Supplementary Material to:

An Introduction to Radio Astronomy

4th edition Cambridge University Press 2019   

Last updated 24/05/2019

 

Chapter 17: The Radio Contributions to Cosmology

 

The Cosmic Microwave Background:

 

Overview Material

 

For an overview of the basics of CMB astrophysics see:

http://background.uchicago.edu/~whu/intermediate/intermediate.html

 

An extensive collection of information on CMB-related matters, both ground and space, is the NASA Legacy Archive for Microwave Background Data Analysis (LAMBDA) site https://lambda.gsfc.nasa.gov/   For an overview of the data products and other resources available on the site see  https://arxiv.org/pdf/1905.08667

This is an overview of the data products and other resources available through

For an overview of the analysis of CMB data: https://space.mit.edu/home/tegmark/cmb/pipeline.html

 

 

The Planck mission

 

Descriptive ESA animations of the Planck mission can be found at :

 

Building up the sky maps: http://sci.esa.int/planck/41071-mapping-the-cosmic-microwave-background/

 

Peeling back the foregrounds: http://sci.esa.int/planck/51556-revealing-the-cosmic-microwave-background-with-planck/

 

Gravitational lensing of the CMB:  http://sci.esa.int/planck/51607-gravitational-lensing-of-the-cosmic-microwave-background-animation/

 

The scientific papers in the Planck 2018 release :

are published in a special issue of Astronomy and Astrophysics;  the list is at https://www.cosmos.esa.int/web/planck/publications .  The paper “Planck 2018 Results 1: The Overview and Cosmological Legacy of Planck” is available at https://arxiv.org/pdf/1807.06205.pdf and gives an up-to-date summary of the main results.  This paper includes

-   all sky maps at the nine observing frequencies

-   the final “foreground-subtracted” total intensity map

-   a discussion of polarisation imagery.

-   statistical analysis in terms of anisotropy spectra

-   cosmological interpretation

-   references to the other papers in the 2018 release

The complete set of Planck images can be seen at https://www.cosmos.esa.int/web/planck/picture-gallery. Below we show the Planck Total Intensity Map. The grey lines around the Galactic plane mark the region where the foreground subtraction is not as accurate as elsewhere. (image credit: ESA and the Planck Collaboration)

 


 An up-to-date collection of plots of the CMB total intensity anisotropy, combining Planck data with higher angular resolution data from ground based telescopes (the South Pole Telescope (SPT) and the Atacama Cosmology  Telescope (ACT) can be found on the NASA  LAMBDA site https://lambda.gsfc.nasa.gov/graphics/

 

Galactic Foreground Spectra

 


A colour version of Fig 17.3 (main text). See also the caption of the simplified intensity spectrum in Chapter 14 of Supp. Mat.

 

Up-to-date plots of CMB polarisation results can be found on the  NASA  LAMBDA site at https://lambda.gsfc.nasa.gov/graphics/ and a collection of references to current foreground measurements can be found  on the same site at https://lambda.gsfc.nasa.gov/product/foreground/fg_diffuse.cfm

 

Polarisation

For introductions to the phenomenology and physics see: 

http://background.uchicago.edu/~whu/intermediate/Polarization/polar5.html

and https://www.cfa.harvard.edu/~cbischoff/cmb/

 

A collection of references to current foreground measurements can be found  on the NASA  LAMBDA site at https://lambda.gsfc.nasa.gov/product/foreground/fg_pol_survey.cfm

 

 

 

The Sunyaev-Zel’dovich Effect

 

ESA animation showing frequency dependence

Fig 17.6 shows how the CMB spectrum is shifted to higher frequencies by the SZ effect.  At frequencies below 218 GHz the result is a decrement in the CMB intensity whilst above 218 GHz there is an increment.  The ESA animation http://sci.esa.int/planck/48231-animation-of-the-sunyaev-zel-dovich-effect/ brings this to life in the context of the Planck mission

Current measurements

A collection of references to current measurements can be found  on the NASA  LAMBDA site at  https://lambda.gsfc.nasa.gov/product/foreground/fg_sz_cluster.cfm

 

Commentary article on the astrophysical Importance of galaxy cluster studies

The article by Rudnick (2018) “The Stormy Life of Galaxy Clusters” https://arxiv.org/ftp/arxiv/papers/1901/1901.09448.pdf, while covering much more ground than radio studies alone, provides a highly readable, “big picture” overview of the astrophysical issues associated with clusters of galaxies.

 

Strong gravitational lenses

 

eMERLIN /HST image of the first gravitational lens to be discovered:

 

 

Double Quasar

 

 

 

 

 

The so called “Double Quasar” 0957+561A,B was the first gravitational lens to be identified (Walsh et al 1979 Nature, 279, 381) from follow-up observations of the 966 MHz survey carried at Jodrell Bank. Fig 17.8  (main text) shows radio contour maps  of the Double Quasar at two resolutions. The image above is a composite of an e-MERLIN radio image of the Double Quasar and an earlier Hubble Space Telescope (HST) optical image. One of the lensed quasar core images is visible at lower right. The radio emission generated by the black hole as seen with e-MERLIN is visible as the compact bright region superimposed on the (yellow-green) optical emission seen by HST. The radio jet, moving at speeds approaching that of light, is seen in the e-MERLIN image arcing away from the black hole towards the upper left. The jet shows several regions of enhanced brightness before it ends in a hotspot where it is ploughing through the tenuous matter filling the space around the quasar. The e-MERLIN image is shown in false-colour with a colour table ranging from blue through red to white, where the colours represent the brightness of the radio emission. The HST image is made from WFPC2 images through two filters: the F555W filter (V-band) is coloured green and the F814W filter (I-band) is coloured red.  Image and Text Credit: Jodrell Bank Centre for Astrophysics, University of Manchester – see http://www.jb.man.ac.uk/news/2010/emerlin1/

 

 

A VLBI image of an extended lensed arc:

 

A superb high resolution VLBI image of the CLASS lens 1938+666 (see JVAS/CLASS survey entry below) showing extended lensed arcs of emission can be found in the presentation by J. McKean et al. :  http://evn2014.oa-cagliari.inaf.it/EVN2014/Talks/01%20Tue%20Morning/McKean_EVN2014.pdf

and the paper by C. Spingola et al: (2019)   https://arxiv.org/abs/1902.07046.

 

 

An ALMA lens image:

 

With its sensitivity to dusty galaxies at high redshift ALMA is proving to be a powerful new tool for the study of gravitational lensing – a recent example is https://arxiv.org/abs/1707.00702

 

The JVAS/CLASS  survey:

 

Currently the only complete survey for strong gravitational lenses was carried out with the VLA at X-band by the JVAS/CLASS collaboration

http://www.jb.man.ac.uk/research/gravlens/class/class.html

 

The individual JVAS/CLASS images and related discussion on each lensed system can be found http://www.jb.man.ac.uk/research/gravlens/lensarch/lens.html

 

http://www.jb.man.ac.uk/research/gravlens/class/class_lenses.jpg

 

 

Lens time delays and Ho: (entry composed with A. Biggs, ESO Garching)

 

Determining the time delay between lensed images provides a direct route to the determination of the Hubble constant.  Detailed descriptions of the analysis techniques can be found in the papers by A. Biggs and I.W.A.  Browne  2018, MNRAS, 476, 5393 (https://arxiv.org/pdf/1802.10088.pdf ) and C. Fassnacht et al., 2002, ApJ, 581, 823.  As of January 2019 there are seven radio lens systems with published time delays:

 

Source

Radio time delay (days)

Reference

JVAS B0218+357

11.3 ± 0.2

Biggs & Browne, 2018, MNRAS, 476, 5393

B0957+561          

409 ± 30

Haarsma et al. 1999, ApJ,510, 64

JVAS B1030+074

146 ± 6

Biggs, 2018, MNRAS, 481, 1000

JVAS B1422+231

(multiple images cf. one of them)

1.5 ± 1.4

7.6 ± 2.5

8.2 ± 2.0

Patnaik & Narasimha, 2001, MNRAS, 326, 1403

(detections have low signal-to-noise ratios in some cases)

CLASS B1600+434

47 ± 6

Koopmans et al., 2000, A&A, 356, 391

CLASS B1608+656

(multiple images cf. one of them)

31.5 ± 1.5

36.0 ± 1.5

77.0 ± 1.5

Fassnacht et al., 2002, ApJ, 581, 823

PKS 1830-211       

26 ± 4.5

24 ± 4.5

Lovell et al., 1998, ApJ, 501, L51;

Wiklind & Combes, 2001, ASP Conf.  Series, Vol. 237, p. 155



Notes: 1) All the determinations were made with the VLA, except for PKS 1830-211 which used the Australia Telescope Compact Array (ATCA; Lovell et al, 1998) and the Swedish-ESO sub-millimetre Telescope (SEST; Wiklind & Combes, 2001). 

 

2) B0957+561 is the original “Double Quasar” – see the eMERLIN/HST image above. An optically derived delay of 422.6 ± 0.6 days is given by Oscoz et al., 2001, ApJ, 552, 81 who, however, discuss how the published delays fall into short and long values (417d and 425d).

3) The time delay for B1422+231 has significant uncertainty and differs from values expected from a model (Raychaudury et al., 2003, AJ, 126, 29).


To derive values of the Hubble constant one requires both accurate time delays and reliable mass models – Jackson (2015)  (see https://link.springer.com/article/10.1007%2Flrr-2015-2) discusses the challenges.  Currently of the lenses with accurate delays the most useful for Ho purposes are B0218+357 and B1608+656 and only values for those are listed below.

Source

Ho

km/s/Mpc

Comments

JVAS B0218+357

72.9 ± 2.6

Good modelling constraints (Einstein ring)

B0957+561          

 

Modelling difficult due to cluster

JVAS B1030+074

 

Few lensing constraints (double) and possibly two lensing galaxies

CLASS B1600+434

 

Few constraints (double) and a secondary lensing galaxy

CLASS B1608+656

70.6 ± 3.1

Good constraints (a quadruple lens) and the model has received a lot of attention (e.g. Suyu et al., 2010, ApJ, 711, 201)

PKS 1830-211       

 

Potentially has very good constraints (Einstein ring) but there is uncertainty over the lens position and there is a perturbing galaxy at lower redshift. More observations and modelling  required.