分类： 天文学 >> 天文学 提交时间： 2023-02-19
Renzhi Su
Elizabeth K. Mahony
Minfeng Gu
Elaine M. Sadler
S. J. Curran
James R. Allison
Hyein Yoon
J. N. H. S. Aditya
Yogesh Chandola
Yongjun Chen
Vanessa A. Moss
Zhongzu Wu
Xi Shao
Xiang Liu
Marcin Glowacki
Matthew T. Whiting
Simon Weng
摘要： We present new upgraded Giant Metrewave Radio Telescope (uGMRT) HI 21-cm observations of the ultra-luminous infrared galaxy IRAS 10565+2448, previously reported to show blueshifted, broad, and shallow HI absorption indicating an outflow. Our higher spatial resolution observations have localised this blueshifted outflow, which is $\sim$ 1.36 kpc southwest of the radio centre and has a blueshifted velocity of $\sim 148\,\rm km\,s^{-1}$ and a full width at half maximum (FWHM) of $\sim 581\,\rm km\,s^{-1}$. The spatial extent and kinematic properties of the HI outflow are consistent with the previously detected cold molecular outflows in IRAS 10565+2448, suggesting that they likely have the same driving mechanism and are tracing the same outflow. By combining the multi-phase gas observations, we estimate a total outflowing mass rate of at least $140\, \rm M_\odot \,yr^{-1}$ and a total energy loss rate of at least $8.9\times10^{42}\,\rm erg\,s^{-1}$, where the contribution from the ionised outflow is negligible, emphasising the importance of including both cold neutral and molecular gas when quantifying the impact of outflows. We present evidence of the presence of a radio jet and argue that this may play a role in driving the observed outflows. The modest radio luminosity $L_{\rm1.4GHz}$ $\sim1.3\times10^{23}\,{\rm W\,Hz^{-1}}$ of the jet in IRAS 10565+2448 implies that the jet contribution to driving outflows should not be ignored in low radio luminosity AGN.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Renzhi Su
Elizabeth K. Mahony
Minfeng Gu
Elaine M. Sadler
S. J. Curran
James R. Allison
Hyein Yoon
J. N. H. S. Aditya
Yogesh Chandola
Yongjun Chen
Vanessa A. Moss
Zhongzu Wu
Xi Shao
Xiang Liu
Marcin Glowacki
Matthew T. Whiting
Simon Weng
摘要： We present new upgraded Giant Metrewave Radio Telescope (uGMRT) HI 21-cm observations of the ultra-luminous infrared galaxy IRAS 10565+2448, previously reported to show blueshifted, broad, and shallow HI absorption indicating an outflow. Our higher spatial resolution observations have localised this blueshifted outflow, which is $\sim$ 1.36 kpc southwest of the radio centre and has a blueshifted velocity of $\sim 148\,\rm km\,s^{-1}$ and a full width at half maximum (FWHM) of $\sim 581\,\rm km\,s^{-1}$. The spatial extent and kinematic properties of the HI outflow are consistent with the previously detected cold molecular outflows in IRAS 10565+2448, suggesting that they likely have the same driving mechanism and are tracing the same outflow. By combining the multi-phase gas observations, we estimate a total outflowing mass rate of at least $140\, \rm M_\odot \,yr^{-1}$ and a total energy loss rate of at least $8.9\times10^{42}\,\rm erg\,s^{-1}$, where the contribution from the ionised outflow is negligible, emphasising the importance of including both cold neutral and molecular gas when quantifying the impact of outflows. We present evidence of the presence of a radio jet and argue that this may play a role in driving the observed outflows. The modest radio luminosity $L_{\rm1.4GHz}$ $\sim1.3\times10^{23}\,{\rm W\,Hz^{-1}}$ of the jet in IRAS 10565+2448 implies that the jet contribution to driving outflows should not be ignored in low radio luminosity AGN.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Lei Yang
Xinwen Shu
Fabao Zhang
Yogesh Chandola
Daizhong Liu
Yi Liu
Minfeng Gu
Margherita Giustini
Ning Jiang
Ya-Ping Li
Di Li
David Elbaz
Stephanie Juneau
Maurilio Pannella
Luming Sun
Ningyu Tang
Tinggui Wang
Hongyan Zhou
摘要： RX J1301.9+2747 is a unique active galaxy with supersoft X-ray spectrum that lacks significant emission at energies above 2 keV. In addition, it is one of few galaxies displaying quasi-periodic X-ray eruptions that recur on a timescale of 13-20 ks. We present multi-epoch radio observations of RX J1301.9+2747 using GMRT, VLA and VLBA. The VLBA imaging at 1.6 GHz reveals a compact radio emission unresolved at a scale of 5x10^7 K. The radio emission is variable by more than a factor of 2.5 over a few days, based on the data taken from VLA monitoring campaigns. The short-term radio variability suggests that the radio emitting region has a size as small as 8x10^{-4} pc, resulting in an even higher brightness temperature of T_b ~10^{12} K. A similar limit on the source size can be obtained if the observed flux variability is not intrinsic and caused by the interstellar scintillation effect. The overall radio spectrum is steep with a time-averaged spectral index alpha=-0.78+/-0.03 between 0.89 GHz and 14 GHz. These observational properties rule out a thermal or star-formation origin of the radio emission, and appear to be consistent with the scenario of episodic jet ejections driven by magnetohydrodynamic process. Simultaneous radio and X-ray monitoring observations down to a cadence of hours are required to test whether the compact and variable radio emission is correlated with the quasi-periodic X-ray eruptions.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We present results from an HI counterpart search using the HI Parkes All Sky Survey (HIPASS) for a sample of low surface brightness galaxies (LSBGs) and ultradiffuse galaxies (UDGs) identified from the Dark Energy Survey (DES). We aimed to establish the redshifts of the DES LSBGs to determine the UDG fraction and understand their properties. Out of 409 galaxies investigated, none were unambiguously detected in HI. Our study was significantly hampered by the high spectral rms of HIPASS and thus in this paper we do not make any strong conclusive claims but discuss the main trends and possible scenarios our results reflect. The overwhelming number of non-detections suggest that: (A) Either all the LSBGs in the groups, blue or red, have undergone environment aided pre-processing and are HI deficient or the majority of them are distant galaxies, beyond the HIPASS detection threshold. (B) The sample investigated is most likely dominated by galaxies with HI masses typical of dwarf galaxies. Had there been Milky Way (MW) size (R_e) galaxies in our sample, with proportionate HI content, they would have been detected, even with the limitations imposed by the HIPASS spectral quality. This leads us to infer that if some of the LSBGs have MW size optical diameters, their HI content is possibly in the dwarf range. More sensitive observations using the SKA precursors in future may resolve these questions.
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