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We have investigated the mode changing properties of PSR B0329+54 using 31 epochs of simultaneous 13 cm/3 cm single-pulse observations obtained with the Shanghai Tian Ma 65 m telescope. The pulsar was found in the abnormal emission mode 17 times, accounting for ∼13% of the 41.6 hr total observation time. Single-pulse analyses indicate that mode changes took place simultaneously at 13 cm/3 cm within a few rotational periods. We detected occasional bright and narrow pulses whose peak flux densities were 10 times higher than that of the integrated profile in both bands. At 3 cm, about 0.66% and 0.27% of single pulses were bright in the normal mode and abnormal mode, respectively, but at 13 cm the occurrence rate was only about 0.007%. We divided the pulsar radiation window into three components (C1, C2, and C3) corresponding to the main peaks of the integrated profile. The bright pulses preferentially occurred at pulse phases corresponding to the peaks of C2 and C3. Fluctuation spectra showed that C2 had excess red noise in the normal mode, but broad quasi-periodic features with central frequencies around 0.12 cycles/period in the abnormal mode. At 3 cm, C3 had a stronger quasi-periodic modulation centered around 0.06 cycles/period in the abnormal mode. Although there were some asymmetries in the two-dimensional fluctuation spectra, we found no clear evidence for systematic subpulse drifting. Consistent with previous low-frequency observations, we found a very low nulling probability for B0329+54, with upper limits of 0.13% and 1.68% at 13 cm/3 cm, respectively. [ABSTRACT FROM AUTHOR]

We performed a systematic 6.7 GHz Class II methanol maser survey using the Shanghai Tianma Radio Telescope toward targets selected from the all-sky Wide-Field Infrared Survey Explorer (WISE) point catalog. In this paper, we report the results from the survey of those at high Galactic latitudes, i.e., 2°. Of 1473 selected WISE point sources at high latitude, 17 point positions that were actually associated with 12 sources were detected with maser emission, reflecting the rarity (1%–2%) of methanol masers in the region away from the Galactic plane. Out of the 12 sources, 3 are detected for the first time. The spectral energy distribution at infrared bands shows that these new detected masers occur in the massive star-forming regions. Compared to previous detections, the methanol maser changes significantly in both spectral profiles and flux densities. The infrared WISE images show that almost all of these masers are located in the positions of the bright WISE point sources. Compared to the methanol masers at the Galactic plane, these high-latitude methanol masers provide good tracers for investigating the physics and kinematics around massive young stellar objects, because they are believed to be less affected by the surrounding cluster environment. [ABSTRACT FROM AUTHOR]

Integrated pulse profiles at 8.6 GHz obtained with the Shanghai Tian Ma Radio Telescope (TMRT) are presented for a sample of 26 pulsars. Mean flux densities and pulse width parameters of these pulsars are estimated. For 11 pulsars these are the first high-frequency observations and for a further four, our observations have a better signal-to-noise ratio than previous observations. For one (PSR J0742−2822), the 8.6 GHz profile differs from previously observed profiles. A comparison of 19 profiles with those at other frequencies shows that in nine cases, the separation between the outmost leading and trailing components decreases with frequency, which is roughly in agreement with radius-to-frequency mapping, whereas in the other 10 the separation is nearly constant. Different spectral indices of profile components lead to the variation of integrated pulse profile shapes with frequency. In seven pulsars with multi-component profiles, the spectral indices of the central components are steeper than those of the outer components. For the 12 pulsars with multi-component profiles in the high-frequency sample, we estimate the core width using Gaussian fitting and discuss the width-period relationship. [ABSTRACT FROM AUTHOR]

We report Shanghai Tian Ma Radio Telescope (TMRT) detections of several long carbon-chain molecules in the C and Ku bands, including HC3N, HC5N, HC7N, HC9N, C3S, C6H, and C8H toward the starless cloud Serpens South 1a. We detected some transitions (HC9N J = 13–12, F = 12–11, and F = 14–13; H13CCCN J = 2–1, F = 1–0, and F = 1–1; HC13CCN J = 2–1, F = 2–2, F = 1–0, and F = 1–1; HCC13CN J = 2–1, F = 1–0, and F = 1–1) and resolved some hyperfine components (HC5N J = 6–5, F = 5–4; H13CCCN J = 2–1, F = 2–1) for the first time in the interstellar medium. The column densities of these carbon-chain molecules in the range 1012–1013 cm−2 are comparable to two carbon-chain molecule rich sources, TMC-1 and Lupus-1A. The abundance ratios are 1.00:(1.11 ± 0.15):(1.47 ± 0.18) for [H13CCCN]:[HC13CCN]:[HCC13CN]. This result implies that the 13C isotope is also concentrated in the carbon atom adjacent to the nitrogen atom in HC3N in Serpens South 1a, which is similar to TMC-1. The [HC3N]/[H13CCCN] ratio of 78 ± 9, the [HC3N]/[HC13CCN] ratio of 70 ± 8, and the [HC3N]/[HCC13CN] ratio of 53 ± 4 are also comparable to those in TMC-1. Serpens South 1a proves to be a suitable testing ground for understanding carbon-chain chemistry. [ABSTRACT FROM AUTHOR]

In this paper, we report radio observations of the Galactic Center magnetar PSR J1745–2900 at six epochs between 2014 June and October. These observations were carried out using the new Shanghai Tian Ma Radio Telescope at a frequency of 8.6 GHz. Both the flux density and integrated profile of PSR J1745–2900 show dramatic changes from epoch to epoch, showing that the pulsar was in its “erratic” phase. On MJD 56836, the flux density of this magnetar was about 8.7 mJy, which was 10 times larger than that reported at the time of discovery, enabling a single-pulse analysis. The emission is dominated by narrow “spiky” pulses that follow a log-normal distribution in peak flux density. From 1913 pulses, we detected 53 pulses whose peak flux densities are 10 times greater than that of the integrated profile. They are concentrated in pulse phase at the peaks of the integrated profile. The pulse widths at the 50% level of these bright pulses were between 0.°2 and 0.°9, much narrower than that of the integrated profile (∼12°). The observed pulse widths may be limited by interstellar scattering. No clear correlation was found between the widths and peak flux density of these pulses and no evidence was found for subpulse drifting. Relatively strong spiky pulses are also detected in the other five epochs of observation, showing the same properties as those detected in MJD 56836. These strong spiky pulses cannot be classified as “giant” pulses but are more closely related to normal pulse emission. [ABSTRACT FROM AUTHOR]