HI clouds in the center of the Virgo cluster

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In summary, the paper discusses the discovery of a HI cloud near the center of the Virgo cluster, potentially stripped from a nearby galaxy by tidal forces or ICM gas pressure. It also questions the existence of a dark galaxy in the same region and suggests that further research is needed to determine the origin of VIRGOHI21.
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hellfire
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This paper http://arxiv.org/astro-ph/0505397 reports the discovery of a HI cloud near the center of the Virgo cluster. According to the morphology and kinematics of a plume in a nearby galaxy (NGC 4388), it is assumed that tidal forces or the pressure of the ICM gas have stripped this HI gas from NGC 4388.

At the end of the paper it is also postulated that the reported discovery of a "dark galaxy" (VIRGOHI21) in http://arxiv.org/abs/astro-ph/0502312 might be wrong and that VIRGOHI21 may be also of similar nature than the recently discovered cloud. In that paper it was stated that the absence of nearby clouds as well as the absence of galaxies located close enough to VIRGOHI21 were the reasons to discard tidal interactions as the origin of VIRGOHI21. Therefore, it was assumed that a dark galaxy was found (their existence is predicted by the CDM model of structure formation).

However, in that paper no mention of a possible stripping by ICM gas was made. Is it possible that a mechanism like stripping by ICM gas pressure can produce an isolated cloud with a high rotation velocity (as reported in astro-ph/0502312)? Or shall I assume that the authors of astro-ph/0505397 are expecting new discoveries of HI-clouds near VIRGOHI21 such that the assumption of tidal interactions could make sense?
 
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It is possible that a mechanism like stripping by ICM gas pressure could produce an isolated cloud with a high rotation velocity, such as reported in astro-ph/0502312. This could explain the presence of VIRGOHI21 without requiring the existence of a dark galaxy. However, more research is necessary to determine whether or not this is the case. The authors of astro-ph/0505397 may be expecting new discoveries of HI-clouds near VIRGOHI21 in order to support the assumption of tidal interactions, and further research into this matter could help to answer this question.
 

1. What are HI clouds in the center of the Virgo cluster?

HI clouds are large accumulations of neutral hydrogen gas that exist in the center of the Virgo cluster, a collection of galaxies located approximately 54 million light years away from Earth.

2. How were these HI clouds discovered?

The HI clouds in the center of the Virgo cluster were first discovered through radio telescopes, which can detect the radio signals emitted by neutral hydrogen gas. The first detection of these clouds was made in the 1970s.

3. Why are HI clouds important to scientists?

HI clouds provide valuable information about the formation and evolution of galaxies in the Virgo cluster. They also offer insights into the distribution and dynamics of dark matter, as these clouds are thought to be embedded within larger dark matter structures.

4. How do scientists study HI clouds in the center of the Virgo cluster?

Scientists use various telescopes and instruments, including radio telescopes, optical telescopes, and X-ray telescopes, to study the HI clouds in the Virgo cluster. By observing the radio signals and other emissions from these clouds, scientists can gather data about their size, composition, and movement.

5. What have scientists learned about HI clouds in the center of the Virgo cluster?

Through studying HI clouds in the Virgo cluster, scientists have learned that these clouds are actively interacting with each other and with the galaxies in the cluster. They have also found evidence of gas being stripped from galaxies and falling into the cluster, providing further insights into the evolution of galaxies in dense environments.

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