1,271 research outputs found
A search for near infrared counterparts of 3 pulsar wind nebulae
While pulsar wind nebulae (PWNe) and their associated isolated pulsars are
commonly detected at X-ray energies, they are much rarer at near infrared (nIR)
and optical wavelengths. Here we examine three PWN systems in the Galactic
plane - IGR J14003-6326, HESS J1632-478 and IGR J18490-0000 - in a bid to
identify optical/nIR emission associated with either the extended PWNe or their
previously detected X-ray point sources. We obtain optical/nIR images of the
three fields with the ESO - New Technology Telescope and apply standard
photometric and astrometric calibrations. We find no evidence of any extended
emission associated with the PWNe in any of the fields; neither do we find any
new counterparts to the X-ray point sources, except to confirm the magnitude of
the previously identified counterpart candidate of IGR J18490-0000. Further
observations are required to confirm the association of the nIR source to IGR
J18490-0000 and to detect counterparts to IGR J14003-6326 and HESS J1632-478,
while a more accurate X-ray position is required to reduce the probability of a
chance superposition in the field of the latter.Comment: Accepted to A&A (4 pages, 1 figure
A Review Of Implementing Adc In Rfid Sensor
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The general considerations to design a sensor interface for passive RFID tags are discussed. This way, power and timing constraints imposed by ISO/IEC 15693 and ISO/IEC 14443 standards to HF RFID tags are explored. A generic multisensor interface is proposed and a survey analysis on the most suitable analog-to-digital converters for passive RFID sensing applications is reported. The most appropriate converter type and architecture are suggested. At the end, a specific sensor interface for carbon nanotube gas sensors is proposed and a brief discussion about its implemented circuits and preliminary results is made.Region Rhone-Alpes (France)CNPq (Brazil)INCT/NAMITEC (Brazil)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
The nature of the X-ray binary IGR J19294+1816 from INTEGRAL, RXTE, and Swift observations
We report the results of a high-energy multi-instrumental campaign with
INTEGRAL, RXTE, and Swift of the recently discovered INTEGRAL source IGR
J19294+1816. The Swift/XRT data allow us to refine the position of the source
to RA= 19h 29m 55.9s Dec=+18deg 18' 38.4" (+- 3.5"), which in turn permits us
to identify a candidate infrared counterpart. The Swift and RXTE spectra are
well fitted with absorbed power laws with hard (Gamma ~ 1) photon indices.
During the longest Swift observation, we obtained evidence of absorption in
true excess to the Galactic value, which may indicate some intrinsic absorption
in this source. We detected a strong (P=40%) pulsation at 12.43781 (+-0.00003)
s that we interpret as the spin period of a pulsar. All these results, coupled
with the possible 117 day orbital period, point to IGR J19294+1816 being an
HMXB with a Be companion star. However, while the long-term INTEGRAL/IBIS/ISGRI
18--40 keV light curve shows that the source spends most of its time in an
undetectable state, we detect occurrences of short (~2000-3000 s) and intense
flares that are more typical of supergiant fast X-ray transients. We therefore
cannot make firm conclusions on the type of system, and we discuss the possible
implications of IGR J19294+1816 being an SFXT.Comment: 7 pages, 6 figures, accepted for publication in A&
A Review Of Implementing Adc In Rfid Sensor
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The general considerations to design a sensor interface for passive RFID tags are discussed. This way, power and timing constraints imposed by ISO/IEC 15693 and ISO/IEC 14443 standards to HF RFID tags are explored. A generic multisensor interface is proposed and a survey analysis on the most suitable analog-to-digital converters for passive RFID sensing applications is reported. The most appropriate converter type and architecture are suggested. At the end, a specific sensor interface for carbon nanotube gas sensors is proposed and a brief discussion about its implemented circuits and preliminary results is made.Region Rhone-Alpes (France)CNPq (Brazil)INCT/NAMITEC (Brazil)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
INTEGRAL, XMM-Newton and ESO/NTT identification of AX J1749.1-2733: an obscured and probably distant Be/X-ray binary
AX J1749.1-2733 is an unclassified transient X-ray source discovered during
surveys by ASCA in 1993-1999. A multi-wavelength study in NIR, optical, X-rays
and hard X-rays is undertaken in order to determine its nature. AX J1749.1-2733
is a new high-mass X-ray binary pulsar with an orbital period of 185.5+/-1.1 d
(or 185.5/f with f=2,3 or 4) and a spin period of ~66 s, parameters typical of
a Be/X-ray binary. The outbursts last ~12 d. A spin-down of 0.08+/-0.02 s/yr is
also observed, very likely due to the propeller effect. The most accurate X-ray
position is R.A. (2000) =17h49m06.8s and Dec. = -27deg32'32".5 (unc. 2"). The
high-energy broad-band spectrum is well-fitted with an absorbed powerlaw and a
high-energy cutoff with values NH=(20+/-1)e22 cm-2, Gamma=1.0+/-0.1, and
Ecut=21+/-3 keV. The only optical/NIR candidate counterpart within the X-ray
error circle has magnitudes of R=21.9+/-0.1, I=20.92+/-0.09, J=17.42+/-0.03,
H=16.71+/-0.02, and Ks=15.75+/-0.07, which points towards a Be star located far
away (> 8.5 kpc) and highly absorbed (NH~1.7e22 cm-2). The average 22-50 keV
luminosity is (0.4-0.9)e36 erg/s during the long outbursts and 3e36 erg/s
during the bright flare that occurred on MJD 52891 for an assumed distance of
8.5 kpc.Comment: accepted A&A, 11 pages, 9 figure
Collider Bounds on Lee-Wick Higgs Bosons
We study the constraints on the Lee-Wick Higgs sector arising from direct
collider searches. We work in an effective-field theory framework, where all of
the Lee-Wick partners are integrated out, with the sole exception of the
Lee-Wick Higgs bosons. The resulting theory is a two-Higgs doublet model where
the second doublet has wrong-sign kinetic and mass terms. We include the bounds
coming from direct Higgs searches at both LEP and Tevatron using the code
HiggsBounds, and show the currently excluded parameter space. We also analyze
the prospects of LHC Run-I, finding that with a total integrated luminosity of
5 fb and a center-of-mass energy of 7 TeV, most of the parameter space
for the SM-like CP-even Higgs will be probed.Comment: 26 pages, 5 figures, matches version published by PR
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