J/ApJ/779/133 X-ray & radio fluxes of unassociated 2FGL sources (Acero+, 2013)
Hunting for treasures among the Fermi unassociated sources: a multiwavelength
approach.
Acero F., Donato D., Ojha R., Stevens J., Edwards P.G., Ferrara E.,
Blanchard J., Lovell J.E.J., Thompson D.J.
<Astrophys. J., 779, 133 (2013)>
=2013ApJ...779..133A 2013ApJ...779..133A
ADC_Keywords: Gamma rays ; X-ray sources ; Radio continuum ; Ultraviolet
Keywords: galaxies: active; gamma rays: general; pulsars: general;
quasars: general; radio continuum: galaxies; ultraviolet: galaxies;
X-rays: galaxies
Abstract:
The Fermi Gamma-Ray Space Telescope has been detecting a wealth of
sources where the multiwavelength counterpart is either inconclusive
or missing altogether. We present a combination of factors that can be
used to identify multiwavelength counterparts to these Fermi
unassociated sources. This approach was used to select and investigate
seven bright, high-latitude unassociated sources with radio, UV,
X-ray, and γ-ray observations. As a result, four of these
sources are candidates to be active galactic nuclei, and one to be a
pulsar, while two do not fit easily into these known categories of
sources. The latter pair of extraordinary sources might reveal a new
category subclass or a new type of γ-ray emitter. These results
altogether demonstrate the power of a multiwavelength approach to
illuminate the nature of unassociated Fermi sources.
Description:
The Swift/XRT observations were analyzed (see Section 3.1) to identify
potential X-ray counterparts within the Fermi R95 error ellipse.
Among the selected 22 γ-ray sources, 16 had at least one X-ray
counterpart detected with a significance greater than 3σ.
From the list of 16 γ-ray sources with at least one X-ray
counterpart, radio observations of seven sources were obtained with
the Australia Telescope Compact Array (ATCA). These objects are
presented in Table 1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 41 13 Multiwavelength properties of the observed
sample of seven 2FGL unassociated sources
table2.dat 64 117 Multiwavelength fluxes for the 4 sources
presented in Fig. 2
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See also:
J/ApJS/217/4 : 2FGL sources observed between 5-9GHz (Schinzel+, 2015)
J/MNRAS/432/1294 : Fermi unassociated sources ATCA observations (Petrov+, 2013)
J/ApJS/208/25 : Swift X-ray observations of 1FGL sources (Takeuchi+, 2013)
J/ApJS/206/13 : Blazars with γ-ray counterparts. II. (Massaro+, 2013)
J/ApJ/756/33 : X-ray sources near 2 γ-ray sources (Cheung+, 2012)
J/MNRAS/424/L64 : AGN/pulsar distinction for 2FGL sources (Mirabal+, 2012)
J/ApJ/753/83 : Associations to 1FGL sources (Ackermann+, 2012)
J/ApJ/752/61 : Blazars in unidentified γ-ray sources (Massaro+, 2012)
J/A+A/541/A160 : Planck + X/γ observations of blazars (Giommi+, 2012)
J/ApJS/199/31 : Fermi LAT second source catalog (2FGL) (Nolan+, 2012)
J/ApJ/743/171 : The 2LAC catalog (Ackermann+, 2011)
J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)
J/A+A/458/245 : 2 Unidentified Gamma-ray Sources obs. (La Palombara+, 2006)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Name 2FGL identifier (JHHMM) as in table 2
7- 11 F5.3 --- P(AGN) [0.5/1]? Probability of the source
to be an AGN (1)
13- 14 A2 --- XID X-ray name as in Figure 1 (2)
16- 19 F4.1 --- Det [3/43] Detection significance (σdet) (2)
21- 23 F3.1 --- Var [3/10]? Significance of X-ray variability (2)
24 A1 --- f_Var N: No significant variability was observed
(σvar<3)
26- 29 A4 --- UV Detection of an UV counterpart in the 4
Swift/UVOT U, W1, M2 and W2 filters (3)
36- 41 A6 --- Radio Detection of a radio counterpart at 5.5, 9,
17, 19, 38, and 40GHz with ATCA (3)
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Note (1): For each γ-ray source, we report the probability of the source
to be an AGN on the basis of its GeV properties (Mirabal et al.
2012, J/MNRAS/424/L64), see Section 5 for more details.
Note (2): For each X-ray source within or very close to the γ-ray
uncertainty ellipse, we report (1) the label as shown in Figure 1;
(2) the detection significance of the X-ray source; (3) the
significance of X-ray variability (σvar). If σvar is
blank, the variability could not be tested (only one observation
available).
Note (3): For both the UV and radio rows, "1" and "0" represent a detection and
an upper limit, respectively. A dash means that the source was not
observed in that specific filter/frequency. The sources A3, B1, and
D1 have a faint radio counterpart just above the detection threshold,
and although they are not detected at high frequency, a radio flat
spectrum is not excluded. The source J1129.5+3758 could not be
observed at higher radio frequencies because of its low elevation
angle.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Name 2FGL identifier (JHHMM)
7- 16 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
18- 28 F11.7 deg DEdeg Declination in decimal degrees (J2000)
30- 38 F9.6 [Hz] lognu [7.8/25.2] Log of the frequency ν
40- 49 F10.6 [mW/m2] logF [-15.7/-10.9] Log of the flux; erg/s/cm2
51- 58 F8.6 [mW/m2] e_logF [0/0.3] Error in logF
60- 64 F5.3 [Hz] e_lognu [0/0.8] Error in lognu
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 07-May-2015