I am a final year IMPRS Ph.D. student at the Max Planck Institute for Astrophysics (MPA), Garching, Germany. My research is being supervised by Prof. Dr. Guinevere Kauffmann and Dr. Dylan Nelson. I graduated with BS - MS in Physics from the Indian Institute of Science (IISc), Bangalore, in July 2017. For about a year, I was a Junior Research Fellow (JRF) at the National Institute of Advanced Studies (NIAS), Bangalore.
I am from a small village of Champaran, Bihar, India ( Fun fact: the same district where Mahatma Gandhi started the final phase of Indian independence movement and famous novelist George Orwell was born). Then we moved to Patna (the capital city of Bihar and also one of the oldest continuously inhabitated cities in the world, see this), where I finished my schooling at St. Xavier's High School (up to class 10th) and DAV Public School (for 10+2). Bihar is also the land of Buddha and the greatest empire India had in the past, the Maurya Empire.
The gas surrounding galaxies known as the circumgalactic medium (CGM) holds important information about the processes that drive the galaxy evolution. Different metal absorption lines detected in spectra of bright background sources (e.g., Quasi-Stellar Objects (QSOs) or Quasars, see cartoon below) at redshifts smaller than the quasar redshifts have opened a new window to study this gas, that remains nearly invisible otherwise. These absorption features can reveal the physical nature of the CGM as they trace the different phases and properties of the gas. One of the most extensively studied among them is MgII (Mg+) doublet line, which traces the cold gas (~104 K) in the CGM. It is an UV line that can be detected in quasar spectra at optical wavelengths for redshifts, z > 0.3. In my first PhD project, I developed a fully automated pipeline to estimate quasar continuum and detect intervening MgII absorption line systems. I ran the pipeline on ~1 million quasars from SDSS Data Release (DR16) and compiled a large MgII absorber catalogue of ~ 160,000 absorber systems. Combining these absorbers systems with a large set of SDSS luminous red galaxies (LRGs) and emission line galaxies (LRGs) , I studied the properties of cool CGM in these galaxies. Our analysis implies that cool circumgalactic gas has a different physical origin for star forming versus quiescent galaxies. For technical details, see our paper [arXiv] [ADS]. To understand our work in broader context see this highlight that I wrote for the broad audience. For a quick look to our paper see this astrobites summary.
MgII Absorber Catalogue is publicly available at [Link]
CGM in absorption.
Giant gaseous layers (termed "superdisks") have been hypothesized in the past to account for the strip-like radio emission gap (or straight-edged central brightness depression) observed between the twin radio lobes, in over a dozen relatively nearby powerful Fanaroff - Riley II radio galaxies. They could also provide a plausible alternative explanation for a range of observations. Although several explanations have been proposed for the origin of the superdisks (SDs), little is known about their material content. In my MS project, I did a HI 21 cm emission line studies from VLA radio continuum data for these SDs as a first attempt to understand and constrain their physical properties. For more details see-
Hydrogen deficient stars (Hds) are almost devoid of hydrogen (~1 % by number). The most abundant elements are helium (98% by number) and carbon (1-2% by number). They are old and generally evolved. For the main sequence stars, hydrogen is an inherent source of continuum opacity, but this is not true for Hds. The spectroscopic abundance analysis of hydrogen deficient stars is a challenge as the source of opacity is not known. The line strength of different transitions is a function of the opacity of the medium. Also, opacity is a strong function of the temperature of the medium and the wavelength of the emitted photon. With robust information about the sources of continuum opacity, a precise abundance analysis of Hds stars can be performed. The aim of my bachelor's project was to find these sources that dominate the opacity in Hds. I found the major sources of continuum opacity in optical and UV for cool and moderately hot hydrogen deficient stars.
2018 - present: Dr. rer. nat in Physics, Ludwig Maximilian University - Max Planck Institute for Astrophysics (MPA), Germany.
Advisors: Prof. Dr. Guinevere Kauffmann, MPA & Dr. Dylan Nelson, ITA, Heidelberg.
2016 - 2017: MS, Physics, Indian Institute of Science (IISc), Bangalore, India.
Thesis: "A sensitive search for HI 21 cm emission from super disks in radio galaxies"
Advisor: Dr. Nirupam Roy, IISc.
2012 - 2016: BSc (Research), Physics, Indian Institute of Science, Bangalore, India.
Thesis: "Sources of Continuum Opacity in Hydrogen deficient stars"
Advisor: Prof. Gajendra Pandey, Indian Institute of Astrophysics (IIA), Bangalore.
A. Anand, D. Nelson and G. Kauffmann, “Characterizing the abundance, properties, and kinematics of the cool circumgalactic medium of galaxies in absorption with SDSS DR16", 2021, MNRAS, 504, 65 [arXiv] [ADS]
A. Anand, N. Roy and Gopal-Krishna, “Search for H I emission from superdisk candidates associated with radio galaxies", 2019, Research in Astronomy and Astrophysics (RAA) 19, 83 [arXiv] [ADS]
German Astronomical Society Meeting 2021: "The cool circumgalactic medium in absorption with large spectroscopic surveys", 16 Sep, 2021 (Zoom talk).
SDSS-IV Collaboration Meeting 2021: "The cool circumgalactic medium in SDSS galaxies", 12 Aug, 2021 (Zoom talk + poster).
MIAPP Workshop: High-Energy Plasma Physics Phenomena in Astrophysics, MIAPP, Garching, Jul 19 - 30, 2021 (Zoom participant).
IMPRS Advanced Course: AGN Physics, Max Planck Institute for Extraterrestrial Physics (MPE), Garching, Jun 28 - Jul 2, 2021 (Zoom).
MPA Galaxy Group Retreat: Fraueninsel, Chiemsee, Jun 14 - 17, 2021 (Talk).
Galaxy Group Meeting: Paper Presentation, MPA, Garching, 26 May 2021 (Zoom).
IMPRS Advanced Course: Astrophysical Dynamics, MPE, Garching, Apr 12 - 23, 2021 (Zoom).
Fundamental of Gaseous Halos Workshop: KITP, UCSB, Jan 11 - Mar 5, 2021 (Participant via Zoom).
IMPRS Advanced Course: Cosmic Microwave Background, MPE, Garching, Nov 3 - Dec 3, 2020 (Zoom).
Galaxy Introductory Symposium: MPA, Garching, 27 Oct 2020 (Zoom talk).
Institute Seminar: Max Planck Institute for Astrophysics (MPA), Garching, 26 Oct 2020 (Zoom talk).
IMPRS Students' Symposium: MPE, Garching, 30 - 31 July 2020 (Zoom talk).
Galaxy Group Meeting: Paper Presentation, MPA, Garching, 15 Jul 2020 (Zoom).
IMPRS Advanced Course: Formation and Evolution of Galaxies, MPE, Garching, Mar 2 - 6, 2020.
IMPRS Advanced Course: Cosmic Structure Formation, MPE, Garching, Nov 25 - 29, 2019.
CGM Conference: Berlin, Germany, Oct 3 - 5, 2019 (Participation).
Summer School in Galaxy Formation: Spetses, Greece, Aug 28 - Sept 5, 2019.
IMPRS Soft Skills Course: Python Programming Course, MPE, Garching, May 6 - 10, 2019.
IMPRS Advanced Course: Galaxy Evolution from the Galaxies' Perspective, MPE, Garching, Apr 8 - 12, 2019.
IMPRS Soft Skills Course: Git/Bash Programming, MPE, Garching, Mar 19 - 22, 2019.
IMPRS Advanced Course: High Resolution Imaging Methods in Astronomy, MPE, Garching, Jan 14 - 18, 2019.
Python for HPC: attended at MPCDF, Garching, Nov 20 - 21, 2018.
Analysis of Wilberforce Pendulum: talk given at NIAS, Bangalore, Dec 2019.
Neighbourhood Astronomy Meeting: International Centre for Theoretical Sciences, Bangalore, Mar 2016.
Multiwavelength photometric study of young open star cluster NGC1931: talk given at ARIES, Nainital, Jul 2013.