The NuSTAR View of the Seyfert 2 Galaxy NGC 4388

We present an analysis of NuSTAR X-ray observations in the 3–79 keV energy band of the Seyfert 2 galaxy NGC 4388, taken in 2013. The broadband sensitivity of NuSTAR, covering the Fe Kα line and Compton reflection hump, enables tight constraints to be placed on reflection features in AGN X-ray spectra, thereby providing insight into the geometry of the circumnuclear material. In this observation, we found the X-ray spectrum of NGC 4388 to be well described by a moderately absorbed power law with non-relativistic reflection. We fit the spectrum with phenomenological reflection models and a physical torus model and find the source to be absorbed by Compton-thin material (NH = (6.5 ± 0.8) × 1023 cm−2) with a very weak Compton reflection hump (R < 0.09) and an exceptionally large Fe Kα line eV) for a source with weak or no reflection. Calculations using a thin-shell approximation for the expected Fe Kα EW indicate that an Fe Kα line originating from Compton-thin material presents a possible explanation.

[1]  Mauricio Solar,et al.  Astronomical data analysis software and systems , 2018, Astron. Comput..

[2]  D. Walton,et al.  A GROWTH-RATE INDICATOR FOR COMPTON-THICK ACTIVE GALACTIC NUCLEI , 2016, 1606.09265.

[3]  W. Brandt,et al.  NuSTAR observations of water megamaser AGN , 2016, 1602.03185.

[4]  Kristin K. Madsen,et al.  CALIBRATION OF THE NuSTAR HIGH-ENERGY FOCUSING X-RAY TELESCOPE , 2015, 1504.01672.

[5]  A. Markowitz,et al.  TRACKING THE COMPLEX ABSORPTION IN NGC 2110 WITH TWO SUZAKU OBSERVATIONS , 2014, 1403.1904.

[6]  A. Markowitz,et al.  FULL SPECTRAL SURVEY OF ACTIVE GALACTIC NUCLEI IN THE ROSSI X-RAY TIMING EXPLORER ARCHIVE , 2013, 1306.4376.

[7]  William W. Zhang,et al.  THE NUCLEAR SPECTROSCOPIC TELESCOPE ARRAY (NuSTAR) HIGH-ENERGY X-RAY MISSION , 2013, Astronomical Telescopes and Instrumentation.

[8]  M. Elitzur.  ON THE UNIFICATION OF ACTIVE GALACTIC NUCLEI , 2012, 1202.1776.

[9]  Cfa,et al.  Hard X-ray spectral variability of the brightest Seyfert AGN in the Swift/BAT sample , 2011, 1108.6017.

[10]  S. Soldi,et al.  Studying the long-time variability of the Seyfert 2 galaxy NGC 4388 with INTEGRAL and Swift , 2011 .

[11]  M. Reid,et al.  THE MEGAMASER COSMOLOGY PROJECT. III. ACCURATE MASSES OF SEVEN SUPERMASSIVE BLACK HOLES IN ACTIVE GALAXIES WITH CIRCUMNUCLEAR MEGAMASER DISKS , 2010, 1008.2146.

[12]  K. Nandra,et al.  An XMM–Newton spectral survey of 12 μm selected galaxies – I. X-ray data , 2010, 1012.3345.

[13]  T. Yaqoob,et al.  An X-ray spectral model for Compton-thick toroidal reprocessors , 2009, 0905.3188.

[14]  P. S. Bunclark,et al.  Astronomical Data Analysis Software and Systems , 2008 .

[15]  T. Tsuru,et al.  Detailed Hard X-Ray Measurements of Nuclear Emission from the Seyfert2 Galaxy NGC4388 with Suzaku , 2008 .

[16]  S. Komossa.  Narrow-line Seyfert 1 galaxies , 2007, 0710.3326.

[17]  Observatoire de la Cote d'Azur,et al.  Resolving the complex structure of the dust torus in the active nucleus of the Circinus galaxy , 2007, 0709.0209.

[18]  Martin Elvis,et al.  An Unveiling Event in the Type 2 Active Galactic Nucleus NGC 4388:A Challenge for a Parsec-Scale Absorber , 2004, astro-ph/0407291.

[19]  N. Gehrels,et al.  INTEGRAL AND XMM-NEWTON SPECTRAL STUDIES OF NGC 4388 , 2004, astro-ph/0406553.

[20]  G. Risaliti,et al.  The BeppoSAX view of bright Compton-thin Seyfert 2 galaxies , 2002, astro-ph/0202392.

[21]  T. J. Turner,et al.  Physical Diagnostics from a Narrow Fe Kα Emission Line Detected by Chandra in the Seyfert 1 Galaxy NGC 5548 , 2000, astro-ph/0008471.

[22]  J. Wilms,et al.  Absorption Of X-rays In The Interstellar Medium , 2000, astro-ph/0008425.

[23]  R. Terlevich,et al.  Seyfert 1 Mutation of the Classical Seyfert 2 Nucleus NGC 7582 , 1999, astro-ph/9905147.

[24]  D. A. Verner,et al.  Atomic data for astrophysics. II. New analytic fits for photoionization cross sections of atoms and ions , 1996 .

[25]  A. Zdziarski,et al.  Angle-dependent Compton reflection of X-rays and gamma-rays , 1995 .

[26]  Robert Antonucci,et al.  Unified models for active galactic nuclei and quasars , 1993 .

[27]  Andrew C. Fabian,et al.  X-ray reflection from cold matter in Active Galactic Nuclei and X-ray binaries , 1991 .

[28]  Julian H. Krolik,et al.  Molecular tori in Seyfert galaxies - Feeding the monster and hiding it , 1988 .

[29]  D. Malin,et al.  NGC 4388: a Seyfert 2 galaxy in the Virgo cluster , 1982 .

[30]  D. Schwartz.  The X-ray luminosity function of Abell clusters. , 1976 .