[IPARCOS astro-seminar] 30/11/2023
Sophia Stuber (Max-Planck-Institut für Astronomie, MPIA, Heidelberg, DE)
Title: Molecular gas morphologies in nearby main sequence Galaxies
Abstract: The morphology of a galaxy results from secular and environmental processes during its evolutionary history. As such, it is an important tracer of galaxy evolution.
In this talk, I present the first visual classification of morphologies based solely on the molecular gas distribution for a large sample of 79 nearby main-sequence galaxies, using 1″ resolution CO(2-1) ALMA observations taken as part of the PHANGS survey.
We devised a morphology classification scheme for different types of bars, spiral arms (grand-design, flocculent, multi-arm and smooth), rings (central and non-central rings) similar to the well-established optical ones, and further introduced classes to describe the shape of bar lanes. I will present our results on spiral arms and stellar bars, and their (dis-)agreement with literature classifications based on the stellar distribution.
In addition, we find that more curved bar lanes show a shorter radial extend in molecular gas and have lower molecular to stellar mass ratios than those with straighter geometries.
Since these bar lanes consist of gas being efficiently funnelled to the centers of galaxies, I further highlight results on inflows to and outflows from the centres of PHANGs galaxies, as well as the central rings that can result from the funneling.
This is advisor so in that sense we are like doctoral siblings and she is um member of the fs collaboration which she will tell us about today she’s visiting the Madrid particularly she’s staying at the observatory until the 15th of December and yeah it is a pleasure to
Introduce her and hope you will enjoy her talk thank you for the introduction and first of all big thank you to the organizers for letting talk here play in Madrid it’s Sol raining today but actually the weather is so much better than German I’m really happy to be here
Um yeah and as Miguel said I’m a PhD student from heidleberg Germany um and I’m here today to present you some of the work that I’ve been doing which is about the morphologies of nearby galaxies from TS based on a molecular Gas Distribution but before I go into
This in more detail let me give you a brief overview what this talk is going to be about works okay um so morphologies can mean a lot of different things um so what I mean if I say morphologies are dynamical structures such as bar and firealarms which I’ll
Spend most of the time talking about but also about Bings of dusts I’ll explain them init later um I ALS Al also talk about gas flows due to these features um and last a little bit different types of rings that we can have in these galaxies okay
And to make it really clear exactly what I’m talking about just one example how this and roughly between half or even up to two of all Gala Universe to have these features so they are relatively common and we also see that features correlate with other parameters in galaxies increase Central gas
Concentra peanut bulges we have gas screaming motions due to these features and generally also the ages of cell populations on bars are older than on this so these features really have an impact on the evolution of galaxies they’re even assumed to be one of the main drivers of the secular evolution of
Galaxies so we really want to know of course we any Galaxy if they have a bar or not so let’s say you found a new Galaxy or maybe your supervisor assigned you a new Galaxy and says okay please study this Galaxy and now you know of
Course how important it is to know if your Galaxy has the bar or not so you were asking yourself the question does the Galaxy have a bar well this question can be answered quite simple there’s two things what you can do to get an answer to this question
First you can try to look it up online you can simply Google your Galaxy and find out out if there’s any classification that tells you if this galaxy has it um and what usually pops up is something like this classifications like sa telling you it’s an unbought spiral galaxy that there is
This bar in this galaxy which even goes back to the original Hubble sequence that edin Hubble um started to classify um back then it was still napul on the sky to classify if you see structures or not and some of these classifications are still used nowadays um of course
They got expanded so there’s also intermediate bar types in some of the cataloges and if you dig a little further then there’s also intermediate intermed and if you get confused by all these different classifications and there’s even more out there there’s of course a second option of to you can simply try yourself
And there’s nothing wrong with that because a lot of these catalogs out there are based on visual classifications so astronomers looking at images of galaxies classifying that they see a structure in there if they see a bar or not so you can do the same of course but then there’s another
Question at you say if you want to do that what weight link should you use what image should you look at because I mean nowadays for some galaxies We have basically covered the full spectrum we have observations from Radio to x-ray data and you potentially could use any
Of those does it matter at all well in the literature there’s this idea out there that actually it depends that some morphological structures are more easily visible in some WS compared to others just to give you an example for example this’s the soal stronger bar effect if
You want to classify bars based on infrared data they tend to be classified in slightly stronger categories than if you would use Optical data the same galaxies and also if you look have a look at bar fractions bar fractions from surveys using infraed data tend to be higher than bar factions from service
Using optical data and of course there’s a lot more playing a role here like the survey selection which type of galaxies are included but one aspect might also be that bars are simply more easily visible in INF data compared to object so there might be a dependence between
Morphology and what way things you look at but most of these classifications in the in the literature are either INF or Optical and both of that Chas mostly the Stellar distribution in galaxies we know that our galaxies there’s not only stars in them there’s
Also a lot of dust and gas so we were asking the question why don’t we use molecular Gas Distribution instead to classify whether we see bars or spirals or other structures and I don’t see really surprised phases or excited phases now so let me let me actually rephrase this
Question why should we do that for those that are still not convinced um well there’s two simple reasons for that first of all molecular gas is quite dissipating so it sticks to the underlying vitational potential really well so we expect to see also changes in the potential we expect to see them
Reflected in the molecular Gas Distribution generally it’s a really thin dis compared to the Stellar distribution which cre more expending and the second reason brings me to this soal Barian life if we have a look at stars in our galaxies they don’t just come out of nowhere it’s actually a cycle where gas
Gets recycled um over and over again so galaxies we have Atomic gas diffuser gas which some um conditions are right it can cool down it can become denser and denser for molecules so we get dense molecular gas and if it becomes even denser and denser at one point might
Collapse and we might end up with nuclear fusion and we have a star that’s born and these Stars they don’t live forever a lifetime they eject material back into the surrounding into cell medium and this material can be recycled interestingly here though the face that I’m looking at is the dense
Molecular gas pH so it is the dense phase of the in medium out of which stars in the future might be born so we’re looking at the material for future star formation so looking at where this dense gas is might tell us something about where Stars not form so by trying
To classify the morphologies of these galaxies based on a molecular Gas Distribution might be able to link directly on the underlying gravitational potential with processes of star formation but this was the motivation behind this work and so we actually did this trying to classify the morphologies based solely on the molecular Gas
Distribution and to do that we were using observations of monoxide second most common molecule in our universe most common molecule molecular hydrogen is a symmetric molecule does not have a permanent dipole moment it’s pretty hard to observe so easiest way what we can do is take the second most abundant
Molecule carbon monoxide transition 2 to one observed with ar and these observations I’ll tell a little more about them in a second because they are actually part of collaboration which is dis formation and um I want to spend just a couple minutes is talking about his collaboration
Because we have actually a lot of people working on the data set that we have here so f is not just galaxies it’s also people here just a couple of them from our team meeting in February this year and there a lot more also here in Madrid
So we have Miguel weia we have eno we have Marina and I hope I didn’t forget anybody um so we have a lot people um from thans working Madrid so if you want to know more um about what FS actually doing and the details you can also ask
Them yeah um so this is the collaboration and thans actually stands for physics a high angular resolution in your by gxes so the goal is to study the physics of um of the galaxies pet res scales so we’re not necessarily interested how one in single star FS Al
Not maybe how out of one Cloud several stars fall but rather to connect it on Galactic scales so to see how stars are formed how they are impacted by dynamical structures such as Firearms or bars um how this always connected and since one Galaxy can always be an
Outlier we’re using about 100 galaxies so a full sample of galaxies and these galaxies are not just any type of galaxies but they’re actually carefully selected so in our Nea Universe if you have a look at the star formation of galaxies is a function
Of this then we see that this is just a cartoon and then we see that most galaxies actually together to form the so main sequence of star from galaxies we have of course galaxies down here red andad elliptical for example um where not that many stars are formed and we
Have Starburst galaxies in which a lot of stars are form um but if we now want to study the star formation typical star formation in typical galaxies and you want have galaxies that this and that is also how they are selected so here’s now the actual plot
The star formation Stellar Mass so in data points from the Zs survey so just typical galaxies nearby galaxies and in blue the data points is the galaxies obser armor in our Fang sample which is about 100 galaxies and I’m quoting different numbers here because the number is increasing so in my study I’m
Using 90 galaxies but actually I think the number is above 100 by now um because there’s more and more data sets in the archive that we can use to define and dig up so um yeah please apologies if I say different numbers from time to time and some of the galaxies are also
Observed with different instruments about 19 observed Muse um about 39 with HD and we also have the first J WB images um it should be in the end also about 19 I think um that will be oberved with Jam laap I think not all of the observations are complete yet and some
Of the data reduction is still ongoing but there also will be a lot more data to use and all of these galaxies are nearby so less than 30 MEAP so that we can um resolve the structures well resolve potentially also some larger molecular clouds in there and they’re close to
Face on um so that we can also see the structures and for example see the difference between the arm and interarm region we can actually really see that how that correlates with moleular guas okay so this is how the galaxies are selected and just to give you a
Couple of examples how the data looks like so one of the Agy images Angy 628 nice Galaxy with spiral arms the same galaxy observed with Ms Al image and of course I guess most of you have seen a similar version of this world at one point NGC 628 observed by the J
Telescope this was one of the first galaxies that have been observed with the James telescope um yeah but there will be more data to use in the future and what I’m looking at again is Den gas of molecular gas so carbon monoxide the large millimeter and submillimeter array okay
So this is the setup basically we want to do so we have our sample sample our 100 galaxies our data monoxide what about the methods so we want to classify morphological structures and what we did is we just stick to a visual classification I know it’s 2023 and machine learning is on the
Rise so we also consider um the possibility of doing that but this kind of classification has never been done on the molecular gas before so there wouldn’t be any training data to use and we don’t know what to expect we don’t even know if it’s working at all so we
Stick to a visual classification but we had 10 people doing this classification to ensure that we are really tracing beautiful features and we have a good agreement and not just one person and we had a flow chart of different things that we went through to basically just say okay what are the
Features that we’re looking at what we see and I’m going to go through all of these and I’m going to start first of all with one brief comment because I get this ask a lot of times there are some outliner in fangs so some galaxies that
Were selected and later on we found out that the incarnations actually a lot higher or lower so some galaxies turned out to be more or less Edon so we removed all of them of galaxies but the detections are not really nice so we made sure we’re really using all this
Thing we can actually see so of course we classifi the largest features which is bars and SP arms and since we don’t really know what to expect from a clumpy molecular medium we came up with three new classifications for the bars because as you’ll see later on bars actually
Look quite different in the molecular so a meaning is unbarred B meaning there’s a thicker bar the surrounding region is not really cleared out and C meaning that either surrounding region is really nicely cleared out of gas or we have two lanes that connect with the
Center for the we stick with the usual classification so two arms meaning brand design multiple arms flocculent segments and in about two or three galaxies which are sort of more or less early type galaxies there a small molecule I guess disc in the center so they look like EOS
Um so they have a really completely smooth disc in the center which is also very small so we had to come up with this classification um but it’s about two or three galaxies so they’re not that specif so what is the result how do bars and spiral arms look like in
Aular well you’re already looking at one ofs because this picture does not only show beautifully how the molecular gas looks like but it actually encodes the results of our classification so on the left side you can see colored in purple whether the galaxies are classified as
Being barred or R if they classified as being unot and on the right side the SP classifications so in red clent in yellow multi or and of course there’s a lot of galaxies classified way this is because again we had 10 people doing this classification and we went wanted to
Make sure that we’re really only getting the features where all people are grean so we said that at least six or seven people need to agree in a feature otherwise we drop it from any further analysis and those end up in this way okay this already looks quite nice
But we can of course do a little more these galaxies as I said are selected to be from the main sequence so star foration is a function of C so of course the first thing we want to do is check where are those the main sequence and we can see that the unb
Galaxies couple of the lower M compared to galaxies in green this is in agreement with some studies on the literature but there also some studies that bu if we have a look at the spirals we can see that the flul Galaxy um in blue are at a lower cell mass in competive R
Design the two arm spiral systems also in agreement with some and now that we see that both Spirals and bars correlate with still on mass it is quite unsurprising that most of our grand designs are also in galaxies that have a bar and most of the
Flul systems are also without a bar and I could only find a very old paper that found the same thing from 1982 actually this this this connection between the teaches is still up to discussion I was on a conference in July in Gada and at this conference we
Actually had a discussion whether there could be a connection or not could it be that it’s triggered star formation triggered spiral arm formation that the presence of a stellar bar can trigger the formation of spars not or maybe it’s just a coincidence there was a stud my
Team who look at the pitched ankles and couldn’t find any connection with the persons around par so this is a l to discussion if any of you have any insight on that feel free to talk to me I’m happy to learn more about this so for now we don’t really know what’s
Going on here potentially there is some connection potentially not but we also have to admit that the Fang sample is maybe not the most suitable to answer this question because in the end we’re still talking about roughly 90 galaxies and in the literature there are samples
With many more galaxies in them and all of these galaxies are nearby so they have been mostly studied in the literature as well so what we should do is of course compare our classifications with those from the literature which are mostly based on the Stellar distribution that’s exactly what we’re
Going to do that next we do a ler comparison so um what we compare our classifications with classification from the literature from bu 2015 which is internet data or if not available the vo 1991 which is Optical data so we’re comparing our molecular gas based classifications with classifications
From the St distribution and the confusion Matrix looks a little messy but let me get into that in more detail let’s start with the spiral Arms This one is easier let’s so generally on the diagonal there is sort of it’s a little darker so there is some agreement here but we also don’t
Expect it to be perfect um I mean here the flul part not nice but we can especially spot the multi part did not work too well so what is going on we have to look at the reasons for that so multi-arms are generally known to have a reduced arm interarm contrast or tighter
Pitch angles which might make it harder to see these features in molecular gas because it is really clumpy also they they have a smaller arm width compared to Grand designs smaller arm width could mean that there’s less gas that can accumulate on the arms and again make it
Hard to see it in like that on the other hand molecular gas responds to the underlying features so if in a multi-arm system there’s two arms that stronger it could also be that therefore because the molecular gas response to these done better that we see these two arms especially in the
Molecular we don’t know exactly what’s going on here but that would be some of the explanations what’s going on but mul arms are a little special anyway in most cases we detected that there is a bar at all which is what we basically hoped for so we didn’t expect perfect agreement
For most galaxies it turned out to be however there’s four galaxies is where apparently literature said it’s a grand design sparm so two beautiful sparms which we didn’t see at all in our survey so we looked into this in more detail we looked where are these galaxies in our main sequence
Plot anywhere special so we had a look at the images how do these galaxies look like and just giving you two of these examples of these four galaxies you can see what was the problem here it’s a field of fuel this is one of the major disadvantages of the
The spiral arms that are in these images are very likely just outside of our field of F and we cannot really see these features and this is sort of by design of the survey because molecular gas is mostly confined in the central parts of galaxies so the field of few is
Also constrained to only record the central parts of the Galaxy obervation time is expensive and also we don’t expect to see much molecular gas throughout but if you ever want to do any similar study of this kind be aware in the outer regions the spiral arms are
Really far out you will not be able to see them okay going from the spiral arms back to the bars this one looks a more but we have to admit that we’re not comparing equal classifications here so we have this ABC this weird kind of classification system which is not
Directly comparable to the sabore BSB classification generally there is sort of some Trend here but again we have a couple of outliers which are pretty extreme which I’m what going to talk about so for example we have six galaxies where the leg says there is strong evidence
For a bar which we don’t see in our molecular medium so we have a look at these galaxies and if we look where they are the main sequence they’re all at the lower Stellar Mar and if you remember earlier I said that you SE this beautiful Stellar M the
Bar galaxies are all at the upper end here well if these galaxies would be B this TR not look so nice anymore so these six galaxies are actually a problem for us so we also had a closer look into them and here’s just one example and you be 1550 59 so here in
The top left Z observations bottom left 3.6 Micron is what was used for the internet literature classifications Al for comparison and here in the 3.6 M there is is some elongated feature here we don’t see it in MO we don’t see it all there’s no evidence for a bar in the
Molecular gas Med and the other galaxies are similar some are more bigger some less but in all these cases it’s not really sure what’s going on it could be that maybe it’s a gas bar maybe it’s a bar where there’s just no gas accumulating on it maybe there stuff
Fromc mimic elongated structure so there is no actual bar we cannot say for sure but what we know is that the bars at the lowest cell mass in of our sample they are really bigest and what we also learn is the bars at if they are bars they look completely
Different so what we usually do is when we when we have a look at surveys that cover a large range of Sol masses we expect the bars to all look the same but they don’t look all the same so we really need to be careful if we have a
Look at bars lower Sol masses they behave differently they look differently maybe they are’t even B we don’t know for sure but certainly we need to be careful about that and just to emphasizes even more we can calculate the bar fraction based on our classifications of course
About 90 galaxies is not really that large of a of a sample number to constrain an actual bar fraction but if we do that we find about 45% bar fraction based on our molecular gas classifications which is very similar to Optical service um in a sample of similar
Galaxies if you now take the same galaxies and the bar fraction based in the literature this ends up with a fraction of 73% so just to emphasize of course this is the six galaxies going in here but also a couple more that I classified as sa s aore b which I didn’t
Show here but these galaxies can really make a difference here in our little example here so we really want to get these classifications right and what we probably should do for the future is also have a look at the kilom mattic so be careful with galaxies at lowest St masses because the bars
May may not be bars okay one last example that I want to show now more positive example is one Galaxy where the literature did not find the bar but we found a bar so it’s the opposite case we’re not missing bars we found an additional and this galaxy is NGC
4941 again the same images and if you’re used if you’re not used to looking at vs and molecular medium this probably doesn’t look too special to you actually really hard to see on the screen though um if you’re used to looking at bars the molecular medium
Over and over again as I’ve done then you immediately spot that there’s two lanes that connect to the center a little easier to see of course in the left um which you simply cannot see in the other images because the center is also super white and these lanes are
Actually a clear sign of B this is where we expect the bottom of tuck in molecular gas to have these two lanes to connect with the center and also in the literature there’s some inclusive um classification so other classifications classify that there is a bar whereas the
One that we were using for this comparison that there is no bar so it is not that clear for this but with the molecular gas we can say for sure that there is a still bar and this is one of theor advantages of bance what are
Balance let me talk about these BS now as the second part of this talk so if we have a look at a bar um the Stellar orbits give us these nice orbits here X1 orbits along the bar more or less Center we can have just perpendicular orbits X2
Orbits um but the gas actually behaves a little different the gas can get stocked and then fbl to the center along these orbits and therefore a bar in a molecular gas is not just an elated feature but actually we expect to see these two lanes that connect Gally to the ring in the
Center but even just giving you these two examples it becomes clear that they also don’t all look the same this is the theoretical example what we might expect to see but of course in reality things are a little different here so here of course POS we went and had a look at the
Different bar LS of the sample and we classified the length of them meaning how much molecular gas we see does the structure connect with your features or is there actually a hole in between reach out to any other structure so we classify this as short short or long and
We also compareed these Bings with simulations from up 1992 to see what the curvature of these features is if they not curved or rather straight and then addition to that we also went to P our coordinates radius as a angle we had a look at these B features we masked out
Everything else like sparm centers and what remains is like exponential function which is these bar try to measure um the length of and by doing that we end up with this plot here on the x-axis is the measurement whether these bins are measured as be whether short or long covered by the visual
Classification of short or long in Orange and in blue and orange um and on the y- axis is the curvature whether they were straight or curved and it’s not a super duper clear part but what we see first of all is the visual classification agrees with our measurements the points especially the
Darker ones which is the ones that trust more because more people AG on that feature they are more to the left and the orange points are really more to right and generally it looks like there’s two clumps in here so we have up here and up here which basically tells
Us that bar lines that are shorter tend to be more curv and bar Lins that are longer in the molecular gas tend to be straighter and we also checked for the correlations we found that this is also correlated with the global molecular gas fraction so the more molecular gas that
Is globally Ava um and we only found a very very weak correlation here so it’s more L of data points but of course we’re also only looking at less than 20 galaxies here but the statistic is also not an our any and this was a similar
Thing was also found by com in 2009 lack of data points in one of the Bas um so there might be a tenative Trend this last here but we should um confirm this in the future maybe with a larger um sample but if we get a better statistic
On this might be able to make constraints about global parameters of galaxies or even the B CL of a galaxy by Simply Having a look at the geometry that would be of course ideal but again we’re a little bit lacking a better statistic here so potentially in
The future with the James W measurements where we see the dust Lings might be able to get that atra okay with that I want to come to um the third part of this talk now looking at all these bar linges what we see is gas on these lanes that is transported to
The center gas that is funnel to the center so of course we also want to ask question how much gas is actually moving to the center how much gas is following and this is a work that was done by maani Ashley me and we actually tried to isolate these violent features try to
Measure them how gas is on them and the result is an inflow rate of about three solar per year which is nice can we put it into perspective well yes we can because we can try to find out if the mass budget we have gas flowing inwards along
These bar Lanes gas that Fels to the center we have gas that is consumed by global star formation so it gets removed from this equation which is about two solar muscles for year we also gas is being pushed outwards again outflows and the soal outflow weate is
About so in this case Al giving you large uncertainties um the values add them nicely but of course the goal is to expand this to more galaxies which Marina will have a look into in the future um to really find out if this Mass budget also works for other
Galaxies in this one Galaxy this one Galaxy 1097 works out nicely talking about these outs how do we even know that Galaxies have outows do all Galaxies have outows or not and if not what kind of galaxies actually have outflows from the centers and going then back to what we just
Learned about how much gas outl out of the centers can we compare it with infl and well this is another study that I did in 2021 so I want to briefly talk about it first of all what is an outflow an outflow is a relatively small amount of mass moving relatively High
Velocities so we’re looking for broad rings in a spectrum or if we take a Precision velocity diagram we expect to s shaped rotation curve we’re looking for something suspicious on top of that and we can also take These boad Wings integrate over them where is this emission actually coming from in a map
Of the Galaxy and we did this also for the full Fang sample and we found that about 25% of the Fang galaxies show evidence for outflows in their centers and we also did more we tried to estimate them um what is the act outflowing rate the masses of these
Outflows the outl rate so here you can see the outflow rate Sol masses could be compar and then red is our measured dat point it is 25% um and in blue is point of the literature from mainly starbur galaxies we can see that our relatively typical boring way main sequence galaxies from
Fangs they have outflows that are very much comparable with those from villes they expand to this low machine so it’s not really that these galaxies there’s nothing happening and these starburs there’s all the star formation happening in these extreme conditions all that happens in main sequence galaxies as
Well just on a little small SP yes and of course we were also asking question what kind of galaxies um have outflows because of course 25% means not all of our Galaxies have ales so we been having a look at the AG faction because that is one of the main mechanisms that
Could drive an AR well only about half of these outl candidates have an A which is still more than that we have a full sample including these these galaxies here but so half of the galaxies do not have AGM but there’s also another driving mechanism which could be just starbur in
The center of the we also checked is for the bar factions we can see that nearly all of these out candidates have a bar which is also more than a fun sample but all these out candidates are also at highest level masks so it could be just a coincidence that both these Al
Features they are may be larger they may be more massive at higher at higher Stellar masses so we are able to detect them and theas are also more coincidentally more prevalent at higher solell Muses potentially there’s also connection potentially the bars are actually necessary to first of all T
Enough gas to the center so that a central Star Stream can build up so we have some energy source that can drive the outflow and of course we need gas in the center to have an outflow without gas there cannot be an outflow so we
Don’t know for sure but this is one of the reasons that could happen why we see such a high bar fraction here and this again tells us why it is so important to get classifications of bars right because they correlate with so many things they also correlate with the
Gas okay talking about the gas res one Center this’s the last point that I want to talk about um asking a question okay we have this gas can be removed from the center finally to the center what has happened in the center well in some cases the gas can
Accumulate on these x two orbits and we can have R from so here’s a couple examp of rings because rings can happen on different states the rings that I was just introducing the Rings in the centers of galaxies two top examples but of course rings can also happen in the
Other SPS of galaxies outside of a bar outside of spiral on so we were classifying whether we see these kind of rings so whether we see Central Rings literature often referred to as nuclear rings in case we get confused and we call it non Central rings so all kind of
Rings that is outside of a bar for example and for these non- Central rings I can make it a little quick it’s about 8% that we find the problem is again that our field of view potentially is not large enough so we not really sure if
We’re missing some of these Rings or not um we find that they’re mostly in B galaxies um which is in agreement with some studies but although not with all but again our field of view might be one of the reasons why we not detecting some of these rings so this is not entirely
Sure however we have will look at the central Rings also known as inner Rings you see that well not always it’s the perfect Rings sometimes a little elongated but these features um mainly exist due to the funneling of gas inside bars and orbits that can be accumulated
By gas so about 30% of our Galaxies have these wings and most of them are in galaxies that are also nicely in agreement with some just and to look into this even further a bachelor student for me Daman guys I actually currently to quantify the amount of gas
That is in these rings so by isolating um these ring structures and trying to measure what is the amount of molecular gas and so far but it’s still preliminary we find that there’s about 6% is deflection of molecular gas in the ring compared to the full Galaxy which
Is pretty comparable what we found as so maybe this is just um the same in all other galaxies here but again this is preliminary s probably right now sitting at at his computer trying to figure out the the numbers okay with that I want to come to a brief future
Outlook talking about JW because there’s the first images that we have more data so incoming and of course rings and baring are really nicely visible in well what we see with the J image mostly the dust structures dust is able to Shield molecular gas from being destroyed by
Radiation of stars so some of the features to show us very similar structures than what we see in the mo gas so these bar Lanes might be able to see them here as well in my dat to ca as well so this is one of the future things
That we might want to have a look into more details and with that I hope I could convince you that the molecular gas is actually able to trace molecular features quite well we don’t have a perfect agreement but we didn’t expect it because there are some physical
Reasons why this not and especially at the lower cell mass in our G IES be careful with bars they might not actually be bars maybe they are and they’re just behaving completely different um so something to find out um we also could see that bar Lanes is one
Of the nice things that we can see in the molecular Gas Distribution can try it to do a lot of studies here and we saw the both Central rings and Galactic Outpost are preferentially in galaxies with they are so we really need to get this classification from it and in case
You’re using YouTube I just want to advertise we started a YouTube channel called panks team there’s currently about three videos in there so we just started um but one of the videos is actually a shorter version of this talk so if you feel like you want to hear it
Again um you can check it out thank you very much yeah so I it’s just to basically build up a g once so I don’t think the B necessarily has any dynamical impact on that um but to so I mean this is still after to study so this is what my
Me but generally in the centers I mean there’s these rings that you see there Starburst so a lot of star formation happening this could be one of the mechanisms to drive the out the energy source because if we don’t have an AG we need a different energy source why so
That could be one of the reasons that because because of the bars we get so much gas in the center that these stos can build up um in the ring and the second reason is that um we just need enough gas in the center so in some
Galaxies if there’s just no gas in the center there’s nothing we can push out even if there’s an energy source we have nothing that we can see here so we need enough G to get push all so that was the argument here because we haven’t done
Any calculations on this so this is just the idea that could theoretically work out does that make sense um no we we don’t have any full sample observations I neutral gas as far as I’m aware so the only one that we have this so there’s currently also
Master at the ionized gas because ala should be even easier to detect an ionized gas but he’s also on it right now so he hasn’t done that also these 100 Galaxies have only observe the Dharma so we don’t have any other observ as far as I’m aware of any other
Observations that cover all these 100 galaxies so that’s sort of a limit here but that’s of course something to check so yeah ionized gas is checked by m St noral other gas faces yeah that’s that’s true yeah questions Yeah question with M yeah for sure well I think is it’s already happening there’s really a right so if I say low mass I mean is not galaxies but 10 to n or something so you can go lower yes cly yeah g show areem be um
Yes that’s a good question so my takeway is that for the can you repeat the question for the people online um yes the question is if we are um if due to inter parameters we’re missing some diffuse emission that might help us to that that that we would see bars that
Are otherwise that by now we don’t see the data so my take for this would be that um so at higher sell mes of course the bars might be different but the bars generally these two bar lines that we see a higher resolution would be better
To see them so it’s not necessarily the fuse component that’s missing but yes we have total power yeah yeah I mean we don’t cover the full page but so they are all with with short spacing corrected so we we we add total power to that but still I think um it’s it’s not
Necessarily this the bars wouldn’t be like a board structure or something so the high resolution is actually better to to detect them I um is that okay is there any question uh from the audience online you have a question just your mic on okay any other question here and
Of face of the the Galaxy can May or of the G that potentially yes yeah potentially this is an evolutionary thing um so one thing that would be really good is also to get um the ages of the bars but this is a really hard thing to constraint so I
Think y Norman is currently looking into this if we can get some I think there was some paper just recently about how to estimate the ages of the bars because I mean that would really help you find out is actually the the bar becoming older over time and all the gas funnel
So and maybe there’s no more gas coming inwards so this is an older case basically an evolutionary case but I think we’re lacking a little bit um the age constraint on that so any good methods on age determination and virus feel free to tell Me S when like an increasing the start formation like formation history so she can constrain the ook of bar formation by looking at theory of the compar with that the the will yeah see Mak Con on the edge of the bar not the edge of the St but yeah I mean
But getting like consistent Result sorry who someone there um um yeah an yeah an can you you can ask a question if you want hi hi Sophia very nice talk uh uh I I have a question concerning the the bar morphologies that you you you find you said that you find
Some short bars in radius but do you find any evidence for nested bars like in bed bars like as the model proposed by sh in I think 98 something like that of this set of nested bars so the bars within bars yeah thanks for the question this
Is really nice um let me think about it so uh couple I think there’s a couple of but do we have them in our yes we have some right um yeah so I didn’t look into that in much more detail but that’s definitely something good to do um two two cases
Yeah um and we have the observation I should look into that so we haven’t done this yet but this is something I should check yes okay thanks and if I can ask another question quickly um you you said that you find this inner rings as well
Like uh in Co do you have any further evidence of um structures inside the ring because we we have some observations but is are much um smaller sample of the noua galaxies and for some of them we found evidence of nuclear spires that are inside the
The inner ring so I wonder if you also see this for some of the galaxies in the fun s so I’m pretty certain that some of the Galaxies have that the problem is um that our Alma observations have about 100 pass resolution and these rings are
Just a couple of hundred pic in size so I think nuga has a lot higher resolution observation so for the molecular gas pH we certainly lacking the resolution here I’m not too sure about the James I think there’s already something going on to find yeah people are staring at the
James images right now so we would be able to see them here did somebody start into this yes yeah so but with the AL observations 100 par I think is not enough to to resolve these features unfortunately okay thank okay have a suggest for the relation between the the bar and and the
Ground and it’s was the theory of the man by yeah yeah and yeah I mean in her Theory Grand designs need a need so because there so there will be a clear connection and fact you can you can actually fify you find from that will be
A yeah I think I just remember that I also read some papers that really nicely explain how you could form a bar could form sparms with with a bar but I think some of the simulation side they see that there’s not necessarily a COR connection but I’m also not too good
With maybe now maybe now they say well I don’t I think manold they need a but make itly but I think is is it proven well it’s a I mean not okay okay any last question for sopia then weeks okay so we weeks is keep tuned we will announce it uh on thank
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