J/A+A/676/A49 J1030+0524 field spectral catalog (Signorini+, 2023)
X-ray properties and obscured fraction of AGN in the J1030 Chandra field.
Signorini M., Marchesi S., Gilli R., Brusa M., Comastri A., D'Amato Q.,
Iwasawa K., Lanzuisi G., Mazzolari G., Mignoli M., Peca A., Prandoni I.,
Tozzi P., Vignali C., Vito F., Norman C.
<Astron. Astrophys. 676, A49 (2023)>
=2023A&A...676A..49S 2023A&A...676A..49S (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; X-ray sources ; Redshifts
Keywords: galaxies: active - X-rays: general - galaxies: high-redshift -
quasars: supermassive black holes
Abstract:
The 500ks Chandra ACIS-I observation of the field around the z=6.31
quasar SDSS J1030+0524 is currently the fifth deepest extragalactic
X-ray survey. The rich multi-band coverage of the field allowed an
effective identification and redshift determination of the X-ray
source counterparts; to date, a catalog of 243 extragalactic X-ray
sources with either a spectroscopic or photometric redshift estimate
in the range z~=0-6 is available over an area of 355 arcmin2. Given
its depth and the multi-band information, this catalog is an excellent
resource to investigate X-ray spectral properties of distant active
galactic nuclei (AGN) and derive the redshift evolution of their
obscuration. We performed a thorough X-ray spectral analysis for each
object in the sample, and measured its nuclear column density NH and
intrinsic (de-absorbed) 2-10keV rest-frame luminosity, L2-10.
Whenever possible, we also used the presence of the Fe Kα
emission line to improve the photometric redshift estimates. We
measured the fractions of AGN hidden by column densities in excess of
1022 and 1023cm-2 (f22 and f23, respectively) as a function
of L2-10 and redshift, and corrected for selection effects to
recover the intrinsic obscured fractions. At z∼1.2, we found
f22∼0.7-0.8 and f23∼0.5-0.6, respectively, in broad agreement with
the results from other X-ray surveys. No significant variations in
X-ray luminosity were found within the limited luminosity range probed
by our sample (logL2-10∼42.8-44.3). When focusing on luminous AGN
with logL2-10∼44 to maximize the sample completeness up to large
cosmological distances, we did not observe any significant change in
f22 or f23 over the redshift range z∼0.8-3. Nonetheless, the
obscured fractions we measure are significantly higher than is seen in
the local Universe for objects of comparable intrinsic luminosity,
pointing toward an increase in the average AGN obscuration toward
early cosmic epochs, as also observed in other X-ray surveys.
We finally compared our results with recent analytic models that
ascribe the greater obscuration observed in AGN at high redshifts to
the dense interstellar medium (ISM) of their hosts. When combined with
literature measurements, our results favor a scenario in which the
total column density of the ISM and the characteristic surface density
of its individual clouds both increase toward early cosmic epochs as
NH,ISM∝(1+z)delta, with delta∼3.3-4 and
{SIGMA}c*∝(1+ z)2, respectively.
Description:
We present the results of the X-ray spectral fitting for the 243 AGN
in the Chandra J1030 survey, the fifth-deepest X-ray survey currently
available.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 253 243 Chandra J1030 spectral catalog
fig/* . 243 Individual NH probability distribution curve
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See also:
J/A+A/637/A52 : Deep Chandra survey in J1030+0524 field (Nanni+, 2020)
J/A+A/656/A117 : Chandra J1030 redshift identification (Marchesi+, 2021)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- XID Chandra J1030 ID (from Nanni et al.,
2020A&A...637A..52N 2020A&A...637A..52N, Cat. J/A+A/637/A52)
(XID)
5- 6 I2 h RAh Right Ascension, X-ray source (J2000)
(RACORRX_H)
8- 9 I2 min RAm Right Ascension, X-ray source (J2000)
(RACORRX_M)
11- 15 F5.2 s RAs Right Ascension, X-ray source (J2000)
(RACORRX_S)
17 A1 --- DE- Declination sign, X-ray source (J2000)
(DECCORRX_s)
18- 19 I2 deg DEd Declination, X-ray source (J2000)
(DECCORRX_D)
21- 22 I2 arcmin DEm Declination, X-ray source (J2000)
(DECCORRX_M)
24- 28 F5.2 arcsec DEs Declination, X-ray source (J2000)
(DECCORRX_S)
30 A1 --- l_z [<] Lower limit flag on z (nothing if
the photometric redshift probability
curve is flat)
32 A1 --- f_z [0/1] 1 if spectroscopic, 0 if photometric
redshift (1)
34- 40 F7.5 --- z Source redshift: spectroscopic when
available, photometric otherwise
42- 62 F21.17 --- e_z ?=-99 Lower error on the source redshift
estimate (2)
64- 84 F21.17 --- E_z ?=-99 Higher error on the source redshift
estimate
86- 92 F7.2 ct ct Source counts in the 0.5-7keV range
94-111 F18.15 [cm-2] log(NH) Logarithm of the source column density
113-133 F21.17 [cm-2] e_log(NH) ?=-99 Lower error on the logarithm of the
source column density,
135-155 F21.17 [cm-2] E_log(NH) ?=-99 Higher error on the logarithm of the
source column density
157-162 F6.4 --- Gamma Photon index of the spectral power-law.
Fixed to 1.9 if the source has less than
148 counts in the 0.5-7keV range
164-171 F8.4 --- e_Gamma ?=-99 Lower error on the photon index
Gamma (3)
173-180 F8.4 --- E_Gamma ?=-99 Higher error on the photon index
Gamma (3)
182-186 F5.2 [10-7W] log(L2-10)d Intrinsic (de-absorbed) rest-frame 2-10keV
luminosity in erg/s
188-209 F22.18 [10-7W] e_log(L2-10)d ?=-99 Lower error on the intrinsic
(de-absorbed) rest-frame 2-10keV
luminosity in erg/s
211-232 F22.18 [10-7W] E_log(L2-10)d ?=-99 Higher error on the intrinsic
(de-absorbed) rest-frame 2-10keV
luminosity in erg/s
234-253 A20 --- FileName Name of the file in subdirectory fig
with NH probality distribution curve
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Note (1): spectroscopic redshifts are provided with no uncertainty, while the
uncertainties on photometric redshift estimates are provided as e_z and E_z.
Note (2): -99 if the redshift is spectroscopic (f_z=1), or if the redshift
provided is a lower limit (l_z=0).
Note (3): -99 if the photon index Gamma is fixed to 1.9
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Byte-by-byte Description of file: fig/*
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 24 E24.20 [cm-2] logNH Logarithm of the source column density
26- 50 E25.20 --- p(NH) NH probability
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Acknowledgements:
Matilde Signorini, matilde.signorini(at)unifi.it
(End) Patricia Vannier [CDS] 17-Jul-2023