A longer XMM-Newton look at i Zwicky 1: Variability of the X-ray continuum, absorption and iron Kα line

L. C. Gallo, W. N. Brandt, E. Costantini, A. C. Fabian, K. Iwasawa, I. E. Papadakis

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

We present the second XMM-Newton observation (85 ks) of the narrow-line Seyfert 1 galaxy (NLS1) I Zw 1 and describe its mean spectral and timing characteristics. On average, I Zw 1 is ∼35 per cent dimmer in 2005 than in the shorter (20 ks) 2002 observation. Between the two epochs the intrinsic absorption column density diminished, but there were also subtle changes in the continuum shape. Considering the blurred ionized reflection model, the long-term changes can be associated with a varying contribution of the power-law component relative to the total spectrum. Examination of normalized light curves indicates that the high-energy variations are quite structured and that there are delays, but only in some parts of the light curve. Interestingly, a hard X-ray lag first appears during the most distinct structure in the mean light curve, a flux dip ∼25 ks into the observation. The previously discovered broad, ionized Fe Kα line shows significant variations over the course of the 2005 observation. The amplitude of the variations is 25-45 per cent and they are unlikely due to changes in the Fe Kα-producing region, but perhaps arise from orbital motion around the black hole or obscuration in the broad iron-line-emitting region. The 2002 data are re-examined for variability of the Fe Kα line at that epoch. There is evidence of energy and flux variations that are associated with a hard X-ray flare that occurred during that observation.

Original languageEnglish (US)
Pages (from-to)391-401
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Volume377
Issue number1
DOIs
StatePublished - May 1 2007

Fingerprint

K lines
XMM-Newton telescope
newton
continuums
iron
light curve
time measurement
x rays
long-term change
energy
power law
occultation
flares
time lag
examination
galaxies
orbits

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Gallo, L. C. ; Brandt, W. N. ; Costantini, E. ; Fabian, A. C. ; Iwasawa, K. ; Papadakis, I. E. / A longer XMM-Newton look at i Zwicky 1 : Variability of the X-ray continuum, absorption and iron Kα line. In: Monthly Notices of the Royal Astronomical Society. 2007 ; Vol. 377, No. 1. pp. 391-401.
@article{d0531a75b23b46c7a7f870d6c15597e8,
title = "A longer XMM-Newton look at i Zwicky 1: Variability of the X-ray continuum, absorption and iron Kα line",
abstract = "We present the second XMM-Newton observation (85 ks) of the narrow-line Seyfert 1 galaxy (NLS1) I Zw 1 and describe its mean spectral and timing characteristics. On average, I Zw 1 is ∼35 per cent dimmer in 2005 than in the shorter (20 ks) 2002 observation. Between the two epochs the intrinsic absorption column density diminished, but there were also subtle changes in the continuum shape. Considering the blurred ionized reflection model, the long-term changes can be associated with a varying contribution of the power-law component relative to the total spectrum. Examination of normalized light curves indicates that the high-energy variations are quite structured and that there are delays, but only in some parts of the light curve. Interestingly, a hard X-ray lag first appears during the most distinct structure in the mean light curve, a flux dip ∼25 ks into the observation. The previously discovered broad, ionized Fe Kα line shows significant variations over the course of the 2005 observation. The amplitude of the variations is 25-45 per cent and they are unlikely due to changes in the Fe Kα-producing region, but perhaps arise from orbital motion around the black hole or obscuration in the broad iron-line-emitting region. The 2002 data are re-examined for variability of the Fe Kα line at that epoch. There is evidence of energy and flux variations that are associated with a hard X-ray flare that occurred during that observation.",
author = "Gallo, {L. C.} and Brandt, {W. N.} and E. Costantini and Fabian, {A. C.} and K. Iwasawa and Papadakis, {I. E.}",
year = "2007",
month = "5",
day = "1",
doi = "10.1111/j.1365-2966.2007.11601.x",
language = "English (US)",
volume = "377",
pages = "391--401",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "1",

}

A longer XMM-Newton look at i Zwicky 1 : Variability of the X-ray continuum, absorption and iron Kα line. / Gallo, L. C.; Brandt, W. N.; Costantini, E.; Fabian, A. C.; Iwasawa, K.; Papadakis, I. E.

In: Monthly Notices of the Royal Astronomical Society, Vol. 377, No. 1, 01.05.2007, p. 391-401.

Research output: Contribution to journalArticle

TY - JOUR

T1 - A longer XMM-Newton look at i Zwicky 1

T2 - Variability of the X-ray continuum, absorption and iron Kα line

AU - Gallo, L. C.

AU - Brandt, W. N.

AU - Costantini, E.

AU - Fabian, A. C.

AU - Iwasawa, K.

AU - Papadakis, I. E.

PY - 2007/5/1

Y1 - 2007/5/1

N2 - We present the second XMM-Newton observation (85 ks) of the narrow-line Seyfert 1 galaxy (NLS1) I Zw 1 and describe its mean spectral and timing characteristics. On average, I Zw 1 is ∼35 per cent dimmer in 2005 than in the shorter (20 ks) 2002 observation. Between the two epochs the intrinsic absorption column density diminished, but there were also subtle changes in the continuum shape. Considering the blurred ionized reflection model, the long-term changes can be associated with a varying contribution of the power-law component relative to the total spectrum. Examination of normalized light curves indicates that the high-energy variations are quite structured and that there are delays, but only in some parts of the light curve. Interestingly, a hard X-ray lag first appears during the most distinct structure in the mean light curve, a flux dip ∼25 ks into the observation. The previously discovered broad, ionized Fe Kα line shows significant variations over the course of the 2005 observation. The amplitude of the variations is 25-45 per cent and they are unlikely due to changes in the Fe Kα-producing region, but perhaps arise from orbital motion around the black hole or obscuration in the broad iron-line-emitting region. The 2002 data are re-examined for variability of the Fe Kα line at that epoch. There is evidence of energy and flux variations that are associated with a hard X-ray flare that occurred during that observation.

AB - We present the second XMM-Newton observation (85 ks) of the narrow-line Seyfert 1 galaxy (NLS1) I Zw 1 and describe its mean spectral and timing characteristics. On average, I Zw 1 is ∼35 per cent dimmer in 2005 than in the shorter (20 ks) 2002 observation. Between the two epochs the intrinsic absorption column density diminished, but there were also subtle changes in the continuum shape. Considering the blurred ionized reflection model, the long-term changes can be associated with a varying contribution of the power-law component relative to the total spectrum. Examination of normalized light curves indicates that the high-energy variations are quite structured and that there are delays, but only in some parts of the light curve. Interestingly, a hard X-ray lag first appears during the most distinct structure in the mean light curve, a flux dip ∼25 ks into the observation. The previously discovered broad, ionized Fe Kα line shows significant variations over the course of the 2005 observation. The amplitude of the variations is 25-45 per cent and they are unlikely due to changes in the Fe Kα-producing region, but perhaps arise from orbital motion around the black hole or obscuration in the broad iron-line-emitting region. The 2002 data are re-examined for variability of the Fe Kα line at that epoch. There is evidence of energy and flux variations that are associated with a hard X-ray flare that occurred during that observation.

UR - http://www.scopus.com/inward/record.url?scp=34247868036&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34247868036&partnerID=8YFLogxK

U2 - 10.1111/j.1365-2966.2007.11601.x

DO - 10.1111/j.1365-2966.2007.11601.x

M3 - Article

AN - SCOPUS:34247868036

VL - 377

SP - 391

EP - 401

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 1

ER -