Current stage of the ATCA follow-up for SPLASH

Four ground-state OH transitions were detected in emission, absorption and maser emission in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH). We re-observed these OH masers with the Australia Telescope Compact Array to obtain positions with high accuracy (~1 arcsec). According to the positions, we categorised these OH masers into different classes, i.e. star formation, evolved stars, supernova remnants and unknown origin. We found one interesting OH maser source (G336.644-0.695) in the pilot region, which has been studied in detail in Qiao et al. (2016a). In this paper, we present the current stage of the ATCA follow-up for SPLASH and discuss the potential future researches derived from the ATCA data.Comment: 2 pages, conference, IAU symposium 33

Detection of HC3_3N maser emission in NGC253

We report the detection of maser emission from the $J=4-3$ transition of HC$_3$N at 36.4~GHz towards the nearby starburst galaxy NGC253. This is the first detection of maser emission from this transition in either a Galactic or extragalactic source. The HC$_3$N maser emission has a brightness temperature in excess of 2500 K and is offset from the center of the galaxy by approximately 18 arcsec (300 pc), but close to a previously reported class~I methanol maser. Both the HC$_3$N and methanol masers appear to arise near the interface between the galactic bar and the central molecular zone, where it is thought that molecular gas is being transported inwards, producing a region of extensive low-velocity shocks.Comment: Accepted for publication in ApJ Letters, 7 pages, 3 figure

Detection of a methanol megamaser in a major-merger galaxy

We have detected emission from both the 4_{-1}-3_{0} E (36.2~GHz) class I and 7_{-2}-8_{-1} E (37.7~GHz) class II methanol transitions towards the centre of the closest ultra-luminous infrared galaxy Arp 220. The emission in both the methanol transitions show narrow spectral features and have luminosities approximately 8 orders of magnitude stronger than that observed from typical class I methanol masers observed in Galactic star formation regions. The emission is also orders of magnitude stronger than the expected intensity of thermal emission from these transitions and based on these findings we suggest that the emission from the two transitions are masers. These observations provides the first detection of a methanol megamaser in the 36.2 and 37.7 GHz transitions and represents only the second detection of a methanol megamaser, following the recent report of an 84 GHz methanol megamaser in NGC1068. We find the methanol megamasers are significantly offset from the nuclear region and arise towards regions where there is Ha emission, suggesting that it is associated with starburst activity. The high degree of correlation between the spatial distribution of the 36.2 GHz methanol and X-ray plume emission suggests that the production of strong extragalactic class I methanol masers is related to galactic outflow driven shocks and perhaps cosmic rays. In contrast to OH and H2O megamasers which originate close to the nucleus, methanol megamasers provide a new probe of feedback (e.g. outflows) processes on larger-scales and of star formation beyond the circumnuclear starburst regions of active galaxies.Comment: Accepted for publication in ApJ

Integrated Power Supply for MEMS Sensor

The recent expansion of wireless sensor networks and the rapid development of low-power consumption devices and MEMS devices have been driving research on harvester converting ambient energy into electricity to replace batteries that require costly maintenance. Harvesting energy from ambient environment vibration becomes an ideal power supply mode. The power supply module can be integrated with the MEMS sensor. There are many ways to convert ambient energy into electrical energy, such as photocells, thermocouples, vibration, and wind and so on. Among these energy-converting ways, the ambient vibration energy harvesting is more attractive because the vibration is everywhere in our daily environment. Based on the analysis of the basic theory of the electret electrostatic harvester, the basic equations and equivalent analysis model of electret electrostatic harvester are established. The experimental tests for the output performance of electret electrostatic harvester are completed. For the electret material, the material itself can also provide a constant voltage to avoid the use of additional power, which provides an effective way for electrostatic harvesting. Therefore, the electret electrostatic harvesting structure is a kind of ideal energy harvesting method using ambient vibration and can be easily integrated with the MEMS system

Adsorption of phenylacetylene on Si(100)-2×1: Reaction mechanism and formation of a styrene-like π-conjugation system

This is the published version. Copyright 2003 American Physical SocietyThe interactions of phentylacetylene and phenylacetylene−α−d1 with Si(100)−2×1 have been studied as a model system to mechanistically understand the adsorption of conjugated π-electron aromatic substitutions on Si(100)−2×1. Vibrational signatures show that phenylacetylene covalently binds to the surface through a [2+2]-like cycloaddition pathway between the external C≡C and Si=Si dimer, forming styrene-like conjugation structure which was further supported by the chemical-shift of C 1s core level. These experimental results are consistent with the density-functional theory [B3LYP/6−311//+G(d)] calculations. The resulting styrene-like conjugation structures may possibly be employed as an intermediate for further organic syntheses and fabrication of molecular architecture for modification and functionalization of Si surfaces, or as a monomer for polymerization on Si surfaces

Accurate OH maser positions II. the Galactic Center region

We present high spatial resolution observations of ground-state OH masers, achieved using the Australia Telescope Compact Array (ATCA). These observations were conducted towards 171 pointing centres, where OH maser candidates were identified previously in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH) towards the Galactic Center region, between Galactic longitudes of $355^{\circ}$ and $5^{\circ}$ and Galactic latitudes of $-2^{\circ}$ and $+2^{\circ}$. We detect maser emission towards 162 target fields and suggest that 6 out of 9 non-detections are due to intrinsic variability. Due to the superior spatial resolution of the follow-up ATCA observations, we have identified 356 OH maser sites in the 162 of the target fields with maser detections. Almost half (161 of 356) of these maser sites have been detected for the first time in these observations. After comparing the positions of these 356 maser sites to the literature, we find that 269 (76\%) sites are associated with evolved stars (two of which are planetary nebulae), 31 (9\%) are associated with star formation, four are associated with supernova remnants and we were unable to determine the origin of the remaining 52 (15\%) sites. Unlike the pilot region (\citealt{Qie2016a}), the infrared colors of evolved star sites with symmetric maser profiles in the 1612 MHz transition do not show obvious differences compared with those of evolved star sites with asymmetric maser profiles.Comment: 24 pages, 12 figures, accepted by ApJ