A pilot search for extragalactic OH absorption with FAST

Zhang, Zheng; Li, Di; Sadler, E. M.; Allison, J. R.; Tang, Ningyu

doi:10.1093/mnras/staa3033

Cited by 12 publications

(7 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…During the observation, all 19 beams, each with a field of view of ∼3′ (Jiang et al 2020), were working simultaneously. Following Zheng et al (2020), we selected a specific OFF point so that when the central beam, 01, was off the source, beam 14 was on the source. Therefore, both beam 01 and beam 14 were observing J1452+0627, and the total onsource time was 9450 s. The data were recorded every 0.1 s, and the high noise diode, ∼12.5 K, was injected for 5 × 90 s to calibrate the flux.…”

Section: Observation and Data Reductionmentioning

confidence: 99%

FAST Discovery of a Fast Neutral Hydrogen Outflow

Su,

Gu,

Curran

et al. 2023

ApJL

Self Cite

View full text Add to dashboard Cite

In this letter, we report the discovery of a fast neutral hydrogen outflow in SDSS J145239.38+062738.0, a merging radio galaxy containing an optical type I active galactic nucleus (AGN). This discovery was made through observations conducted by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) using redshifted 21 cm absorption. The outflow exhibits a blueshifted velocity likely up to ∼−1000 km s−1 with respect to the systemic velocity of the host galaxy with an absorption strength of ∼−0.6 mJy beam−1 corresponding to an optical depth of 0.002 at v = −500 km s−1. The mass outflow rate ranges between 2.8 × 10−2 and 3.6 M ⊙ yr−1, implying an energy outflow rate ranging between 4.2 × 1039 and 9.7 × 1040 erg s−1, assuming 100 K < T s < 1000 K. Plausible drivers of the outflow include the starbursts, AGN radiation, and radio jet, the last of which is considered the most likely culprit according to the kinematics. By analyzing the properties of the outflow, AGN, and jet, we find that if the H i outflow is driven by the AGN radiation, the AGN radiation does not seem powerful enough to provide negative feedback, whereas the radio jet shows the potential to provide negative feedback. Our observations contribute another example of a fast outflow detected in neutral hydrogen and demonstrate the capability of FAST in detecting such outflows.

show abstract

Section: Observation and Data Reductionmentioning

confidence: 99%

FAST Discovery of a Fast Neutral Hydrogen Outflow

Su,

Gu,

Curran

et al. 2023

ApJL

Self Cite

View full text Add to dashboard Cite

show abstract

“…The observations were carried out based on a "Shared-Risk" project, using the position switch ON-OFF mode recording two polarizations (XX and YY) for each target. The ON-source and OFF-source integration time is 120 s in most cases, and the overhead time (switch between ON-source and OFF-source positions) is 30 s. We have carefully chosen the OFF point for each source so that a side beam (M08 or M14 7 ) would be pointing to the source when the central beam (M01) is pointing to the OFF point (Zheng et al 2020). This strategy successfully reduced the overhead time rates down to around 20%.…”

Section: Deep Observations With Fastmentioning

confidence: 99%

Neutral Hydrogen Content of Dwarf Galaxies in Different Environments

Guo

Renard

et al. 2023

Res. Astron. Astrophys.

Self Cite

View full text Add to dashboard Cite

Environments play an important role in galaxy formation and evolution, particularly in regulating the content of neutral gas. However, current H {\sc i} surveys have limitations in their depth, which prevents them from adequately studying low H {\sc i} content galaxies in high-density regions. In this study, we address this issue by employing the Five-hundred-meter Aperture Spherical radio Telescope (FAST) with extensive integration times to complement the relatively shallow Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) H {\sc i} survey. This approach allows us to explore the gas content of dwarf galaxies across various environments. We observe a positive relationship between H {\sc i} mass and stellar mass in dwarf galaxies, with a well-defined upper boundary for H {\sc i} mass that holds true in both observations and simulations. Furthermore, we find a decrease in the H {\sc i}-to-stellar mass ratio ($\rm M_{\rm HI}/M_*$) as the density of the environment increases, irrespective of whether it is determined by the proximity to the nearest group or the projected number density. Comparing our observations to simulations, we note a steeper slope in the relationship, suggesting a relatively slower gas-stripping process in observational data. Additionally, we find that the scaling relation between the $\rm M_{\rm HI}/M_*$ and optical properties can be improved by incorporating galaxy environments.

show abstract

“…The ON-source and OFF-source integration time are set to be 45 seconds, and the switch time between ONsource and OFF-source positions (overhead) is 30 seconds. For all other 100 galaxies, and the 6 test galaxies, we follow the observation strategy of Zheng et al (2020), i.e. covering the target using M01 and M14 beams in turns during ON-source and OFF-source mode respectively, so that the M14 (M01) is ON-source when the M01 (M14) is OFF-source.…”

Section: Hi Detection By Fastmentioning

confidence: 99%

“…The FAST spectra are contaminated by ∼ 1 MHz ripples caused by reflections between the feed cabin and the reflecting surface. Following Zheng et al (2020), we remove the 1 MHz ripple by subtracting a sinusoidal function fitted using spectra around the HI frequency of the target.…”

Section: Hi Detection By Fastmentioning

confidence: 99%

HI content of massive red spiral galaxies observed by FAST

Wang¹,

Zhang²,

Hao³

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

A sample of 279 massive red spirals was selected optically by Guo et al. (2020), among which 166 galaxies have been observed by the ALFALFA survey. In this work, we observe HI content of the rest 113 massive red spiral galaxies using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). 75 of the 113 galaxies have HI detection with a signal-to-noise ratio (S/N) greater than 4.7. Compared with the red spirals in the same sample that have been observed by the ALFALFA survey, galaxies observed by FAST have on average a higher S/N, and reach to a lower HI mass. To investigate why many red spirals contain a significant amount of HI mass, we check color profiles of the massive red spirals using images observed by the DESI Legacy Imaging Surveys. We find that galaxies with HI detection have bluer outer disks than the galaxies without HI detection, for both ALFALFA and FAST samples. For galaxies with HI detection, there exists a clear correlation between galaxy HI mass and g-r color at outer radius: galaxies with higher HI masses have bluer outer disks. The results indicate that optically selected massive red spirals are not fully quenched, and the HI gas observed in many of the galaxies may exist in their outer blue disks.

show abstract

A pilot search for extragalactic OH absorption with FAST

Cited by 12 publications

References 46 publications

FAST Discovery of a Fast Neutral Hydrogen Outflow

FAST Discovery of a Fast Neutral Hydrogen Outflow

Neutral Hydrogen Content of Dwarf Galaxies in Different Environments

HI content of massive red spiral galaxies observed by FAST

Contact Info

Product

Resources

About