Astrophysics researcher

Centro de Estudios de Física del Cosmos de Aragón

Tel. (+34) 978 266 221

aaorsi at


I'm a Chilean researcher at Centro de Estudios de Fisica del Cosmos de Aragon (CEFCA) in the city of Teruel, Spain. My research interests include Galaxy formation and evolution, Large Scale Structure, Semi-analytical models, High redshift galaxies and Lyman-alpha radiative transfer.

My work is mostly concentrated in predicting galaxy properties from hierarchical semi-analytical models of galaxy formation.

I have developed models for nebular emission in star-forming galaxies by combining radiative transfer and photoionisation codes to semi-analytical models. In order to understand the properties of Ly-alpha emitters, I developed a Monte Carlo radiative transfer code of Ly-alpha photons that allows us to predict the escape fraction and line profiles of these photons.

Many large cosmological surveys are currently targeting emission line galaxies (ELGs) to probe the Large Scale Structure of the Universe, particularly at high redshifts. I'm especially interested in characterising the properties of ELGs to be used as cosmological probes. In my latest paper, we demonstrate that capturing the Galaxy Formation mechanisms that shape the galaxy population studied is crucial for modelling their clustering, even on large scales. Specifically, we developed a model to describe satellite kinematics, showing that this leads to and accurate description of the multipoles of the correlation function down to sub-Mpc scales.

I'm an active member of the J-PAS survey, an ~8500 square degrees survey of the northern sky with 56 optical narrowband filters. Within this collaboration, I coordinate the "Global Galaxy Properties" Science Group. J-PAS is carried out in the OAJ observatory that is operated by CEFCA. The survey is scheduled to start by 2018.

I am also member J-PLUS, a predecessor of J-PAS. This survey was designed to provide the photometric calibration for J-PAS, but its data allow for multiple science projects from stellar to extragalactic astrophysics. In J-PLUS, I am a member of its Survey Science Committee. I'm also leading a project to detect and characterise z~0.75 ELGs detected by their [OII] 3727 emission..

I obtained a PhD in 2010 from Durham University, UK, under the supervision of Dr. Cedric G. Lacey and Prof. Carlton M. Baugh. My thesis title is "The Nature of Emission-Line galaxies in Hierarchical Cosmologies", and it's available here.


1. Violeta Gonzalez Perez; J Comparat; P Nordberg; C. M. Baugh; S. Contreras; C. Lacey; N. McCullagh; A. Orsi; J. Helly; J Humphries. The host dark matter halos of [O ii] emitters at z ∼ 1. Monthly Notices of the Royal Astronomical Society. 18/05/2017.

2. Alvaro A. Orsi; Raul E. Angulo. The impact of galaxy formation on satellite kinematics and redshift-space distortions, astro-ph/1708.00956v1, Submitted to MNRAS. 02/08/2017

3. Muñoz Arancibia, A. M.; Padilla, N. D.; Cora, S. A.; Gawiser, E.; Navarrete, F. P.; Orsi, A. A.; Guaita, L.; Kurczynski, P.; Ruiz, A. N. The Proxy+Matching Technique. XV Latin American Regional IAU Meeting Cartagena 2016 (Eds. Mario Armando Higuera Garzón & Santiago Vargas Domínguez) Revista Mexicana de Astronomía y Astrofísica (Serie de Conferencias) Vol. 49, pp. 128-128 (2017)

4. H. Awan; E. Gawiser; P. Kurczynski; R.~L. Jones; H. Zhan; N.~D. Padilla; A.~M. Muñoz Arancibia; A. Orsi; S.A. Cora; P. Yoachim. Testing LSST Dither Strategies for Survey Uniformity and Large-scale Structure Systematics. ApJ, 829, pp. 50 - 50. 09/2016.

5. C.A. Vega-Martínez; S.A. Cora; N.D. Padilla; A.M. Muñoz Arancibia; A. A. Orsi; A.N. Ruiz. The Multi-SAG project: filling the MultiDark simulations with semi-analytic galaxies. Boletin de la Asociacion Argentina de Astronomia La Plata Argentina. 58, pp. 48 - 50. 08/2016.

6. R. M. Bielby; P. Tummuangpak; T. Shanks; H. Francke; N. H. M. Crighton; E. Bañados; J. González-López; L. Infante; A. Orsi. The VLT LBG redshift survey - V. Characterizing the z = 3.1 Lyman-alpha emitter population. Monthly Notices of the RAS. 456, pp. 4061 - 4080. 03/2016.

7. A. A. Orsi; N. Fanidakis; C. G. Lacey; C. M. Baugh. The environments of high-redshift radio galaxies and quasars: probes of protoclusters. Monthly Notices of the RAS. 456, pp. 3827 - 3839. 03/2016.

8. P. Troncoso Iribarren; L. Infante; N. Padilla; I. Lacerna; S. Garcia; A. Orsi; A. Muñoz Arancibia; J. Moustakas; J. Cristóbal-Hornillos; M. Moles; A. Fernández-Soto; V. J. Martínez; M. Cerviño; E. J. Alfaro; B. Ascaso; P. Arnalte-Mur; L. Nieves-Seoane; N. Benítez. The evolution of Balmer jump selected galaxies in the ALHAMBRA survey. Astronomy & Astrophysics, Volume 588, id.A132, 14 pp.

9. A. N. Ruiz; S. A. Cora; N. D. Padilla; M. J. Domínguez; C. A. Vega-Martí­nez; T. E. Tecce; A. Orsi; Y. Yaryura; D. García Lambas; I. D. Gargiulo; A. M. Muñoz Arancibia. Calibration of Semi-analytic Models of Galaxy Formation Using Particle Swarm Optimization. The Astrophysical Journal. 801, pp. 139 - 139. 03/2015.

10 .T. Saito; Y. Matsuda; C. G. Lacey; I. Smail; A. Orsi; C. M. Baugh; A. K. Inoue; I. Tanaka; T. Yamada; K. Ohta; C. De Breuck; T. Kodama; Y. Taniguchi. The environments of Ly-alpha blobs - I. Wide-field Ly-alpha imaging of TN J1338-1942, a powerful radio galaxy at z~4.1 associated with a giant Ly-alpha nebula. Monthly Notices of the RAS. 447, pp. 3069 - 3086. 03/2015.

11. I. D. Gargiulo; S. A. Cora; N. D. Padilla; A. M. Muñoz Arancibia; A. N. Ruiz; A. A. Orsi; T. E. Tecce; C. Weidner; G. Bruzual. Chemoarchaeological downsizing in a hierarchical universe: impact of a top-heavy IGIMF. Monthly Notices of the RAS. 446, pp. 3820 - 3841. 02/2015.

12. A. Orsi; N. Padilla; B. Groves; S. Cora; T. Tecce; I. Gargiulo; A. Ruiz. The nebular emission of star-forming galaxies in a hierarchical universe. Monthly Notices of the RAS. 443, pp. 799 - 814. 09/2014.

13. J. J. Feldmeier; A. Hagen; R. Ciardullo; C. Gronwall; E. Gawiser; L. Guaita; L. M. Z. Hagen; N. A. Bond; V. Acquaviva; G. A. Blanc; A. Orsi; P. Kurczynski. Searching for Neutral Hydrogen Halos around z ~ 2.1 and z ~ 3.1 Ly-alpha Emitting Galaxies. The Astrophysical Journal. 776, pp. 75 - 75. 10/2013.

14 A. Orsi; C. G. Lacey; C. M. Baugh. Modelling Ly-alpha emitters in a hierarchical Universe: a hybrid approach. Asociacion Argentina de Astronomia La Plata Argentina Book Series. 4, pp. 100 - 100. 2013.

15 A. Orsi; C. G. Lacey; C. M. Baugh. Can galactic outflows explain the properties of Ly-alpha emitters. Monthly Notices of the RAS. 425, pp. 87 - 115. 09/2012.

16. L. Samushia; W. J. Percival; L. Guzzo; Y. Wang; A. Cimatti; C. Baugh; J. E. Geach; C. Lacey; E. Majerotto; P. Mukherjee; A. Orsi. Effects of cosmological model assumptions on galaxy redshift survey measurements. Monthly Notices of the RAS. 410, pp. 1993 - 2002. 01/2011.

17. Y. Wang; W. Percival; A. Cimatti; P. Mukherjee; L. Guzzo; C. M. Baugh; C. Carbone; P. Franzetti; B. Garilli; J. E. Geach; C. G. Lacey; E. Majerotto; A. Orsi; P. Rosati; L. Samushia; G. Zamorani. Designing a space-based galaxy redshift survey to probe dark energy. Monthly Notices of the RAS. 409, pp. 737 - 749. 12/2010.

18. C. G. Lacey; C. M. Baugh; C. S. Frenk; A. J. Benson; A. Orsi; L. Silva; G. L. Granato; A. Bressan. Predictions for Herschel from Lambda-cold dark matter: unveiling the cosmic star formation history. Monthly Notices of the RAS. 405, pp. 2 - 28. 06/2010.

19. A. Orsi; C. M. Baugh; C. G. Lacey; A. Cimatti; Y. Wang; G. Zamorani. Probing dark energy with future redshift surveys: a comparison of emission line and broad-band selection in the near-infrared. Monthly Notices of the RAS. 405, pp. 1006 - 1024. 06/2010.

20. J. E. Geach; A. Cimatti; W. Percival; Y. Wang; L. Guzzo; G. Zamorani; P. Rosati; L. Pozzetti; A. Orsi; C. M. Baugh; C. G. Lacey; B. Garilli; P. Franzetti; J. R. Walsh; M. Kümmel. Empirical H-alpha emitter count predictions for dark energy surveys. Monthly Notices of the RAS. 402, pp. 1330 - 1338. 02/2010. Type of production: Scientific paper Format: Journal

21. A. Orsi; C. G. Lacey; C. M. Baugh; L. Infante. The clustering of Ly$\alpha$ emitters in a $\Lambda$CDM Universe. Monthly Notices of the RAS. 391, pp. 1589 - 1604. 12/2008.

22. E. Gawiser; H. Francke; K. Lai; K. Schawinski; C. Gronwall; R. Ciardullo; R. Quadri; A. Orsi; L. F. Barrientos; G. A. Blanc; G. Fazio; J. J. Feldmeier; J.-s. Huang; L. Infante; P. Lira; N. Padilla; E. N. Taylor; E. Treister; C. M. Urry; P. G. van Dokkum; S. N. Virani. Ly-alpha-Emitting Galaxies at z = 3.1: L* Progenitors Experiencing Rapid Star Formation. The Astrophysical Journal. 671, pp. 278 - 284. 12/2007.

23. K. K. Nilsson; A. Orsi; C. G. Lacey; C. M. Baugh; E. Thommes. Narrow-band surveys for very high redshift Lyman-alpha emitters. Astronomy and Astrophysics. 474, pp. 385 - 392. 11/2007.

24. C. Gronwall; R. Ciardullo; T. Hickey; E. Gawiser; J. J. Feldmeier; P. G. van Dokkum; C. M. Urry; D. Herrera; B. D.Lehmer; L. Infante; A. Orsi; D. Marchesini; G. A. Blanc; H. Francke; P. Lira; E. Treister. Ly-alpha Emission-Line Galaxies at z = 3.1 in the Extended Chandra Deep Field-South. The Astrophysical Journal. 667, pp. 79 - 91.


25. Kim Nilsson; Johan Fynbo; Palle Moller; Alvaro Orsi. An Ongoing Multi-wavelength Survey of Ly-alpha Emitters at Redshifts z = 2 - 8. Deepest Astronomical Surveys. 380, pp. 61. Astronomical Society of the Pacific Conference Series, 12/2007.