<p>Suppose I have a rough estimate of HI gas content (in solar mass units) in a local dwarf galaxy located at a distance say d parsec (at some RA and Dec co-ordinates) with a half-light radius r and I am assuming a velocity width of 10-20 km/s. Now equipped with this info I need to figure out how much would be the approx integrated radio flux on earth. Any idea how to get it (or what other information I'll need)?</p>

CC BY-SA 4.0
2023-07-10T22:02:55.540Z
*Welcome to Stack Exchange!* Have you tried reading anything on the topic? If so, it will be much better to include what you've tried so far and where you're stuck. Without that, this looks more like a "please look this up for me, I'm too busy to do any reading" question and many not receive any attention.
uhoh
CC BY-SA 4.0
2023-07-12T09:55:17.937Z
@uhoh Thank you for responding. I had just read a line flat out stating "galaxy containing X amount of Hydrogen, located d MPc away will result in Z Jy km/s flux at 1.42 GHz for which i couldn't find reference to get an idea on how it was derived. All I could find for a couple of days was the relationship between atomic gas velocity dispersions & flux which I didn't fully understand the relevance of to my original doubt so I was unsure about what information was even relevant/needed (hence included that last line). Currently I'm seeing whether I can connect the two via gas density estimates.
RADagASTtheBROWN
<radio-astronomy><dwarf-galaxy>
How to find integrated radio flux for the 21-cm line due to HI content in a dwarf galaxy?
RADagASTtheBROWN
# How to find integrated radio flux for the 21-cm line due to HI content in a dwarf galaxy?

(Asked by: username_0 on 2023-07-07)

Suppose I have a rough estimate of HI gas content (in solar mass units) in a local dwarf galaxy located at a distance say d parsec (at some RA and Dec co-ordinates) with a half-light radius r and I am assuming a velocity width of 10-20 km/s. Now equipped with this info I need to figure out how much would be the approx integrated radio flux on earth. Any idea how to get it (or what other information I'll need)?

**Tags:** radio-astronomy, dwarf-galaxy
> **Comments:**
> **username_1**: *Welcome to Stack Exchange!* Have you tried reading anything on the topic? If so, it will be much better to include what you've tried so far and where you're stuck. Without that, this looks more like a "please look this up for me, I'm too busy to do any reading" question and many not receive any attention.  
> **username_0**: @uhoh Thank you for responding. I had just read a line flat out stating "galaxy containing X amount of Hydrogen, located d MPc away will result in Z Jy km/s flux at 1.42 GHz for which i couldn't find reference to get an idea on how it was derived. All I could find for a couple of days was the relationship between atomic gas velocity dispersions & flux which I didn't fully understand the relevance of to my original doubt so I was unsure about what information was even relevant/needed (hence included that last line). Currently I'm seeing whether I can connect the two via gas density estimates.  

---

## 0 answers

