| 1. |
- Tanaka, Masaomi, et al.
(författare)
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DISCOVERY OF DRAMATIC OPTICAL VARIABILITY IN SDSS J1100+4421 : A PECULIAR RADIO-LOUD NARROW-LINE SEYFERT 1 GALAXY?
- 2014
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Ingår i: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 793:2, s. L26-
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Tidskriftsartikel (refereegranskat)abstract
- We present our discovery of dramatic variability in SDSS J1100+4421 by the high-cadence transient survey Kiso Supernova Survey. The source brightened in the optical by at least a factor of three within about half a day. Spectroscopic observations suggest that this object is likely a narrow-line Seyfert 1 galaxy (NLS1) at z = 0.840, however, with unusually strong narrow emission lines. The estimated black hole mass of similar to 10(7) M-circle dot implies bolometric nuclear luminosity close to the Eddington limit. SDSS J1100+4421 is also extremely radio-loud, with a radio loudness parameter of R similar or equal to 4 x 10(2)-3 x 10(3), which implies the presence of relativistic jets. Rapid and large-amplitude optical variability of the target, reminiscent of that found in a few radio- and gamma-ray-loud NLS1s, is therefore produced most likely in a blazar-like core. The 1.4 GHz radio image of the source shows an extended structure with a linear size of about 100 kpc. If SDSS J1100+4421 is a genuine NLS1, as suggested here, this radio structure would then be the largest ever discovered in this type of active galaxies.
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| 2. |
- Giorgianni, Flavio, et al.
(författare)
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Melting of magnetic order in NaOsO3 by femtosecond laser pulses
- 2022
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 105:15
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Tidskriftsartikel (refereegranskat)abstract
- NaOsO3 has recently attracted significant attention for the strong coupling between its electronic band structure and magnetic ordering. Here, we used time-resolved magnetic x-ray diffraction to determine the timescale of the photoinduced antiferromagnetic dynamics in NaOsO3. Our measurements are consistent with a sub-100 fs melting of the antiferromagnetic long-range order that occurs significantly faster than the lattice dynamics as monitored by the transient change in intensity of selected Bragg structural reflections, which instead show a decrease of intensity on a timescale of several ps.
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| 3. |
- Kamae, Tuneyoshi, et al.
(författare)
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PoGOLite - A high sensitivity balloon-borne soft gamma-ray polarimeter
- 2008
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 30:2, s. 72-84
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Tidskriftsartikel (refereegranskat)abstract
- We describe a new balloon-borne instrument (PoGOLite) capable of detecting 10% polarisation from 200 mCrab point-like sources between 25 and 80 keV in one 6-h flight. Polarisation measurements in the soft gamma-ray band are expected to provide a powerful probe into high energy emission mechanisms as well as the distribution of magnetic fields, radiation fields and interstellar matter. Synchrotron radiation, inverse Compton scattering and propagation through high magnetic fields are likely to produce high degrees of polarisation in the energy band of the instrument. We demonstrate, through tests at accelerators, with radioactive sources and through computer simulations, that PoGOLite will be able to detect degrees of polarisation as predicted by models for several classes of high energy sources. At present, only exploratory polarisation measurements have been carried out in the soft gamma-ray band. Reduction of the large background produced by cosmic-ray particles while securing a large effective area has been the greatest challenge. PoGOLite uses Compton scattering and photo-absorption in an array of 217 well-type phoswich detector cells made of plastic and BGO scintillators surrounded by a BGO anticoincidence shield and a thick polyethylene neutron shield. The narrow Held of view (FWHM = 1.25 msr, 2.0 deg x 2.0 deg) obtained with detector cells and the use of thick background shields warrant a large effective area for polarisation measurements (similar to 228 cm(2) at E = 40 keV) without sacrificing the signal-to-noise ratio. Simulation studies for an atmospheric overburden of 3-4 g/cm(2) indicate that neutrons and gamma-rays entering the PDC assembly through the shields are dominant backgrounds. Off-line event selection based on recorded phototube waveforms and Compton kinematics reduce the background to that expected for a similar to 100 mCrab source between 25 and 50 keV. A 6-h observation of the Crab pulsar will differentiate between the Polar Cap/Slot Gap, Outer Gap, and Caustic models with greater than 5 sigma significance; and also cleanly identify the Compton reflection component in the Cygnus X-1 hard state. Long-duration flights will measure the dependence of the polarisation across the cyclotron absorption line in Hercules X-1. A scaled-down instrument will be flown as a pathfinder mission from the north of Sweden in 2010. The first science flight is planned to take place shortly thereafter.
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| 4. |
- Kawai, Mayumi, et al.
(författare)
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C-type natriuretic peptide as a possible local modulator of aldosterone secretion in bovine adrenal zona glomerulosa
- 1996
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Ingår i: Endocrinology. - : Oxford University Press. - 0013-7227 .- 1945-7170. ; 137:1, s. 42-46
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Tidskriftsartikel (refereegranskat)abstract
- Although atrial and brain natriuretic peptides are well known to be involved in the regulation of cardiovascular and endocrine functions as circulating hormones, the roles of the C-type natriuretic peptide (CNP) remain unknown. We examined the effects of CNP on the secretion of aldosterone and cyclic nucleotides from bovine adrenal zona glomerulosa cells in culture. CNP produced a dose-dependent increase in the basal secretion of cGMP, with an EC50 of 3.8 x 10(-10)M. CNP significantly inhibited the ACTH-induced increase in aldosterone and cAMP in a dose-related manner, with an IC50 of 3.6 x 10(-10)M. Although ACTH itself did not increase cGMP secretion, the addition of CNP elicited a significant increase in cGMP secretion. The effects of CNP on the basal secretion of cGMP and the ACTH-induced secretion of aldosterone were significantly reversed by a nonpeptide natriuretic peptide receptor antagonist, HS-142-1. CNP immunoreactivity was localized in the zona glomerulosa by immunohistochemical staining. In addition, expression of CNP messenger RNA and natriuretic peptide B receptor messenger RNA was demonstrated by RT-PCR in the zona glomerulosa tissue and cells in culture. These findings suggest that CNP is a local factor regulating ACTH-induced aldosterone secretion through a guanylyl cyclase-cGMP pathway.
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| 5. |
- Morokuma, Tomoki, et al.
(författare)
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Kiso Supernova Survey (KISS) : Survey strategy
- 2014
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Ingår i: Nippon Tenmon Gakkai obun kenkyu hokoku. - : Oxford University Press (OUP). - 0004-6264. ; 66:6
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Tidskriftsartikel (refereegranskat)abstract
- lThe Kiso Supernova Survey (KISS) is a high-cadence optical wide-field supernova (SN) survey. The primary goal of the survey is to catch the very early light of a SN, during the shock breakout phase. Detection of SN shock breakouts combined with multi-band photometry obtained with other facilities would provide detailed physical information on the progenitor stars of SNe. The survey is performed using a 2 degrees.2 x 2 degrees.2 field-of-view instrument on the 1.05-m Kiso Schmidt telescope, the Kiso Wide Field Camera (KWFC). We take a 3-min exposure in g-band once every hour in our survey, reaching magnitude g similar to 20-21. About 100 nights of telescope time per year have been spent on the survey since 2012 April. The number of the shock breakout detections is estimated to be of the order of 1 during our three-year project. This paper summarizes the KISS project including the KWFC observing setup, the survey strategy, the data reduction system, and CBET-reported SNe discovered so far by KISS.
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