RGZ's first paper has been submitted

• by ivywong scientist, admin

  Here is the link to our blog announcing that the first RGZ paper has been submitted for publication:
  http://blog.galaxyzoo.org/2015/03/02/first-radio-galaxy-zoo-paper-has-been-submitted/

  Thanks heaps as always and keep up the awesome effort as we still have 68% of the project to go !

  Cheers,
  Julie & Ivy

  Posted March 2, 2015 5:52 AM

• by JeanTate in response to ivywong's comment.

  Very cool! 😄

  And it has a most impressive list of authors too. Suggestion for a future Journal Club or Chat Discussion thread: who chooses who gets to be an author of a paper like this, and how is the production of such a paper organized (the writing is surely one of the minor aspects)?

  Very nice to also read that the first "giants" paper is now close to being submitted!

  Posted March 2, 2015 1:52 PM

• by DZM Zooniverse Team

  This is fantastic news, @ivywong ... thank you so much for sharing!

  When it's actually published, if possible, please let someone at Zooniverse know where we can get a version that we can add it to the Publications page. It'll be great to have another project represented there.

  Congratulations!!

  Posted March 2, 2015 4:58 PM

• by ivywong scientist, admin

  @JeanTate: yes, many people have put in a lot of time to creating the project that you see today. We had 2 years of brainstorming and alpha-testing before we even tried launching a beta. The writing & cohesion is maintained by the first 3 authors but every co-author contributes their thoughts towards the paper. Essentially, the order is based upon the amount of work each person has contributed.

  @DZM: Thanks. Naturally, it will be on the Zooniverse once it is accepted for publication.

  Posted March 3, 2015 1:03 AM

• by JeanTate in response to ivywong's comment.

  Thanks Ivy.

  The story of how the original Galaxy Zoo came to be, from the first 'pub meeting' to 'servers melting' to the main GZ paper is relatively well-known to 'oldbie' zooites; however, I think it's fair to say that that of RGZ is known only to the science (+) team members involved. I think it deserves to be better known, including the parts where technical challenges were tackled by the clever and hard-working team members who we almost never hear about. Is there an Ann Finkeiner in the house? 😉

  Posted March 3, 2015 2:08 AM

• by ivywong scientist, admin

  No worries @JeanTate. Note that I was not as heavily involved in the very early days of RGZ so Julie will have more information on the very early days. I joint in 2011 as a GZ advisor when I began at CSIRO (where Julie & Ray were based). Fresh from the success of GZ, the newly-formed RGZ team (mainly the folks from the ATLAS survey and in anticipation of EMU) were very excited about the prospect of help from like-minded citizen scientists. Ray was especially keen because he had just estimated that ~7 million of the 70 million that he expected from EMU will be too difficult for automatic computer classifiers.

  At the beginning, Julie and Melanie Gendre (now retired) were leading the team in collaboration with Arfon (now retired). We began with a wish-list of all the properties that the science team would like from each classified object and so RGZ had a huge decision tree at the start. When we implemented this at Adler Planetarium for an alpha-testing, the feedback we got was not great and we realised that we needed to reduce the size of the decision tree to minimise confusion.

  After the alpha-testing, we started from scratch and made a better decision tree which became our beta-test. The current working version should be the lambda version because we had a gamma-test which we labelled beta_v2. So that is our story 😃

  Posted March 5, 2015 1:24 AM

• by akapinska scientist in response to JeanTate's comment.

  If I may jump into the discussion, writing sometimes is half the work for a publication @JeanTate! 😉

  Posted March 5, 2015 1:48 PM

• by ivywong scientist, admin

  Thanks @akapinska ! 😃 I expect that you may have something shortly for the RGZ-ites too 😉

  Posted March 6, 2015 4:20 AM

• by DZM Zooniverse Team

  ... ooh, exciting! 😄

  Posted March 6, 2015 6:24 PM

• by ivywong scientist, admin

  The link to Anna's blogpost about RGZ's 2nd submitted paper can be found here:

  http://blog.galaxyzoo.org/2015/03/13/radio-galaxy-zoo-searches-for-hybrid-morphology-radio-galaxies-hybrid/

  😃

  Posted March 13, 2015 9:37 AM

• by JeanTate in response to ivywong's comment.

  Cool! 😃

  What's a LERG? a HERG?

  "Low/high energy radio galaxy", perhaps?

  Posted March 13, 2015 11:58 AM

• by akapinska scientist in response to JeanTate's comment.

  Hi @JaneTate,

  no, LERGs/HERGs are "low/high excitation radio galaxies". This classification is actually based on optical spectra, where you would look for strong emission lines of OIII and a few others. Of course, there are also low/high excitation galaxies that may not be radio sources.

  You may have a look at a really nice recent paper that will explain the difference and give more references and discussed our current understanding of this classification
  http://adsabs.harvard.edu/abs/2012MNRAS.421.1569B

  (follow the arxiv link)

  Posted March 13, 2015 12:08 PM

• by JeanTate in response to akapinska's comment.

  Thanks! The Best and Heckman paper looks most interesting.

  So, in Figure 4 (per the blog post), the sole elliptical host HyMoRS, and one of the QSO HyMoRS, is both a LERG and a NLRG, and the sole Seyfert is a HERG and a NLRG ... am I reading this correctly?

  Further, the sole Seyfert HyMoRS must be - by definition - an SDRAGN ('spiral' - actually disk galaxy - double radio source AGN), right? Also, while Seyferts can have broad emission lines (type I or 1), this one is has narrow emission lines (type II or 2), yes?

  Posted March 13, 2015 1:08 PM

• by akapinska scientist in response to JeanTate's comment.

  Well, it's not exactly that simple. These are diagnostic diagrams rather than criteria to satisfy classification. So, the only thing this figure can tell us is:

  • the elliptical hymors you refer to is likely LERGs

  • QSO cannot be LERG, but note

  • sources separated by the solid line to the left of the figure are 70% LERGs and 30% HERGs, so the only thing we can do here is set a probability the sources that fall in that part of the figure are LERGs (check out Gurkan+ 2014 from whom these divisions are taken), but 40% of all LERGS in the figure still lie to the right of this line

  • most HERGs and BLRGs are to above the dashed line, but that doesn't mean they can't lie below that line, rather probability of this happening based on current data, is rather small. But look we already have 2 QSOs below this line

  So, the bottom point to realise here is that one cannot say that some object definitely "is" based on this diagnostic diagram, rather "it is likely to be". It's really way the real science is 😉

  Posted March 14, 2015 5:38 AM

• by akapinska scientist in response to JeanTate's comment.

  oh, by the way NLRG, BLRG and QSO are all HERGs, so one galaxy cannot be both NLRG and LERG 😃

  NLRG = narrow line radio galaxy

  BLRG = broad line radio galaxy

  QSO = quasi stellar object

  HERG = high excitation radio galaxy

  LERG = low excitation radio galaxy

  Posted March 14, 2015 5:43 AM

• by akapinska scientist

  Ah, and that Seyfert in the plot is a very well known radio galaxy NGC612, have a look at these papers:

  http://adsabs.harvard.edu/abs/2001A%26A...375..791V ,

  http://adsabs.harvard.edu/abs/2008MNRAS.387..197E and references there,

  http://adsabs.harvard.edu/abs/1978A%26A....69L..21E

  Posted March 14, 2015 6:30 AM

• by JeanTate in response to akapinska's comment.

  Thanks akapinska.

  Having read the Best&Heckman paper, I now better appreciate that these distinctions are much less like M-giant vs M-dwarf (from spectroscopy), say, and more like trying to distinguish AGN from star-forming (and each from 'both'!) in a BPT diagram.

  Having only the text of Figure 4 to go by, and missing what's in the paper, I'm puzzled by the distinctions being made. Here's why:

  • 'elliptical' is a morphological classification, from an optical/visual (or perhaps IR) image; technically its radial surface brightness profile is well-approximated by a single, Sersic component (with n~4); they may have a strong point-source nucleus
  • 'Seyfert' is a kinda hybrid classification; Seyfert galaxies have a disk (optical) morphology (and a bulge), and a prominent point-source nucleus; spectrally they are AGNs (or composites)
  • 'QSO' can be a lot of different things; morphologically, in SDSS images, the nucleus is so bright as to make morphological classification impossible (most of the time); they are distinguished from 'mere' AGNs by an arbitrary absolute mag threshold (i-band, for SDSS). Spectroscopically, they are simply AGNs, with nothing to distinguish them from other AGNs (except for an arbitrary flux threshold).

  So, in Figure 4, if you had a high resolution optical image (from Hubble, say), perhaps taken with a coronograph, all the QSOs could be split into 'elliptical', 'disk galaxy' (a.k.a. 'spiral', a.k.a. 'Seyfert'), merger/irregular (maybe), ... if so, then don't labels like 'elliptical' and 'Seyfert' merely reflect selection biases?

  Good old NGC612! 😃 It's one of Julie's fave objects, if I recall correctly. And it makes my point about selection bias very well ... we know the morphology of the host only because it's so local ...

  Posted March 15, 2015 11:58 PM

• by ivywong scientist, admin

  Hi Jean,

  Once an object is classed as a QSO, the emission from the AGN outshines the emission from the stellar components so it is very difficult to study the host galaxy's morphology unless the source is at low redshifts.

  This paper by Bahcall et al 1997 might be of interest to you: http://arxiv.org/abs/astro-ph/9611163

  And yes, NGC612 is one of Julie's favourites 😃

  cheers,
  Ivy

  Posted March 16, 2015 1:36 AM

• by JeanTate in response to ivywong's comment.

  Thanks Ivy.

  I'm not sure how much definitions have changed since 1997 (and Bahcall is one my all time fave astronomers/astrophysicists; if only everyone could write as clearly as he did!), but SDSS is chock-a-block full of "QSOs" (defined spectroscopically) whose hosts are easily discernable (see below). True, they are certainly at low redshifts (~0.1 is a good cutoff for being able to tell morphology for many purposes, and the original GZ had a cutoff of 0.25, as did GZ2 too I think).

  Here's (left) z_sp 0.084 SDSS J113246.66+062624.4, which has a nice broadline spectrum, with a continuum rising into the UV (no starburst galaxy has that!); and (right) z_sp 0.059 SDSS J104109.43+344301.0, whose spectrum the SDSS pipeline automatically classifies as "QSO AGN BROADLINE":

  

  Posted March 16, 2015 2:14 AM