[Lofarpwg] TULIPP paper draft for final review

Wed Nov 10 07:05:13 UTC 2021

Hi Aris, Cees, et al.,

Thanks for your emails. And sorry for my slow reply, I’ve been working on all the comments I’ve received, in the hope of submitting the paper tomorrow!

Thank you for reading the TULIPP paper, Aris. You’re more than welcome to become more involved as a co-I in any future TULIPP observing proposals etc., as is anyone else who is interested?

You’re right that the two quantities being compared between imaging and beamformed data are not quite the same, your summary equations are correct. I have added more specific text into the imaging (S2) and pulsar (S3) observations to briefly explain how the fractional linear polarisation measurements were calculated, I realise I hadn’t explicitly included that before. I also expanded the text in S4.4 related to why the fractional linear polarisation in the LoTSS data is much smaller than obtained through the beamformed data for PSR J2227+3038, e.g. the large swing in P.A values across the pulse profile.  I mentioned Karastergiou et al, in prep. in relation to this, but please let me know if there’s more suitable reference(s)?

I will be interested to read your MeerKAT paper, and also happy to provide any input.
I have been thinking (along with others) about a possible related relevant LOFAR project: cross-matching the LoTSS and pulsar catalogues, to obtain the image properties for the known pulsars detected (in I,L, and V,) and comparing this to beamformed data for these pulsars. That will provide valuable information about the percentage of pulsars that are polarised at low frequencies (which will also be dependent on distance, Gl, ISM foreground, etc.); and future candidate identification, e.g. insight into the ‘types’ of pulse profiles that this kind of targeted search might find, or miss, going forward.

Please just let me know if you have any follow-up questions or comments?

Many thanks and best wishes,
Charlotte

From: Cees Bassa <bassa at astron.nl>
Date: Wednesday, 10 November 2021 at 5:15 am
To: Aris Karastergiou <aris.karastergiou at physics.ox.ac.uk>, Sobey, Charlotte (S&A, Kensington WA) <Charlotte.Sobey at csiro.au>, lofarpwg at astron.nl <lofarpwg at astron.nl>, Evan Keane <evan.keane at nuigalway.ie>, e.vanderwateren at science.ru.nl <e.vanderwateren at science.ru.nl>
Subject: Re: [Lofarpwg] TULIPP paper draft for final review
Hi Aris,

On Tue, 2021-11-09 at 12:38 +0000, Aris Karastergiou wrote:
> Have you perhaps had a chance to consider my email?

Thanks for the reminder. Your remark was briefly discussed at the PWG
meeting last Monday, but as far as I'm aware it has not yet been
addressed in the paper. Given that you are writing a paper on the
distinction in definitions, are you okay with adding a paragraph about
this when comparing imaging vs folded polarization fractions?

Regards,
   Cees

>
> Cheers
> Aris
>
> Get Outlook for Android
> From: lofarpwg <lofarpwg-bounces at astron.nl> on behalf of Aris
> Karastergiou <aris.karastergiou at physics.ox.ac.uk>
> Sent: Friday, October 29, 2021 10:57:24 AM
> To: Sobey, Charlotte (S&A, Kensington WA)
> <Charlotte.Sobey at csiro.au>;lofarpwg at astron.nl <lofarpwg at astron.nl>;
> Evan Keane <evan.keane at nuigalway.ie>; e.vanderwateren at science.ru.nl
> <e.vanderwateren at science.ru.nl>
> Subject: Re: [Lofarpwg] TULIPP paper draft for final review
> Hi Charlotte,
>
> That's a nice paper. I wish I had the time and energy this past year
> and a half to follow this work closer, but I didn't. I was reading
> through it now and had a comment that you might want to consider.
> Simply put, I think you are comparing two different quantities when
> you compare the fractional linear polarization in the images to what
> is traditionally published in pulsar papers. In fact, I did not see
> the formulas you use to determine the average L/I in these two cases,
> but could they be the following?
>
>    1. In imaging, L = sqrt( Sum(Q)^2 + Sum(U)^2 ), and I is just
> Sum(I), where the sums are over the entire integration time.
>    2. In time domain obs, L = Sum( sqrt(Q^2+U^2) ), and I is again
> Sum(I). Here the sums are across pulse phase. I think this is what is
> traditionally published in pulsar papers.
> I have ignored the L bias correction in both cases.
>
> If so (as per the norm), then the imaging L/I is always going to be
> less than the timing L/I, depending in fact on the PA swing and the
> shape of the profile. I think this is clear in your figure 2, where
> in the timing data the pulsar is very highly polarized.
>
> We are currently writing up a MeerKAT paper where we are highlighting
> this distinction in definitions, and I have been thinking about the
> impact this could have in identifying pulsars in images. You may want
> to consider this here, and even perhaps write a few sentences along
> the lines mentioned above. If somehow I have missed relevant
> discussion that exists in the manuscript already, please ignore the
> above.
>
> Cheers,
> Aris
>
>
>
>
> From: lofarpwg <lofarpwg-bounces at astron.nl> on behalf of Sobey,
> Charlotte (S&A, Kensington WA) <Charlotte.Sobey at csiro.au>
> Sent: 21 October 2021 15:19
> To: lofarpwg at astron.nl <lofarpwg at astron.nl>; Evan Keane
> <evan.keane at nuigalway.ie>; e.vanderwateren at science.ru.nl
> <e.vanderwateren at science.ru.nl>
> Subject: [Lofarpwg] TULIPP paper draft for final review
> Dear All,
>
> I hope this email finds you well.
>
> It is a pleasure to share the initial ‘TULIPP’ paper with the PWG.
> The paper title is currently “A pulsar survey of polarized point
> sources from the LOFAR imaging surveys: description and initial
> discoveries”
> It can be viewed/downloaded from google drive here:
> https://drive.google.com/file/d/1rdfFh8njcF4639sBtREP9ZNJyWv9kZIc
> Please feel free to email me with any impressions/comments before
> your close of business onFriday 29 October.
> I hope to submit the final version of the paper shortly afterwards.
>
> Many thanks and best wishes,
> Charlotte
> --
> Dr Charlotte Sobey(she/her/they/them)
> Postdoctoral Fellow
> Space & Astronomy  |  CSIRO
> charlotte.sobey at csiro.au  |  +61 8 6436 8781
> PO Box 1130, Bentley, WA 6102, Australia
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> waters, of the area that we live and work on across Australia. We
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> CSIRO Australia’s National Science Agency  |  csiro.au
>
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