PMN J0525-3343: Soft X-ray spectral flattening in a blazar at z = 4.4

A. C. Fabian, A. Celotti, K. Iwasawa, R. G. McMahon, C. L. Carilli, W. N. Brandt, G. Ghisellini, I. M. Hook

Research output: Contribution to journalArticle

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Abstract

We report optical, radio and X-ray observations of a new distant blazar, PMN J0525-3343, at a redshift of 4.4. The X-ray spectrum measured from ASCA and BeppoSAX flattens below a few keV, in a manner similar to the spectra of two other z > 4 blazars, GB 1428+4217 (z = 4.72) reported by Boller et al. and RXJ1028.6-0844 (z = 4.28) reported by Yuan et al. The spectrum is well fitted by a power-law continuum which either is absorbed or breaks at a few keV. An intrinsic column density corresponding to 2 × 1023 H-atoms cm-2 at solar abundance is required by the absorption model. This is however a million times greater than the neutral hydrogen, or dust, column density implied by the optical spectrum, which covers the rest-frame ultraviolet emission of the blazar nucleus. We discuss the problems raised and suggest that, unless there is intrinsic flattening in the spectral distribution of the particles/ seed photons producing X-rays via inverse Compton scattering, the most plausible solution is a warm absorber close to the active nucleus.

Original languageEnglish (US)
Pages (from-to)373-379
Number of pages7
JournalMonthly Notices of the Royal Astronomical Society
Volume323
Issue number2
DOIs
StatePublished - May 11 2001

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flattening
blazars
nuclei
x rays
ultraviolet emission
optical spectrum
seeds
absorbers
dust
continuums
power law
scattering
photons
hydrogen
radio
seed
atoms

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Fabian, A. C. ; Celotti, A. ; Iwasawa, K. ; McMahon, R. G. ; Carilli, C. L. ; Brandt, W. N. ; Ghisellini, G. ; Hook, I. M. / PMN J0525-3343 : Soft X-ray spectral flattening in a blazar at z = 4.4. In: Monthly Notices of the Royal Astronomical Society. 2001 ; Vol. 323, No. 2. pp. 373-379.
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abstract = "We report optical, radio and X-ray observations of a new distant blazar, PMN J0525-3343, at a redshift of 4.4. The X-ray spectrum measured from ASCA and BeppoSAX flattens below a few keV, in a manner similar to the spectra of two other z > 4 blazars, GB 1428+4217 (z = 4.72) reported by Boller et al. and RXJ1028.6-0844 (z = 4.28) reported by Yuan et al. The spectrum is well fitted by a power-law continuum which either is absorbed or breaks at a few keV. An intrinsic column density corresponding to 2 × 1023 H-atoms cm-2 at solar abundance is required by the absorption model. This is however a million times greater than the neutral hydrogen, or dust, column density implied by the optical spectrum, which covers the rest-frame ultraviolet emission of the blazar nucleus. We discuss the problems raised and suggest that, unless there is intrinsic flattening in the spectral distribution of the particles/ seed photons producing X-rays via inverse Compton scattering, the most plausible solution is a warm absorber close to the active nucleus.",
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Fabian, AC, Celotti, A, Iwasawa, K, McMahon, RG, Carilli, CL, Brandt, WN, Ghisellini, G & Hook, IM 2001, 'PMN J0525-3343: Soft X-ray spectral flattening in a blazar at z = 4.4', Monthly Notices of the Royal Astronomical Society, vol. 323, no. 2, pp. 373-379. https://doi.org/10.1046/j.1365-8711.2001.04181.x

PMN J0525-3343 : Soft X-ray spectral flattening in a blazar at z = 4.4. / Fabian, A. C.; Celotti, A.; Iwasawa, K.; McMahon, R. G.; Carilli, C. L.; Brandt, W. N.; Ghisellini, G.; Hook, I. M.

In: Monthly Notices of the Royal Astronomical Society, Vol. 323, No. 2, 11.05.2001, p. 373-379.

Research output: Contribution to journalArticle

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T2 - Soft X-ray spectral flattening in a blazar at z = 4.4

AU - Fabian, A. C.

AU - Celotti, A.

AU - Iwasawa, K.

AU - McMahon, R. G.

AU - Carilli, C. L.

AU - Brandt, W. N.

AU - Ghisellini, G.

AU - Hook, I. M.

PY - 2001/5/11

Y1 - 2001/5/11

N2 - We report optical, radio and X-ray observations of a new distant blazar, PMN J0525-3343, at a redshift of 4.4. The X-ray spectrum measured from ASCA and BeppoSAX flattens below a few keV, in a manner similar to the spectra of two other z > 4 blazars, GB 1428+4217 (z = 4.72) reported by Boller et al. and RXJ1028.6-0844 (z = 4.28) reported by Yuan et al. The spectrum is well fitted by a power-law continuum which either is absorbed or breaks at a few keV. An intrinsic column density corresponding to 2 × 1023 H-atoms cm-2 at solar abundance is required by the absorption model. This is however a million times greater than the neutral hydrogen, or dust, column density implied by the optical spectrum, which covers the rest-frame ultraviolet emission of the blazar nucleus. We discuss the problems raised and suggest that, unless there is intrinsic flattening in the spectral distribution of the particles/ seed photons producing X-rays via inverse Compton scattering, the most plausible solution is a warm absorber close to the active nucleus.

AB - We report optical, radio and X-ray observations of a new distant blazar, PMN J0525-3343, at a redshift of 4.4. The X-ray spectrum measured from ASCA and BeppoSAX flattens below a few keV, in a manner similar to the spectra of two other z > 4 blazars, GB 1428+4217 (z = 4.72) reported by Boller et al. and RXJ1028.6-0844 (z = 4.28) reported by Yuan et al. The spectrum is well fitted by a power-law continuum which either is absorbed or breaks at a few keV. An intrinsic column density corresponding to 2 × 1023 H-atoms cm-2 at solar abundance is required by the absorption model. This is however a million times greater than the neutral hydrogen, or dust, column density implied by the optical spectrum, which covers the rest-frame ultraviolet emission of the blazar nucleus. We discuss the problems raised and suggest that, unless there is intrinsic flattening in the spectral distribution of the particles/ seed photons producing X-rays via inverse Compton scattering, the most plausible solution is a warm absorber close to the active nucleus.

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