Quasars as lighthouses for the

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i P Heidi Lietzen Instituto de Astrofísica de Canarias (IAC, Spain)

Collaborators: Changbom Park, Hyunmi Song (KIAS) Maret Einasto, Erik Tago, Enn Saar, Juhan Liivamägi, Jaan Einasto (Tartu Observatory) Pekka Heinämäki (Tuorla Observatory) Why quasars?

Planned eBOSS coverage of the universe. http://www.sdss.org/sdss-surveys/eboss/ Some ancient history...

A drawing of the Lighthouse of Alexandria, also known as Pharos, by German archaeologist Prof. H. Thiersch (1909).

Quasars are not in very dense environments

Quasars in the luminosity-density field of SDSS DR5 (Lietzen et al. 2009, A&A, 501, 145).

Almost half of quasars in voids at z<0.4

Distribution of quasars, radio galaxies, and luminous red galaxies in the luminosity-density field of LRGs (Lietzen et al.

2011, A&A, 535, A21). Quasar environments

● Our result: low-redshift quasars avoid the densest environments.

● On the other hand: – Shen et al. (2007, AJ, 133, 2222): strong clustering of quasars at z~3 – Croom et al. (2005, MNRAS, 356, 415): clustering increases towards high redshifts

More recent work

Fuencaliente, La Palma

They made a brave claim

Huge-LQG or U1.27 (Huge-Large Quasar Group!)

Figure: Clowes et al. 2013, MNRAS, 429, 2910

Can we also find this structure?

● Quasars from SDSS DR7

● Redshifts 1.0 < z < 1.8

● Friend-of-friend analysis – Linking lengths from 20 to 85 Mpc/h

● Comparison to random points

Quasar groups with linking length of 70 Mpc/h

Triples with linking length 20 Mpc/h

Grey: systems with 10 – 24 quasars

Blue: systems with 25 – 49 quasars

Red: systems with at least 50 quasars

Fig. 5 of Einasto et al. 2014, A&A, 568, A46 The work goes on...

Puerto de la Cruz, Tenerife. Image by Silvio Dellacqua Gigantic LQG Clowes et al.'s Huge-LQG

Even bigger LQG

Figure from Park et al. 2014, submitted to ApJ Quasars in the Gigantic LQG

Quasars in the Gigantic LQG with LRGs

Quasars in the Gigantic LQG with superclusters

272 superclusters in this box!

Quasars in the Gigantic LQG with LRGs in superclusters

That was too big even for me!

Abona, Tenerife

Quasars are closer to LRGs than random points

Quasars are in superclusters more often than random points

Quasar groups with LL = 40 Mpc/h

Group 12

Quasar groups with LL = 40 Mpc/h

Group 19

Quasar groups with LL = 40 Mpc/h

Group 25

What next?

Study the small quasar groups systematically – With the luminous red galaxies (LRGs) in the redshift range 0.1 < z < 0.5 – With the BOSS/CMASS galaxy sample at 0.45 < z < 0.7

Punta del Hidalgo, Tenerife. Picture by Klaus Peter.

Want to know more?

For more information on quasars and the large-scale structure, see Lietzen et al. 2009, A&A, 501, 145 Lietzen et al. 2011, A&A, 535, A21 Clowes et al. 2013, MNRAS, 429, 2910 Einasto et al. 2014, A&A, 568, A46

And near-future papers by Park et al., Song et al., Lietzen et al.....

For more information on lighthouses at the Canary Islands, see http://www.unc.edu/~rowlett/lighthouse/cnr.htm