN: 0-07-247227-8].

E. Figueroa-Feliciano, A.J. Anderson, D. Castro, D.C. Goldfinger, J. Rutherford, M.E. Eckart, R.L. Kelley, C.A. Kilbourne, D. McCammon, K. Morgan et al. Searching for kev sterile neutrino dark matter with X-ray microcalorimeter sounding rockets. Astrophys. J. 814, 82 (2015).

https://doi.org/10.1088/0004-637X/814/1/82

T. Takahashi, K. Mitsuda, R. Kelley, F. Aharonian, H. Akamatsu, F. Akimoto, S. Allen, N. Anabuki, L. Angelini, K. Arnaud et al. The ASTRO-H X-ray astronomy satellite. In Society of Photo-Optical Instrumentation Engineers (SPIE), Conference Series (2014), vol. 9144 of Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, p. 25.

K. Mitsuda, R.L. Kelley, H. Akamatsu, T. Bialas, K.R. Boyce, G. V. Brown, E. Canavan, M. Chiao, E. Costantini, J.-W. den Herder et al. Soft X-ray spectrometer (SXS): the high-resolution cryogenic spectrometer onboard ASTROH. in Society of Photo-Optical Instrumentation Engineers (SPIE), Conference Series (2014), vol. 9144, p. 2.

Hitomi Collaboration, F. Aharonian, H. Akamatsu, F. Akimoto, S. W. Allen, N. Anabuki, L. Angelini, K. Arnaud, M. Audard, H. Awaki et al. The quiescent intracluster medium in the core of the Perseus cluster. Nature 535, 117 (2016).

https://doi.org/10.1038/nature18627

D. Barret, J.W. den Herder, L. Piro, L. Ravera, R. Den Hartog, C. Macculi, X. Barcons, M. Page, S. Paltani, G. Rauw et al. The hot and energetic universe: The X-ray integral field unit (X-IFU) for athena+. e-prints http:// adsabs.harvard.edu/abs/2013arXiv1308.6784B (2013).

L. Ravera, D. Barret, J.W. den Herder, L. Piro, R. Cl´edassou, E. Pointecouteau, P. Peille, F. Pajot, M. Arnaud, C. Pigot et al. The X-ray integral field unit (X-IFU) for athena. In Society of Photo-Optical Instrumentation Engineers (SPIE), Conference Series (2014), vol. 9144, p. 2.

K. Nandra, D. Barret, X. Barcons, A. Fabian, J.-W. den Herder, L. Piro, M. Watson, C. Adami, J. Aird, J.M. Afonso et al. The hot and energetic Universe: A white paper presenting the science theme motivating the athena+ mission. e-prints http://adsabs.harvard.edu/abs/2013arXiv1306.2307N (2013).

D. Barret, K. Nandra, X. Barcons, A. Fabian, J.W. den Herder, L. Piro, M. Watson, J. Aird, G. BranduardiRaymont, M. Cappi et al. Athena+: The first deep universe X-ray observatory. In SF2A- 2013: Proceedings of the Annual Meeting of the French Society of Astronomy and Astrophysics, edited by L. Cambresy, F. Martins, E. Nuss, and A. Palacios (2013), p. 447.

A. Merloni, P. Predehl, W. Becker, H. B¨ohringer, T. Boller, H. Brunner, M. Brusa, K. Dennerl, M. Freyberg, P. Friedrich et al. eROSITA science book: Mapping the structure of the energetic universe. e-prints http://adsabs.harvard.edu/abs/2012arXiv1209.3114M (2012).

S. Zane, D. Walton, T. Kennedy, M. Feroci, J.- W. Den Herder, M. Ahangarianabhari, A. Argan, P. Azzarello, G. Baldazzi, M. Barbera et al. The large area detector of LOFT: The large observatory for X-ray timing. in Society of Photo-Optical Instrumentation Engineers (SPIE), Conference Series (2014), vol. 9144, p. 2, 1408.6539.

A. Boyarsky, J. den Herder, A. Neronov, O. Ruchayskiy. Search for the light dark matter with an X-ray spectrometer. Astroparticle Phys. 28, 303 (2007), astro-ph/0612219.

https://doi.org/10.1016/j.astropartphys.2007.06.003

A. Boyarsky, D. Iakubovskyi, O. Ruchayskiy. Next decade of sterile neutrino studies. Physics of the Dark Universe 1, 136 (2012).

https://doi.org/10.1016/j.dark.2012.11.001

A. Neronov, A. Boyarsky, D. Iakubovskyi, O. Ruchayskiy. Potential of the large observatory for X-ray timing tele648 scope for the search for dark matter. Phys. Rev. D 90, 123532 (2014).

https://doi.org/10.1103/PhysRevD.90.123532

D. Iakubovskyi. Checking the potassium origin of the new emission line at 3.5 keV using the K XIX line complex at 3.7 keV. Mon. Not. R. Astr. Soc. 453, 4097 (2015).

https://doi.org/10.1093/mnras/stv1955

A. Neronov, D. Malyshev. Toward a full test of the MSM sterile neutrino dark matter model with Athena. Phys. Rev. D 93, 063518 (2016).

https://doi.org/10.1103/PhysRevD.93.063518

F. Zandanel, C. Weniger, S. Ando. The role of the eROSITA all-sky survey in searches for sterile neutrino dark matter. JCAP 9, 060 (2015).

A. Neronov, D. Malyshev, D. Eckert. Decaying dark matter search with NuSTAR deep sky observations. Phys. Rev. D 94, 123504 (2016).

https://doi.org/10.1103/PhysRevD.94.123504

K. Perez, K.C.Y. Ng, J.F. Beacom, C. Hersh, S. Horiuchi, R. Krivonos. (Almost) Closing the MSM sterile neutrino dark matter window with NuSTAR. Phys. Rev. D 95, 123002 (2017).

https://doi.org/10.1103/PhysRevD.95.123002

F.A. Harrison, W.W. Craig, F.E. Christensen, C.J. Hailey, W.W. Zhang, S.E. Boggs, D. Stern, W.R. Cook, K. Forster, P. Giommi et al. The nuclear spectroscopic telescope array (NuSTAR) high-energy X-ray mission. Astrophys. J. 770, 103 (2013).

https://doi.org/10.1088/0004-637X/770/2/103

K.A. Arnaud. XSPEC and PyXSPEC. In AAS/High Energy Astrophysics Division (2016), vol. 15, p. 115.02.

J.S. Kaastra, J.A.M. Bleeker. Optimal binning of X-ray spectra and response matrix design. Astr. Astrophys. 587, A151 (2016).

https://doi.org/10.1051/0004-6361/201527395

Published
2018-12-13
How to Cite
Savchenko, D., & Iakubovskyi, D. (2018). Toward Robust Detection of a Faint Narrow Line in X-Rays – the Role of Continuum-Induced Systematics. Ukrainian Journal of Physics, 62(7), 642. https://doi.org/10.15407/ujpe62.07.0642
Section
Astrophysics and cosmology