J/ApJS/217/21 XMM-Newton survey of local OVII absorbers (Fang+, 2015)
XMM-Newton survey of local O VII absorption lines in the spectra of
active galactic nuclei.
Fang T., Buote D., Bullock J., Ma R.
<Astrophys. J. Suppl. Ser., 217, 21 (2015)>
=2015ApJS..217...21F 2015ApJS..217...21F
ADC_Keywords: BL Lac objects ; Active gal. nuclei ; Equivalent widths ;
Redshifts ; X-ray sources
Keywords: Galaxy: disk; Galaxy: halo; ISM: general; quasars: absorption lines;
X-rays: ISM
Abstract:
Highly ionized, z=0 metal absorption lines detected in the X-ray
spectra of background active galactic nuclei (AGNs) provide an
effective method to probe the hot (T∼106K) gas and its metal content
in and around the Milky Way. We present an all-sky survey of the
Kα transition of the local OVII absorption lines obtained by
Voigt-profile fitting archival XMM-Newton observations. A total of 43
AGNs were selected, among which 12 are BL Lac-type AGNs, and the rest
are Seyfert 1 galaxies. At above the 3σ level the local OVII
absorption lines were detected in 21 AGNs, among which 7 were newly
discovered in this work. The sky covering fraction, defined as the
ratio between the number of detections and the sample size, increases
from about 40% for all targets to 100% for the brightest targets,
suggesting a uniform distribution of the OVII absorbers. We correlate
the line equivalent width with the Galactic coordinates and do not
find any strong correlations between these quantities. Some AGNs have
warm absorbers that may complicate the analysis of the local X-ray
absorber since the recession velocity can be compensated by the
outflow velocity, especially for nearby targets. We discuss the
potential impact of warm absorbers on our analysis.
Description:
We searched the entire XMM-Newton archive of the AGNs with enough
Reflection Grating Spectrometer (RGS) 1 photon counts to warrant a
spectral analysis.
The RGS resolution has a FWHM of ∼50mÅ. We define one resolution
element as half of the FWHM, or 25mÅ.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 151 43 The AGN sample
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See also:
B/xmm : XMM-Newton Observation Log (XMM-Newton Science Operation Center, 2012)
J/ApJ/773/92 : XMM survey of soft background III. Galactic halo (Henley+, 2013)
http://asc.harvard.edu/ : Chandra X-Ray Observatory (CXC) home page
http://xmm.esa.int/ : XMM-Newton Science Operations Centre home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Target identifier
17 I1 --- Type [1/2] Target type (1=BL Lac or 2=Seyfert 1)
19- 25 F7.3 deg GLON Galactic longitude
27- 33 F7.3 deg GLAT Galactic latitude
35- 40 F6.4 --- z [0.002/0.6] Redshift
42- 46 F5.2 10+20/cm2 NHI Dickey & Lockman (1990ARA&A..28..215D 1990ARA&A..28..215D)
H I column density
48- 51 I4 ks Exp [29/1086] Total exposure time
53- 57 I5 --- CPRE [21/14554] Counts per resolution element
59- 63 F5.2 [cm-2] logNO [15.6/19]? Log OVII column density
65- 68 F4.2 [cm-2] E_logNO [0.2/3]? Upper 1σ uncertainty in logNO
70- 73 F4.2 [cm-2] e_logNO [0.3/3]? Lower 1σ uncertainty in logNO
75- 77 I3 km/s b [20/300]? Doppler-b parameter
79- 81 I3 km/s E_b [0/280]? Upper 1σ uncertainty in b
83- 85 I3 km/s e_b [0/280]? Lower 1σ uncertainty in b
87- 90 I4 km/s Vel [-120/142]? Velocity shift of line center
92- 94 I3 km/s E_Vel [0/240]? Upper 1σ uncertainty in Vel
96- 98 I3 km/s e_Vel [0/240]? Lower 1σ uncertainty in Vel
100 A1 --- l_EW1 The 3σ upper limit flag on EW1 (1)
102-107 F6.2 10-13m EW1 [5/65]? Method 1 equivalent width;
in milliAngstroms unit
109-113 F5.2 10-13m e_EW1 [0.6/25.2]? The 1σ uncertainty in EW1
115-118 F4.1 --- S/N1 [1/20]? Signal-to-Noise ratio from method 1 (2)
120-123 I4 --- C [12/2567]? C-statistic
125-128 I4 --- dof [12/2535]? Degree of freedom
130-134 F5.2 10-13m EW2 [5.6/61.1]? Method 2 equivalent width;
in milliAngstroms unit (3)
136-140 F5.2 10-13m e_EW2 [0.5/30.3]? The 1σ uncertainty in EW2 (3)
142-145 F4.1 --- S/N2 [0.6/22]? Signal-to-Noise ratio from
method 2 (2)
147-151 A5 --- Note Additional note(s) (4)
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Note (1): For targets with a significance of less than 1σ we list
the 3σ upper limits of EW.
Note (2): We do not list the line parameters if the line is not
detected (defined as the S/N falls below 1).
Note (3): For most AGNs, we cannot constrain both the Doppler-b parameter and
velocity shift of the line center, so we also test another model in
which we fix both values: we set the velocity shift of the line center
at 0km/s and the Doppler-b parameter at 100km/s. We listed the EW and
the significance evaluated with this method in columns EW2 and e_EW2,
respectively. See section 2.2.
Note (4): The references that first reported the detection of the
z=0 OVII absorption line in the target. References as follows:
1 = Rasmussen et al. (2003ASSL..281..109R 2003ASSL..281..109R);
2 = Fang et al. (2002ApJ...572L.127F 2002ApJ...572L.127F);
3 = Nicastro et al. (2002ApJ...573..157N 2002ApJ...573..157N);
4 = Fang et al. (2003ApJ...586L..49F 2003ApJ...586L..49F);
5 = Bregman (2007ARA&A..45..221B 2007ARA&A..45..221B);
6 = McKernan et al. (2004ApJ...617..232M 2004ApJ...617..232M);
7 = Fang et al. (2006ApJ...644..174F 2006ApJ...644..174F);
8 = Ren et al. (2014ApJ...782L...6R 2014ApJ...782L...6R);
9 = Miller & Bregman (2013ApJ...770..118M 2013ApJ...770..118M);
10 = Williams et al. (2006ApJ...645..179W 2006ApJ...645..179W);
11 = Kaspi et al. (2002ApJ...574..643K 2002ApJ...574..643K);
12 = Buote et al. (2009ApJ...695.1351B 2009ApJ...695.1351B);
13 = Steenbrugge et al. (2003A&A...408..921S 2003A&A...408..921S);
* = This work.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 11-May-2015